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diy solar

Battery storage over winter and water level drop

Rod64

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Aug 20, 2020
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So i have had my system going for about 4 months without issue. 1Kw of panels-60A Charge Controller-3000W Inverter/Charger and 8 6V 235Ah batteries wired to 24V.
I am in Eastern Canada and will eventually have to winterize the cabin and my access to place over winter will be sporadic and dependant on snow until March/April. I am not worried about temperature effect on the batteries however i am concerned about evaporation of the electrolyte in the FLAs since typically humidity is much lower in winter. I would appreciated to hear about members experience with this. Thanks
 
The cells/caps should be vented, not open to air, i.e., humidity shouldn't matter.

You should only lose electrolyte when they "burp" or vent due to charging.

Do you intend to leave the solar system running and charging the batteries in your absence? If not, this is the worst possible thing for them as they'll lose 15% capacity per month and possibly be ruined in 3 months sitting at a low state of charge. At a minimum, you'll need to conduct some aggressive equalization charges to hope to recover them.

If these were my T-1275's, I would make sure they're fully charged and tippy-tippy-topped up. Set bulk to 14.4 (down from 14.8) and float at 13.2V.

Try to check electrolyte level once per month.

BTW... my batteries are in the high desert where 12% humidity is muggy. I spend a lot of time away and have only had to top them off every 2-3 months.
 
Thanks. I intended to leave the panels and charge controller connect in order to maintain full charge.
 
Cody's Lab in storing a starting battery fully charged it then drained the acid and stored it separately. He claimed it can then be stored for years without being damaged.
 
Batteries have shipped dry from time to time for that reason. If sealed off, they won't degrade. There was a period that every motorcycle battery I bought had to be filled before use.

Issue is more with the OP needing to empty, store (each cell separately) and refill 24 different cells for a few months of storage when they can simply leave the system on and charging in their absence.
 
I had not seen this technique in this forum yet, The OP now knows it is an option and can make their own decision.
 
Can I leave my solar system on, with no load and charging over winter (Sudbury, Ontario, -30 C sometimes)? Should I build an insullated box for the two lead acid batteries, Torjan SPRE 06 255? Any other considerations?
 
To clarify, system is in a remote cabin, and only occupied for 5 months. Rest of the year (late fall and winter) it sits empty with no load required.
 
I had not seen this technique in this forum yet, The OP now knows it is an option and can make their own decision.
Yeah right! This is the same guy that makes his own lead-acid batteries from left over trash with nothing but a pair of dishwashing gloves. Melting that trash down an i-beam and tacking that all together. That's not the guy to trust. Maybe in 1900.

I just had to laugh - reminded me of a Simpsons episode ..

Hi, I'm Troy McClure, you may remember me from such films as "Lead Paint - delicious but deadly."
 
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I'm still looking for advice on winter battery storage in Canada (Sudbury, Ontario, as cold as - 25 C some days), and whether or not an insulating box for the batteries is a good idea. I plan to leave the batteries (Two x Torjan SPRE 06 255) connected to the solar panel (150 watts) through the controller, and disconnect the inverter. Is an insulating box worth the trouble, and are there any considerations when sizing it (enclosed tightly, or leave some space around the batteries). Thoughts? Daniel
 
I'm still looking for advice on winter battery storage in Canada (Sudbury, Ontario, as cold as - 25 C some days), and whether or not an insulating box for the batteries is a good idea. I plan to leave the batteries (Two x Torjan SPRE 06 255) connected to the solar panel (150 watts) through the controller, and disconnect the inverter. Is an insulating box worth the trouble, and are there any considerations when sizing it (enclosed tightly, or leave some space around the batteries). Thoughts? Daniel
Correction: the solar panel is 350 Watt, 60-cell mono PV module
 
I'm still looking for advice on winter battery storage in Canada (Sudbury, Ontario, as cold as - 25 C some days), and whether or not an insulating box for the batteries is a good idea. I plan to leave the batteries (Two x Torjan SPRE 06 255) connected to the solar panel (150 watts) through the controller, and disconnect the inverter. Is an insulating box worth the trouble, and are there any considerations when sizing it (enclosed tightly, or leave some space around the batteries). Thoughts? Daniel
For sure you want it trickle charging the entire winter…

insulating won’t help, unless it is heated… with ZERO load on the battery, it will lose enough voltage to self discharge to lower the electrolyte sg and allow it to freeze solid.

keep it charging.
 
Duh. Right, no heat source, no benefit. I suppose I could connect a small 6 volt light to the battery to generate heat. Seems like a potential complication though if trickle charging the entire winter is all that is needed.
 
Here is a link that might help. I'm sure Trojan has a comparable document.

Also remember that the self discharge rate of a healthy battery is minimal at those low temps because the chemical reaction is retarded by cold and increased with heat. If there are internal issues due to shedding and flaking of the Positive plates or dendrites between the Positive and Negative plates all bets are off. There are many charts on line that show the freezing temp of different specific gravity of electrolyte and the self discharge rate of warm or cold batteries.
 
I'm still looking for advice on winter battery storage in Canada (Sudbury, Ontario, as cold as - 25 C some days), and whether or not an insulating box for the batteries is a good idea. I plan to leave the batteries (Two x Torjan SPRE 06 255) connected to the solar panel (150 watts) through the controller, and disconnect the inverter. Is an insulating box worth the trouble, and are there any considerations when sizing it (enclosed tightly, or leave some space around the batteries). Thoughts? Daniel
My cottage is just south of sudbury (Estaire area). I leave my system on all winter, have for the past 7 years with no ill effects. There should be minimal drain (unless your running something), so its just going to be a trickle/top up charge which is very easy on the batteries. Mine don't lose any noticeable amount of water over the winter and batteries are always fully charged when I arrive. Mine are 6v Interstate lead acid batteries but should make no difference with your Trojans.
 
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