Batteries in Detached Outdoor Shed

[randypi]

I'm just getting into solar and have set up my small system to power my outdoor shed. My question is do I need to keep my batteries warm in the winter time (I live in northern WI)?

I have read different opinions that the batteries will be fine if they are hooked to a charge controller and always charging if need. I'm just wondering what others have done to prevent the batteries from getting to cold or freezing.

I've read that people using small reptile heating mats to assist in keeping the batteries warm.

I'm using (2) 35Ah Deep Cycle sealed batteries that are located in a 2" thick Styrofoam cooler inside the outdoor shed. I have a 50W solar panel feeding the charge controller. Tied into the battery bank is a 1000W inverter.

Any assistance would be greatly appreciated. Thank you for your time!!!

[lkruper]

I'm just getting into solar and have set up my small system to power my outdoor shed. My question is do I need to keep my batteries warm in the winter time (I live in northern WI)?

I have read different opinions that the batteries will be fine if they are hooked to a charge controller and always charging if need. I'm just wondering what others have done to prevent the batteries from getting to cold or freezing.

I've read that people using small reptile heating mats to assist in keeping the batteries warm.

I'm using (2) 35Ah Deep Cycle sealed batteries that are located in a 2" thick Styrofoam cooler inside the outdoor shed. I have a 50W solar panel feeding the charge controller. Tied into the battery bank is a 1000W inverter.

Any assistance would be greatly appreciated. Thank you for your time!!!

Sealed batteries deal with cold better than Flooded, and fully charged flooded are good down around -70F. However, if you are going to heat them with heating pads, I would recommend running utility power to the shed

[Mike90250]

wow, a 50W panel and a 1,000 inverter. put the inverter under the 70ah (total) batteries and it will help keep them warm ?

Seriously, this a totally unbalanced system. Pane and battery are not bad, but the inverter will never be able to deliver full power for more than a moment with those small batteries. And the idle loss from that large inverter will drain the batteries quickly

[Sunking]

Well I am not going to comment about the system, and just answer the question.

What do you call cold?

Unless you answer something like more than -20 below zero, you do not have much to worry about. In really cold climates you can store Lead Acid batteries up to 1 month if fully charge. If you winter day high temps 40/50's and maybe 2 or 3 weeks.


You see cold is not bad for batteries. Exact opposite is true as cold really slows down self discharge and sulfate crystal formation. So the colder it is, the longer you can store it. The trick is to store it fully EQ charged battery. That gives you FREEZE protection down to -40 at 100% SOC.

Best way in any climate is to store batteries is using a low wattage panel as a Float Trickle Charger. Batteries can Float for very long periods of time measured in years, and some cases like commercial decades.

[randypi]

I agree that the "system is unbalanced" and that the inverter is oversized, but had it laying around and wanted to put it to use for now instead of buying a new one. What would be a food size of inverter to buy for the current size of this system?

As I stated this is my 1st solar project (learning as I go) and didn't spend a lot of money to put it together since it's just to run a few dusk to dawn lights for now. In the future I would like to expand it.

Again, Thanks for your assistance!!!

wow, a 50W panel and a 1,000 inverter. put the inverter under the 70ah (total) batteries and it will help keep them warm ?

Seriously, this a totally unbalanced system. Pane and battery are not bad, but the inverter will never be able to deliver full power for more than a moment with those small batteries. And the idle loss from that large inverter will drain the batteries quickly

[randypi]

Thank you for the information. This is my 1st solar project and have a lot of questions, some probally seem dumb, but fiqured it can't hurt to ask.

Again, Thanks for your assistance!!!

Well I am not going to comment about the system, and just answer the question.

What do you call cold?

Unless you answer something like more than -20 below zero, you do not have much to worry about. In really cold climates you can store Lead Acid batteries up to 1 month if fully charge. If you winter day high temps 40/50's and maybe 2 or 3 weeks.


You see cold is not bad for batteries. Exact opposite is true as cold really slows down self discharge and sulfate crystal formation. So the colder it is, the longer you can store it. The trick is to store it fully EQ charged battery. That gives you FREEZE protection down to -40 at 100% SOC.

Best way in any climate is to store batteries is using a low wattage panel as a Float Trickle Charger. Batteries can Float for very long periods of time measured in years, and some cases like commercial decades.

[randypi]

Thank you for the information!!!

Sealed batteries deal with cold better than Flooded, and fully charged flooded are good down around -70F. However, if you are going to heat them with heating pads, I would recommend running utility power to the shed

[Sunking]

Again if the battery is on a charger, unless you get to -40 below ZERO F for days on end, is a non issue as charged batteries do not freeze. Only thing that happens is everything SLOWS DOWN real SLOW.

Aging almost comes to a stop
Self Discharge almost comes to a stop.
Capacity falls off a cliff where your 100 AH battery is now a 30 AH battery at -40.

None of that matters is being stored and left on a charger. Come spring when it warms up, th ecapacity comes back, battery starts self discharging, and lead sulfate crystals begin to form, harden-off, and kill your battery.

Pb batterie and most battery chemistry all do this. It is trying to balance on a razors edge which you can never achieve balance. When a battery is war, is has maximum capacity and short life. Cold is reduced capacity, longer life, and sluggish performance. You cannot win as it is impossible.

[frankssheds]

Sometimes the battery will fix the problem if you open it and re-tighten all connectors. My tip is to avoid extreme temperatures. Very hot or cold temperatures can negatively affect the the performance of the battery and shorten its expected life. Avoid storing and charging you battery in a garage or outdoor shed that could be subject to really hot or cold temperatures. Instead, charge and store your battery in a moderate temperature area.

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[Shane.R13]

can you dump excess load to say like a car battery heater mat?