Battery Trouble

[Folkmanfan]

I am hoping to get some guidance...

My 87 weekender has killed two batteries.

This began after the Small Car Subaru conversion.

The first one I chalked up to being an old battery, but now with a second casualty this is clearly not the case.

I measured the draw at ~0.5 mA, which seems like it shouldn't be killing the battery.

Thoughts and suggestions welcome.

Thanks

[Steve M.]

Need more info...
Define killing the battery?
What kind of battery?
How old the battery?
Do you have a battery load tester?
Is the battery warm after driving?
What the charging voltage at idle rpm and at 3000rpm?
Did you use a new alternator or a used alternator after the conversion?
What is the battery voltage at the battery right after you shut down after a steady drive?
If you were to disconnect the battery right after stopping for the day, what does the battery voltage read before you reconnect it?
How often do you drive it?
If you don't drive it often do you put the battery charger to keep the battery topped off?

If you walk out to the Vanagon after it sitting overnight and without putting the key in the ignition are any fuses warm to touch? Any relays warm?
_________________
This free advice is worth exactly what you paid for it.

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[Ahwahnee]

[Folkmanfan]

Guys thanks for your reply.

Define killing the battery? Battery no longer holds a charge

What kind of battery? Duralast

How old the battery? Less than a year old

Do you have a battery load tester? I do not

Is the battery warm after driving? I have not checked. I will.

What the charging voltage at idle rpm and at 3000rpm? Forgive me, how do I figure this out

Did you use a new alternator or a used alternator after the conversion? The alternator appears to be the one that came with the Subaru engine


What is the battery voltage at the battery right after you shut down after a steady drive? I have not checked. I will.

If you were to disconnect the battery right after stopping for the day, what does the battery voltage read before you reconnect it? I have not checked. I will.

How often do you drive it? Once weekly

If you don't drive it often do you put the battery charger to keep the battery topped off? Yes - a battery tender

Thanks again for thinking about this problem and taking the time to respond. I will get answers to your questions I haven't answered yet.

Thanks again.

[Wildthings]

Batteries don't charge very well when below 32°F so maybe get an electric heating pad for the battery.

[stevey88]

The battery tender can kill your battery too if the output voltage is too high. I suggest you check that. To be save, build this battery charger :

http://www.instructables.com/id/How-to-Make-a-12V-...dium=email

You don't need a lot of electronic knowledge to build this. Cost a little over $20 plus mounting hardware.

Set the output voltage 13.5V to 13.8V for float charging, set the current to less than an amp. You can also set the current higher if you want to use it as a charger. I set mine to 4A. It will charge the battery at constant current at 4A, when the voltage of the battery goes up, the current will drop, and the current will drop to very low when the battery voltage gets to what you set the output voltage to.

There are many suggestions for the float voltage, find one that you agree with on the web.
_________________
Steve

87 Westfalia full camper 4 speed

[Steve M.]

[termuehlen]

Double check your draw to make sure it is only 0.5mA. If that is the case, I have no answer.

If your draw is more like 0.5A, then disconnect the alternator and check it again. If the draw is eliminated by disconnecting the alternator, I suggest tracing the wiring in the alternator harness. I had this problem about 5 years ago and I switched one of the wires in the alternator harness from B+ to Ign+ in the junction box on the fire wall of the engine compartment, which solved my problem. The alternator was drawing current with the engine off/key out. Switching the connection to Ign+ solved my problem.
_________________
1988 Westfalia automatic Subaru OBD1
1986 syncro tintop wbx

[crazyvwvanman]

Nice little project there stevey88, I might have to build a couple. I could have used your design recently when I put together something similar. I built mine for powering my dc fridge when plugged into AC, while at the same time topping up the aux battery. I needed it to have universal AC input power so that meant most USA chargers couldn't be of use. Mine doesn't have a trim pot for max current though and mine cost a lot more.

Mark

[jberger]

Is your battery dying over time? Meaning, does the van sit for months at a time? If so, any amp draw even MA can contribute to killing a battery.

J

[vanagonjon]

bring the battery back to Autozone and have them check it out.
You said it was Duralast, isn't it warranteed?

John

[davevickery]

I use one of these. It's is more convenient than using a multimeter at the battery and mine is very close to true battery voltage. Most only have one decimal place but this has 2 which is much more accurate. I don't leave it plugged in unless I am on the charger because it by itself uses some power.

I can plug it into the front dash plug and see what the starting battery is at. And with the engine running I can tell if it is charging and at what voltage. I have a 12V plug in back that runs off the house battery so I can check the house battery too (when the van isn't running) and I can tell if the house battery is charging when the van is running.

I can also see how my trickle charger is doing from this. Really handy. And it helps me guesstimate how much my batteries are depleted after a night of running the heater.

If you are trickle chargng your batteries, it should stay charged up all the time. Most trickle chargers would not hurt your battery, they are made to be left on. I would also check that your battery connections are tight. You don't have an OBDII port connected to your subaru all the time do you? That can draw a bit of power.

[stevey88]

Mark,
It is not my design. I actually use an old Sony laptop power supply that can supply 8A instead of the switching power supply module.