Best way of changing the battery?

step_change · Post by **step_change** » Thu Mar 08, 2018 2:02 pm

Hi,
Can you change a battery by placing a charger on the car's cables that attach to the battery and then remove the battery - keeping the car "powered" by the charger whilst installing the new battery? To save clearing radio codes etc?
What's the best way of doing this pls? My son's Z4 needs a new battery.
Thanks.

Ducklakeview · Post by **Ducklakeview** » Thu Mar 08, 2018 2:03 pm

Not advisable as this can cause voltage spikes when you remove the battery. What year is his car?

Mike

ph001 · Post by **ph001** » Thu Mar 08, 2018 2:14 pm

I have a small 12V lead acid for this on crocodile clips. Works a treat.... https://www.ebay.co.uk/itm/Yuasa-NP1-2- ... SwoFVac1QR

Just do a quick measure of the voltage of both batteries before you connect. Ideally you want them within 0.2V of each other.

Ducklakeview · Post by **Ducklakeview** » Thu Mar 08, 2018 2:17 pm

The reason I asked what year the car is was if it's an E85/6 then yo can simply swap it, there is no radio code and the most you will have to do is reset the clock, and possibly the windows. E89 needs to be told the battery has been swapped via Carly or diagnostic in order to reset the charging parameters.

Mike

step_change · Post by **step_change** » Thu Mar 08, 2018 2:53 pm

Hi and thanks guys,
It's an E89 23 Sdrive.

Ducklakeview · Post by **Ducklakeview** » Thu Mar 08, 2018 3:22 pm

step_change wrote: ↑Thu Mar 08, 2018 2:53 pm Hi and thanks guys,
It's an E89 23 Sdrive.

Again, just a straight swap, but you'll need to tell it about the change so to speak.

Mike

step_change · Post by **step_change** » Thu Mar 08, 2018 5:05 pm

So how to "tell it"? Not everyone has Carly etc...???? If I took it to Kwik-Fit/Halfrauds etc they would do this recoding of the battery?

Is it easy enough to do yourself if you have the Carly app?

ph001 · Post by **ph001** » Thu Mar 08, 2018 5:14 pm

Yeh, most garages that sell batteries can do it. Carly can do it easily too but I think battery registration used to be a bolt on that you had to pay a little extra for - may not be the case now.

Alternatively, you could just not bother registering it! .... https://z4-forum.com/forum/viewtopic.ph ... c&start=15

step_change · Post by **step_change** » Thu Mar 08, 2018 5:26 pm

Thanks!
Just as a matter of interest, since my own E89 (35is) has been in the garage for two weeks locked up I thought I'd measure the voltage across the terminals - battery still connected to the car. 11.68V! WTF!!! I put my Optimate 4 charger/conditioner on it (7 years old). Flashing RED

So I thought I'd start the car and it fired straight away - instantaneously. Measure across the terminals with engine running and 14.8V. So alternator looks good.
Car drove perfectly for 20 minutes drive - and great to drive it again.

Get home and measure again with engine off. 12.21V. But Optimate still Red - maybe not enough juice put into it from the drive. Nothing seems wrong with the car or battery and previous owner Keith always used a CTEK conditioner on it when in the garage.

My Optimate 4 is fine with my marine lead acid batteries.

Does the measuring circuitry in the more modern BMW's influence what these charger thingy's say????
Steve

mcbutler · Post by **mcbutler** » Thu Mar 08, 2018 5:31 pm

step_change wrote: ↑Thu Mar 08, 2018 5:05 pm So how to "tell it"? Not everyone has Carly etc...???? If I took it to Kwik-Fit/Halfrauds etc they would do this recoding of the battery?

Is it easy enough to do yourself if you have the Carly app?

its not 'essential' just desirable.. The car will still run quite happily if you don't tell it (code it)..

ph001 · Post by **ph001** » Thu Mar 08, 2018 5:43 pm

step_change wrote: ↑Thu Mar 08, 2018 5:26 pm Thanks!
Just as a matter of interest, since my own E89 (35is) has been in the garage for two weeks locked up I thought I'd measure the voltage across the terminals - battery still connected to the car. 11.68V! WTF!!! I put my Optimate 4 charger/conditioner on it (7 years old). Flashing RED So I thought I'd start the car and it fired straight away - instantaneously. Measure across the terminals with engine running and 14.8V. So alternator looks good.
Car drove perfectly for 20 minutes drive - and great to drive it again.

Get home and measure again with engine off. 12.21V. But Optimate still Red - maybe not enough juice put into it from the drive. Nothing seems wrong with the car or battery and previous owner Keith always used a CTEK conditioner on it when in the garage.

My Optimate 4 is fine with my marine lead acid batteries.

Does the measuring circuitry in the more modern BMW's influence what these charger thingy's say????
Steve

11.68V is pretty highly discharged so yes, it would definitely need more than a 20 min drive to fully recharge. The reason your optimate charger is red is that the battery is still taking current from the charger (bulk charge), which is understandable from such a short drive. The led will only go yellow / green after the voltage has reached around 14.3V or so. The optimate 4 is a very weedy little charger to be honest and only puts out 1A at best. It would take almost 5 days for it to fully recharge a flat battery....apart from the fact that the Optimate automatically shuts down after 48hrs so you have to disconnect it, turn mains on and off and reconnect it again to finish charging

. They are more of a maintenance charger for storage to be honest.

Also, are you using this directly across the battery or on the charge terminals under the bonnet?

step_change · Post by **step_change** » Thu Mar 08, 2018 5:47 pm

That makes sense mate, thanks.
+Ve on the battery positive terminal and -Ve on the chassis.
What charger do I need then? Will buy one if needs be that can be left in the car.2

ph001 · Post by **ph001** » Thu Mar 08, 2018 5:54 pm

Ctek MXS 5.0... https://www.amazon.co.uk/CTEK-MXS-5-0-T ... B00FC42HAA

...as a slight aside, purists will tell you that you should be using the charge points under the bonnet. Doing it straight across the battery is bypassing the IBS module and screwing up all the IBS data. Personally I think the IBS stuff is a load of crock anyway so I wouldn't be losing any sleep over it!

step_change · Post by **step_change** » Thu Mar 08, 2018 5:57 pm

Is my method of connecting OK? I plan on leaving the thing in the car and just hook it up when in the garage. Already wired in a socket near the rear end of the car for this purpose. And a red rag on the rear view mirror to remind me if it is connected when in the garage!

step_change · Post by **step_change** » Thu Mar 08, 2018 5:59 pm

ph001 wrote: ↑Thu Mar 08, 2018 5:54 pm Ctek MXS 5.0... https://www.amazon.co.uk/CTEK-MXS-5-0-T ... B00FC42HAA

...as a slight aside, purists will tell you that you should be using the charge points under the bonnet. Doing it straight across the battery is bypassing the IBS module and screwing up all the IBS data. Personally I think the IBS stuff is a load of crock anyway so I wouldn't be losing any sleep over it!

Thanks mate. Easier to leave it in the boot all the time IMO. I will put some heat shrink over the CTEK's mains cable so that repeated closing of the boot lid does not start to damage the cable.

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