Join Date: Jan 2003
Location: Maine Coast
Thanked 286 Times in 219 Posts
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Re: Winter is coming -Battery Question?
If you can aim the panel at the prevailing sun angle for winter, and ensure it does not get occluded by snow, it happens, and your controller is a good quality controller with a float stage, then you'd be fine leaving it connected.
Often times when we get a storm that starts out as rain and then turns to snow the rain on the panel turns to ice and then the snow sticks to it. I have seen some panels with very steep winter angles full and loaded with snow due to this phenomenon. Usually it melts in a few days but I know more than one owner who's banks were killed despite being connected to solar due to this phenomenon. Some controllers draw more than other for "self power" and this is why disconnecting from the rest of the system, and its parasitic loads, is critical....
#1 All system connections other than solar should be disconnected from the batteries. I find the NEG connections often easiest to disconnect. Only the controller should remain connected to the batteries.
#2 You will only be able to charge one bank of batteries unless you have a very low draw method of "combining" banks at charge voltages. If the panel becomes occluded you can drain your bank with an ACR or Echo charger, if it is occluded for long enough. If the panel is large enough it will recover the banks but if is "maintainer" size you'll likely never recover.
#3 Colder temps drastically slow the rate of self discharge and help prolong battery life. However you have LESS usable capacity in colder temps so that .3A parasitic draw effectively becomes much larger in colder temps. The batteries should be 100% charged before disconnecting them and this usually means less than 0.5% of Ah capacity in acceptance at 14.2V.
#4 I would advise a "top up" charge every six to eight weeks if you disconnect and let sit.. Usually only 4-8 hours is needed as the self discharge in colder temps is very low. This is more to get the electrolyte moving to prevent stratification. Be sure your charger can go into absorption first, and remain there for a few hours, to get the electrolyte moving..
-Maine Sail / CS-36T
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