2007 Silverado 2500 HD - Battery Drain

[obabika]

For three years while under warranty GM has attempted to fix a problem which drains the battery in my 2500 HD Silverado. All they could ever offer me was two new batteries and a list of 'possibly' this and 'possibly' that. The problem is still there today, and is well documented on various websites, with few concrete actions to resolve this intermittent problem. In the four years this has occurred on average of about 3 ;times per year and always in cold weather.

 

I'm considering attempting my own solution to bypass this problem so that I can at least get the truck going when the battery runs down again. Since the truck has a second battery box I was going to simply parallel a second battery ( reserve battery) to the original battery and place a relay circuit so that once the reserve battery is charged it can be isolated from the original battery and used to start the truck if the original battery dies.

 

I have several questions on this; 1) Do I stand the risk of damaging the charging circuit by charging the two batteries at the same time.? 2) If the original battery goes dead are there any risks in connecting the reserve charged battery into the original battery .? (this would seem to be the same as clipping on a set of booster cables unto the dead battery)?

 

I would welcome any insight on this .

 

thanks

[Killerbee]

An intermittent drain issue like this is usually a module refusing to "hibernate". I would replace the BCM, I think they are the issue most times.

 

You can use a battery isolator I think, to add the 2nd battery.

[dewfpo]

I have several questions on this; 1) Do I stand the risk of damaging the charging circuit by charging the two batteries at the same time.? 2) If the original battery goes dead are there any risks in connecting the reserve charged battery into the original battery .? (this would seem to be the same as clipping on a set of booster cables unto the dead battery)?

 

I would welcome any insight on this .

 

thanks

 

 

1) When the engine is running both batteries are being charged now.

2) As long as the primary battery doesn't have an internal short (and is just low) this would work fine. The same a jumping.

 

You could wire in a simple high amp solenoid from the aux. battery to the starter such that the aux. battery would connect when you turn the key to the start position so you would have it available for starting power, then it would disengage from the starting circuit (but yet be charged by the alternator when the engine was running).

 

DEWFPO

[waumo1]

You could just install a Priority Start on the primary battery. I had one on my 98 truck because I sometimes didn't drive it for weeks and I had some aftermarket audio equipment that caused too much parasitic drain. The Priority Start disconnects the battery at 11.something volts and then reconnects it as soon as you open a door, etc.

[ak63]

I had a similar problem until the radio was reprogrammed a few years ago. Before the programming I was lucky if the battery would last overnight or sometimes up to 6 days. No issues since then for anything less than about 14 days (although apparently it will drain if you leave it standing for 23 days!).

 

See here: http://www.gm-trucks...l=&fromsearch=1

[aalbanezjr]

Your truck is already wired for a battery isolater. I installed a second battery in my HD with no issues. Let me know and I will get you all the part numbers you'll need and pictures of the install also.

[Diesail]

I would stay on the dealer about this. I have heard of problems with the BCM and heated seats just to name two causing a problem like this. The need to put a meter on it and start pulling fuses until they find the circuit with the draw. This type of problem is common, if your dealer isn't fixing it go to another.