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MI drew
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# Posted: 20 Feb 2015 11:17am
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Ok... so been at the cabin for a week. Temps here in northern MI have got down to as low as -27. Batteries were good for the first day or 2. Just not getting full capacity because if the temps. We have 2 6v 210ah golf cart batteries and 400w of solar panels. Have a generator for back up but that went out on our 2nd night here. (Just replaced it yesterday under extended warranty... whew). The batteries just got down to low one night... all it took. I went out and bought 2 more batteries so now we have 420ah capacity. Was putting a charge on each set last night to get them equal before I hooked them together and that's when I noticed the original set was partially frozen. Still had some liquid in them but the tops were slushy. Hard part was they have been hooked up to the panels the whole time. I have them defrosting now. I have a very good charger that has the capacity to bring back bad batteries. But how bad am I screwed? ? Are my batteries toast? Going to test with my hydrometer once charged again. These 2 batteries are just at 1yr 1mth old. Advice please.
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razmichael
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# Posted: 20 Feb 2015 12:46pm
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Impossible to say if they are toast. Maybe they can be recovered if the electrolyte did not really freeze and damage the plates. All you can do is try buit be careful and warm them up slowly watching for leaks.
Good chart here for the freezing point at different charges:
Trojan . There is a major difference between a fully charged and even a 60% charge. Another point - is the charge controller temp compensated? This can make a large difference in how well it will charge cold batteries. I don't bother with an external sensor for mine as it has an internal sensor and is at the same ambient temperature as the batteries. If they were not located at the same temperature I would use the external sensor option.
I left my batteries connected to the panels all last winter without an issue and hopefully will find the same thing when I get back in the cabin. Winter temperatures can get below -30C easily.
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creeky
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# Posted: 20 Feb 2015 12:51pm
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this cold is nutso. Go get some polyiso or xps insulation and completely wrap your batteries. I've got 3" around my batteries now. when they get below freezing I open one side, put a radiant propane heater on 'em. and then rewrap. it's the only way to get decent performance out of them.
could your panels have been covered with snow and not charging?
the only way I can think of that batteries would freeze at that temp is if they weren't charged and the electrolyte has stratified. so there's water at the top of the battery.
ouch. good luck with recharging. i'll be interested in how it goes.
(ahchooo-LFP batteries-achooo  )
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MtnDon
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# Posted: 20 Feb 2015 02:28pm
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If it was only frozen to slush you are likely okay. Hard freezes can/will damage the battery internally, maybe even split a case.
Does your solar charge controller have temperature compensation? If not that can be problematic as the voltage won't be high enough for a full charge at that kind of temperature.
Thaw the batteries and give 'em a full charge and you know soon enough if they still work well.
Now, with the new extra batteries you may have a problem having enough sun to keep all 4 charged, IF you run them down low. More batteries need more panels as a rule.
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MI drew
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# Posted: 20 Feb 2015 08:33pm
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Thanks for all the replies. We're in a high lake effect area here so sun during the winter can be sparse at times. Usually I top off my batteries at night while we're winding down playing cards or watching a movie. Just with my genny going out on night #1 of our week... it screwed up my usual charge program. My charge controller is a MPPT and has a temp meter built into it. Our 4x100 panels should be at about 70deg in winter but I have them at 90deg and now get zero snow build up. I've had the batteries on my charger for about 6hrs now off the genny. They seem to be stuck at 5amps. It's a 40amp charger. The one batt is reading good on the hydrometer. The other its a mid to high fair. Think I'll take the 2 home and put then on the charger reconditioning mode. See what happens. Hmm
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MI drew
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# Posted: 22 Feb 2015 11:06pm
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Well I put them on my charger on reconditioning mode when we got home last night. After the process they now go to float and got past being stuck at 5amps of charge. Before the charger was throwing an error code at that point. Don't really like the hydrometer reading but their in the garage and its 5deg out and I know I need to compensate for that. Both batteries are reading fair. Think I'll bring them inside and get then up to temp to take a good reading. The 2 new batteries I bought are still north and now in their temporary box. I hope that well keep a little warmth on them. I will be making a actual box for then next year that's insulated. Maybe I'll pick up 2 more so I don't risk draining then down too much in the winter months. Now I'm at a point... do I stay 12v or go 24v (my system goes either way). I guess that's another topic for a different post.
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MI drew
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# Posted: 22 Feb 2015 11:07pm
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MI drew
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# Posted: 22 Feb 2015 11:08pm
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MI drew
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# Posted: 4 Mar 2015 11:02pm - Edited by: MI drew
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Ok... been working with the batteries and they seem like.the have come back but.... I can't seem to get past 14.9v and about 2.5 amps. Give you an idea what I have been doing. Got them on.my charger in refresh mode and was able to get the charger to go into float mode by the next night. Took a hydrometer reading on both batts... one was a high good, the other a mid fair. So I let them rest for a day. Same readings on the hydrometer. So I switched up so my positive lead from what the charger was on the lower rated battery. I now have great hydrometer readings in both but again the charger will not go into float mode. Batteries are bubbling nicely. So, figured I'd put the batteries on my 6v 15amp charger. The batts were bubbling like crazy... heard a little fart noise from one so I decided to stop that process. On 6v the charger was pegged at 12amps. I see the plate separators on one batt have distorted a little. Not sure from that or when I had the frozen slush in the batt. From what I understand... this is not an issue. Also... they charger went from reconditioning mode to 5amps yesterday night and has been sitting at the rates in the pix below for almost 24hrs.
Any thoughts... leave them on the charger. Get new ones? Here are some pix.
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MI drew
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# Posted: 4 Mar 2015 11:04pm
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MI drew
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# Posted: 4 Mar 2015 11:04pm
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MI drew
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# Posted: 4 Mar 2015 11:05pm
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MI drew
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# Posted: 4 Mar 2015 11:06pm
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MI drew
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# Posted: 4 Mar 2015 11:06pm
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MI drew
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# Posted: 4 Mar 2015 11:07pm
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creeky
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# Posted: 5 Mar 2015 10:04am
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Neat pics. interesting topic. i'ze got some thoughts
MI, your panels are charging/maintaining the new batteries while you're away right?
One thing I thought of later. When you're up at the cabin and using power you might want to change the angle of your panels to catch more sun. 90 keeps the panels open and working while you're away. Maybe when you're there you could use the extra watts.
Battery troubles document
pretty neat doc that sums up what you've gone through and a bit about why.
according to the doc, part of what causes buckling plates is overcharging from seriously depleted state. so the trickle charge you saw initially was probably for the best.
have you tried putting a load on the batteries and seeing how much capacity remains?
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MI drew
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# Posted: 5 Mar 2015 07:46pm
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Thanks for the article. Very informative, that's for sure. Well shortly after I put up that post my batts went to float. I looked at the plates and they all look straight. Seems like I just have one separator a little warped. I have not put it in a load. I'm going up this weekend and will put my inverter on them and see what happens. I just checked the batts again after being unplugged all day and the levels on the hydrometer all look very good... all rated at high good. Plugged the charger back on them and went to float within about 5 minutes. They are 1yr and 1mth old and have not had too many charge cycles through them. Hope their still good.
Yeah, when im gone from the cabin they stay hooked up to the panels and are fully charged when I get up there. I was just dumb and took them way too low when my genny went out. The concerning part is im not sure what night they started to freeze and how much of a charge the panels gave them. Didn't think to check my water levels until the day after I hooked the 2nd set of batteries to them... which was also the coldest night of -24. I want to say it was that night. Had all 4 hooked up from 6pm to the following morning and at that time my reading was right at 12v with the inverter going all night. Started to throw all 4 on the charger when I checked the water in all 4. They were not frozen solid... slush at the top and could hear some water sloshing around in the lower part. Brought them inside and they were all back to water in about a couple hours.
Next year I will adjust the panels while im up there... I'm already planning an easy adjust for them.
Thanks again for all the ideas!
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