Replacing battery on Z4M roadster

louie12 · Post by **louie12** » Sun Jan 15, 2023 12:57 pm

Hi all. Apologies if this has been covered b4 but I couldn't find anything through the search function. I believe there can be issues when changing the battery. How should I go about doing this without causing problems when connecting a new battery? TIA

AndyBeech · Post by **AndyBeech** » Sun Jan 15, 2023 1:24 pm

No issues at all, done it loads of times. Crack on!
Might have to reset windows, takes less than a minute.

Nick W · Post by **Nick W** » Sun Jan 15, 2023 1:38 pm

Or just put a stable 12v supply to the terminals under the bonnet to guarantee no resets but as above you won't do any damage by just swapping.

Mr Tidy · Post by **Mr Tidy** » Sun Jan 15, 2023 8:17 pm

Yes, it's really straightforward - to the extent that I managed to swap mine successfully!

It's only later BMWs that need a new battery to be coded to the car.

louie12 · Post by **louie12** » Mon Jan 16, 2023 8:07 am

Many thanks all.

Argenta · Post by **Argenta** » Tue Jan 17, 2023 5:23 pm

There cannot be issues. Its a traditional setup. Take out. Put in.

SGRG · Post by **SGRG** » Wed Jan 18, 2023 10:14 am

Sorry to hijack the convo OP but has anyone tried any of the light weight batteries available?

I have seen lite blox used on BMWs including E46 M3s. Just wondering if anyone has any first hand experience with this.

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TomK · Post by **TomK** » Wed Jan 18, 2023 3:18 pm

SGRG wrote: ↑Wed Jan 18, 2023 10:14 am Sorry to hijack the convo OP but has anyone tried any of the light weight batteries available?

I've had this in the car since 2018 or so, never had any issues. I also installed a kill switch as the car gets left for long periods of time, always fires up fine as lithium holds charge really well.
https://www.edfmotorsports.co.uk/produc ... rlite-ps20

SGRG · Post by **SGRG** » Wed Jan 18, 2023 3:46 pm

TomK wrote: ↑Wed Jan 18, 2023 3:18 pm
SGRG wrote: ↑Wed Jan 18, 2023 10:14 am Sorry to hijack the convo OP but has anyone tried any of the light weight batteries available?
I've had this in the car since 2018 or so, never had any issues. I also installed a kill switch as the car gets left for long periods of time, always fires up fine as lithium holds charge really well.
https://www.edfmotorsports.co.uk/produc ... rlite-ps20

Thanks Tom for the response.

That is quite the weight saving there compare to run of the mill battery from Halfords for our cars. Did you have to make any modifications to the battery housing to fit the new one?

173x87x154mm (2.40 kg)
vs
278x175x190mm (19.5 kg) Halfords

TomK · Post by **TomK** » Wed Jan 18, 2023 4:15 pm

SGRG wrote: ↑Wed Jan 18, 2023 3:46 pm Thanks Tom for the response.

That is quite weight saving there compare to run of the mill battery from Halfords for our cars. Did you have to make any modifications to the battery housing to fit the new one?

173x87x154mm (2.40 kg)
vs
278x175x190mm (19.5 kg) Halfords

Yes it is a big difference. I imagine you could fairly easily mount it in the normal spot, my idea originally was to mount it to the bulkhead in order to fit the boot trim from a 3.0si and gain back the battery box space, however in the end I cut the bulkhead out and put a cage in.

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SGRG · Post by **SGRG** » Wed Jan 18, 2023 4:53 pm

TomK wrote: ↑Wed Jan 18, 2023 4:15 pm
SGRG wrote: ↑Wed Jan 18, 2023 3:46 pm Thanks Tom for the response.

That is quite weight saving there compare to run of the mill battery from Halfords for our cars. Did you have to make any modifications to the battery housing to fit the new one?

173x87x154mm (2.40 kg)
vs
278x175x190mm (19.5 kg) Halfords
Yes it is a big difference. I imagine you could fairly easily mount it in the normal spot, my idea originally was to mount it to the bulkhead in order to fit the boot trim from a 3.0si and gain back the battery box space, however in the end I cut the bulkhead out and put a cage in.
IMG-20190130-WA0003.jpg
IMG-20190625-WA0001.jpg

Yeah that is what I want to do as well, add the e86 boot fitting to gain back some of that space.

TomK · Post by **TomK** » Wed Jan 18, 2023 5:30 pm

SGRG wrote: ↑Wed Jan 18, 2023 4:53 pm Yeah that is what I want to do as well, add the e86 boot fitting to gain back some of that space.

It's doable I'm sure. In an ideal world the battery would be thinner but I couldn't find anything more suitable at the time. Keep in mind that you would probably want to cut some kind of access holes through the trim to allow connecting the battery charger supplied (I'm not sure I'd want to charge it through the bonnet terminals, but maybe that's fine I don't know). And, if you have a 10 speaker sound system the amp will also be on the bulkhead. I can't remember on mine if that was an issue, as you can see I had removed it at that point, but I'm sure you could probably figure something out.

buzyg · Post by **buzyg** » Wed Jan 18, 2023 7:49 pm

There were a few isues with the sat nav getting damaged. I recall the advice was to be certain the battery was off the car for at least a minute. before the new one was fitted. Took me longer than that any way. Never had an issues changed the battery twice while I had the car.

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