Recommendations for battery charger/maintainer.

[philip hedley]

I'm in the process of garaging my Z4 for the winter and was looking for reasonably priced battery charger and maintainer to connect. The AA 6V/12V Smart Trickle Car Battery Charger looks favourite for under £30 looks favourite atm. Does anyone have any preference?
I've read some horror stories of electronics going t#ts up in Z4's and I was going to leave the battery in place but disconnect it before connecting the charger, the radio doesn't seem to have a security code AFAIK, is there anything else I need to be aware of re: car alarm etc.

TIA

 

[Stuartt]

Hi
No need to disconnect the battery just hook up the maintainer to it or to the connection under the bonnet.
CTEK are probably the industry leaders for battery maintainers.

Stuart

 

[mr.tourette]

Everyone seems to rave over ctek but Ive always just hooked mine up to my much cheaper priced motorcycle charges, probably not as quick as designed for smaller batteries but always do the job just fine, if you want one with a digital display the Oxford Oximiser is a decent bit of kit that won't break the bank

Oxford Oximiser 900 Essential Battery Management System, Black/Yellow https://amzn.eu/d/av5yzDv

 

[Nick W]

You seem to get what you pay for. I've had a CTEK MXS 7 around 5 years now and it will charge, maintain or refresh Quad bike to tractor batteries, normal or AGM. It's small, waterproof and the supply function is great for changing batteries without loosing codes. Will cost around £100 but worth the bit extra.

 

[B21]

Lidl do a version for not a lot of money..I have two, an earlier and later one..the CTEKs can do some clever things if you have deeply discharged your battery and I think auto start after a power cut..but for a lot less the Lidl ones do everything else to the same logic..

As others have said you can just charge via the red engine bay post and leave the OE battery connected up..

 

[DMike]

Some previous thread covering similar grounds:
https://z4-forum.com/forum/viewtopic.php?t=121046
https://z4-forum.com/forum/viewtopic.php?p=1882748
On E85s with no battery monitoring hw it’s ok to connect directly to the battery terminals, but on more modern ones, the consensus is that terminals under the bonnet are preferable. On my F13 I have succesfully installed a CTEK in the boot, though, leaving the monitoring components between the eyelets and the battery.

 

[Pondrew]

Worth mentioning that my Ctek leads aren't long enough to reach both engine bay connectors on the E89 without extensions.

I have a really cheap trickle charger (1.5 amp) for the E89 (as it has longer leads) and use the Ctek for other cars. Both work as they should and have had no problems with either.

 

[Zed Baron]

I started off with the LIDL one and it was great except over time the plastic insulation on the wires went where it connected to the unit showing the copper. So I bought a ctek its fitted on the wall of the garage with its extension cable to the bonnet (switches at opposite end of garage) been able to pernamently connect the ctek to the charging points under the bonnet, no messing about pull the rubber cap off and connect and hit the switch when you leave the garage. Nice easy tidy job.

 

[Special Kay]

Lidl do a version for not a lot of money..I have two, an earlier and later one..the CTEKs can do some clever things if you have deeply discharged your battery and I think auto start after a power cut..but for a lot less the Lidl ones do everything else to the same logic..

As others have said you can just charge via the red engine bay post and leave the OE battery connected up..

I was advised by a mechanic to buy one of the lidl ones for around £20 if I remember right. I've not used my car this summer and the car has remained sorned and locked up for a few months until next spring. The battery condition monitor on top of the battery wasn't showing green when I took the battery out of the car. But, once connected to the charger, it slowly began to condition the battery as well as charge it. All in all, it was a great purchase for a very small outlay.

 

[jenniferlouise]

As with others, CTEK for me. Bought one last year on recommendation and it performed perfectly all winter. Don’t be tempted to fit the battery connections. Dropping the charge to the car is probably not so clever and I ended up stripping a thread to the connecting bolts. Doh! Simply use the jump connections under the bonnet. Simple.

 

[jenniferlouise]

Worth mentioning that my Ctek leads aren't long enough to reach both engine bay connectors on the E89 without extensions.

Interesting comment as mine fit. True there’s not much extra but they do fit.

 

[Deepseaskateboard]

https://www.ebay.co.uk/itm/174797160477?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=ivhsJMteRHm&sssrc=2349624&ssuid=S3Gt5YgISya&var=&widget_ver=artemis&media=COPY


You can buy an ‘OEM’ one from BMW for a discounted price here.

Inverted commas due to BMW rebranding a Ctek, but a decent offer none the less.

(Code TAKEIT10 for extra 10% off discounted price)

 

[Ole gits rule]

I purchased one of these 18 months ago - works great https://www.ebay.co.uk/itm/374073119373?hash=item57187ed28d:g:2K4AAOSw8ZhiffdH&amdata=enc%3AAQAHAAAAsCraWuE8emZ81egDLuayfJ2XrG0RMQoxxaLaYbuvNK%2BdeZFbTisK4mOz%2FNhW3LXER8oF3inERaZCgEb980QGv89bpvfuEvEEff0%2BTrFiZB58rYpwI2O5I0ILYmTRUpuYBTNfUKIQ3sJvcXflpKbfexyShmmBXnULToABC%2FUfldbuhFgolA4NEhOLjtGYBHCRkx9ePT4767Ga0oorxXY3LTVG3LbmG%2BV8%2FV81muGoNbV1%7Ctkp%3ABk9SR_CW-siJYQ

 

[obewan]

I purchased one of these 18 months ago - works great https://www.ebay.co.uk/itm/374073119373?hash=item57187ed28d:g:2K4AAOSw8ZhiffdH&amdata=enc%3AAQAHAAAAsCraWuE8emZ81egDLuayfJ2XrG0RMQoxxaLaYbuvNK%2BdeZFbTisK4mOz%2FNhW3LXER8oF3inERaZCgEb980QGv89bpvfuEvEEff0%2BTrFiZB58rYpwI2O5I0ILYmTRUpuYBTNfUKIQ3sJvcXflpKbfexyShmmBXnULToABC%2FUfldbuhFgolA4NEhOLjtGYBHCRkx9ePT4767Ga0oorxXY3LTVG3LbmG%2BV8%2FV81muGoNbV1%7Ctkp%3ABk9SR_CW-siJYQ

+1

 

[B21]

My cheapo Amazon 15 amp charger bit the dust.

In parallel (pun)..my Lidl chargers didn’t seem to ‘float’ charge…ie once they had charged the battery they seemed to go offline…so I bought one of the eBay BMW aka CTEK chargers…

This for sure does float charge and if I ever buy a M3 or M4 will charge my lithium car batteries too..

Expensive ish but a result…

 

[Johnbmwz4]

I have both CTEK MX5 and the cheap Lidl one. I have 2 cars and didn’t want to spend loads of cash on 2 CTEKs. Both work great and the Lidl one has very long wires which reach to both terminals under the bonnet of the E89 unlike the CTEK. The only thing wrong with the Lidl if the power goes off you have to turn it back on again unlike the CTEK that turns itself back on to the last setting. I have had both chargers ( one at a time) charging my E89 for long periods with no issues at all.

 

[B21]

I have both CTEK MX5 and the cheap Lidl one. I have 2 cars and didn’t want to spend loads of cash on 2 CTEKs. Both work great and the Lidl one has very long wires which reach to both terminals under the bonnet of the E89 unlike the CTEK. The only thing wrong with the Lidl if the power goes off you have to turn it back on again unlike the CTEK that turns itself back on to the last setting. I have had both chargers ( one at a time) charging my E89 for long periods with no issues at all.

I ran a data logger on one of the Lidl ones and it charged the battery fine but once it reached capacity it trip off line and wouldn't recharge without explicitly being disconnected and reconnected..maybe I didn't wait long enough for it to re-charge..haven't tested the other one yet..

We have power drop outs quite often here (end of a long piece of damp string up the valley) so went belt n braces..since I go into the my new garage several times a week probably fairly academic..but we will see..

I'll try all three back to back over the winter..

 

[philip hedley]

I ended up buying an Einhell 4 amp smart charger, it has a dedicated AGM battery charging profile, the conditioning stage is selectable and there was £11 off the RRP at amazon. Some smart chargers don't have a dedicated AGM charging cycle (CTEK do) and the reconditioning cycle is not deselectable. Apparantly AGM batteries shouldn't be reconditioned. Einhell also recommend the battery is disconnected whilst charging to err on the side of caution.

 

[B21]

I ended up buying an Einhell 4 amp smart charger, it has a dedicated AGM battery charging profile, the conditioning stage is selectable and there was £11 off the RRP at amazon. Some smart chargers don't have a dedicated AGM charging cycle (CTEK do) and the reconditioning cycle is not deselectable. Apparantly AGM batteries shouldn't be reconditioned. Einhell also recommend the battery is disconnected whilst charging to err on the side of caution.

Repetitive charging the battery on an E89 whilst it’s off the car and /or via the battery terminals confuses the Intelligent Battery System IBS..resulting in incorrect charging profiles and failure to predict when load shedding should be applied.

If the battery charger has the possibility of damage to the car’s electronics it’s not really the charger for a car such as the E89 which is so sensitive in so many areas to correct battery capacity and it’s management.

In general for an E89 if you have reached the point where you are looking at having to recondition a battery it’s time to get a new one.