BMW Battery Charger-Tender

[21F90M5C]

Hi,
I have the BMW Charger and was wondering if I can leave it wired to the terminals under the hood even though the unit shows the battery is fully charge.

I don’t drive the car until the weekend and was wondering if I need to remove the Charger connection right after the battery has been fully charge up

Also, I was told not to leave the hood up with the car locked because it will sound an alarm due to the hood being up. I left the car unlocked but noticed that it locked up after a few minutes without me using the key fob

Can I leave the hood up with the car locked up while the battery is being charge?

Thanks for your help

[arucano]

The modern chargers are usually "charger and maintainers". If so you can leave it connected since the car has a slight drain when switched off anyway. Which charger is it you have?

Quote:
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. If the charging procedure is carried out at low temperatures, it should not be ended until the charge current drops below 1.5 A. If the battery is to be charged while it is still installed, it must be charges using the jump start terminal points. Only then can you be sure that charging is correctly recognised by the vehicle electronics on vehicles with an intelligent battery sensor (IBS). If the battery is charged directly at the battery terminals, this could lead to a misinterpretation of the battery condition and even unwanted Check Control messages or fault entries. The cigarette lighter gets his voltage supply by the front power distribution box via the switched terminal 30B. After terminal 30B off, the relay de-energises. This means that a trickle charger connected at the cigarette lighter would be disconnected from the battery. Only charge the battery via the jump start terminal point.
Unquote

https://www.newtis.info/tisv2/a/en/f...ttery/BdzoqEna

[21F90M5C]

BMW 82-11-0-049-788 Battery (Tender (AGM/LI):619080)

[Larry77]

Why do you need a trickle charger? Wouldn't you have to drive it really rarely for a charger to be necessary?

[21F90M5C]

Since I hardly drive it at all during the week, I was told battery drain is a problem

[Fast.F10]

Originally Posted by 16F10M5

Since I hardly drive it at all during the week, I was told battery drain is a problem

This is the one I purchased to use in conjunction with BimmerCode but will also be connecting it to my M5 on any trips out of town greater than 4 days.

[BMWM5NYC]

Originally Posted by Larry77

Why do you need a trickle charger? Wouldn't you have to drive it really rarely for a charger to be necessary?

I have always trickle charged my BMWs and Motorcycles. Since they are weekend vehicles mostly. My Batteries tend to last twice as long as most people because they stay fully charged and never really see the killer "deep cycle discharge."

[Larry77]

Originally Posted by BMWM5NYC

I have always trickle charged my BMWs and Motorcycles. Since they are weekend vehicles mostly. My Batteries tend to last twice as long as most people because they stay fully charged and never really see the killer "deep cycle discharge."

I've never had a weekend vehicle but I'll keep this in mind when I do :-)

[NotSooFast]

I used trickle charger for my F10. The fan runs overtime on the battery to cool it down after a drive - the load on these batteries is higher than normal and I have seen my battery outlast that of my colleagues X5M, even though he daily's his car (~10 miles to work).

[Craze]

Any idea how to hook up the tender more permanently with a discreet connection to plug and unplug?