battery drain

Hey folks,

I have an 89 Jetta GL 5speed. Original motor and trans. Thursday I drove the car all over Memphis and got home a couple hours after my little road tour and parked the car.

Lights were off, radio disconnected (detachable face) and went in the house. I came out a few hours later and the battery was pretty much dead.

I put the battery on a 10amp charge and it charged back up within an hour.

I put it in the engine compartment but did NOT connect it since i wanted to see if there was a drain from the system or if the battery was starting to give out.

*note: battery is only 1 year old

So yesterday (24hrs after charging) I hooked the battery back up, turned the ignition and if fired right up. Drove it around for about 5 minutes and parked it.

I checked it two more times during the day, both times about 1 hour apart.

On the second try, battery was dead.

So, before I take it to Metric and have them trace the problem, is there anything I can do to try and _find_ the problem myself ? I've never traced an electrical problem before so any pointers would be helpful.

*other things of note: there was some corrosion on the positive battery connector.

Finally, could it really _be_ the battery ?

TIA

Chris

Reply to
Chris Etzel
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Charging 1 hour at 10 amps could, at most, charge the battery to 10 amp-hours. Plus, a "10 amp charger" might only be charging perhaps 5 amps after a bit. So you may have only had a partial charge into a

10 amp-hr battery.

An ammeter in series with the battery with all car loads off would be the normal way to troubleshoot. Normal draw would be maybe 10 ma??? (1/100 amp)? Well under an amp anyway. So if you had more, you would look for loads that are not letting go-- such as the relay that drives the rear window defroster grid.

Another way that can serve without a meter is to connect and disconnect the negative terminal battery with loads off. You can see better out of the sun. Do you see a spark? If so, look to loads being engaged. Pull fuses etc to try to find the cause, or engage somebody to track this down for you. A good mechanic would be efficient. Your friends might get into it if you have more time. Troubleshooting that stuff can be fun if you are not time-sensitive.

Yes, but it seems less likely based upon what I am reading.

One safety comment: remove the negative terminal first and attach it last. That way if your wrench touches the chassis, there is no fire/explosion.

And while you are troubleshooting, you can just keep that one terminal disconnected rather than moving the whole battery to the back seat.

Reply to
Tom's VR6

I meant into a 50 amp-hr battery.

Reply to
Tom's VR6

One option is to measure the draw (WITH THE CAR OFF)--use an ammeter inline between the battery positive and battery cable (i.e. disconnect battery positive cable from battery, use ammeter or multimeter between battery and cable, and see draw); if you notice a significant draw, start pulling fuses one at a time until it goes away. The fuse you just pulled is for the problem circuit, which most likely is either (a) stuck on, a la a trunk light with a bad switch or (b) has a short to ground of some sort that allows for ongoing drain even when it should be off. Note that most cheaper multimeters have low-current ammeters; mine tops out at 10A (unfused, no less, but that's why I got the warranty), so you should be fine doing this for a small drain but would probably be ill-advised to do it for a particularly large one.

Another option, somewhat less scientific, is to pull a few fuses each time you park the car and narrow it down that way. Of course, you might want to make sure you have a source for a jump if you don't happen to pull the right fuses, but you should eventually figure it out.

Finally, don't forget to check general charging system health; I went through three alternators on my Jetta before realizing that the alternator cable had corroded inside one of the end lug connectors, so it would make a good connection wiggled one way and not the other (and eventually fell out altogether with the connector still on the starter bolt, hence me noticing). So you should probably check the condition of the battery cables as well as the starter->alternator cable (corrosion on the ends should be at least cleaned up and may indicate more serious corrosion inside the cables that needs to be addressed) and the output of the alternator. I'd expect that, given the scenarios you've described, the alternator is probably working at least reasonably well; however, poor general charging system health will exacerbate a slow drain pretty quickly.

Reply to
Kevin 'Sparty' Broderick

Then it isn't holding too much charge. It should take several hours to recharge. Take it in & get it checked - how old is this battery anyway?

I.

Reply to
Iain Miller

Thanks for all the help folks.

I recharged the battery again overnight on a 2amp trickle with much better results. Its reading 13.5 volts now. I noticed a lot of corrosion on the positive connector and post (we've had like 200 tons of rain in the past 2 weeks) so I cleaned the post, replaced the connector and its running fine.

Chris

Reply to
Chris Etzel

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