Parasitic Battery Drain

[jimmyz79]

Sy/Ty'ers,

My TY has had a never ending battery drain for a while :banghead: and I'm pretty sure (hopefully) that I traced it to the unswitched power line to the stock radio/cd. The unit works fine as does the clock. I know an E-Z fix would be to change out the unit, but I would like to keep it stock. Any of you audio guys ever hear of this?

 

[Ian Turgeon]

pull the radio for a short time and see if it still kills the batt.

if not, i guess your solution is to get a new one.

never had experience of a deck draining power.. is it stock?

might be elsewhere..

I believe there is a way with a multimeter to check if something is pulling power from the battery, That would probly be your best bet.. hook it up, have a frind watch the numbers, and start unplugging stuff/fuses.

 

[Loeryder]

What's the easiest way to narrow down battery drain problems liek this?

Pull the fuse and wait and see can't be the method of choice.

I have heard of:
Make sure ALL switches are off and doors are closed (no circuits Open)
Remove battery,
Hook Ohmmeter to bettery leads, should be high resistance
Pull fuses one by one looking for a significant change in resistance.

 

[myclone]

Here is a place to start..

Get out your trusty meter and set it to read Amps (current). Disconnect one of the two battery cables and put the meter in series between the cable and the batt term (be sure the meter is connected properly).

Be sure key is off, doors are shut, and the light bulb under the hood is disconnected. Observe the current draw. Im guessing it should be 1 amp or less normally. If its above that then have a bud watch the meter while you get inside and start pulling fuses one at a time (door needs to be shut during this time so the inter lights are off). Once you pull the fuse that drops the amp reading down to 1 amp (preferably less) you just found the ckt thats prolly the source of the drain.

Note which fuse it is and determine what components are powered by that ckt /fuse. That will give you a place to start checking components/wiring.

BTW... Are you sure the glove box light is not staying on all the time? How bout that under hood light? Both of those could prolly kill a marginal batt over night.

HTH

 

[Fred Aldrich]

One amp is no where near good enough. Sy/Ty battery is about 70 AmpHrs so 1 amp will drain the battery DEAD in 70 hrs. A good target is about 25ma. That should give something like 60 days to no start. GM radios in this era pull about 7ma.

 

[myclone]

One amp is no where near good enough. Sy/Ty battery is about 70 AmpHrs so 1 amp will drain the battery DEAD in 70 hrs.

True for a fairly new/good battery. Ive chased the under hood/glove box "on all the time" battery drain before. One or both of them can drain a marginal battery over night. What do those two bulbs draw alone or even combined? Maybe 800mA at the most for both? I wouldnt think they could kill one myself but Ive chased that gremlin a coupla times over the years. Something to look at IMO.

A good target is about 25ma. That should give something like 60 days to no start. GM radios in this era pull about 7ma.

Agreed, 25mA would prolly keep the ECM/stereo memory happy for a long time and not kill a used but good battery provided there is no other drain on the system.

What type of battery do you have? What rating (CCA)? How old is the battery? How long does the truck have to sit before the battery is dead?

 

[jimmyz79]

Yeah, did the "Fuse pull" test. The only thing I found that drew more milliamps than anything else was the hot radio lead. When I disconnected that, the drain was almost unmeasureable. Battery is about 2-3 years old -730 CA, 570 CCA. I've kept a battery maintainer on it as a band-aid, but I really wants to fix this thing.

For a comparision, I also have a 93 Sonoma - I have left that thing sit for up to 2 months, and it starts fresh every time.

Thanks for the responses.

 

[Loeryder]

What kind of Ammeters are you guys using?

Because both the ones I have measure in Milliamps and I recall them not having a very high range before "letting the smoke out".

 

[4C FED]

Any of the Fluke series will handle the job.
There are a variety of other manufacturers that make comparable DVM's that work just as well and for less money.

 

[sy#2921]

Re: Parasitic Battery Drain

edited

 

[bezerk]

Re: Parasitic Battery Drain

glove box light, engine comp. light?

 

[sy#2921]

Re: Parasitic Battery Drain

door wasnt shut all the way

 

[attackdog]

Re: Parasitic Battery Drain

You can also use a test light the same way. It is much safer than an ohm meter. Hook it in series with the negative terminal and start pulling fuses. Good Luck.

 

[myclone]

Re: Parasitic Battery Drain

It is much safer than an ohm meter.

Hows that? Even the cheapest DVM has a pretty high impedence unless you mistakenly have it set up to read current and get across supply voltage (even then it will blow the internal fuse).

 

[jimmyz79]

Re: Parasitic Battery Drain

Wow, this is an old post - It ended up being the cd driver in the stock radio - it was puliing milliamps ar rest for some reason. I had a guy that fixes GM radios for dealerships fix it, everthing is fine, battery holds juice for a long time now (but i still keep a battery tender on it :tup: )