Not enough power for off the grid

Martin_QLD · Veteran Member

Not enough power for off the grid

Aus-Kiwi · Guru

Seems your right . Battery is not taking full charge or not enough AH to keep volts through night . Is it full charging through the day ?

dogbox · Guru

what size battery and how old

Martin_QLD · Veteran Member

Hi Guru, the batteries are two 100amp and they are about three years old, during the day everything is great more than enough power it seems when there is nothing going in that they wont stand up, I am guessing they are ok until the fridge kicks in early in the morning and the batteries cant handle the sudden need to supply power, i used the same fridge with an ark pak with one 100amp battery and would get a few days from it with just the trickle charge from the auxiliary socket and a 7amp charger. I believe its the batteries but just wanted to see if I was missing something. Thanks for your feedback.

cheers
Martin

PeterInSa · Guru

Martin, Could well be the batteries, but having run them down to 11.2 v a few times, I think it will be very hard to get them up to full charge again.

But I would also investigate you having enough solar to charge up the batteries to a fully charged state when you have a number of overcast days. This could be the problem that caused your battery problem in the first instance.

Peter

Izabarack · Guru

I suggest you first charge the battery bank, unconnected to load, rest 24 hours and measure voltage. I also suspect you will need to increase the amount of solar, a lot.

Iza

Martin_QLD · Veteran Member

Thanks Iza, I will give that a go. I have them on charge at the moment with a CTEK smart charger and have it on the recond setting which may help to rejuvenate them for a short time anyway. I can only remeber once when we struggled to keep the charge up and that was last Easter, no sun and electrics were put to the test as we were in a big group and the only one with power (charging phones etc etc), anyway will leave a comment once I have tried all options.

Martin

swamp · Senior Member

Hi
Capacity test on batteries first.
Remember 250watts of solar is good in great sunny weather but add some cloud and recovery time would be to long
A 160-200 watts per 100-120 ah batt is best for good performance .
Your situation is if the batteries are run down to low capacity due to cloud , your batteries then struggle to recover because of not enough hours in the day . That's why more solar would be ideal .

250watts harvests about 60 ah
A 200ah bank has 50% usable = 100ah
Fridge uses 20-50ah per day

Existing system takes way to long to recover after a cloudy day if at all
Eg say after
1st day 40ah consumption
2nd day no solar but fridge still using so total consumption is now 80ah
3rd day has to replace 120 ah your only producing 60ah solar
On the 3rd day if u were producing solar at 100-120ah [eg 400 watts]

Aus-Kiwi · Guru

Just get a generator. They are 10% more efficient if you fit a Chev badge and take the muffler off . Sarcasm on high . Itâs Saturday morning !!

Kebbin · Guru

Not everyone has your resources or the will to carry a degenerator around with them Kiwi.

Aus-Kiwi · Guru

Was holding a BIG stirring spoon . Lol ð

Kebbin · Guru

I realise you where having a go in the second part, but your a known generator user/supporter, so I ad a dig.

swamp · Senior Member

Hi all

Ahh how I miss holidays next to a power station .

Warren-Pat_01 · Guru

Hi Martin,
I would suggest the best thing to do with your fridge/freezer would be to turn it up a bit (more cold) while you have adequate charge going in & then turn it off for the night. We took frozen whiting fillets in our Trailblazer 60L fridge from (old home) Ceduna to (new home) Townsville one year.

Referring to the chart shown here - www.energymatters.com.au/components/battery-voltage-discharge/, your batteries can not be in very good condition. With careful charging & discharging you may get them to come good but do not expect continual abuse to give you good battery life.

Kiwi's suggestion of a generator might be the best!

T1 Terry · Guru

You could always add the cost of replacement batteries and a generator together and compare it to the cost of a battery that won't suffer from being discharged to the point it shuts off to protect itself yet can accept 100% of the charging available all the way to 99% full, not a tapering recharge rate once past around the 70% full mark. I'll get hounded that I'm just advertising our workshop or pushing a certain battery chemistry barrow so I won't even mention the names, but you can PM me for free advice if you want

T1 Terry

yobarr · Guru

T1 Terry wrote:
You could always add the cost of replacement batteries and a generator together and compare it to the cost of a battery that won't suffer from being discharged to the point it shuts off to protect itself yet can accept 100% of the charging available all the way to 99% full, not a tapering recharge rate once past around the 70% full mark. I'll get hounded that I'm just advertising our workshop or pushing a certain battery chemistry barrow so I won't even mention the names, but you can PM me for free advice if you want

T1 Terry

Great post Terry,and,after much research, I had the same thoughts,which is why I fitted 540 AH of Lithium batteries. Off grid I can run my AC all night on 18 degrees,(testing) and the batteries still are over 90% charged. There you go,I hope that helped get your message out? Cheers.

daffyfrancis · Senior Member

Perhaps we should all get the same AC as yours as would'nt need lithium ie: Run it all night at 18c & only use less than 54AH (over 90% remaining out of 540AMP batteries) or was the outside temp also 18c smile

David

PeterD · Guru

Martin, the set up you have should support you in Qld. One thing I have spotted was what regulator are you using? Are you using the regulators that come on the panels? Are you using one of those cheap EvilBay regulators (particularly those labelled MPPT?) There is a strong possibility you are not getting your batteries charged properly. Are you seeing your absorption voltage going well over 14.0 V and the system voltage dropping back to float voltage by 1100 or mid day? If that is not happening you are not getting the full possibility of your panels.

Aus-Kiwi · Guru

Start with plenty good solar, regular, batteries . Other >get buy < measures youâll find just costs . If you have room for more solar ? Fit more . I would guess itâs storage in batteries ? As said check if they ARE fully charged and HOLDING charge !!!

Dav4Cris · Senior Member

I would also be thinking about increasing your Solar capacity, when you look at 250watts trying to recharge 200Ah battery, it never will. I would be looking for at least another 150watts if not more and then your batteries will last longer. 2 watts per 1Ah of battery is the recommendation.

woofta and precious · Senior Member

Surely it's not a 3 way fridge running on 12 volt?

Woody n Sue · Guru

Martin we are in our forward fold camper now this is day 9 we have a diesel heater running about 2-3 hours each night a95 L waeco fridge freezer and a cpap all night and the usual iPad iPhone charger and I have not plugged the andson plug into the Ute since day one we have 400 w solar on the boat rack mostly not facing the morning sun and batteries are back up to 99% by the time we have finished breakfast and packed up , have not seen the batteries below 12.4 pre dawn yet , couldnt be happier with the setup .

Woody

yobarr · Guru

woofta and precious wrote:
Surely it's not a 3 way fridge running on 12 volt?

When I was researching fridges I was advised that you are able to run a 3-way fridge off 12volt,but they use over 3 times as much power as does a compressor fridge/freezer,which is what I eventually bought.....175 litre Evakool fridge/freezer. Cheers

T1 Terry · Guru

yobarr wrote:
woofta and precious wrote:
Surely it's not a 3 way fridge running on 12 volt?
When I was researching fridges I was advised that you are able to run a 3-way fridge off 12volt,but they use over 3 times as much power as does a compressor fridge/freezer,which is what I eventually bought.....175 litre Evakool fridge/freezer. Cheers

These days it's far more economical in both energy use and $$ terms to use a household type inverter fridge/freezer and its own dedicated inverter. In return you get an auto defrost fridge that is Aust Standards tested to function in 43*C to very rigid requirements of even cooling throughout the test load of 5*C in the fridge and -5*C in the freezer in the test 15hr period, all that and using less battery power than any equivalent low voltage (12v/24v) fridge with a cost outlay of around the $500 mark. They have proved to outlast the 12v fridges on the market in the roughest of terrain so reliability is way in front as well

T1 Terry

Martin_QLD · Veteran Member

Thanks Woody and Sue, what i have done is replace the batteries and installed a cut off switch (set to drop in if the voltage drops below 12v), so far so good, we haven't had any trouble up until now and have taken the camper free camping without any issues. We now have 210 a/hr in the camper a 125 a/hr as the second battery in the back of the Ranger and a victron solar controller and CTEK 240 v charger (we have a generator as well) so I recon we have it sorted. After our next trip I am going to mount the solar controller and the 240 CTEK charger in the camper, under one of the seats and have access points from the outside near the fuse box, do you know if I am able to connect both of them up to the batteries without damaging the charger which is not active, eg, if I connect the 240v charger will it send voltage towards the solar controller (which is not connected) and damage it. Do you have a battery management system on you FF.

Cheers

Martin

-- Edited by Martin_QLD on Friday 3rd of August 2018 07:02:49 PM

swamp · Senior Member

Hi
I have my solar controller hard wired permanently on . Off only when driving .
I have my 240v charger hard wired under the seat . Access to switch on/off if needed .
Car altenator charge whilist driving .

Low volt disconnect set at 12.oo v
On/off isolater fitted = 100% shut down = storage [need to turn on for solar charging /solar controllers can use small amounts of power on stand by mode, causing eventual battery drain ]. Some Low volt disconnects can leach power also.

I have solar controller , on/off isolater and remote 240v batt charger switch in easy access front boot compartment .

Batts, LVD, circuit breakers 240v charger all under seats .

Highly recommend 200w per 100-120ah batts

Martin_QLD · Veteran Member

Thanks Swamp, looks like we have the solar sorted 250 watt for 210 ah and from what you are saying you do have circuit breakers for the 240, is that right. With the draw of current from the solar controller I may be better off having isolation switches on both the 240 and solar, to disconnect the units when charging through the Anderson plug and switch on the mode of charge (disconnect the Anderson plug) whichever is applicable when stopped. I have the usual circuit breakers for the load side of the camper. I have found speaking to auto electricians they all have different ideas but they all funnel towards whatever they are selling.

Cheers

Martin

swamp · Senior Member

HI
MY camper is a Jayco so it has a 240v mains fuses setup . I plug in at van parks like full size vans . I run a surge protector to the 240v batt charger.
My 240 volt comes from inside from the van power point cabled to and wired to wall switch inside front boot then onto charger under seat .

Isolation is for the 12v dc ON/OFF wired in the neg battery cable . Located inside front boot
Low volt disconnect wired to battery pos cable . Located under seat .

My solar has to be disconnected when travelling . Solar controller in front boot . Solar panel connector is an Anderson plug on draw bar

U have potential to use up to 50% of capacity . 210ah total ==Usable potential 105ah
250watts generates around 60 ah in 24 hrs
U cannot use full potential of system as u can only recharge 60ah leaving 40 ah still usable if solar was increased .