e60-545i

I had low battery warning a week ago. A fellow member suggested that I try the BMW battery charger since the car is not being driven everyday. So today, I bought one of those OEM BMW battery chargers and just finished connecting the charger. And so far, it seems to be working fine. Yet, I have few questions that needs to be answered. Forgive me for asking these questions as this is the first time I had to use a battery charger.

1. Can I have the charger connected for several weeks?

The manual of the charger says when the light is green, the battery is fully charged and ready for use. But it does not mention whether it can be remain connected even after the battery is fully charged for storage purposes. Would you guys recommend to disconnect it soon after the battery is fully charged or leave it on until I need to use the vehicle?

2. Are there any ill-effects as to leaving the hood open for prolonged period?

The manual says to leave the hood open while the battery is being charged. The car is kept in a garage but it has a window which is open for ventilation. And at night, it does get bit chilly and relatively more humid than during the day. Thus, by having the hood open for prolonged period, are there any risks for engine compartment parts being damaged due to rust etc?

Thank you in advance

merklebob

heres the discription based on that its ok to leave on all the time. you could hace gotten a computer controled maintainer for less that $10 that would have done the same thing.


from the charger accessory page.

"This is a must for your car if you park it for extended periods! The Advanced Battery Charging System is a 1.25 Amp battery charger designed to fully charge and maintain a battery at a proper storage voltage without the damaging effects caused by trickle chargers. The new BTP micro-chip technology applies the correct peak charge, then automatically maintains the battery at the perfect float voltage which virtually eliminates battery destroying sulfation! Temperature compensation ensures optimal charge voltage even in extreme weather conditions. Powder coated aluminum chassis. Spark Proof! Reverse polarity protection ensures safety. Built in 72 hour timer will protect a marginal battery from over charging. "

e60-545i

Thanks for the reply.

Yes, i read that description on the box but that 72 hour timer part confuses me. So it would stop charging after 72 hours?

HotLap

Sounds like it is not a fully automatic battery charger? I have a fully automatic charger that you can leave on indefinitely...automatically senses state of charge and reduces or stops charge current accordingly. It also has a "ramp down" charge feature where it starts on full charge and then gradually decreases the charge as the battery becomes more fully charged (easier on the battery I guess). The 72 hour timer part seems like a saftey shut down in case you should forget and leave the charger on?

s4iscool

just get a Battery Tender. It will monitor the status of the battery and charge accordingly. You can keep it plugged into the wall indefinetly. Dont worry about the hood being open. My battery tender connection cable is thin enough to simply let the hood close.

kennedylar

I've used the BMW charger for over 2 years on my 540i -- keeping it in Santa Fe, NM where it can drop below 0 (even in the garage) during winter nights. I pull in there after several months on the East Coast, unplug the charger and just drive as normal. It's one of the better products I've gotten.

e60-545i

Great, thats great to hear. It gives me an assurance that the product is in fact reliable. My charger entered the storage mode after fully charging the battery. So it looks like it's working well.

Thanks for the replies.

merklebob

schrouider[sp] make a 1.5amp step dow charger. that enought current to actually over time charge the car. its $30. harbor freight sell a 125ma step down for $5.

wasupdu

The BMW charger is a rip-off. You can find the exact same battery tender (minus the BMW logo) for less than half the price at most car parts stores. I picked one up at AutoZone for under $25.

e60-545i

I didn't know I could have bought a virtually same one for much cheaper. I paid $75 ($69 + tax). Since this was my first battery charger purchase, I had no idea I could buy it from elsewhere for MUCH cheaper. Looks like I paid unnecessary premium for BMW-branded one