The caravan I built has a 130AH AGM battery. We are happy to continue running everything off this battery. caravan Tare 730kg, ATM 1000kg with a 1000kg single axle. The tug can tow 1000kg max.
We camp NOT in the summer hence winter, less sun. We have 300w solar and often that isn't enough (cold cloudy days lots of TV).
If at a caravan park or home we have a 30 amp Vitron smart charger (in the van boot)but we free camp 90% of the time.
We have a solenoid set up under the tug bonnet turns on at 13.2v and off at 12.4 v. But once parked that solonoid switches off after a couple of hours so the AGM is on its own. A cloudy day next day and we are in trouble. Using the car alternator v6 petrol to get charge into the AGM isn't ideal fuel cost wise nor healthy charging.
My alternatives are-
Take my companion 1000w generator and use the Victron charger. Pros- it's quiet, economical and near new. Cons- it weighs 20kg wet+say 2 litres extra fuel. A generator alloy box on the drawbar would weigh 12kg. Total 34kg. Considering my hitch max downforce is 85kg that would challenge me to balance the van. The 34kg AGM is already just past the axle as is 84 litre water tank. Go lithium and reduce battery weight from 34kg to 17kg is a possibility but not desirable.
Store the genny under the bed. It will mean lifting and carrying it out/in the van though. Or install a door to outside as I know the frame well I could do that.
Buy a DC-DC charger. Say 40 amp (expensive). I'd eliminate that solonoid. Being 40 amp car engine running would be minimal but I don't know how long for a complete charge.
Buy an inverter. I already have a 300w one for drill batteries but not big enough for my 30amp AC smart charger. So say I bought a 1000w inverter and utilised the large cables in the tug that the solonoid uses I could utilise the smart charger I already have.
Buy a solonoid that has a lower cut out say 12.2v as opposed to 12.4v.
I cannot increase my tugs battery size due to lack of room. And the tiny boot is only large enough for tools etc.
Your thoughts?
Tony
-- Edited by Eaglemax on Tuesday 22nd of June 2021 06:01:39 PM
Whenarewethere said
06:48 PM Jun 22, 2021
How many days did you have to run the car's engine?
& the total accumulated time, therefore the cost?
It may not be actually enough for the headache of the other options.
Sometimes it is easier to simply blow some money.
Is your Victron 30amp charger a Bluetooth model. If so, write down the volts & amps every 10 minutes during a charge cycle, a bit tedious, but you only need to do this once. You maybe pretty much at the limit of what the AGM battery will take. Certainly in the second half of the charge cycle.
I have two Victron 9amp dumb DC-DC chargers in parallel set at 13.89 volts. The total output is about 12amps maximum into four 26HA gel batteries, reduces to about 3amps when fully charged.
If I wind the voltage up to 14.4 volts, I can't remember the actual amps, but it is less than 18amps & reduces to somewhere around 7amps when the batteries are fully charged.
My Victron 10amp Bluetooth charger, as the four 26AH batteries get charged, obviously will sit on 10amps longer as the batteries can soak this up, but I have noticed that at some point not overly late in the charge cycle that the rate starts dropping below 10amps.
Same with my car's 85AH starter battery.
So you may not actually be getting full amps out of a 30amp charger for very long on a 130AH battery.
So going to a 40amp DC-DC charger may simply be a waste.
A bit more solar?
Eaglemax said
07:53 PM Jun 22, 2021
Hi Jonathan,
thankyou. That makes sense.
Solar- I have another 2 square metres of roof that's vacant.
Worth some thought on that option. But on cloudy winter days?
Tony
-- Edited by Eaglemax on Tuesday 22nd of June 2021 07:55:12 PM
Whenarewethere said
08:53 PM Jun 22, 2021
May be a bit more solar will be enough except on say 3 occasions a year!
Probably looking at about 15kg per square metre of installed solar. So still a weight issue.
I have a Victron 100/20 MPPT which has Bluetooth & if you connect to the load terminals, you have data for solar input & power consumption (not much consumption here as I was fiddling around with connections).
Hi all, The caravan I built has a 130AH AGM battery. We are happy to continue running everything off this battery. caravan Tare 730kg, ATM 1000kg with a 1000kg single axle. The tug can tow 1000kg max
We camp NOT in the summer hence winter, less sun. We have 300w solar and often that isn't enough (cold cloudy days lots of TV). If at a caravan park or home we have a 30 amp Vitron smart charger (in the van boot)but we free camp 90% of the time.
We have a solenoid set up under the tug bonnet turns on at 13.2v and off at 12.4 v. But once parked that solonoid switches off after a couple of hours so the AGM is on its own. A cloudy day next day and we are in trouble. Using the car alternator v6 petrol to get charge into the AGM isn't ideal fuel cost wise nor healthy charging.
My alternatives are-
Take my companion 1000w generator and use the Victron charger. Pros- it's quiet, economical and near new. Cons- it weighs 20kg wet+say 2 litres extra fuel. A generator alloy box on the drawbar would weigh 12kg. Total 34kg. Considering my hitch max downforce is 85kg that would challenge me to balance the van. The 34kg AGM is already just past the axle as is 84 litre water tank. Go lithium and reduce battery weight from 34kg to 17kg is a possibility but not desirable.
Store the genny under the bed. It will mean lifting and carrying it out/in the van though. Or install a door to outside as I know the frame well I could do that.
Buy a DC-DC charger. Say 40 amp (expensive). I'd eliminate that solonoid. Being 40 amp car engine running would be minimal but I don't know how long for a complete charge.
Buy an inverter. I already have a 300w one for drill batteries but not big enough for my 30amp AC smart charger. So say I bought a 1000w inverter and utilised the large cables in the tug that the solonoid uses I could utilise the smart charger I already have.
Buy a solonoid that has a lower cut out say 12.2v as opposed to 12.4v.
I cannot increase my tugs battery size due to lack of room. And the tiny boot is only large enough for tools etc. Your thoughts? Tony
Possibly I do not fully understand your problem and I am not sure how some of your options can help ?
The VSR and your alternator is a powerful charger and with the right heavy wiring to the AGM should charge it in a couple of hours depending on the alternator. Not ideal but best you have now. Check out what amps you are getting now and you might have to rev up the engine a bit to say 2000RPM. I do that if needed.
I do not understand why you would change that for an expensive DC-DC 40A charger. You should be getting twice that amps now. If you are not then find out why !
I also do not understand where you would get the power for an inverter from the battery to run a charger for the battery. No that is not a working idea. Or did I miss something ??
Changing the VSR cutoff voltage lower will just use some of the tug battery as well as the AGM but will probably shorten its life and always leave you with a half flat tug battery. I would not do that.
My best suggestion would be to get (or make) a 12V DC charger. You can buy 50A ones and not so heavy as 240V ones. Or make one !
http://www.christieengineering.com.au/products/12-volt-55-amp/ I bought mine second hand for a good saving
The other suggestion might be to buy some lightweight semi flexible panels and use them as portable panels where you might get more out of them than flat on the roof.
Jaahn
Eaglemax said
09:56 PM Jun 22, 2021
Hi Jaahn,
I thought a DC-DC charger was a 12v dc charger? This is where it's confusing.
I wouldn't be able to tackle building a charger.
Flexible solar is a consideration.
Storing the genny over the van axle is also an idea. Its 24kg with 2 spare litres of fuel. I could carry 24 litres less water??
Lots to ponder on.
Thankyou.
Tony
Eaglemax said
09:59 PM Jun 22, 2021
Whenarewethere wrote:
May be a bit more solar will be enough except on say 3 occasions a year!
Probably looking at about 15kg per square metre of installed solar. So still a weight issue.
I have a Victron 100/20 MPPT which has Bluetooth & if you connect to the load terminals, you have data for solar input & power consumption (not much consumption here as I was fiddling around with connections).
Jonathan
My victron has Bluetooth also but I do get confused with all of these numbers. I'm just not electronic savvy.
All the Bluetooth controller have solar input data. But only the 100/20 & smaller controllers have an inbuilt load output to show basic consumption as a figure near the bottom of the screen for each day.
The larger controllers you need a battery monitor.
The graph with the 3 shades, the bottom (lightest) is bulk charge.
The middle is absorption charge.
The top (darkest) is float charge.
On this day I had 640Wh input of solar.
& 160Wh of consumption.
& because I don't have rubbish solar panels I have got up to 125 watts out of 120 watts of panels!
Your AGM will have a maximum charge current of around 35A and a maximum charge voltage or around 14.7 volts - you must not exceed either of these. The battery will only accept 35A when it is more than (say) 50% discharged once it charges beyond that the charge current will fall as the internal resistance of the battery rises; my experience of charging a 100Ah AGM from around 50% discharge with 27A (its maximum) is that charging takes around four hours. For this reason *no way* would I run the vehicle engine at idle to perform this function.
I am going through the same issues as you Tony; camping in Victoria, in forest and especially in winter is not conducive to solar panels and although I intend to increase my solar by 230W from my current 160W I have come to the conclusion that I am always going to need a generator.
Whenarewethere said
08:12 AM Jun 23, 2021
Eaglemax wrote:
We camp NOT in the summer hence winter, less sun. We have 300w solar and often that isn't enough (cold cloudy days lots of TV).
I have hardware calibration for computer monitors & run them at very low brightness for colour accuracy.
I have noticed that the heat coming of the monitors is a lot less. This would be a bit too dark for TV viewing, but can you turn the brightness down to an acceptable level to reduce power consumption.
While touching on the subject of colour accuracy, calibrate your eyes:
https://www.xrite.com/hue-test
Jaahn said
09:48 AM Jun 23, 2021
Eaglemax wrote:
Hi Jaahn, I thought a DC-DC charger was a 12v dc charger? This is where it's confusing. I wouldn't be able to tackle building a charger. Flexible solar is a consideration. Storing the genny over the van axle is also an idea. Its 24kg with 2 spare litres of fuel. I could carry 24 litres less water??
Lots to ponder on. Thankyou. Tony
Hi Tony
You are getting lots of ideas ! I guess you have a basic problem if you use too much power. Then you have to reduce that useage or make more power, or possibly both ! Have you looked at reducing your power usage by increasing your efficiency by getting better suited electrical items that use less power. We do not use inverters normally and have 12V chargers and TV and led lights. We live on a 140Ahr battery with 190W solar and the alternator as backup. I select a good spot for solar if possible. I must say I have not taken that 12V 55A generator away with us.
To comment on your reply above !
A DC-DC charger is for charging a second battery from your car alternator system but only while it is running. Your VSR should do that now. DC-DC chargers are needed with the newer variable voltage (smart) alternators now commonly fitted.
You said you could not build a DC charger. Obviously if you can build your own car and your own caravan you might be able to do it I have built a couple of chargers for off grid friends using a small motor and car alternator. Any size you want really, look on the web ! I built a 200A 24V charger for a very large battery bank that the guy ran on biodiesel but not portable for camping. Not much theory needed !
A normal 240V AC generator is OK but needs a 240-12V charger and the associated losses and weight. But you do own it now .
Cheers Jaahn
Eaglemax said
05:06 PM Jun 23, 2021
Hi guys and thankyou so much for your replies.
I do have the answer. See this question came up while we were travelling around Victoria. Therefore I was going on memory with the weight of the Companion 1000w generator as being 22kgs wet. We just got home and it is 14.3kg with a full tank. See pic. The 22kg was for a previous larger generator we used while building our house.
Furthermore. I should have weighed the hitch downforce weight at the beginning of our trip. I thought it was 85kgs. But, that was actually the maximum towball weight allowed for the towball on the JBA tug. I measured the hitch weight (van loaded) as soon as I arrived home and it was 62kgs. As we know 10% is the benchmark. So I'm 23kgs light to make up to 85kgms.
The exterior "(white) boot on the drawbar weighs 7kg so I will detach that. The blue 15L water container also on the drawbar can go in the back seat for water reserve. So that leaves 30 kgms to make up to get to 85kgms.
Most of the small generator alloy boxes on the market are 12kgms. That leaves 18kgs spare for the 14.3kgms generators and spare fuel.
I'm happy now that where ever I go I have a source of guaranteed power to power the Vitron 30amp 240V smart charger. The Genny is very economical. Re: Mike Harding - you are indeed having the same situation and it is frustrating as you see the AGM go flat.
I also have the solonoid connection for when we are driving and the solar when camped but as we have proved even in sunlight the last 3 days the solar panels being flat on the roof with no clouds it is not very efficient in these cold months.
So now I'll rearrange the drawbar. By the way my 130AH battery has 3 possible locations that I designed into the van. Currently just behind the axle (likely another reason why the hitch weight was light), under my bed before the boot and in the boot. So at all times I can place it in a place that will give me close tow ball weight such is the situation with ultra light caravans.
So problem solved.
PS Jaahn I didnt build the kit car. Had it 5 years and it was built in 2001 in Perth. The van I wired and built and I know positive and negative and such basics but electronics baffle me. Thre van lights are LED, the kitchen sink cold water is with hand plunger. If hot water required we have a Joolca Hottap on the exterior rear wall of the caravan (Gas only connected when camped) and that runs a Joolca 12 volt pump. The TV is a 18 inch modern unit that takes the most power. I have a CPAP but that runs all night without any voltage drop and the fridge a 12v waeco drawer fridge.
So consumption is quite resonable....its the bloody lack of sunlight thats the real problem!.
Jonathan- I scored 2 on the eye test- no problem there.
Thanks again, I learned a lot in the process and likely other readers to.
I do have the answer. See this question came up while we were travelling around Victoria. Therefore I was going on memory with the weight of the Companion 1000w generator as being 22kgs wet. We just got home and it is 14.3kg with a full tank. See pic. The 22kg was for a previous larger generator we used while building our house.
Furthermore. I should have weighed the hitch downforce weight at the beginning of our trip. I thought it was 85kgs. But, that was actually the maximum towball weight allowed for the towball on the JBA tug. I measured the hitch weight (van loaded) as soon as I arrived home and it was 62kgs. As we know 10% is the benchmark. So I'm 23kgs light to make up to 85kgms.
The exterior "(white) boot on the drawbar weighs 7kg so I will detach that. The blue 15L water container also on the drawbar can go in the back seat for water reserve. So that leaves 30 kgms to make up to get to 85kgms.
Most of the small generator alloy boxes on the market are 12kgms. That leaves 18kgs spare for the 14.3kgms generators and spare fuel.
I'm happy now that where ever I go I have a source of guaranteed power to power the Vitron 30amp 240V smart charger. The Genny is very economical. Re: Mike Harding - you are indeed having the same situation and it is frustrating as you see the AGM go flat.
I also have the solonoid connection for when we are driving and the solar when camped but as we have proved even in sunlight the last 3 days the solar panels being flat on the roof with no clouds it is not very efficient in these cold months.
So now I'll rearrange the drawbar. By the way my 130AH battery has 3 possible locations that I designed into the van. Currently just behind the axle (likely another reason why the hitch weight was light), under my bed before the boot and in the boot. So at all times I can place it in a place that will give me close tow ball weight such is the situation with ultra light caravans.
So problem solved.
PS Jaahn I didnt build the kit car. Had it 5 years and it was built in 2001 in Perth. The van I wired and built and I know positive and negative and such basics but electronics baffle me. Thre van lights are LED, the kitchen sink cold water is with hand plunger. If hot water required we have a Joolca Hottap on the exterior rear wall of the caravan (Gas only connected when camped) and that runs a Joolca 12 volt pump. The TV is a 18 inch modern unit that takes the most power. I have a CPAP but that runs all night without any voltage drop and the fridge a 12v waeco drawer fridge.
So consumption is quite resonable....its the bloody lack of sunlight thats the real problem!.
Jonathan- I scored 2 on the eye test- no problem there.
Thanks again, I learned a lot in the process and likely other readers to.
Tony
10% is only a very rough estimate. In Europe 6% is considered a good ratio for tow ball weight. So long as the van tows well I would,nt be concerned about the ball weight (unless its on the heavy sideor very near to manufacturers max weight.
Whenarewethere said
06:00 PM Jun 23, 2021
A really basic question. Are the solar panels spotlessly clean?
It doesn't take much for output to be nobblled with a tiny shadow or a film of muck.
Eaglemax said
06:19 PM Jun 23, 2021
Yep, cleaned them before our trip.
Tony
Eaglemax said
06:37 PM Jun 23, 2021
Dicko1 wrote:
Eaglemax wrote:
Hi guys and thankyou so much for your replies.
I do have the answer. See this question came up while we were travelling around Victoria. Therefore I was going on memory with the weight of the Companion 1000w generator as being 22kgs wet. We just got home and it is 14.3kg with a full tank. See pic. The 22kg was for a previous larger generator we used while building our house.
Furthermore. I should have weighed the hitch downforce weight at the beginning of our trip. I thought it was 85kgs. But, that was actually the maximum towball weight allowed for the towball on the JBA tug. I measured the hitch weight (van loaded) as soon as I arrived home and it was 62kgs. As we know 10% is the benchmark. So I'm 23kgs light to make up to 85kgms.
The exterior "(white) boot on the drawbar weighs 7kg so I will detach that. The blue 15L water container also on the drawbar can go in the back seat for water reserve. So that leaves 30 kgms to make up to get to 85kgms.
Most of the small generator alloy boxes on the market are 12kgms. That leaves 18kgs spare for the 14.3kgms generators and spare fuel.
I'm happy now that where ever I go I have a source of guaranteed power to power the Vitron 30amp 240V smart charger. The Genny is very economical. Re: Mike Harding - you are indeed having the same situation and it is frustrating as you see the AGM go flat.
I also have the solonoid connection for when we are driving and the solar when camped but as we have proved even in sunlight the last 3 days the solar panels being flat on the roof with no clouds it is not very efficient in these cold months.
So now I'll rearrange the drawbar. By the way my 130AH battery has 3 possible locations that I designed into the van. Currently just behind the axle (likely another reason why the hitch weight was light), under my bed before the boot and in the boot. So at all times I can place it in a place that will give me close tow ball weight such is the situation with ultra light caravans.
So problem solved.
PS Jaahn I didnt build the kit car. Had it 5 years and it was built in 2001 in Perth. The van I wired and built and I know positive and negative and such basics but electronics baffle me. Thre van lights are LED, the kitchen sink cold water is with hand plunger. If hot water required we have a Joolca Hottap on the exterior rear wall of the caravan (Gas only connected when camped) and that runs a Joolca 12 volt pump. The TV is a 18 inch modern unit that takes the most power. I have a CPAP but that runs all night without any voltage drop and the fridge a 12v waeco drawer fridge.
So consumption is quite resonable....its the bloody lack of sunlight thats the real problem!.
Jonathan- I scored 2 on the eye test- no problem there.
Thanks again, I learned a lot in the process and likely other readers to.
Tony
10% is only a very rough estimate. In Europe 6% is considered a good ratio for tow ball weight. So long as the van tows well I would,nt be concerned about the ball weight (unless its on the heavy sideor very near to manufacturers max weight.
I get you Dicko,
Yes it does tow very stable even in side winds. I'm now just capitalising on the other 4% to enable me to carry a genny on the drawbar and squeezing that extra weight into the atm.
It's amusing calculating things with such a light van e.g. water 88 litres is about 9% of ATM, a full porta potti is 3%, battery 3%, 3x3wheels with tyres 4%, drop axle and electric drums 11%. Prior to building these figures gave me insight to needing some lightweight items like plastic cupboards and wardrobe and lightweight Fallata ply for benchtop and bed tops.
Off topic lol
Tony
Eaglemax said
05:29 PM Aug 26, 2023
Dicko1 wrote:
Eaglemax wrote:
Hi guys and thankyou so much for your replies.
I do have the answer. See this question came up while we were travelling around Victoria. Therefore I was going on memory with the weight of the Companion 1000w generator as being 22kgs wet. We just got home and it is 14.3kg with a full tank. See pic. The 22kg was for a previous larger generator we used while building our house.
Furthermore. I should have weighed the hitch downforce weight at the beginning of our trip. I thought it was 85kgs. But, that was actually the maximum towball weight allowed for the towball on the JBA tug. I measured the hitch weight (van loaded) as soon as I arrived home and it was 62kgs. As we know 10% is the benchmark. So I'm 23kgs light to make up to 85kgms.
The exterior "(white) boot on the drawbar weighs 7kg so I will detach that. The blue 15L water container also on the drawbar can go in the back seat for water reserve. So that leaves 30 kgms to make up to get to 85kgms.
Most of the small generator alloy boxes on the market are 12kgms. That leaves 18kgs spare for the 14.3kgms generators and spare fuel.
I'm happy now that where ever I go I have a source of guaranteed power to power the Vitron 30amp 240V smart charger. The Genny is very economical. Re: Mike Harding - you are indeed having the same situation and it is frustrating as you see the AGM go flat.
I also have the solonoid connection for when we are driving and the solar when camped but as we have proved even in sunlight the last 3 days the solar panels being flat on the roof with no clouds it is not very efficient in these cold months.
So now I'll rearrange the drawbar. By the way my 130AH battery has 3 possible locations that I designed into the van. Currently just behind the axle (likely another reason why the hitch weight was light), under my bed before the boot and in the boot. So at all times I can place it in a place that will give me close tow ball weight such is the situation with ultra light caravans.
So problem solved.
PS Jaahn I didnt build the kit car. Had it 5 years and it was built in 2001 in Perth. The van I wired and built and I know positive and negative and such basics but electronics baffle me. Thre van lights are LED, the kitchen sink cold water is with hand plunger. If hot water required we have a Joolca Hottap on the exterior rear wall of the caravan (Gas only connected when camped) and that runs a Joolca 12 volt pump. The TV is a 18 inch modern unit that takes the most power. I have a CPAP but that runs all night without any voltage drop and the fridge a 12v waeco drawer fridge.
So consumption is quite resonable....its the bloody lack of sunlight thats the real problem!.
Jonathan- I scored 2 on the eye test- no problem there.
Thanks again, I learned a lot in the process and likely other readers to.
Tony
10% is only a very rough estimate. In Europe 6% is considered a good ratio for tow ball weight. So long as the van tows well I would,nt be concerned about the ball weight (unless its on the heavy sideor very near to manufacturers max weight.
I thought I'd give a late reply here as the situation changed a lot since I last posted.
I have since sold my home built caravan and purchased a well known make 16ft without solar. So armed with all the information above I installed 480W of flexible (3) panels and rang Sikaflex to find the most suitable adhesive to glue 10mm coreflute to the fibreglass roof (think its 252) then glued the panels to the coreflute. Coreflute allowing ventilation. A 40amp MPPT controller and new 125amp AGM battery. I also had a win purchasing a Yamaha 1kw generator new in Ballarat at $1215 which was way under retail.
Been away several times and its become obvious there is little need for the genny except rather than using a inverter for the washing machine we use it for that and backup for solar if cloudy for several days in a row but if getting low charge only one hour or so and the charge is back up there so am extremely pleased with not only the experience in learning how much solar we needed but also the information you guys have provided. Thankyou
Hi all,
The caravan I built has a 130AH AGM battery. We are happy to continue running everything off this battery. caravan Tare 730kg, ATM 1000kg with a 1000kg single axle. The tug can tow 1000kg max.
We camp NOT in the summer hence winter, less sun. We have 300w solar and often that isn't enough (cold cloudy days lots of TV).
If at a caravan park or home we have a 30 amp Vitron smart charger (in the van boot)but we free camp 90% of the time.
We have a solenoid set up under the tug bonnet turns on at 13.2v and off at 12.4 v. But once parked that solonoid switches off after a couple of hours so the AGM is on its own. A cloudy day next day and we are in trouble. Using the car alternator v6 petrol to get charge into the AGM isn't ideal fuel cost wise nor healthy charging.
My alternatives are-
I cannot increase my tugs battery size due to lack of room. And the tiny boot is only large enough for tools etc.
Your thoughts?
Tony
-- Edited by Eaglemax on Tuesday 22nd of June 2021 06:01:39 PM
How many days did you have to run the car's engine?
& the total accumulated time, therefore the cost?
It may not be actually enough for the headache of the other options.
Sometimes it is easier to simply blow some money.
Is your Victron 30amp charger a Bluetooth model. If so, write down the volts & amps every 10 minutes during a charge cycle, a bit tedious, but you only need to do this once. You maybe pretty much at the limit of what the AGM battery will take. Certainly in the second half of the charge cycle.
I have two Victron 9amp dumb DC-DC chargers in parallel set at 13.89 volts. The total output is about 12amps maximum into four 26HA gel batteries, reduces to about 3amps when fully charged.
If I wind the voltage up to 14.4 volts, I can't remember the actual amps, but it is less than 18amps & reduces to somewhere around 7amps when the batteries are fully charged.
My Victron 10amp Bluetooth charger, as the four 26AH batteries get charged, obviously will sit on 10amps longer as the batteries can soak this up, but I have noticed that at some point not overly late in the charge cycle that the rate starts dropping below 10amps.
Same with my car's 85AH starter battery.
So you may not actually be getting full amps out of a 30amp charger for very long on a 130AH battery.
So going to a 40amp DC-DC charger may simply be a waste.
A bit more solar?
Hi Jonathan,
thankyou. That makes sense.
Solar- I have another 2 square metres of roof that's vacant.
Worth some thought on that option. But on cloudy winter days?
Tony
-- Edited by Eaglemax on Tuesday 22nd of June 2021 07:55:12 PM
May be a bit more solar will be enough except on say 3 occasions a year!
Probably looking at about 15kg per square metre of installed solar. So still a weight issue.
I have a Victron 100/20 MPPT which has Bluetooth & if you connect to the load terminals, you have data for solar input & power consumption (not much consumption here as I was fiddling around with connections).
________________________________________________________________________________________________________________________________
Hi Tony
Possibly I do not fully understand your problem and I am not sure how some of your options can help ?
The VSR and your alternator is a powerful charger and with the right heavy wiring to the AGM should charge it in a couple of hours depending on the alternator. Not ideal but best you have now. Check out what amps you are getting now and you might have to rev up the engine a bit to say 2000RPM. I do that if needed.
I do not understand why you would change that for an expensive DC-DC 40A charger. You should be getting twice that amps now. If you are not then find out why !
I also do not understand where you would get the power for an inverter from the battery to run a charger for the battery. No that is not a working idea. Or did I miss something ??
Changing the VSR cutoff voltage lower will just use some of the tug battery as well as the AGM but will probably shorten its life and always leave you with a half flat tug battery. I would not do that.
My best suggestion would be to get (or make) a 12V DC charger. You can buy 50A ones and not so heavy as 240V ones. Or make one !
http://www.christieengineering.com.au/products/12-volt-55-amp/ I bought mine second hand for a good saving
The other suggestion might be to buy some lightweight semi flexible panels and use them as portable panels where you might get more out of them than flat on the roof.
Jaahn
I thought a DC-DC charger was a 12v dc charger? This is where it's confusing.
I wouldn't be able to tackle building a charger.
Flexible solar is a consideration.
Storing the genny over the van axle is also an idea. Its 24kg with 2 spare litres of fuel. I could carry 24 litres less water??
Lots to ponder on.
Thankyou.
Tony
Jonathan
My victron has Bluetooth also but I do get confused with all of these numbers. I'm just not electronic savvy.
Tony
I hope this helps:
https://www.victronenergy.com/media/pg/MPPT_Solar_Charge_Controllers/en/introduction.html
All the Bluetooth controller have solar input data. But only the 100/20 & smaller controllers have an inbuilt load output to show basic consumption as a figure near the bottom of the screen for each day.
The larger controllers you need a battery monitor.
The graph with the 3 shades, the bottom (lightest) is bulk charge.
The middle is absorption charge.
The top (darkest) is float charge.
On this day I had 640Wh input of solar.
& 160Wh of consumption.
& because I don't have rubbish solar panels I have got up to 125 watts out of 120 watts of panels!
Your AGM will have a maximum charge current of around 35A and a maximum charge voltage or around 14.7 volts - you must not exceed either of these. The battery will only accept 35A when it is more than (say) 50% discharged once it charges beyond that the charge current will fall as the internal resistance of the battery rises; my experience of charging a 100Ah AGM from around 50% discharge with 27A (its maximum) is that charging takes around four hours. For this reason *no way* would I run the vehicle engine at idle to perform this function.
I am going through the same issues as you Tony; camping in Victoria, in forest and especially in winter is not conducive to solar panels and although I intend to increase my solar by 230W from my current 160W I have come to the conclusion that I am always going to need a generator.
I have hardware calibration for computer monitors & run them at very low brightness for colour accuracy.
I have noticed that the heat coming of the monitors is a lot less. This would be a bit too dark for TV viewing, but can you turn the brightness down to an acceptable level to reduce power consumption.
While touching on the subject of colour accuracy, calibrate your eyes:
https://www.xrite.com/hue-test
Hi Tony
You are getting lots of ideas ! I guess you have a basic problem if you use too much power. Then you have to reduce that useage or make more power, or possibly both ! Have you looked at reducing your power usage by increasing your efficiency by getting better suited electrical items that use less power. We do not use inverters normally and have 12V chargers and TV and led lights. We live on a 140Ahr battery with 190W solar and the alternator as backup. I select a good spot for solar if possible. I must say I have not taken that 12V 55A generator away with us.
To comment on your reply above !
A DC-DC charger is for charging a second battery from your car alternator system but only while it is running. Your VSR should do that now. DC-DC chargers are needed with the newer variable voltage (smart) alternators now commonly fitted.
You said you could not build a DC charger. Obviously if you can build your own car and your own caravan you might be able to do it
I have built a couple of chargers for off grid friends using a small motor and car alternator. Any size you want really, look on the web ! I built a 200A 24V charger for a very large battery bank that the guy ran on biodiesel but not portable for camping. Not much theory needed !
A normal 240V AC generator is OK but needs a 240-12V charger and the associated losses and weight. But you do own it now
.
Cheers Jaahn
Hi guys and thankyou so much for your replies.
I do have the answer. See this question came up while we were travelling around Victoria. Therefore I was going on memory with the weight of the Companion 1000w generator as being 22kgs wet. We just got home and it is 14.3kg with a full tank. See pic. The 22kg was for a previous larger generator we used while building our house.
Furthermore. I should have weighed the hitch downforce weight at the beginning of our trip. I thought it was 85kgs. But, that was actually the maximum towball weight allowed for the towball on the JBA tug. I measured the hitch weight (van loaded) as soon as I arrived home and it was 62kgs. As we know 10% is the benchmark. So I'm 23kgs light to make up to 85kgms.
The exterior "(white) boot on the drawbar weighs 7kg so I will detach that. The blue 15L water container also on the drawbar can go in the back seat for water reserve. So that leaves 30 kgms to make up to get to 85kgms.
Most of the small generator alloy boxes on the market are 12kgms. That leaves 18kgs spare for the 14.3kgms generators and spare fuel.
I'm happy now that where ever I go I have a source of guaranteed power to power the Vitron 30amp 240V smart charger. The Genny is very economical. Re: Mike Harding - you are indeed having the same situation and it is frustrating as you see the AGM go flat.
I also have the solonoid connection for when we are driving and the solar when camped but as we have proved even in sunlight the last 3 days the solar panels being flat on the roof with no clouds it is not very efficient in these cold months.
So now I'll rearrange the drawbar. By the way my 130AH battery has 3 possible locations that I designed into the van. Currently just behind the axle (likely another reason why the hitch weight was light), under my bed before the boot and in the boot. So at all times I can place it in a place that will give me close tow ball weight such is the situation with ultra light caravans.
So problem solved.
PS Jaahn I didnt build the kit car. Had it 5 years and it was built in 2001 in Perth. The van I wired and built and I know positive and negative and such basics but electronics baffle me. Thre van lights are LED, the kitchen sink cold water is with hand plunger. If hot water required we have a Joolca Hottap on the exterior rear wall of the caravan (Gas only connected when camped) and that runs a Joolca 12 volt pump. The TV is a 18 inch modern unit that takes the most power. I have a CPAP but that runs all night without any voltage drop and the fridge a 12v waeco drawer fridge.
So consumption is quite resonable....its the bloody lack of sunlight thats the real problem!.
Jonathan- I scored 2 on the eye test- no problem there.
Thanks again, I learned a lot in the process and likely other readers to.
Tony
10% is only a very rough estimate. In Europe 6% is considered a good ratio for tow ball weight. So long as the van tows well I would,nt be concerned about the ball weight (unless its on the heavy sideor very near to manufacturers max weight.
A really basic question. Are the solar panels spotlessly clean?
It doesn't take much for output to be nobblled with a tiny shadow or a film of muck.
Yep, cleaned them before our trip.
Tony
I get you Dicko,
Yes it does tow very stable even in side winds. I'm now just capitalising on the other 4% to enable me to carry a genny on the drawbar and squeezing that extra weight into the atm.
It's amusing calculating things with such a light van e.g. water 88 litres is about 9% of ATM, a full porta potti is 3%, battery 3%, 3x3wheels with tyres 4%, drop axle and electric drums 11%. Prior to building these figures gave me insight to needing some lightweight items like plastic cupboards and wardrobe and lightweight Fallata ply for benchtop and bed tops.
Off topic lol
Tony
I thought I'd give a late reply here as the situation changed a lot since I last posted.
I have since sold my home built caravan and purchased a well known make 16ft without solar. So armed with all the information above I installed 480W of flexible (3) panels and rang Sikaflex to find the most suitable adhesive to glue 10mm coreflute to the fibreglass roof (think its 252) then glued the panels to the coreflute. Coreflute allowing ventilation. A 40amp MPPT controller and new 125amp AGM battery. I also had a win purchasing a Yamaha 1kw generator new in Ballarat at $1215 which was way under retail.
Been away several times and its become obvious there is little need for the genny except rather than using a inverter for the washing machine we use it for that and backup for solar if cloudy for several days in a row but if getting low charge only one hour or so and the charge is back up there so am extremely pleased with not only the experience in learning how much solar we needed but also the information you guys have provided. Thankyou