How to use a battery charger --with batt in car?

Messages
998
Location
Lexington, SC
I am trying to charge a '96 Lumina battery with the battery in the car. I am asking whether I need to remove the 'positive and/or the negative' cables from the battery before attaching the 12V charger. The battery is hidden and so it is very difficult to get to the terminals -much less disconnect them and then try to put a bolt in the side term's to allow the charger clips to be attached. You have to remove one of the body braces, the windshield washer reservoir, and the fuse panel and the air filter housing has to be loosened and shifted just to remove the battery. I had one auto discount store say they couldn't replace the battery for me, when I purchased a new battery!
 
Messages
1,007
Location
Dallas, TX
In a perfect world, it shouldn't make any difference to the car whether or not you take the cables off or not. Having said that, I know someone who fried some of the electronics in his car while receiving a 'jump'. Apparently (and I'm in no way an electrical engineer) arcing can somehow find its way to the more delicate electronics in a car's systems and fry them, much in the same way lightening can fry your home computer. I vote better safe than sorry...remove the cables before hooking up the charger.
 
Messages
4,036
Location
Chicago, IL
you do not need to disconnect the battery in order to charge it. of course, I want to question: why is the battery low? was something electrical left on in the car? has it been parked for awhile? if the battery is "dead" because it will no longer hold a charge, then it will not help to charge it. is the battery older than 4 years?
 

Jim Spahr

Thread starter
Messages
998
Location
Lexington, SC
I should make clear that on most GM cars including this one, when you remove the cables from the side terminals, you have NO PLACE to connect the charger aligator clips or the jumper cables. So you have to attach a new term bolt you can get from the auto parts store. This allows you to connect the clips.
 

Jim Spahr

Thread starter
Messages
998
Location
Lexington, SC
Q? Why is battery low? I now drive two cars and this one doesn't get driven enough to keep it fully charged. It has a new battery. I am trying to charge it up to 12.5 VDC so I can put a 'battery float charger' on it. This device will charge only when the battery gets below a certain level. The float charger won't continuously charge and over charge the battery.
 
Messages
110
Location
Maryland
Unless the car has been sitting a very long time (a year or so), then you should check the car for a parasitic drain on the battery (greater than 50-100 mA). I had this problem on a 96 Tahoe that would kill the (new) battery in 7 days of sitting. Recharged the battery with it installed for a half-a-day and it was back to normal. The source of the drain ended up being the interior light fuse... Your new battery will eventually be dead as well, if it is continually drained/charged. Car batteries don't tolerate deep cycling...
 
Messages
10,597
Location
Nokesville, VA
If the cigarette lighter socket is live when the car is off, get a cigarette lighter cable (an extension cable works if you cut the socket end off), and connect your battery charger to that. Otherwise, most GM vehicles have a remote positive terminal for jumpstarting. It's often located in or near the underhood fusebox.
 
Messages
5,530
Location
San Francisco Bay Area
 Originally Posted By: brianl703
If the cigarette lighter socket is live when the car is off, get a cigarette lighter cable (an extension cable works if you cut the socket end off), and connect your battery charger to that. Otherwise, most GM vehicles have a remote positive terminal for jumpstarting. It's often located in or near the underhood fusebox.
I've tried using a jump starter connected to the lighter socket via an adapter - to keep the power alive when changing the battery. There are some jump starters that only work through the lighter socket by slowly charging up the drained battery. The strange thing was that the electrical system (radio was most noticeable) came to life even without the ignition on. I'm thinking that it wasn't actually connected to the battery until I turned the ignition to accessory mode. I'm thinking those remote terminals may not be as effective due to resistance across the wires. I've used jump starters and sometimes they just didn't work well and I connected ground directly to the battery (they had on-off switches so I didn't make the connection directly at negative) rather than the recommended grounded part of the engine block. I know there's a risk if there's hydrogen gassing from the dead battery, and I will clarify that it's not supposed to be the "right way".
 
Messages
35,989
Location
ME
Charging is safer than jumping. Plug the charger into the wall outlet after the battery connections are made and look secure. As said above you can find other +12v hot sources under the hood. Even if not labelled as a jumping spot you can charge at the underhood fusebox or even the alternator positive terminal, both hidden under little rubber covers. Look for an 8 gauge or so (~1/4") heavy duty red wire. The only issue is you may hear a 60 hz buzz listening to AM radio with the charger connected. But who would do that? Charge with the key fully off.
 
Messages
1,389
Location
Nebraska
If you're using a float charger like a Battery Tender, you won't need to charge it before you put on the tender. My BT came with clips that will hold on to about any set of terminals. I have the same problem with seldom-used vehicles and put the charger on them, close the hood, and charge for however many days I feel like charging. No issues. Just ensure you have the extension cord join under the hood in case of rain.
 
Top