as y'all know my defender has been a garage queen this past few months and only have 925 miles since I got it october, 2020. its been starting fine until the other day when I left the driver door open inside my garage and of course the key was in the car as well. Come next morning, the park lights were ON indicating a discharged battery? entertainment screen as well as dash are OFF. Tried to trickle charge it with alligator clips and the and rover battery tender to no avail after 4 hours. So, ended up jump starting it with jumper cables attached to my escalade. It was prodded to start after keeping it connected for a few minutes. Can the alternator charge the battery if I use it or does it have to be benched charged.

 

If the battery is good (Which it should be at its current age, barring a bad cell or something), the alternator will charge it back up, but you need to drive it a bit to get back to a full charge. If you didn't let it run / drive it after jumping it, it will probably need to be jumped again.

 

lol! will start driving it again. I idled it for a few minutes and this morning it started right up but still says low batt.

 

I could easily be wrong here but I do not think that AGM batteries do very well charging from the alternator once they've been drained.

They make special maintenance chargers for AGM and people who don't drive their cars very much. Might be a good idea to look into one.

 

So far, my only AGM experience has been with motorcycles, and I find they hold their charge for a VERY long time if the vehicle isn't run, so that's a plus. I haven't had any issues charging one with a standard trickle charger if they do run down a bit, either. Might depend on how "low" it gets?

 

You should keep her on a trickle charger if sitting for long periods. This is a good practice for any car and by the sounds of it you might need a new battery?

 

it did good so far. drove it a few miles and the battery started no problems.

 

Nice