who is stealing my aux power?

[jkidd152]

At the risk of exposing myself as a true idiot, here is my first question/problem for you wise ones:

I just set up my auxilliary battery in my 1985 vanagon gl westy. I used a very simple setup because my needs are modest. I ran a wire from the main through a Busdepot relay to the positive on the aux battery. I also have the sink/fridge wire running through the relay onto the positive terminal. The third and last thing on the aux is a 12v outlet which is connected directly (don't worry! has a fuse!) to both pos and neg terminals. Of course the neg terminal is also grounded to the frame. It would seem to be a success. When the engine is running, the voltage goes up telling me the alternator is charging it. But the battery keeps going dead overnight. Yes, the fridge switch is on shore power. Any suggestions? I plan to disconnect the 12v outlet and wait and see if it's the culprit.
I still want to divert my radio and lights to aux power but this is slowin me down.

Thanks for your time!
John
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'85 Syncro Westy

[MarkWard]

Sounds like a fairly basic setup. To drain the battery overnight is a pretty good draw. I am wondering if the battery is new? Is the relay actually isolating the battery with the key off? A simple test would be to put a test light between the auxilary battery and it's ground. If the light lights, you have a draw. You then need to disconnect one by one your auxilary consumers until the test light goes out. If it does not, then you can bet the relay is not isolating the van's running system. The factory relay was designed to be "energized" by the engine starting and the alternator charging. This kept the refrig from working unless the engine was running. Let us know what you find.
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[PDXWesty]

Check the voltage at the battery and check it at the alternator output. It may also be that your alternator in not putting out high enough voltage to properly charge the battery, or the voltage by the time it gets to the battery is too low. Check it with the engine running and some load like the headlights on. The alternator output should be 13.7-14.0 and you should see no more that .2-.3 volts drop at the battery. Good luck!
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89 Westy 2.1 Auto

[jkidd152]

thanks for the advice. i will perform the suggested tests and let you know what i find.
just to clarify a few details i left out:
the aux battery is brand new. it's a Werker 44ah sealed deep cycle battery from Batteries Plus. fits perfect by the way with no mods to the compartment and the seat can still swivel. people are always asking what fits....

i did a voltage test after the first mysterious discharge. (and subsequent recharge). both batteries were 12v. started the big 1.9L motor and starter batt jumped up around 13.5. aux battery went up around 13. not as high but still receiving alternator current. couple hours later, i checked the aux battery and again saw around 12v. the next afternoon, the aux battery was dead and the car had not been driven.

thanks again. if this work day ever ends, i can get into my garage and figure this out.
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'85 Syncro Westy

[PDXWesty]

AGM batteries take a higer voltage to charge and get to 100%. My guess is you don't have sufficient voltage to fully charge your battery to 100%. Do an internet search on "agm battery charging" and you'll see that 14.4 volts is recommended for charging an AGM battery.
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89 Westy 2.1 Auto

[jkidd152]

i put a test light between the 12v outlet and the POS terminal and nothing. i put a test light between the fridge/sink wire and POS terminal and nothing. finally i touched the wire from the main (that runs through the bus depot relay) while the clip was on the POS terminal of the aux battery and BAM! sparks, light for a second, now my test light is toast. haha. that was cool. that thing was cheap anyway. my trusty multimeter, however, shows 10.8 (on load test setting).

any ideas why that would be drawing so hard off the main battery?
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'85 Syncro Westy

[MarkWard]

It sounds like you are not testing correctly if I understood your last post. When you check from the positive of the battery to the positive of any part, the test light should not light. A dvom could show a low voltage. That amount would be considered the voltage "drop". Let me provide a simpler way to check for a draw. Remove the battery ground cable from the battery. Wait 15 seconds and then touch the ground cable back to the battery. Did you hear a spark? If so, you have a draw. If not, you can look elsewhere. To draw a battery down overnight, I'd expect a 1 amp draw or more. Depending on the draw, the bigger the spark. Putting a 12 volt test light inline with the ground cable is a way to "see" the draw, not measure it. To measure a draw, you'd need to have a sensitive inductive amp meter pickup or an inline amp meter that can read small loads.

At this point, I would suggest disconnecting both batteries and fully charging them. Testing charging systems accurately require good batteries. Also, the wiring on the factory fridge radiator relay is a little confusing. Looking at the relay it appears that it is wired to supply power on both 87 terminals, which it can. But if you check the Bentley manual, the relay is not wired conventionally. It is wired so the fridge/sink panel has power regardless of if the engine is running or not. It would be easy to confuse these 3 wires on the relay. Regards.
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[jkidd152]

well, i can at least now say that the culprit of all this is the wire from the main battery. last night, i disconnected all consumers except the main battery connection. this morning the auxiliarly battery was considerably down.

is it enough to simply say i have the relay connections mixed up? or could the problem be lurking elsewhere?
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'85 Syncro Westy

[PDXWesty]

if the main battery is bad, it will draw down the other battery if they are connected. The wiring mat be incorrect or you have a bad relay too. I still suspect the charging system as well.
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89 Westy 2.1 Auto

[jkidd152]

the charging system is suspect even though the car has not been driven?
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'85 Syncro Westy

[MarkWard]

If you are using the stock relay, an improved relay, yandina, or isolator. With the engine off, the batteries should be isolated from each other. If not, something is miswired or the relay is defective. The Bentley manual is not exactly clear on this wiring. I believe there are more variations than the manual wiring diagrams show. Basically, the relay has one wire that is hot all the time from the charging system. It has a ground wire which is brown. The earlier ones had a blue wire from the Alternator, later models show this blue wire to be red and black and then two heavy leads for the kitchen. One is cross connected to the charging system for the power of the sink pump and the display panel. The other heavy lead is for the fridge. One is on an 8 amp fuse the other is on a 16 amp fuse. These should be on the door pillar behind the driver's seat.
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[Turk.380]

Almost since the day I bought my van I'd had a "phantom load" on my AUX battery that would suck an Optima Yellow-Top dead in just 3-4 days!

Off and on over the next 3 years I poked around for it but never hit pay dirt. I just lef the van hooked up to shore power with a charger when parked...

Finally this summer I decided to do some under-dash work, and I found that my GPS / stereo interface box (I have a doodad for my TomTom that mutes the radio and announces the intructions over the car speakers) was warm.

Turns out that in the loom for that dealy, there was a jumper wire set incorrectly that controls wether it's on with the key or not. Since I have my stereo wired up to the AUX batter for tunes while camping, I needed to swap over that hidden jumper so that 4 AMP(!!) draw wouldn't be on all the time.


Morale of the story - if you have your wiring modified so that your radio, dash socket, etc are powered by the AUX battery, start checking your audio equipment first!
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Brian W
St. Louis, MO
'64 SO-33 Hatch Top Westy | '87 Syncro Westy: Subaru EZ30D powered | 2002 VW Winnebago Vista

[Bercilak]

As a variation on the stereo theme, my stereo is wired to the aux battery (Odyssey 1200). The stereo has two "off" modes; first is sleep, the second is off. In "sleep" mode, it'll kill a fully charged battery in 2-3 days. Never checked the draw, but my aux battery has either one or two trickle chargers connected to it at all times here in sunny so-cal, and the stereo still kills it.

Also, if it's been warmish up your way, then note that the cooling fan for the fridge is temperature triggered, and works whether the fridge is on or not. Many's the time that fan has been on even on days that weren't all that hot. With the van closed up and in the sun, temperatures rise...

Those are two obvious issues, given your info above, and it's where I'd start.

Best,

B.