Just an idea about what can be done

T1 Terry · Guru

Just an idea about what can be done

dorian · Guru

Please excuse my ignorance, but isn't this a case of too much solar for the relatively small battery capacity? I can see how the panels might provide the power for high-wattage appliances directly via an inverter (can your inverter do that?), but 6 x 270W would be overkill for a battery whose charge rate might be limited to 30A or so. AISI, you would need 6 hours of sunlight, regardless of the number of panels. Moreover, at night time, when you are running on battery, how many hours of operation can you get out of the aircon?

BTW, I had been thinking of doing something similar, so I would be interested in photos and more details, if you would care to expand on your setup.

Kiwoz · Veteran Member

Dorian, not sure why you would think Li batteries will only accept 30a, probably greater than 100a. The PWM could be getting pretty warm at that tho. Still lots to be learnt about this.

Bruce.

Jaahn · Guru

Hi Terry smile

That's a good setup you have there. Pics please. Seems like a bit more batteries would be good but I guess you have 2x 180AH for the 24V which some may not have picked up on.

Dorian, Terry can explain it himself but at 24V charging voltage, ~28-29V it is about 50+A from the panels at best, so the lithium will do that OK. And in poor sun conditions there is still a reasonable charge rate. biggrin Note those panels are 60cell panels so PWM works well.

It is a good example of the principle of needing to generate power before you can use it ! aww Plenty of solar and use most of the power during the day when it is being supplied, including the air conditioner. I like that bit, and turn it down during the night. Terry do you run all household 240V items from your inverter instead of low voltage dc things ?

A lesson for those with a couple of solar panels and hoping to get more out of their batteries. hmm More solar is the answer >>>>>>>>

Jaahn

-- Edited by Jaahn on Saturday 9th of February 2019 11:46:59 AM

-- Edited by Jaahn on Saturday 9th of February 2019 12:26:40 PM

-- Edited by Jaahn on Saturday 9th of February 2019 05:26:29 PM

dorian · Guru

Kiwoz wrote:
Dorian, not sure why you would think Li batteries will only accept 30a, probably greater than 100a. The PWM could be getting pretty warm at that tho. Still lots to be learnt about this.

Bruce.

Hmm, my memory isn't good. I thought I had read that 0.2C was the recommended maximum charge rate, but it appears that 1C is the maximum and 0.5C is recommended. So that means that 90A should be perfectly OK. Thanks for the correction.

Just curious For those that have a 24V house system, what does one do to accommodate 12V / 240VAC appliances when AC power is unavailable? Are fridges, TVS and the like available for universal DC inputs (ie both 12V and 24V), or do we need to purchase step-down supplies for 24V-to-12V conversion? I can see the benefits of a 24V system (eg lower I2R losses), but converters have losses of their own.

-- Edited by dorian on Saturday 9th of February 2019 01:38:21 PM

Peter_n_Margaret · Guru

The big solar input is the reason why Terry can power almost anything when the sun shines. It is a very viable option.
The batteries only need to provide power for the loads when the sun is not shining (or for the odd occasion when the clouds reduce solar to less than the current loads).
The solar collects power. That power is firstly used to power the loads (including any inverter loads). Only what is left over after the loads are satisfied is going to charge the batteries.
If there are no loads, all of that power is offered to the batteries, but the rate of charge is determined by the voltage setting of the solar controller. If that voltage is not too high, no damage will occur to the batteries. This is much like charging a 100Ah crank battery from a 250A alternator.

I will shortly be doing something similar - the 600W of glass solar panels will be replaced with 1320W of light weight panels, all charging 460Ah of very tired 9 year old AGMs. The batteries only need to power 2 compressor fridges, a few lights and a lap top over night. That is typically 25 to 35Ah. Not much battery capacity required to do that and as soon as the sun comes up there will be oodles of power.
Terry is running aircon after the sun goes down and that clearly needs higher battery capacity. We have no plans for A/C, but an induction cook top is on the list so we can get rid of the last gas.
Cheers,
Peter

-- Edited by Peter_n_Margaret on Saturday 9th of February 2019 02:36:55 PM

DeBe · Guru

Dorian most of the fridges have 12/24V compressors in them, they will handle either voltage automaticly.

Jaahn · Guru

dorian wrote:
Hmm, my memory isn't good. I thought I had read that 0.2C was the recommended maximum charge rate, but it appears that 1C is the maximum and 0.5C is recommended. So that means that 90A should be perfectly OK. Thanks for the correction.
Just curious For those that have a 24V house system, what does one do to accommodate 12V / 240VAC appliances when AC power is unavailable? Are fridges, TVS and the like available for universal DC inputs (ie both 12V and 24V), or do we need to purchase step-down supplies for 24V-to-12V conversion? I can see the benefits of a 24V system (eg lower I2R losses), but converters have losses of their own.

Hi Dorian, smile

The reason to run a 24V system usually is the motorhome has a 24V system. Not any great technical reason. It just make life easier to connect to the vehicle battery and lights etc.

My previous 24V MH had a couple of 24-12V converters for a radio and some smaller items. I reduced the number of 12V items by replacing some with 24V to simplify it, which should have been put there before and the fridge was auto DC voltage as DeBe said. Lots of common accessories are available in 24V because it is the standard truck voltage. Inverters and regulators are all available.

Jaahn

T1 Terry · Guru

So many questions to answer, this will be another long post so best get a drink before you start.
The battery is built out of 16 x 90Ah Sinopoly LiFeP04 cells. They were 6 yrs old I think when we bought them from an abandoned DIY electric car project. they have had 24/7 duty for approx. 5 yrs since we fitted them to replace a similar sized Thundersky battery pack that was accidentally tortured to death when left unattended for 4 weeks with the inverter and frdge running but the solar had tripped out for some reason., They were still in their boxes when we bought them, we later discovered Sinopoly load test their cells at a 0.2CA rate for capacity testing and not the 0.5CA rate Winston/Thundersky use, so although marked as 100Ah cells they are only really 90Ah cells if the same 0.5CA capacity testing is used.
Now for what we run off the set up.
The fridge/freezer is an old unit, an LG GN235SQA, probably about 8 to 10 yrs old. It was in the Hino when purchased by a friend some 8 yrs ago and still does the job fine. The shelves have required some re-enforcing because they are crap plastic, but reviews say that even in a house they suffer the same problems. It has dents all round where the original owner did a very poor job of mounting it so it rocked and rolled around in its enclosure and even appears to have fallen forward a few times judging by the marks in the door and the cupboard opposite. It is pre inverter fridge days, but still seems to do the job running directly from the inverter 24/7. When we do the refit it will get retired to beer fridge status and we will fit an inverter fridge with its own dedicated 240vac inverter so that should cut down the over night power draw considerably. Because the fridge needs power 24/7 and my wife has a CPAP machine required all night, the inverter never gets to drop into stand by mode so it is always on the full operating overhead draw that is rather savage, but so be it for the moment.
All the appliances are 240vac household gear, a Phillips airfryer like this one www.thegoodguys.com.au/philips-avance-collection-airfryer-xl-hd924030 except ours is about 4 yrs old I think, but just brilliant for travelling and fast cooking rather than an oven or grill.
An Aldi pod coffee machine, an Aldi milk frother, an Aldi pop up toaster, a slow cooker, can't remember the brand but bought it from Target for $10 probably 6 yrs or more ago.
A Phillips bread maker, probably 13 yrs old at least, the LG inverter split system air con fitted roughly 3 yrs ago, the electric jug died, well started to turn the water rusty so it went in the bin so we will replace it at the next Aldi special Buys I guess.
Then there is the phone chargers, the computer chargers and all those things, and the chargers for the Triton 20v batteries to power all the hand tools and the soldering iron workstation and the hot air gun and ......work stuff.
The 12v stuff:
There is a 12v Fantastic vent, 2 x those 12v fans with the bumper strip around the blade so they don't need a guard, 12v outside LED light strip that has half the LED's failed, 12v water pump with a accumulator tank added up stream, brilliant addition, recommend it to anyone who has a 12v water pump. A cassette toilet that has a 12v light and button to flush it, but I think it relies on the 12v pump for water pressure.
The 24v stuff
24v LED strip lights retro fitted into the original fluro light fixtures ... actually they might have even been 24v globes, the refit was quite a while ago. One of those water heaters that run on gas or 240vac that fit in through the side of the van wall, can't remember the name but it looks like it was fitted about the same time as the fridge, 8 to 10 yrs ago, but it still works fine so .....
Possibly more bit but I'd need to rat through the cupboards and that doesn't go down well with the boss of this establishment :lol:

As far as powering the 12v side goes, I made up a 4 cell battery out of some refugee cells from my old house system back in Lake Illawarra that got tortured for 6 weeks on a direct solar connection while we were away, maybe 5 yrs ago or more, can't remember. Anyway, they act as the storage tank sort of thing to cover any high loads as the cells are charged from a 4 amp Arlec dumb battery charger running 24/7 powered from the inverter. Probably not a terribly efficient arrangement, but the inverter is going 24/7 and I had the charger laying around so .....

As far as the charging rate from the solar array, when I'm away from the trees I'm half parked under at the moment, the input between around 11 am and around 3 pm is 54 amps, I've seen 56 amps a few times but probably cloud edge effect, so realistically the harvest is between 35 amps and 50 amps from around 7 am to 11 am and again from after 3 pm till around 7 pm. It slowly builds up to the 35 amps in the morning are dribbles down to bugger all at night as the light fails.
We aren't getting that at the moment with the trees around us, doesn't really start till around 8 am but it's full on 35 amps about then and stays that way until about 5pm, then it drops off real quick to about 15 amps till dark.
Still enough to get the battery fully charged while powering everything required during the day so there is plenty for the air con on ecco mode, the fridge and the 12v battery charger plus the lights and the CPAP machine over night and no need to wait for the sun to get up far enough before coffee and muffins.
It's a tough life eh :lol:

T1 Terry

Noelpolar · Veteran Member

FWIW.... I'm relatively new to "240v" camping.... and am currently putting together a system for my van (was a electrical/electronic person once upon a time).... and it struck me how cheap solar is now and that a lot of our high energy usage was day light based when camping (coffee machine, hair dryer, toaster etc)... and that in the end we didn't need as big an energy bucket as we thought (lithium battery)... we ended up around 800w of panels to 200ah of lithum. The only major downside to cheapish panels is weight on the roof of the van (ie higher COG).

T1 Terry · Guru

Yes, the light weight solar panels are no where near as cheap or easy to install, but the systems we have installed all have very happy owners .... I still have a few that need to have a replacement installed on the leading edge where the wind tore them off as a road train passed, but we have managed to sort that problem now as well :lol:

I still haven't had a chance to post any photos, well haven't actually taken any yet, but I'll get there and put them up.
I did speak too soon about not having any problems first thing in the morning with the toaster and the coffee pod machine. The problem turned out to be an issue with a new solar controller/BMS we are trialling while we are away on the road. The thing decided it sensed a bad cell and shut down all the charging but didn't put up any warning flags saying that was what it had done. Fortunately I had a separate cell monitor running in parallel so I could keep an eye on the battery condition and it sounded an alarm when the cell voltage drop into the damage zone.
I have now totally bypassed the solar control/BMS and I'm doing it manually by switching loads on and sections of the solar off to stop the warning beeps from the independent cell monitor. No idea how people go with their lithium batteries that don't have cell voltage monitoring, I guess they just don't know when the cells are being tortured I suppose

T1 Terry

-- Edited by T1 Terry on Wednesday 13th of February 2019 12:58:22 AM

denmonkey · Senior Member

Come on Terry, where's the happy snaps

T1 Terry · Guru

Ah, forgot all about it after the dramas that unfolded with the injector pump on the way back from WA. I'll take some today and post them.

T1 Terry

oldtrack123 · Guru

Peter_n_Margaret wrote:
The big solar input is the reason why Terry can power almost anything when the sun shines. It is a very viable option.
The batteries only need to provide power for the loads when the sun is not shining (or for the odd occasion when the clouds reduce solar to less than the current loads).
The solar collects power. That power is firstly used to power the loads (including any inverter loads). Only what is left over after the loads are satisfied is going to charge the batteries.
If there are no loads, all of that power is offered to the batteries, but the rate of charge is determined by the voltage setting of the solar controller. If that voltage is not too high, no damage will occur to the batteries. This is much like charging a 100Ah crank battery from a 250A alternator.

I will shortly be doing something similar - the 600W of glass solar panels will be replaced with 1320W of light weight panels, all charging 460Ah of very tired 9 year old AGMs. The batteries only need to power 2 compressor fridges, a few lights and a lap top over night. That is typically 25 to 35Ah. Not much battery capacity required to do that and as soon as the sun comes up there will be oodles of power.
Terry is running aircon after the sun goes down and that clearly needs higher battery capacity. We have no plans for A/C, but an induction cook top is on the list so we can get rid of the last gas.
Cheers,
Peter
- Edited by Peter_n_Margaret on Saturday 9th of February 2019 02:36:55 PMYes ,

Yes, Lots of solar.

Strange that little detail is always left out!

Perhaps, so some may make a direct inquiry, good for his wife's? business

-- Edited by oldtrack123 on Wednesday 3rd of April 2019 01:17:03 PM

T1 Terry · Guru

T1 Terry wrote:
Yes, the light weight solar panels are no where near as cheap or easy to install, but the systems we have installed all have very happy owners .... I still have a few that need to have a replacement installed on the leading edge where the wind tore them off as a road train passed, but we have managed to sort that problem now as well :lol:

I still haven't had a chance to post any photos, well haven't actually taken any yet, but I'll get there and put them up.
I did speak too soon about not having any problems first thing in the morning with the toaster and the coffee pod machine. The problem turned out to be an issue with a new solar controller/BMS we are trialling while we are away on the road. The thing decided it sensed a bad cell and shut down all the charging but didn't put up any warning flags saying that was what it had done. Fortunately I had a separate cell monitor running in parallel so I could keep an eye on the battery condition and it sounded an alarm when the cell voltage drop into the damage zone.
I have now totally bypassed the solar control/BMS and I'm doing it manually by switching loads on and sections of the solar off to stop the warning beeps from the independent cell monitor. No idea how people go with their lithium batteries that don't have cell voltage monitoring, I guess they just don't know when the cells are being tortured I suppose

T1 Terry

-- Edited by T1 Terry on Wednesday 13th of February 2019 12:58:22 AM

I have to revise this now. A customer we fitted semi flexible panels for well over 2 yrs ago suffered panel failure during the first 12 mths. We put this down to the diode problem and we travelled to WA to replace the panels and fit diodes.

These replacement panels are now giving problems, so we are replacing them with rigid glass 60w panels. I give up on the semi flexibles until a manufacture can prove they will give continuous duty for an acceptable period, I'll wait and see how Peter goes with them on his OKA.

T1 Terry

Noelpolar · Veteran Member

FWIW... I just decided to do glass panels.... seriously considered flexable ones (weight saving would have been nice) but in the end I could achieve what I wanted with glass.... with a far greater certainty of a 10 year service life (or more).

Jaahn · Guru

T1 Terry wrote:
T1 Terry wrote:
Yes, the light weight solar panels are no where near as cheap or easy to install, but the systems we have installed all have very happy owners .... I still have a few that need to have a replacement installed on the leading edge where the wind tore them off as a road train passed, but we have managed to sort that problem now as well :lol:
T1 Terry

I have to revise this now. A customer we fitted semi flexible panels for well over 2 yrs ago suffered panel failure during the first 12 mths. We put this down to the diode problem and we travelled to WA to replace the panels and fit diodes.
These replacement panels are now giving problems, so we are replacing them with rigid glass 60w panels. I give up on the semi flexibles until a manufacture can prove will give continuous duty for an acceptable period, I'll wait and see how Peter goes with them on his OKA.
T1 Terry

Hi Terry smile

Sorry about your diesel problems and expense ! furious

However I and others would be very interested in what goes wrong with the semi flexible panels. I am sure you have looked closely at them after you took the faulty ones off. Do the cells fail or the deposited connections/diodes fail or what ?? I have had no experience with them at all. They certainly seem a good idea if they were as reliable as glass panels. hmm

Jaahn

T1 Terry · Guru

It appears to be the connections between the modules themselves this time. No sign of broken or cracked modules that was the obvious cause in other failures. Some panels appear to work when cold but stop working once they heat up in the sun, yet no sign of cracked module separating like before.
I even removed some of the backing from one panel to track where the connection failed using the continuity setting on my multimeter. The results have left my confused to say the least, I have good continuity between the negative cable and the bottom of the first strip of modules, from that point to the top of the next strip I have no continuity, but from the negative cable to the top of the second strip I have a pulsing continuity, even with the panel face down on a blanket inside the workshop.
I cut the metal strip between the 3 strip of modules and the forth strip, so there can be no continuity, yet I also get a pulsing continuity between the top of the third strip and the top of the forth strip. At about that point I gave up because time was being wasted that I didn't have a lot of to spare. When I have more time I want to investigate further into just what is causing this pulsing continuity reading and try to isolate the point where it is occurring.
There is a possibility the bypass diode between the negative and positive connection plates has something to do with this pulsing, but that is for a later date.
I was looking for a quick fix and there wasn't one that I could find.

T1 Terry

Reed · Senior Member

Terry

What is the power requirement of your air conditioner. The one in our 10.5 m fifth wheel requires 2.5 kW and the one in our 6 m Roadtrek requires about 1.5 kW. This limits us to about 4 hours of air conditioning in the fifth wheel (1.4 kW solar and 9 kW-hrs of LFP and about 2 hours inf Roadtrek (415 W solar and 4.5 kW-hrs of LFP).

We are in US and the voltages are 120 V for AC and 12 V for DC. Mexico and Canada use the same voltages.

We are Goldilockers (not to hot and not to cold, just right) so we have spent most winters in Yucatan (Quintana Roo state in Mexico) and summers in Rocky Mountains. We spend our summer days walking, birding, kayaking (Elaine annoys the fish with her rod and reel) , and sitting about in the shade reading and napping. We then use air conditioning in early evening to cool down the cabin on battery bank alone. We "camp" in National Forest, Bureau of Land Management, and similar CGs (which cost us $5/night) or "dispersed camp" at isolated spots which are: free, quiet, secluded etc and solar means that the wildlife ignores our presence. We have had bull moose fight within 25 metres of the fifth wheel, Coyotes have wandered under the caravan, and birds cluster at the bird feeders (which must be taken down at night by law so as not to attract bears). Most of these sites are above 2500 m and we really enjoy several at 3200 m. The days are around 25 C during day and 4 C at night. There is a map that a meteorologist put on line that permits an RV'er to spend the entire year at spots that are 25 C during the day.

I should like to put another 600 W of solar on the fifth wheel and replace the energy hog a/c with a mini-split; however, my wife and our son asked why since we are Goldilocker andd I have no answer. Over 99% of RVers here stick to expensive RV parks and spend summers in the eastern US where heat and humidity are high. The Roadtrek does have a 100 W and a 315 W panel which required two controllers. it was a question of very limited real estate on Roadtrek.

We try to orient our caravan so that we have sun in morning and early afternoon with tree/brush shade in the late afternoon. We also use the Aluminet we have mentioned earlier which cuts down the solar loading so that the caravan skin is ambient.

We do have have half a dozen 12 V outlets (aka cigarette lighter plugs) so we can use 12 V DC fans to cool things down. This makes sleeping tolerable with cabin temperatures above 32 C.

Son said that he would use the higher efficiency 315 W panels if he were fabricating our system now. 2000 W would be achievable. He would place the LFP in the clothes closet at front of 5th wheel for cold weather amelioration. The LFP in Roadtrek is protected against cold weather as long as w

Reed · Senior Member

We do pull 5th wheel with a 3500 Chevie turbocharged four wheel-drive 6.5 l diesel dualie (four wheels on rear). it comes with a 132 liter main fuel tank and we had a 190 liter reserve tank/tool box installed in the bed. We can get up to 6 km/l but generally about 5 km/l. So we can go 960 miles or 1500 km. We generally refuel about every 700 miles or 1100 km. Fuel is currently about $2.90 US/gallon in US.

Just put this in since I managed to post the below twice and could not figure how to delete it.

-- Edited by Reed on Sunday 14th of April 2019 07:02:00 AM

Reed · Senior Member

Terry

What is the power requirement of your air conditioner. The one in our 10.5 m fifth wheel requires 2.5 kW and the one in our 6 m Roadtrek requires about 1.5 kW. This limits us to about 4 hours of air conditioning in the fifth wheel (1.4 kW solar and 9 kW-hrs of LFP and about 2 hours inf Roadtrek (415 W solar and 4.5 kW-hrs of LFP).

We are in US and the voltages are 120 V for AC and 12 V for DC. Mexico and Canada use the same voltages.

We are Goldilockers (not to hot and not to cold, just right) so we have spent most winters in Yucatan (Quintana Roo state in Mexico) and summers in Rocky Mountains. We spend our summer days walking, birding, kayaking (Elaine annoys the fish with her rod and reel) , and sitting about in the shade reading and napping. We then use air conditioning in early evening to cool down the cabin on battery bank alone. We "camp" in National Forest, Bureau of Land Management, and similar CGs (which cost us $5/night) or "dispersed camp" at isolated spots which are: free, quiet, secluded etc and solar means that the wildlife ignores our presence. We have had bull moose fight within 25 metres of the fifth wheel, Coyotes have wandered under the caravan, and birds cluster at the bird feeders (which must be taken down at night by law so as not to attract bears). Most of these sites are above 2500 m and we really enjoy several at 3200 m. The days are around 25 C during day and 4 C at night. There is a map that a meteorologist put on line that permits an RV'er to spend the entire year at spots that are 25 C during the day.

I should like to put another 600 W of solar on the fifth wheel and replace the energy hog a/c with a mini-split; however, my wife and our son asked why since we are Goldilocker andd I have no answer. Over 99% of RVers here stick to expensive RV parks and spend summers in the eastern US where heat and humidity are high. The Roadtrek does have a 100 W and a 315 W panel which required two controllers. it was a question of very limited real estate on Roadtrek.

We try to orient our caravan so that we have sun in morning and early afternoon with tree/brush shade in the late afternoon. We also use the Aluminet we have mentioned earlier which cuts down the solar loading so that the caravan skin is ambient.

We do have have half a dozen 12 V outlets (aka cigarette lighter plugs) so we can use 12 V DC fans to cool things down. This makes sleeping tolerable with cabin temperatures above 32 C.

Son said that he would use the higher efficiency 315 W panels if he were fabricating our system now. 2000 W would be achievable. He would place the LFP in the clothes closet at front of 5th wheel for cold weather amelioration. The LFP in Roadtrek is protected against cold weather as long as we are using it and keeping it heated.

The real pioneers in LFP in US have a website TECHNOMADIA where they discuss their failures as well as their successes. A major failure was placing the LFP batteries in an unvented compartment with the controller and inverter. Temperatures probably got over 60 C and their

Reed · Senior Member

Cripes

Have not used this computer in a while and have sent the same message twice. Flipping snow is coming down again.

Reed and Elaine

T1 Terry · Guru

During the day the solar produces more than the air con uses, so we have to switch the hot water on as well. We can turn the air con up to maximum fan speed and pull the temp down to 16*C while it's around 50*C outside and this will balance out the solar input, but it gets too cold and putting jumper on doesn't make sense, so we dump power else where. Once the water has reached the 70*C thermostat setting we have to turn parts of the solar off.
The Hino is 24v but 180Ah @ 24v is the same as 360Ah @ 12v, so the Wh capacity remains the same, 4600Wh or 4.6kWh of battery capacity (3.2v nom. x 8 cells x180Ah), so our battery capacity is roughly the same. Because the air con system varies the load continuously due to it being an inverter technology unit, it's impossible to say just how much it draws at any given period. I can tell you the battery is down about 250Ah or 3.8kWh in the morning before the sun starts to replace what we are using and recharging the battery. That over night usage is the Phillips air fryer to cook dinner, the coffee machine to make at least 4 cups of coffee, the 240vac mains fridge on 24/7, my wife's CPAP machine, 2 fans to move the air con cooled air back across the bed, outside lights and inside lights, but they are LED so the use is minuscule, then the toaster, kettle and coffee machine in the morning to make at least 2 cups of coffee and at least one cup of tea. Sometimes a bit less, if the temp drops over night below 20*C we turn the air con off and just use the fans, it tries to switch to a reverse cycle unit and heat the air and we don't need that.

T1 Terry

Reed · Senior Member

Going to WA means go to state of Washington here, not going to Western Australia. No way in the world would we camp at 50 C (122 F). As noted above, we have the option of running away to cooler spots in the mountain west. The poor sods in eastern US have high temperatures and humidity can get well above 80% in summertime.

Ambient is up to 16 C so snow is melting but still have 5 cm on half of each panel so we are only getting 900 W and we are down -3500 W/hrs. Absolute blue sky and Llamas is wandering about most curious. Night temperatures are only 0 C the last few nights.

Reed and Elaine