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How long to charge a dead battery Schumacher 2/10/50/start/ dumb charger

S

schiker

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I need to charge my boat battery that is dead. I have a Schumacher charger and assume I should disconnect the battery and put it on 2 amps for several hours. The timer only goes to I think 90 minutes or so. I again assume put in on hold for 6-8 hours. How long do you trickle charge at 2amps? Its a starting battery not a deep cycle.
 
charge it for 12 hours then disconnect to let it cool and settle for a couple hours. Then just like shampoo, repeat as necessary.

If it is a serviceable battery, fill the cells with distilled water first. remember that while charging and for a little afterwards, any outgassing is flammable.
 
I personally like to charge at a higher current myself. I have an automatic charger that varies between 10-25 amps, and shuts itself off when it's done. It monitors voltage and amperage and can charge as high as 16 volts during charging. Charging at a lower current can increase sulfation of the plates. As for how long to charge, how many amp hours is the battery? If it is say 50 amps reserve capacity, to charge it from dead at 2 amps would take 25 hours, but at 10 amps would take 5 hours.
 
Lower rate causes sulfation? I always thought the slower the charge the better. I need to crack open the chem book and relearn what I thought I knew.
 
Will L. said:
Lower rate causes sulfation? I always thought the slower the charge the better. I need to crack open the chem book and relearn what I thought I knew.
Click to expand...

x2, all these 1-2 amp chargers are supposed to reclaim batteries.
 
I guess I'm old school, but I was always taught that slow charge rates don't allow the battery to break the sulfation loose and increases the buildup on the plates.
 
If you're old school, they didn't have school in my time.

I believe these new chargers have a pulse action that knocks sulfation loose. I have yet to reclaim a bad battery with mine.
 
I thought the slower the better to reduce any heat build up and resistance increase. At least with the older style chargers without the electronics. I assumed the sulfating came from cycling the battery to near dead and recharging quickly. Assumed it kinda came from heat and boiling? at plate surface???

I have the time. Just looking for best method and worried I might overcharge it.

One of those new chargers would be nice but I can get by with my old one for now.
 
Well you know what when you assume.

clipped from battery university website

"Sulfation occurs when a lead acid battery is deprived of a full charge. This is common with starter batteries in cars driven in the city with load-hungry accessories. A motor in idle or at low speed cannot charge the battery sufficiently."

I always knew leaving a battery uncharged was bad. I need to get some battery tenders. Modern chargers can break some sulfation if its not old but once it sets or has time to crystalize its permanent and irreversible according to that website.
 
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