sulfated battery?

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patman

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Apr 27, 2007
11
- - san carlos mex
I have a 6 month old walmart marine battery & I store it on the boat for emergencies & I keep a solar trickle charger on it to keep it charged. Checking the water level it appears that the plates are covered with a grey residue & I cant get it to charge more than 12.5 volts. Even with a regular home charger, so by keeping it charging continously does this cause sulfation? Thanks in advance.
 
May 24, 2004
7,215
CC 30 South Florida
Let's go by what we know. Walmart battery inventory moves fairly quickly so a battery purchased six month ago should be no more than 7 or 8 month old and its age should be not cause for concern. Batteries have a natural rate of discharge even if they are not connected to anything. In six month the battery can loose a fair amount of charge and a battery just partially charged is more prone to sulfation. Solar trickle chargers are usually unregulated and as such the small amount of charge they may supply during daylight may get sucked up at night as the solar charger becomes a draw in the abscence of sunlight. Larger solar panels use a charge controller to prevent that backflow. You mention a marine battery but do not specify if it is a deep discharge battery or a starter battery. The starter battery would be more prone to sulfation than the deep discharge type if left partially charged. It think it is safe to surmise your battery became discharged and sulfated in those 6 months of storage in the boat with an inadequate charge source. The battery needs to be placed on a charger and left for at least 24 hours making sure distilled water is added to the cells as needed then it would need to be equilized. A deep charge may help reverse some of the sulfation process. I doubt the battery may never get back to its original condition but still maybe useful even with a reduced storage capacity. This is the best I could do with the information you provided.
 
Nov 6, 2006
10,219
Hunter 34 Mandeville Louisiana
Wal mart has a replacement warranty that I think is good for at least one year. Take it over there. They'll test it and charge it if needed.. and replace it if you have a dud.. make sure the new one is fully charged before taking it to the boat.. Good luck !
 
May 24, 2004
7,215
CC 30 South Florida
I'm not sure if marine batteries are covered but is worth a try. Don't rely on that solar trickle charger to keep the battery charged on the boat. At least once a month put the battery on a charger.
 
Feb 6, 1998
11,760
Canadian Sailcraft 36T Casco Bay, ME
If the trickle charger is too small then yes it could definitely be sulfated from lack of charging. What is the wattage of the solar panel and what is the Ah rating of the battery? What are your average temps where the battery sits?
 
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