Battery Location in Winter

Oscar13601 · July 2012

I know that the battery bank has to be close to the inverter and charge controller. But, my question is:
Can I locate the batteries outside the house in a wood box insulated with like R42 insulation in the winter?
I'm planing on doing this in upstate NY where it gets very cold in the winter (10-15F) . What is the effect of the deep cycle batteries, inverter and charge controller in the cold? Or can I leave only the batteries outside. I read somewhere that batteries release a toxic gas, but, I'm not sure if this is the same with the gel ones. What do you guys think?

Thanks,
OM

Cariboocoot · July 2012

Re: Battery Location in Winter

No worries.
My flooded cells spend the winter in an insulated box (2" of foam) at temps down to -40. Leave the charge controller hooked up, disconnect the loads; they're fine.

So long as the batteries are kept charged they will not freeze.
They do not release toxic gas, but rather hydrogen and oxygen which is a combustible combination. The percentage is so small that the danger of this is greatly exaggerated in many places on the 'Net. Sealed batteries don't even do this (unless charged at too high a Voltage).

Cold temps won't hurt the equipment either. Damp will, though. Electronics do not like to be damp.

One concern: you used the word "gel". Gel batteries are not a good choice for RE.

BB. · July 2012

Re: Battery Location in Winter

GELs are sealed batteries and won't release gas during normal operation... However, during abnormal operation (over charging) and or as they fail from age, they can out gas (guessing a bit--But GEL should behave like other lead acid batteries).

Also, what is your rate of charge? GEL batteries, from what I understand, cannot take very high charging currents (C/20 or 5% of rated 20 Hour capacity maximum from what I have seen). If you charge too quickly, they develop gas pockets and never are quite the same again.

So, they are not usually a good choice for solar PV systems (OK for standby and slow rate of charge--such as in a UPS type system).

If you install the charge controller inside and the batteries outside, you should get a charge controller that has a Remote Battery Temperature Sensor option. Cold batteries need much higher charging voltage for proper/fast charging. Most charge controllers have an internal temperature sensor--but if they are not in the same space as the batteries, that is not going to help.

-Bill

Photowhit · July 2012

Re: Battery Location in Winter

My batteries live outside in Missouri (-5-10 minimum temps) in an uninsulated box, as do my inverter and charge controller.

There is a serious reduction in their capacity when cold, this returns when warmed. I use less energy in winter and have never ran into any problems, some use more energy in winter and might find a problem with this, as I recall the capacity when the battery is @ zero degrees farenheit the capacity is halved (from my faulty memory) If your using that much insulation the batteries while charging will warm the area and likely not cool too much over night, I might worry more about summer temperatures, batteries don't like getting too hot, and above 80 degrees will shorten their life.

The batteries put off hydrogen gas, which should be vented, also the batteries should not be in the same space as the charge controller and inverter. Also, some inverters at least, don't like too cool of temperatures, I was surprised to read just yesterday that my backup inverter should be above 32 degrees farenheit.

icarus · July 2012

Re: Battery Location in Winter

Battery capacity will be effected by cold, but battery life will be enhanced!

Tony

Cariboocoot · July 2012

Re: Battery Location in Winter

In case it isn't clear: batteries that are in use (current going in or out) will not be at ambient temperature.

vtmaps · July 2012

Re: Battery Location in Winter

If you use a battery monitor don't forget to tell the monitor that your batteries have reduced capacity in winter. Otherwise it will overestimate your state of charge. Winter is good for batteries (as Icarus pointed out) because they will last longer. Bill mentioned the most important thing: make sure your chargers (solar controller and generator charger) have a remote temp sensor). --vtMaps

niel · July 2012

Re: Battery Location in Winter

if your reasoning for putting the batteries outside is because of the outgassing you read on fla types then put them indoors so that they may be warmer.

i agree that gels are not a good choice, but do be sure to charge them properly as they are extremely picky.

Oscar13601 · July 2012

Re: Battery Location in Winter

Do you mean to use GEL Batteries indoors? I'm thinking on a 24V system. Starting with 4 Batteries and then exptending to 4 more totaling to 8 Batteries... This project is in Upstate NY and it gets really cold there in the winter. This is for a vacation home, or like the town calls it a 1.5 family home. 3500 or 4500 W Inverter an starting with 4 230W panels... What u guys think?

Cariboocoot · July 2012

Re: Battery Location in Winter

Oscar13601 wrote: »

Do you mean to use GEL Batteries indoors? I'm thinking on a 24V system. Starting with 4 Batteries and then exptending to 4 more totaling to 8 Batteries... This project is in Upstate NY and it gets really cold there in the winter. This is for a vacation home, or like the town calls it a 1.5 family home. 3500 or 4500 W Inverter an starting with 4 230W panels... What u guys think?

We mean do not use gel batteries if at all possible.
I used to live in Upstate NY and know how cold it gets. No worse than the Cariboo, trust me.

Flooded cells will not release dangerous amounts of gas and can be kept inside. Venting the battery box to the outside is easy. They will not freeze if ket charged.

AGM batteries are probably the best choice for over-all performance, but are pricey per Watt hour.

Starting with one size battery bank and then expanding it is not necessarily so easily done. Batteries of the same model but different ages/uses will have different capacity, and generally adding new batteries to old is not a good plan. If the old ones are not too old and/or used/abused it will be okay.

Four 230 Watt panels will support about 2kW hours AC per day at best. Good for roughly a 300 Amp hours @ 24 Volts battery bank which at 25% DOD would be 1800 Watt hours.

Whether any of this will work depends on your expected loads and how good the sun is. Upstate in Winter = not good sun, but enough to keep the batteries floating 'til Spring.

The inverter is over-sized for what the panels and potential battery bank could handle. If that is also an MSW and/or 12 Volt inverter, forget it; waste of money.

BB. · July 2012

Re: Battery Location in Winter

GEL are not recommended because of the very low peak charging current (around C/20 or 5% is typically the maximum--Higher charging currents cause gas pockets to form in the GEL next the plates and permanently ruin capacity).

AGM will also not gas during normal operation... So they are much "cleaner" and more efficient than Lead Acid batteries (90%+ efficiency vs flooded cell at ~80-90% efficiency). Also, they are more "freeze tolerant" because the electrolyte is in a fiber glass mat with air pockets--not a solid column of electrolyte.

However, any reasonably charged battery will withstand sub zero ^oF without problems. Note, if the AGM is "frozen"--It must be defrosted before recharging.

Any lead acid battery will gas if heavily/over charged and AGM's can vent at the end of their service life (the catalyst metal eventually corrodes and fails to recombine hydrogen and oxygen gases). So, while AGMs are "safer"--It would still pay to be somewhat careful where you install and provide some sort of venting system if in a "sealed" box.

AGM's are almost the "perfect" lead acid battery (efficient, clean, very high current source/sinking capabilities)... But on the down side, they cost 2x or so more than similar flooded cell batteries, can be a bit easier to damage (if over charged and venting), and they may not last quite a long as a similar quality flooded cell battery.

Because so many people "murder" their first set of batteries (either through their own mistakes or a family member/guest), it is not a bad idea to get a "cheaper" set of batteries (like golf cart or similar industrial/flooded cell) and use them for 3-5 years... By that time, you will have made your mistakes and can adjust battery bank size to fit your, now known, needs.

Also, if you have any sort of major "investment" in your battery bank--I would highly suggest a good quality hydrometer (if flooded cell) and a Battery Monitor (or Victron brand is another good one). And for AGM, I would suggest that a Battery Monitor is almost mandatory and will help you get a long life out of your battery bank.

You can do OK with a volt meter and no battery monitor--But you will have to understand what it is telling you during charging and discharging conditions. (battery monitors are not perfect either--So, you have to understand their limitations and how they "reset" back to 100% Sate of Charge and other issues--They do not measure actual bank capacity--they us the numbers you program).

-Bill

Battery Location in Winter

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