E30 Zone

Hi everyone, I've been trying to sort out a perennial problem with my car and need some advice.

Basically, my car has always had a habit of running its battery flat in a few days when parked. This is quite annoying - it's like having a remote control car I have to charge every time before I can use it!

So far I have determined:
Current drain when parked: approx. 113mA

of which...
OBC takes 4mA
Alarm (aftermarket) takes around 30mA
the rest (roughly 80mA) is taken by the instrument cluster, for memory storage and SI battery charging as far as I can tell.

What I need to know is:
1) Does this drain seem high or about right?
2) If it's high has anyone got any idea what might be wrong in the cluster? I've had a look inside it and couldn't find anything untoward on the relevant PCB tracks.
3) If it's normal what can I do about this - maybe get a battery cut off installed?

Cheers!

H

I had this with my old 325i. turned out to be the light in the boot not turning off. I found this out after a new battery. Justt an idea for you

Rich

Hi Rich thanks for the suggestion...I removed the light from the boot some time ago though in the hope it would sort it but it wasn't that I'm afraid!

Hi

Just an idea for you. good luck with it

Rich25i wrote:H

I had this with my old 325i. turned out to be the light in the boot not turning off. I found this out after a new battery. Justt an idea for you

Rich

Same here! 1st thing i'd try now if i have the problem again!

Have e30's got a glovebox light? (I'm e30-less at the moment )

Funny you should mention that - the drain I'm seeing is all through fuse 21 (except the alarm which is on 25), which the glovebox light is on.

It turns out that the bulb is actually stuck into the top of the switch! I'd always wondered where it was and I was surprised to discover this when I yanked out the switch for a laugh yesterday (as you do)...bulb was dead but I happened to have a spare. Must have been my lucky day

I've run e30s for 20 years and had my current 325 convertible since new in 1992. Like yours it has OBC and an aftermarket alarm (Piranha). The boot light does go off as it should.

I can tell you it's needed a new battery every second year to the month as regular as clockwork even when it was being regularly used.

In the last few years I have used it less and less and I now keep a top-up charger running in through the cigarette lighter which helps a lot. Before I did that the battery would run completely flat in about 3 weeks of non-use (this of course shortens battery life hugely).

I rationalised it like this: if background current draw is ~100 mA, then after three weeks that has used 3 x 7 x 24 x 0.100 = 50 Ahr. This is pretty well the full capacity of an alleged 65 Ahr battery after a bit of “running inâ€a. So it's no surprise that with a 100 mA current draw you get flats and lousy battery life if you don't use the car say twice a week.

I never pinned down whether this draw of 100mA is normal but I will say that other cars of the 1980's had this problem and it's probably inherent in the type of electronics of the day. Clearly our SI boards and the methods they use are prehistoric c.f. modern electronics.

Andrew

unfortunately for you, this is a totaly normal parasitic load as far as I'm aware... But shouldn't drain your battery in a couple of days... What's your battery condition like? (full charge and heavy-discharge test)

Happy to have confirmation that 100-110mA is a normal load; I had always suspected it was. I agree that our unusually named friend must have something wrong with his battery. Is it related to his name we wonder?

Andrew

AndrewL wrote:our unusually named friend [...] Is it related to his name we wonder?

There is a subtility I don't get here...

Both my Cab and SE drain there batteries within 5 days if I don't use them. New batteries in both. So far I havn't found the problem ! I've removed bulbs from glovebox and boot ! Someone suggested it could be the "diode" pack on the alternator, Although i havn't proved it yet !

3 weeks to a flat is explicable by normal quiescent drain current as I have shown. 3 days must be a fault condition if the battery is good.

Incidentally when my alternator diode pack failed the lighting circuits (headlamps, dashboard lights) pulsed noticeably after dark but not all failure modes may be the same. Replacement was a 20 minute job with the dealer supplied part being surprisingly reasonable.

Andrew

MY 320I CONVERTIBLE IS THE SAME 2 TO 3 DAYS IF NOT USED BATTERY IS FLAT CHECKED ALL THE SAME THINGS AS ALL YOU GUYS BATTERY IS GOT HAD TEST DONE WAS PUT DOWN TO OLD ELECTRICS AND CLIFFORD ALARM/IMMOB AS MY E34 530 WAS JUST THE SAME ALSO HAD CLIFFORD

This is great! Thanks for all the replies ladies and gents. I kinda figured it would be 'normal', these are old electronics now so probably not terribly low power in standby, and my Clifford only compounds this I guess.

I'm not sure completely how long it takes my battery to drain - 'a few days' was just ballpark. I think it's probably somewhere between a week to two weeks to get flat enough that it won't turn over so this all tallies with the above replies.

Left disconnected the battery will hold a charge for a very long time so I think it's still good, though like Andrew I've been through 3 batteries in the last few years with this car so it's worth monitoring! My car is pretty much used as a toy rather than a daily driver so I might just get a battery cut-off for when it's parked up.

I'm intrigued by this diode pack problem though, my lights do pulse noticeably when on idle so maybe it's worth checking. I seem to recall accidentally pouring a load of coolant over the alternator when I was overhauling the cooling system which can't help it! If it's a cheap replacement it can't do any harm to try...

Don't worry about the name - I'm a bit of a Rage Against the Machine fan; it crops up in their music here and there and it just amused me! Nothing sinister there I'm quite nice really!

Thanks again for everyone's help!

It definitely sounds to me as if your diode pack is shot. I tried around but found the dealer best in the end. There are mainly two types of alternator on these cars (Bosch and a French unit; mine was French). The pack was about £40 from memory and 20 mins is an overestimate if anything. Only tricky part I remember was wiggling it into position around the alternator mounting bracket which in the end I didn't have to adjust.

Andrew

PS. Fixing this probably won't affect the drain problem except inasmuch as it gives your battery a better charge.

Thanks Andrew, I'll be looking into this...

I've never had problems with my battery over the years whether i drive the car or not, until last the last four days where each day the battery has got increasingly weaker. This morning it would turn over at all! It has been used continuously over the last few days. - Would this suggest a faulty battery or alternator? or diode as above (which does what exactly chaps?)

Much appreciated
Jason

First a comment on the thread above, which I must have missed the first time around. 100mA is definitely not a normal drain for an E30! 30mA is about the going rate.
Jay07 - If the red battery light doesn't come on, there's no reason to suspect that it's an alternator fault.
The most likely explanation is a simple dud battery, but you need to get a voltmeter across the battery terminals when the engine is running as a first step towards finding the problem.

hi i had the same problem with my bmw 320i it kept running out after a couple of days after charging it. I took out all of the fuses (apart from the big ones) it turned out to be the seat heater relay which was causing it to drain so i've never put it back in since and the batterys kept a charge so that could be the problem if you havent got the leather seats with heaters with them.


hope this helps

Same problem with my 86 cab, even with a sloar powered battery charger. Take out fuse 27, central locking, after i park up and never had the problem since. Not the ideal solution i know, but works for me.

Hi lads!

Thanks for the replies, I never saw your reply before taking the battery out to charge it so i didn't get the chance to check the battery light. I'll put the battery back in later and get the meter out.

I never had battery problems before so i don't want to start looking for short term solutions, I do however appreciate the advice and if i dont fix the problem at least i now have some ares to start checking.

Question: When on charge if one of the battery cells does not bubble does that actually symbolise a faulty cell?

Oh and i unfortunately dont have leathers ....

Cheers

JP

There are three possible reasons for a flat battery:
1) The battery has failed.
2) The battery is not being charged by the alternator.
3) The battery is being drained while the car is stopped.

The key to finding out which, and then to finding the solution is logical testing, not speculation and wild guesses.
The first step to finding out which, is to charge the battery, refit it, then use a meter to measure the voltage across the battery, both with the engine stopped and running.

Check your alarm system my brother had the same problem with his 316 which has a clifford alarm.
he still hasn't resolve it.


After his battery died I gave him a Bosch Silver battery which i use to have on 320 and his car killed it with in a few months.

My 320 had no alarm and i can let it it for month and it will still start.


Good luck

itec i don't have a clifford in there unfortunately.

Well, I tried to go to work on tuesday am and the battery was completely flat again. So i figured dud battery... anyway, after i left, my dad didn't heed my warning and he went to use the car and sods law it started for him. He went about his way but at some point he could start it and got stranded. My Dad believes in calling out the AA whenever possible to get his money's worth. They came tested the battery and confirmed it has had its day and sold him a new one.

The only problem with my dad is he always tells stories to increase the drama with the AA... It can be handy though i had a rover before my e30 and we called them out for that and they were able to identify and idle switch problem that ended up being an easy fix!

Thanks again for all the posts

J