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Old 05-08-2019, 09:30 PM   #25
Tom Wesenberg
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Join Date: May 2010
Location: Mpls, MN
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Default Re: Charging a dead battery

Quote:
Originally Posted by runewilliam_merc View Post
It's not a good idea to fill water before charging.

When you drain current from the battery, the electrolyte goes into the porus lead, make lead sulfate, and the "water" level will sink. When you charge the battery, the lead sulfate is made into lead and sulfuric acid again. And the "water" level will rise again, but because of heat generated while charging, some water will evaporate.

If you top up water before charging, the added excess "water" will come out through the vents and your acid Will become weaker (a new battery Will measure 1,28 to 1,30 kg/liter)

If you have a dead battery, check the density og the acid, charge with 2,8volts/cell and low current for three days and check again.

If the density has risen, but is below 1,28: charge for a week, check and full water.

If density stays the same after three days: get a new battery.

Rune Waltoft from Norway
Also, if the battery starts getting very warm to the touch, then junk it and buy a new battery.
My favorite charger is my 1960's Sears 6 amp 6/12 volt with an amp meter. This tells me exactly what's going on while charging. A volt meter is pretty useless for knowing true battery condition.
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