funglenn

I tried to google this but it has not really answered my question.


My BMW battery is about 5 years old (yes, probably time). The little sensor window on top is black, thus it always states "not fully charged" even after a long 1 hour drive. I normally drive about 20 minutes to work every day.


I ended up with a free [URL=" and it says it can repair AGM batteries. Should I try this? do I need to remove the battery from the car or can I just hook it up to the positive and negative lead on the battery? Instead should I use the positive post under the hood and the body?


can this thing bring my battery back and put the little sensor window on the top back to green fully charged?


I realize the normal application is for people who store their cars, but it mentions it heals batteries. I am not really the store car type and have no experience with this.


Ireally to get another 6-12 months from the battery would be nice. right now I am about to flush the transmission and after Christmas will replace the water pump. would love not to also need the battery now...


thanks

twh

Forget about repairing a battery. Go online and find a $40 off coupon for Advance Auto Parts and get the same size AGM from them you have in the car now. Should cost you like $140 if bought online and using the coupon. I think the current one is slightly more powerful than the one you probably have, but the specs are pretty similar. Then install it and get the battery registered.

txag_530i

Use coupon code TRT41 for $40 bucks off of a $100 order at advancedautoparts.com.

funglenn

the question is which AGM to get? they have like 3 of them and the older posts reference models that no longer are sold.

twh

First go see what kind of battery is in the car now. I'd just stick with the same type (i.e. AGM or non-AGM). Get the BMW part number off the battery. See if that is AGM or not. See what the AH rating is.

Wife's 2009 X5 already had an AGM and took this one from Advance Auto:
AutoCraft Platinum AGM Battery, Group Size H8, 900 CCA H8-AGM: Advance Auto Parts

If you install it be sure to install the vent tube correctly and plug the vent one on the other side.

westsidebalto

20 minutes should be enough to recharge your battery during your commute, as you seem to have suspected, so I guess you're at the end of the road with this battery.

BimmerFan52

Two ways to really tell if 20 minutes is enough to fully charge a healthy battery low on charge (and I can almost guarantee you it is not) are to either check the voltage with a multimeter after the surface voltage has left the plates (5-6 hours sitting idle or leaving the lights on without the engine for 2 minutes), or put it on a good quality processor driven battery tender and see if it indicates a full charge.

I have a fairly new AGM battery and Valeo alternator, and if my battery is on the low side I can run it on the highway straight for an hour, come back and throw the Battery Tender on it and I am still not even at an 80% charge.

After fully charging with the battery tender and eliminating plate surface voltage, a healthy battery should measure 12.75V +.