car battery issues.

tubabucknut

So my wife's van is having issues with the battery. It is loosing about .5 volts an hour on the battery. of course after several hours it is no go to start. I have replaced the battery a few times, and have confirmed the batteries themselves are not the issue. So how do I best go about tracing the draw? Everything is off, the doors are all shut, no visible lights on from the outside. I will go sit in it tonight when it is dark and see if I can see any lights on. The other thing is the starter seems to struggle. Even on a brand new battery with a full charge it catches before it turns over. When you have a fresh battery and a jump it fires like a champ. The batteries say 800 cold cranking amps. Should I buy a bigger battery? Could it be the starter itself?


Thanks for any input.

ilove22s

here is what i would do. if you already did some things great.....

> google for your make/model/year and see if others have had similar issues. I would be surprised if you were the one and only person with this one and only issue. sometimes you may need to join a board like this to get any info. I consider this low hanging fruit to do searches. Easy peasy. You can also try searching for similar vehicles or vehicles that used the same platforms/chassis.

> If you have any auto parts shops in your area, take your vehicle there and have your alternator checked and iirc would have it checked under load.

> one thing i found out was that if you dont drive the vehicle long enough when you do use it, you may not be "re" charging your battery. on a "new" battery it shouldn't be an issue, but an older battery???

> sometimes a bad ground point could be an issue. it could be rusted where you "think" the connection is good.

others will chime in....

good luck.

Fisheadgib

I don't know the extent of your electrical abilities but most DC multimeters can be placed inline with a small DC amp draw. I had a Jeep Cherokee that had a mystery draw and I disconnected the battery and wired my meter between the battery and the lead and started pulling fuses one at a time while I watched the meter for the draw to stop and that pointed me to the right circuit. At one time , I also had a loose ground at a headlight that was drawing my battery down.

tubabucknut

Thanks guys. Alternator is good, and is charging fine. Battery is good. There is just a draw somewhere.
ilove22s i will try a search. I just started here because I know a bunch of guys here are in the know.

Fisheadgib I am well versed in AC, not so much in DC. But I learn quick. My multimeter has an amp loop. Can I just put this around the positive and measure the draw that way? It is how I check draw when I work on someones house panel.

bisley

Check to make sure your radiator fan is shutting off, for one thing.

roadking

Probably too small of a draw with today's tech, but in the 90s, my glove box light switch failed, and by end of the weekend (it sat), battery was a non starter.

Alarm system? Cigarette socket in use charging something?

Fisheadgib

tubabucknut wrote: »

Fisheadgib I am well versed in AC, not so much in DC. But I learn quick. My multimeter has an amp loop. Can I just put this around the positive and measure the draw that way? It is how I check draw when I work on someones house panel.

That's probably an inductive loop on your meter that will only work with A/C amps. You may have a DCA or uA setting that will read DC amps if the leads are connected in series between the battery and positive lead. Bear in mind that it's usually fused pretty low like one or two amps so if you have a huge draw, it will blow the fuse in your meter.

tubabucknut

Thanks again giys.
Bisley fan is not running but thanks for the thought.
Roadking I think it is something along the lines of a bad switch. It is a 94 Astro. So I gots me some old Tech. There ain't none of Wambli's 5g in this ancient beast. The problem is it is the tricked out version with the TV and the VCR and all that junk. There is a lot to go wrong.

Fishead I will check my meter, but I do not recall the two settings you mentioned. Interestingly I tried the loop since I was last on. It read nothing while the van was off, but registered 6+/- amps while it was running. I wonder if the loop is not sensitive enough to register the draw, and I will have to use the leads as you describe.

snake284

tubabucknut wrote: »

So my wife's van is having issues with the battery. It is loosing about .5 volts an hour on the battery. of course after several hours it is no go to start. I have replaced the battery a few times, and have confirmed the batteries themselves are not the issue. So how do I best go about tracing the draw? Everything is off, the doors are all shut, no visible lights on from the outside. I will go sit in it tonight when it is dark and see if I can see any lights on. The other thing is the starter seems to struggle. Even on a brand new battery with a full charge it catches before it turns over. When you have a fresh battery and a jump it fires like a champ. The batteries say 800 cold cranking amps. Should I buy a bigger battery? Could it be the starter itself?


Thanks for any input.

Me thinks you have a short. Is this by any chance a Chrysler product?

Jermanator

Chevy.

Jermanator

Jermanator wrote: »

Chevy.

https://www.youtube.com/watch?v=oh7chm-A2wQ

tennmike

If it's pulling down the battery .5V/hr that is going to be a big amp draw. It could amp out your multimeter and blow the fuse in it if you hook it up in series to measure amperage normally. Going on Fishhead's idea, pull ALL the fuses, and just hook up the meter to measure voltage across battery terminals. Insert fuses one at a time while watching meter. The offending circuit will show a voltage drop on the meter when the fuse controlling that circuit is inserted.

Farm Boy Deuce

Ah, the Chevy Astro. A box on wheels, my Mom and Dad wore two of them out. The first one was even Dad's farm pickup for a while. You could get three square bales in the very back and at least five five gallon buckets in between the seats.

tubabucknut

Thanks Mike. I will try doing that tomorrow.

Farmboy. Yes they are boxes on wheels, but that is why they are so useful.

Teach

Disconnect a battery cable and wait for dark. Touch the disconnected cable to the battery post and check to see if there's a noticeable spark. If there is, reconnect the cable and go to the alternator and disconnect the big charging lead at the back of the housing. Check for a spark there. It's not uncommon for one or more rectifier diodes to develop a current leak and discharge the battery back through the alternator stator, and the alternator will still be able to charge the battery. If that's the case, swap the alternator.
Jerry

tubabucknut

Teach wrote: »

Disconnect a battery cable and wait for dark. Touch the disconnected cable to the battery post and check to see if there's a noticeable spark. If there is, reconnect the cable and go to the alternator and disconnect the big charging lead at the back of the housing. Check for a spark there. It's not uncommon for one or more rectifier diodes to develop a current leak and discharge the battery back through the alternator stator, and the alternator will still be able to charge the battery. If that's the case, swap the alternator.
Jerry

Thanks Teach. I will try that as well.