battery keeps going dead....need help

[chaos254]

Haven't done any new mods to my car and for some reason now the battery keeps going dead. The other week I installed a new battery(POS walmart one but it still shouldnt be going dead like this) and got a flat tire so I didnt drive the car for a week straight after installing the new battery. Go to start it today after installing my 2 new tires and its dead! I have no clue as to what could be causing the problem. Could you guys give me some suggestions as where to start looking for the problem? I don't really know much about electrical stuff so any help would be great. Especially since I'm going home for spring break on friday so i'd like to have this fixed by then. thanks a lot.

 

[chefster]

might be light in glove box or console staying on, but i would charge the battery then disconnect it and see if it still loosing a charge

 

[badstang123]

It could also be a bad diode in the alternator. It takes five minutes to pull it off and a shop can check that on a bench tester.

 

[91LX_5L]

alternator or you have a draw, go to a mechanic and ask them to do a voltage leak/draw test, do u have a aftermarket stereo, gauges, etc?

 

[chaos254]

just have an aftermarket headunit(alpine) and underdrive pulleys. I've never had a problem though until recently which is why I'm confused. I haven't added anything new to my car that has dealt with anything electrical. Think im gonna bring it down to advanced auto to check the battery and i think they do the alternator as well. I'm hoping its not anything expensive!

 

[badstang123]

Start with testing the alternator and having a load test done on the battery. Those are the two most likely things and a good place to start. Each of the tests only takes seconds and they should check them for free at your local auto part store.

 

[HISSIN50]

I second the vote to check all switched lights in the car (glovebox, trunk, underhood light, vanity mirror lighting (if we have them), etc etc.

You can use a cheap DMM in series to check the draw as you disco accessories/circuits one at a time. It's very simple to do.

Good luck.

 

[mo_dingo]

Yeah, check amp draw with everything off. You will see a small load but not much.
Scott

 

[94-302-vert]

Get the alternator checked. Then if it is good hook up the DMM and start pulling fuses to see what circuits are drawing the power.

 

[chaos254]

got the alternator checked today and there was a bad diode. What confused me was that... will a bad diode draw power even when the car is not running?

I did get the new alternator and now I just have to install it after I get a shop to swap my pullies. New Alternator = $159 plus tax!!

thanks for everyones help...

 

[HISSIN50]

got the alternator checked today and there was a bad diode. What confused me was that... will a bad diode draw power even when the car is not running?

I did get the new alternator and now I just have to install it after I get a shop to swap my pullies. New Alternator = $159 plus tax!!

thanks for everyones help...

That is what a diode does. It's like a one-way valve (check valve) and will allow current to leave the alternator but not flow backwards [from the battery] to the alternator (which is something that would occur when the car is off were the diodes not there).

What you experienced is a common alt failure.

Glad to hear you got it whipped.

 

[mo_dingo]

yeah, a bad diode can make the 12V from the battery power up the alternator coils and toast it, as well as draining your battery...
Scott