How to remove the terminal cap on the battery

[jman4582]

I know this is probably a stupid question, but can someone help me take the terminal cap off the positive side of the car battery? I'd like to attach a trickle charger, but the cap won't allow it even when I pop open the middle. I feel like I must be missing something obvious, but the manual is no help, and just yanking it doesn't feel right, either.

I've attached two pics. Any help would be greatly appreciated. Thank you!

[KennyP]

i have always hooked Ctek charger to my car in the engine bay... red cap on the firewall and a big bolt on right side strut tower.

terminal block came off easily when i replaced battery... i think its that small bolt you see on the first picture. loosen it and gently wiggle it off..

https://www.newtis.info/tisv2/a/en/e...older/8IssnW5G

[KennyP]

Charging lead-acid batteries and AGM batteries
Connect to a charger approved by BMW.
If the battery is charged while it is still installed: always connect the charger to the jump start terminal point in the engine compartment.
Fully charge the battery.

[jman4582]

Wow, I had no idea you weren't supposed to hook up directly to the battery. Thank you so much for your help!

[jman4582]

Originally Posted by KennyP

i have always hooked Ctek charger to my car in the engine bay... red cap on the firewall and a big bolt on right side strut tower.

terminal block came off easily when i replaced battery... i think its that small bolt you see on the first picture. loosen it and gently wiggle it off..

https://www.newtis.info/tisv2/a/en/e...older/8IssnW5G

So Ctek is ok to use on a Z4? I don't have to buy the BMW brand charger? Can you please tell me which Ctek model you have?

[KennyP]

Originally Posted by jman4582

So Ctek is ok to use on a Z4? I don't have to buy the BMW brand charger? Can you please tell me which Ctek model you have?

Ctek makes many Oem chargers... OEM chargers are often Ctek chargers with car brand logo on it.. Bentley, Ferrari etc. BMW uses them too.

Ctek also works with AGM batteries. Our cars use that type of batteries.

I have a bigger model MXS 25. i had rather old battery and with almost everything electric on my car+ driving short distances all the time i needed to top up my battery like once a month, maybe once in 2 months, sometimes 3. In the end i got fed up with it and i replaced and registered a new one. I was on original battery. It lasted 10 and a half years. Now with new battery i dont recharge it that often as before.

You probably can get by with something smaller like Ctek model MXS 5.0 and dont really need to get the big MXS 25. MXS 25 is twice as expensive compared to 5.0. Its more powerful, more amps, charges quicker and is meant for professionals, like small workshops and so on, not so much for a home user.
Then again someone once told me that smaller chargers dont bring back dead batteries as well as bigger more powerful chargers like the MXS 25.

[jman4582]

Amazon is telling me the Ctek 5.0 doesn't fit my 2012 Z4. Any idea why?

Also, in shopping for the Ctek MXS 5.0, I've noticed there's an AGM setting and an AGM/Reconditioning setting. Which setting do you use?

Thanks again for the info. It's all a huge help.

[Bob20124]

I've been running CTEK MUS4.3 connected to the battery for 7+ years with no problems. Original battery lasted 7 yrs.

[KennyP]

Hmm I actually dont know why amazon would say that...it sells million things and cant always be correct, can it? Maybe cables too short... under the hood its quite a stretch from red terminal to the bolt on shocktower. they are more apart than for example e90 3 series. My MXS 25 barely reached the terminals cablewize. Maybe they sell longer cables extra. If so its probably not a bad idea to get them.
I have seen MXS 5.0 used on 3 series on youtube. it should work.

https://www.youtube.com/watch?v=iUiQeSP74ns

https://www.youtube.com/watch?v=IdZES5CQz9I

AGM setting is correct. If your ctek model does not have it then Normal is correct. Reconditioning is for led acid batteries not for glass mat or gel. Reconditioning pumps higher voltages through the battery to revive it...over 15 volts... but thats not good for AGM batteries. Thats what i have read.

[KennyP]

Its better to use terminals in the engine compartment because Bmw uses intelligent battery management system and has IBS (intelligent battery sensor) that measures voltages, amps temps, calculates state of charge and state of health of the battery.It even logs history. If you charge directly BMW system with that sensor probably cant see the charging and or protect the battery by cutting power and so on.

Notes for Service department
General notes
Notice! Charging and trickle charging of the battery
The battery may only be recharged with a battery charger that has been approved by BMW and that has a constant charging voltage of 14.8V.

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.

[B]If the battery is recharged at low temperatures, the charging procedure should not be ended until the charge current drops below 1.5 A.

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 charging is correctly recognised by the vehicle electronics on vehicles with an intelligent battery sensor (IBS).

Except for MINI from R55 model: These vehicles do not have any jump start terminal points in the engine compartment. On these vehicles, the positive terminal of the battery charger must be directly connected to the battery. On vehicles with a petrol engine, the negative terminal can be connected to the lifting eye (suspension lug) on the transmission and on vehicles with diesel engines to a flange on the engine bearing block on the engine.

Im not saying charging directly wont work. it probably does. Im just pointing out proper, meant to be way to do it.
I know people who just got some random cheap battery, didnt check if its AGM or same Ah rating and just replaced their battery. Did not register it or anything.
Car does work and drive. This particular case was on e60 5 series and they have that IBS power management stuff in them aswell.

[jman4582]

If it has to be a constant voltage of 14.8V, how come the Ctek 5.0 is acceptable? It is only 12V, correct?

[KennyP]

Originally Posted by jman4582

If it has to be a constant voltage of 14.8V, how come the Ctek 5.0 is acceptable? It is only 12V, correct?

NO.

normal mode is 14.4V
AGM is 14.7V
Recond. is 15.8V i think for one extra step...

Its all in the manual, all the steps charger does and so on:

https://www.ctek.com/storage/D834312...-low-AU-EN.pdf

[KennyP]

https://shop.bmw.co.uk/bmw-uk-respon...arger/2408593/

This is BMW branded charger. If you check all the specs and information its basically identical to CTEK MXS 5.0.

[jman4582]

I'm sold. Ctek, it is. Thanks again for walking me through all this. I really appreciate it. It's a HUGE help.

[KennyP]

Originally Posted by jman4582

I'm sold. Ctek, it is. Thanks again for walking me through all this. I really appreciate it. It's a HUGE help.

No problem!

[7thGear]

One thing I'll add is that it isn't necessary to use the negative jumper post in the engine bay for trickle charging. Instead, you can clamp the negative cable to one of the big nuts at the cowl, about a foot away from the positive jumper post. Really any suitable ground point is fine for a trickle charger connection. The alligator clip cable that comes with the CTEK won't reach between the two jumper posts, so you'd have to separate the two leads to make it work. Doing that isn't necessary if you just use a nut or bolt head.

[KennyP]

Originally Posted by 7thGear

One thing I'll add is that it isn't necessary to use the negative jumper post in the engine bay for trickle charging. Instead, you can clamp the negative cable to one of the big nuts at the cowl, about a foot away from the positive jumper post. Really any suitable ground point is fine for a trickle charger connection. The alligator clip cable that comes with the CTEK won't reach between the two jumper posts, so you'd have to separate the two leads to make it work. Doing that isn't necessary if you just use a nut or bolt head.

Great idea! That should work.
Mine barely reached to original locations.

[7thGear]

Originally Posted by KennyP

Great idea! That should work.
Mine barely reached to original locations.

Exactly. Instead, connect the negative lead to one of the nuts shown in the circle: