Connect a ctek battery conditioner to battery or engine posts?

mikedelta · Post by **mikedelta** » Sat Oct 05, 2019 11:23 am

I've just bought an E89 Z4 which will be for occasional, fun use. As it will not be used frequently over the winter I will connect a ctek battery conditioner but do I connect directly to the battery terminals or to the jump start connections under the bonnet? I don't want to fry an ecu or electronics etc.

Spot the dinosaur! I'm not up on modern car electronic systems.

Smartbear · Post by **Smartbear** » Sat Oct 05, 2019 11:36 am

mikedelta wrote: ↑Sat Oct 05, 2019 11:23 am I've just bought an E89 Z4 which will be for occasional, fun use. As it will not be used frequently over the winter I will connect a ctek battery conditioner but do I connect directly to the battery terminals or to the jump start connections under the bonnet? I don't want to fry an ecu or electronics etc.

Spot the dinosaur! I'm not up on modern car electronic systems.

It doesn’t really make any difference, some say any sparks near the battery will cause a nuclear explosion but cases seem very rare

Rob

ph001 · Post by **ph001** » Sat Oct 05, 2019 12:03 pm

The E89 has an IBS module which monitors the state of charge of the battery so if you bypass this by going straight on the battery it will contain incorrect information. Now personally I don’t think that is a major issue as the real time information that the IBS gathers will eventually sort it out (which is also why I believe battery coding is just a big money spinner). If you are an advocate of battery coding then you should apply the charger to the under bonnet charge points which doesn’t bypass the IBS.

On the E85 / E86 it doesn’t make a blind bit of difference which one you use.

boreas7 · Post by **boreas7** » Sat Oct 05, 2019 12:04 pm

I have the same charger and used the near engine connections. If you feed the mains cable between the engine and scuttle you can shut the bonnet, whereas I'm not sure how you could close the boot without crushing the mains cable. As Rob has said, I think the engine connections are there to prevent the risk of a spark in the vicinity of a battery 'gassing'.

buzyg · Post by **buzyg** » Sat Oct 05, 2019 12:08 pm

I connect mine positive stud first, simply because that is the more awkward stud in the ///M engine bay.

We also have no real option to connect directly on the ///M, as the battery is hiding in the boot.

Busterboo · Post by **Busterboo** » Sat Oct 05, 2019 12:18 pm

Smartbear wrote: ↑Sat Oct 05, 2019 11:36 am It doesn’t really make any difference, some say any sparks near the battery will cause a nuclear explosion but cases seem very rare
Rob

step_change · Post by **step_change** » Sat Oct 05, 2019 12:28 pm

You should connect it to the terminal in the engine bay.

I have hard wired a CTEK connector into my engine bay, they cost £4.99.
https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1

When the car is in the garage (car is always garaged when I am home), lift the bonnet, plug in (CTEK is mounted on the wall right next to the nearside front wheel), bonnet down, switch on, job's a good 'un.

mikedelta · Post by **mikedelta** » Sat Oct 05, 2019 4:08 pm

Thank you everybody, that's great.

Post by **srhutch** » Sat Oct 05, 2019 6:19 pm

buzyg wrote: ↑Sat Oct 05, 2019 12:08 pm I connect mine positive stud first, simply because that is the more awkward stud in the ///M engine bay. We also have no real option to connect directly on the ///M, as the battery is hiding in the boot.

Mines connected directly to the battery in the boot and left with the boot closed.

Plenty of room for the low volt side cable to pass through the seal.

flybobbie · Post by **flybobbie** » Sat Oct 05, 2019 7:00 pm

From the service manual:

Pbondar · Post by **Pbondar** » Sun Oct 06, 2019 4:53 pm

Further / clearer for your question info for an E89 is ...

The battery may only be recharged by means of chargers that have been approved by BMW and that have a constant charging voltage of 14.8 V.
If possible, the battery temperature should be between 15 °C and 25 °C during charging. Under these preconditions, the battery is adequately charged when the charge current drops below 2.5 amps.
If the battery is recharged at lower temperatures, the process should not be ended until the charge current drops below 1.5 amps.
On vehicles with IBS, recharging the battery directly at the battery terminals could lead to a misinterpretation of the battery condition and even unwanted Check Control messages or fault entries.
If the battery is recharged while it is installed, it must be recharged using the jump start terminal points, whenever jump start terminal points are provided in the engine compartment. Only then can you be sure that recharging is correctly recognised by the vehicle electronics on vehicles with intelligent battery sensor (IBS).

Source TIS

Pbondar · Post by **Pbondar** » Sun Oct 06, 2019 5:00 pm

Smartbear wrote: ↑Sat Oct 05, 2019 11:36 am
mikedelta wrote: ↑Sat Oct 05, 2019 11:23 am I've just bought an E89 Z4 which will be for occasional, fun use. As it will not be used frequently over the winter I will connect a ctek battery conditioner but do I connect directly to the battery terminals or to the jump start connections under the bonnet? I don't want to fry an ecu or electronics etc.

Spot the dinosaur! I'm not up on modern car electronic systems.
It doesn’t really make any difference, some say any sparks near the battery will cause a nuclear explosion but cases seem very rare
Rob

AGM batteries as fitted to all E89s are sealed and do not gas, they recombine charging gases back to water internally ..they only gas if incorrectly charged..

ronk · Post by **ronk** » Sun Oct 06, 2019 8:42 pm

My handbook is quite specific - only use the posts in the engine bay - BMW must have their reasons and Im not qualified to argue.
Previous posts over the years on this forum show many ignore this instruction and connect directly to the battery posts and have done so for years, but I'm not taking the risk of frying anything

mikedelta · Post by **mikedelta** » Wed Oct 09, 2019 11:19 am

Right, I shall connect the charger to the posts under the bonnet. Note to self: the positive terminal may be close to the bonnet when closed so watch for that. I'm assuming a ctek charger would do the job/not be a problem/meet with BMW approval. No point in asking the dealer if a ctek meets with approval, they can't even tell me the correct tyre pressures for our 330 coupe.

ph001 · Post by **ph001** » Wed Oct 09, 2019 11:30 am

The BMW branded chargers that the main dealers sell at massively inflated prices are just Ctek units anyway!

Z4-forum.com

Z4-forum.com