E30 Zone

Hi
My 326i is SORN at the moment but I do not want to let the battrey go flat. I have read a couple of articals that suggest disconnecting the battery from the car before connecting a charger
to protect the ECU. So should I disconnect the positive lead from the battery when the battery is on trickle charge.
Ted

It shouldn't really make any difference, assuming the "intelligent" battery charger does what it's supposed to...

But if your car is going to be off the road for some time, it's wise to disconnect the battery anyway. Beware though, that doing this could adversely affect the SI board batteries.

Thank you for the ifo. Just trying to work out why my ECU failed. Sadly she does spend a lot time off the road, Mr Kahn charges me £12.50 every time i take it out of the garage.
Regards Ted.

Ted_BNJ wrote: ↑

Fri Jun 27, 2025 11:42 am

Thank you for the ifo. Just trying to work out why my ECU failed. Sadly she does spend a lot time off the road, Mr Kahn charges me £12.50 every time i take it out of the garage.
Regards Ted.

Taking the lead on and off can sometimes cause an issue if you dally about and get a spark while doing it. As above leaving it all connected should not be a problem for a good charger (I use a few Ctek 5a chargers that do the job of maintenance charging really well)

I would guess that if you opened your old one it would simply be an old failed component, dry solder joint or a bit of moisture corrosion

Glad it is sorted now though

To help out a bit ,does anyone have a link for an "intelligent" charger ?

Mart.

https://www.ctek.com/uk/smart-battery-charger

Lidl do a cheap version (about £15) which does the job, too.

Ben

Second the Ctek, I've had 2 for a few years now and been great.

Hi.
I use the CTek MXS 5.0. found it excelent.
Ted

I have had 3 of them in the last 12 years and been happy with them. One of them went faulty after about 10 years and Ctek could not repair it so I bought a replacement. The good thing is you do not have to disconnect the battery when charging. Ctek also sell connecting lead with the plug so it makes it simple to connect (can also be part of the kit). It’s also got a desulphate mode to rejuvenate deeply discharged batteries. I think the battery in my E30 is about 15 years old.

Hi,

My car is SORN'd over the winter and I do not disconnect the battery, it sits there with a trickle charger without any issues. The trickle charge is designed to keep the battery in good shape and you don't have to worry about your SI(?) batteries.

I use the NOCO genius 5 as I found the Ctek didn't last.

The intelligent charger helps save batteries and the SI batteries as well.