Dead Battery Charging Trick

DC3

Well-known member
Joined
Dec 9, 2008
Messages
332
Location
Lubbock Texas
My 2 year old DieHard Platinum AGM battery was stone cold dead when I tried to start the Vette today. I had put a small capacitor across the alternator to end some whine in the stereo and the capacitor failed last weekend while cruising around. I could tell the whine was back when I pulled into the garage just before I shut it down. Haven't driven it since until trying today. Figure the capacitor must have shorted and caused the battery drain.

The drain was so deep the battery just would not take a charge. While pondering what to do, I did a quick search of the internet and came across this article from Hot Rod Magazine: http://www.hotrod.com/techarticles/general/hrdp_1009_how_to_charge_a_agm_battery/viewall.html

The article said the trick is to put a second good battery in parallel with the battery that won't take a charge. That tricks the charger into thinking the battery is good enough to take a charge. Apparently many chargers won't try to charge a battery if the voltage is too low and adding the 2nd battery bumps the voltage up enough to where the charger thinks everything is okay. Anyway, it worked like a charm and I am back in business with a fully charged battery.

DC
 
I dunno man, I been pulling batteries up for some years now with just a ten amp trickle charger, and just earlier this week, the vette battery that was about 7 years old or so went south, recharged, and everything looked great in about a couple hours, I"m thinking ALT went south, so tried to start car, bat went to 5 volts or less....

new battery, I posted about Marine Deep Cycle with a ??? about how it works in automotive apps....trick is it was some 30 bux cheaper for same as was in the car...today, so far so good, vette starts/runs great....

so even a charger will say it looks good, but I prefer my DVM over anything else....

:hissyfit:
 
I think the story goes something like, if you drain a new lead acid battery until it is completely dead, when you recharge it, it will have lost 1/3 of it's original capacity. When I have a battery that goes completely flat, I get rid of it pretty soon and buy a new one. I keep a trickle charger on cars I don't drive often just to keep the battery from going dead. To me it's really embarrassing to be away from home, find out the battery is to low to start the car, and then start trying to find a pair of jumper cables to get the car started.
......................

Nickel Cadmium batteries are not harmed by completely discharging them (if they are discharged slowly). I don't know what the situation is with Lithium ion.
 
I dunno man, I been pulling batteries up for some years now with just a ten amp trickle charger, and just earlier this week, the vette battery that was about 7 years old or so went south, recharged, and everything looked great in about a couple hours, I"m thinking ALT went south, so tried to start car, bat went to 5 volts or less....

new battery, I posted about Marine Deep Cycle with a ??? about how it works in automotive apps....trick is it was some 30 bux cheaper for same as was in the car...today, so far so good, vette starts/runs great....

so even a charger will say it looks good, but I prefer my DVM over anything else....

:hissyfit:

I've been using marine batteries for at least 20 years. They were always cheaper and had no problems with them.
Supposedly a complete discharge doesn't affect them like an auto battery.
I've also got an old 6 amp trickle charger from Western Auto that is from the late 60's, no electronics in it, so it charges whatever as long as it's plugged in.
This electronic sensing garbage on newer chargers is a downgrade. :banghead:
 
Story of 2 pickups, a '96 Silverado 5.7 Vortec, and for some reason the silly fuse called LIGHTING was drawing ~300 ma with everything off, no lights lit that we could see....pulled all the bulbs, same shit, I stuck a high amp relay in the feed line of the fuse, actuated by the ign. ckt.......hell with it.....

another had a 10 amp fuse to the 'body control computer'......WTF THAT IS??? at any rate it was about the same symptom....so moved the hot lead over to a switched hot.....so when getting in, turn on the ign. wait will the chimes let off, and then crank...maybe 5 seconds....piss on it too.....

drive me nutz climbing all over some modern engineering dream when I can just do a simple change and screw it......:shocking::pprrtt:
 
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