A 12V Charger DOES NOT Charge the 48V Battery
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Joined: Oct 2005
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From: Frisco Colorado, USA
2024 GLB35 AMG, 2020 S560 Coupe
A 12V Charger DOES NOT Charge the 48V Battery
On my 2023 GLE53: Using a 12V charger on the posts in the engine compartment DOES NOT charge the 48V battery. Only with the engine running (Idle or driving) is the 48V battery charged. These are my conclusions after doing a series of tests using a 6 Amp Schumacher WiFi + Maintenance Charger from AutoZone.
Even with the ignition off, I had thought that the vehicle electronics would keep the 48V battery charged when using a trickle charger or regular charger, but that is not the case. Hereaftrer, I will use the Workshop Menu to monitor the 48V battery and insure that it is adequately charged, particularly after a series of short trips or a period of vehicle storage.
I ran a series of tests.
Test 1) In the first test, the ignition and engine were off with the Schumacher charger initially applying 6.1 Amps:
Initially: 12V at 91%, 48V at 74%
After 2 hours: 12V at 99%, 48V at 73%
After 6 hours: 12V at 99%, 48V at 72% and a Text message that the 12V battery is fully charged.
The 48V battery ACTUALLY DISCHARGED while the 12V charger was attached !!!
Test 2) After two 50 mile drives with some stop and go traffic, the 48V battery went from 76% to 82% each time.
Test 3) In a third test, the ignition and engine were off with the Schumacher charger initially applying 6.1 Amps:
Initially: 12V at 93%, 48V at 76%
After 2 hours: 12V at 94%, 48V at 73%, as DISCHARGED as before !!!
Continuing, I turned on the ignition with the engine off:
After another 2 1/2 hours: 12V at 94%, 48V at 56%, down from 73% !!!
Continuing, I started the engine idling and disconnected the 12V charger:
After only another 10 minutes: 48V at 66%, up from 56%
After another 30 minutes: 48V at 70%
After another 45 minutes: 12V at 95%, 48V at 72% and a text message that the 12V battery is fully charged.
So If you followed all of that, you will reach the same conclusion that I have — a 12V charger does not charge the 48V battery even if the ignition is on. The 48V battery is only charged with the engine running.
NOTE: There is a lot more info on this topic on the GLE53 forum here:
https://mbworld.org/forums/gle63s-gl...v-battery.html
Even with the ignition off, I had thought that the vehicle electronics would keep the 48V battery charged when using a trickle charger or regular charger, but that is not the case. Hereaftrer, I will use the Workshop Menu to monitor the 48V battery and insure that it is adequately charged, particularly after a series of short trips or a period of vehicle storage.
I ran a series of tests.
Test 1) In the first test, the ignition and engine were off with the Schumacher charger initially applying 6.1 Amps:
Initially: 12V at 91%, 48V at 74%
After 2 hours: 12V at 99%, 48V at 73%
After 6 hours: 12V at 99%, 48V at 72% and a Text message that the 12V battery is fully charged.
The 48V battery ACTUALLY DISCHARGED while the 12V charger was attached !!!
Test 2) After two 50 mile drives with some stop and go traffic, the 48V battery went from 76% to 82% each time.
Test 3) In a third test, the ignition and engine were off with the Schumacher charger initially applying 6.1 Amps:
Initially: 12V at 93%, 48V at 76%
After 2 hours: 12V at 94%, 48V at 73%, as DISCHARGED as before !!!
Continuing, I turned on the ignition with the engine off:
After another 2 1/2 hours: 12V at 94%, 48V at 56%, down from 73% !!!
Continuing, I started the engine idling and disconnected the 12V charger:
After only another 10 minutes: 48V at 66%, up from 56%
After another 30 minutes: 48V at 70%
After another 45 minutes: 12V at 95%, 48V at 72% and a text message that the 12V battery is fully charged.
So If you followed all of that, you will reach the same conclusion that I have — a 12V charger does not charge the 48V battery even if the ignition is on. The 48V battery is only charged with the engine running.
NOTE: There is a lot more info on this topic on the GLE53 forum here:
https://mbworld.org/forums/gle63s-gl...v-battery.html
Last edited by slk55er; Feb 23, 2023 at 04:39 PM.
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