Engine battery drain?

[Bison535]

1990 VW T25 Vanagon Campervan 1.9 TCD

My fully charged engine battery ‘drains’ over a period of 4-5 days whilst parked !?! The battery becomes too low a voltage to start the engine!?!

I have used Harry Mann’s light bulb method ( previous post ) to detect the general location of ‘the drain’. It is apparent the ‘drain’ is via the thinner red cable from the battery positive terminal which goes to the engine bay ( little black box LH side ) that contains a bunch of wires and a big fuse !?!
I’m now stuck to identify the actual drain culprit?

Any help, suggestions appreciated please?

Meanwhile, I have disconnected the battery terminals to preserve the voltage.

[TONYT25T25]

Could be an alarm system which remains active even in listening mode, internal light, radio backup to retain memory. Also has the battery been allowed to fully discharge as they rarely recover from this.

[mioba]

How old is the battery. Could just be that cold weather has picked out an old weak battery.

Have you upgraded anything in the bus, new stereo for eg.

[Bison535]

Thanks for your responses guys ! Battery was new this year and has just been fully charged and load tested, so that is ok. I took out the old alarm system so no drain there ! Checked lights etc.

The constant drain is via the red cable (small) which is attached to the Positive block on the battery. This cable runs around the engine bay and up into the Black Box on the LH side. Inside the Black Box is a buggers muddle of wires !!?? So, i dont know where the red wire feeds ?

[multisi]

Shinnster had a battery drain problem and a new ignition switch fixed the problem.

[AngeloEvs]

Fit an isolating switch in the earth side of the battery, not just to isolate it from any potential current drain sources, Radio, Alarm, Fault, etc, but as a safety measure in the event of a short circuit fault that can destroy a loom or start a fire.

[Shinnster]

Shinnster had a battery drain problem and a new ignition switch fixed the problem.

i can confirm thats what my issue was. the guy that found the issue probed the wires on the switch with his lighty screwdriver (technical term) and it showed power was still coming out the switch even without a key in.
hopefully yours is an easy fix like mine was.

i also have a kill switch too just for good measure now!

[Bison535]

Hi guys, thanks for your thoughts/checks. I also fitted negative battery cable switches to both Engine and Service Batteries to 1. protect against leakage 2. As an anti theft device

My ignition switch was replaced not long ago, but will need checking !

What is the Black Box in the LH side of the engine bay ? The thinner red cable from the battery positive leads into that box and that is the cable which is showing a drain via the light bulb test!!!

[Robsey]

The black box to the left should be the engine-bay junction box.

Dependent upon model year, fuel control system and any extras, there will be a whole array of wires coming from this.

The red would be quite a thick wire, and acts as battery live to any heavy consumers in the engine bay.

You say you have a 1.9 TCD, so assuming retro-fit diesel engine.

My "guess" would be that the red wire would feed any one of the following:-
1 - diesel glow-plug relay.
2 - manifold heater via thermo switch
3 - diesel ecu
4 - fuel pump / injector relay
It would also feed back to the alternator too.

Assuming no battery light issue on the dash, we can probably rule out a faulty alternator regulator pack.

So my first thought is a sticking relay, or a faulty manifold thermo-switch.

[Bison535]

Thanks Robsey, good thinking, ive pulled the relays and temp sensors but did not affect the drain ! I also opened up the Ignition Switch and taht seems ok (replaced new about 18 months ago.

I then checked the fuse panel (should have done this first off !!!) and pulled fuses 1 by 1 and found the culprit; No 3 Fuse feeds radio, cigarrete lighter and interior lights; its one of these ! Rain stop play, so further checks needed tommorow and hopefully will find the cause of battery drain

[AngeloEvs]

Most likely the Radio which requires connection to the battery to maintain its memory circuit. Without the memory you would have to tune every channel when switching it on. If you don’t mind doing that you will need to isolate the non ignition feed to the radio.

[Robsey]

I agree - the "usual" culpret is the radio.
It is a very common issue.

The cigarette lighter is a possible if has something plugged in. As it is still live with the ignition is off.

Me personally - I would probably change the cigarette lighter supply voltage to either an ignition live or X-Relief Relay live

Interior lights - not uncommon, although I would hope you could spot an interior light during these cold dark winter nights.

The red wire to the rear junction box is a bit of a red herring in this situation.

[mioba]

Hence my mention if the OP has recently upgraded the stereo. Sony are notorious for battery drain.

If I leave my bus 3 weeks the battery struggles due to the stereo. I remove the fuse on exit.

Interior lights - good call. I have led lights in my bus and noticed the other week the LED is very very dim with the passenger door closed. A few presses of the switch and it works normally - however the switch is sticking even after cleaning. So I have ordered 3 from BW to change them all. Cheap as chips.

Ign live are not straight forward - blue wire on alternator.

[Splurt]

I had a faulty interior light with the previous camper that killed a few batteries before i figured it out.  It was a westy fluorescent tube light and the starter had gone.  It was hot to touch even with the light switched off.  Replaced both fluorescent tubes with led strips, worthwhile mod

[Robsey]

Ign live are not straight forward - blue wire on alternator.

Blue from the alternator is the charge light output, and carries 12 volts when the engine is running.
This is often used to control split charge relays.

Ignition live is usually black.
These wires carry 12 volts with the ignition key in the on position, regardless of whether the engine is running or not.

And X / relief relay live carries 12 volts with the ignition on but NOT during the starter cranking phase.
These wires are often black with a coloured stripe (yellow or white).

Sorry if it sounds like I am being pedantic, but it is good to know what the various wire colours are designed to do.

It should then help to explain whether a circuit is working properly or not.