SL/R230: ONLY THE REAR BATTERY IS CHARGING
11-07-2021, 11:46 AM
#1
Junior Member
Thread Starter
ONLY THE REAR BATTERY IS CHARGING
STARTER BATTERY IS GETTING NO CHARGE BACK ONE IS FINE PUT NEW STARTER BATTERY IN, ANY IDEAS WHAT TO LOOK FOR AND DO YOU THINK I COULD MAKE IT TO THE DEALER 20 MILES AWAY THANKS
11-09-2021, 01:59 PM
#3
Member
You most likely have a bad 100amp fuse in the passenger foot well area. Replace it. It's not the easiest location, but it's full doable. Remove carpet, metal plate under it and the subwoofer (if you have one) and you'll see the round plastic fuse box. There are 2 fuses inside. The one under the big one is bad.
I just went through this exercise on my SL55 and now both batteries are charging just fine. The 100amp fuse was bad on mine, likely caused by a jump start i recently did.
Are you getting the red battery warning light on the dashboard?
I just went through this exercise on my SL55 and now both batteries are charging just fine. The 100amp fuse was bad on mine, likely caused by a jump start i recently did.
Are you getting the red battery warning light on the dashboard?
Last edited by danmm7; 11-09-2021 at 02:02 PM.
The following users liked this post:
g0rsq (04-18-2022)
04-18-2022, 12:47 PM
#4
You all are incredibly helpful, knowledgeable. I thought I had read in the owners manual that the rear battery when on an external trickle charger, has the effect of keeping the starter battery also fully charged. But then, Ive seen YouTube videos with people running trickle chargers on both batteries. Complex. . . .!
04-18-2022, 05:41 PM
#5
Senior Member
You all are incredibly helpful, knowledgeable. I thought I had read in the owners manual that the rear battery when on an external trickle charger, has the effect of keeping the starter battery also fully charged. But then, Ive seen YouTube videos with people running trickle chargers on both batteries. Complex. . . .!
No harm in charging both batteries, though not necessary, unless car is stored with either battery disconnected.
I agree with earlier post to check the 100A fuse (F52)
04-19-2022, 03:49 PM
#6
Senior Member
Dan the MM is correct..! I had the same issue since I suspected than the previous owner let the starter battery positive pole to touch ground..! It is not too bad to access to the fuse nest. I am attaching the literature I collected before I did the job. Make sure you stop by a place where they sell the 100 Amp fuse since is not too common.
