Battery issues

[Rav]

Yet another problem rears its head.

I woke at 3am for my trip to the toilet - you will understand when you get to my age and on the way back to bed, i decided to look out of the window at my B3. I noted that the red led under the rear view mirror was not blinking.
I went out early this morning to find the battery is completely dead. Even the remote locking will not work and no lights etc on the dash.

So my two questions for you clever people are:

1. How do i know that it is the battery at fault and not a parasitic drain? and.....
2. If i do need a new battery - what specification of battery do i need?

Any help much appreciated.

[BarryM]

Can't help with the spec of a B3 battery Rav but Tim on Meeknet has a pretty good process here to check for parasitic drain: https://www.meeknet.co.uk/e38/E38_Battery_Drain.htm

[jolls]

I used these people for my new battery. Good service and a good choice. I chose a Bosch with a little more poke than the original. https://www.tayna.co.uk/car-batteries/

[Bob]

Can't help with the spec of a B3 battery Rav but Tim on Meeknet has a pretty good process here to check for parasitic drain: https://www.meeknet.co.uk/e38/E38_Battery_Drain.htm

Very useful link, thanks Barry

[Yad3100]

I used these people for my new battery. Good service and a good choice. I chose a Bosch with a little more poke than the original. https://www.tayna.co.uk/car-batteries/

I have bought 3 batteries from them in the last 18 months, one of the few places I could get a square pin for the escort. I would also recommend them.

[Charles]

Like others, I can't help with the possible parasitic drain but a quick search on E46 forums points mostly at the Final Stage Resistor (FSR) which can cause battery drain as it starts to fail, as well as unusual behaviour of the heater fan. This is a common problem on the E46 but be warned as you need to be a contortionist to access and replace it from the driver's side front footwell.

In terms of battery spec, this is from my current battery (which is the same as the previous two and the original one before that):
12V
80Ah
640A

The first replacement was a Bosch Silver (which was a few quid cheaper than the BMW one) but I went back to BMW ones because I knew it was right for the car, the 10% parts discount almost wiped out the difference and the extra costs spread out over 5-6 years was minimal.

BMW part no: 61 21 6 818 784

Hope this helps

[davettf2]

Hi Rav

I fitted a 096 3000 Series Car Battery, Typical Details:

Voltage (V) 12
Technology Standard Battery
Capacity [Ah] 75
Width [mm] 175
Height [mm] 190
Length [mm] 278
Hold-down Type B3
UK Ref No 096

Unable to advise on Battery Drain, sorry

Cheers
Dave

[Rav]

Thanks all. The investigation will begin in earnest tomorrow.

I have swapped out the old battery - Bosch Silver 5 which looks pretty new with an older varta battery i saved from my wifes Audi A6 TDI.
I will see how that holds up and will follow the parasetic drain instructions you have kindly shared.

[Xiaorpowr]

Not sure if all the Alpina owners care about weight reductions, but I've been running a lithium battery in my E46 M3 last 3 years. Went down from a 18kg lead-acid to a 3kg battery. Never looked back... https://www.deadweightindustries.co.uk

[Charles]

Not sure if all the Alpina owners care about weight reductions, but I've been running a lithium battery in my E46 M3 last 3 years. Went down from a 18kg lead-acid to a 3kg battery. Never looked back... https://www.deadweightindustries.co.uk

Just seen the price though

[Xiaorpowr]

Just seen the price though

Yeah I know it's a bit of a shock, but on track cars, weight loss is expensive full stop. Compared to carbon panels, forged wheels, bucket seat, it's actually quite cheap per kg lost... That's my man maths

PS. I dream of a E46 B3 Touring!! I assume you have one based on your profile pic? Does it suffer same subframe / boot floor issue?

[hap]

There is asp B3 E46 tourer currently for sale thread
And another we await the op to add further details

[Trilly_UK]

Like others, I can't help with the possible parasitic drain but a quick search on E46 forums points mostly at the Final Stage Resistor (FSR) which can cause battery drain as it starts to fail, as well as unusual behaviour of the heater fan. This is a common problem on the E46 but be warned as you need to be a contortionist to access and replace it from the driver's side front footwell.

Second this issue. Had this issue on my 330ci which Toby tracked down and swapped out the FSR. Part is about £60 and sort of a DIY job but as Charles mentions it’s tricky to get to. Best thing to do if undertaking yourself is take out the drivers seat to get access. Undo 4 bolts and wiring harness and job done, to get access!

[Charles]

PS. I dream of a E46 B3 Touring!! I assume you have one based on your profile pic? Does it suffer same subframe / boot floor issue?

Yup, I have a 2003 B3S Touring which I've owned from new and am about to clock up 350k miles.

No subframe issues here (all checked recently) but it's a 2003 car and those issues tend to be on earlier cars, I believe

[Xiaorpowr]

Yup, I have a 2003 B3S Touring which I've owned from new and am about to clock up 350k miles.

No subframe issues here (all checked recently) but it's a 2003 car and those issues tend to be on earlier cars, I believe

Wow talk about a high milage hero. Glad to see it's getting used properly! Those S52 engines seem to be a bit less sensitive than S54 engines as well!