GLE 450 Voltage Mystery
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Joined: Apr 2014
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From: Gippsland, Australia
GLE 450+ SLK350
GLE 450 Voltage Mystery
I own a GLE450 about 9 months old 5,500km (~3,000mls) but only acquired it 3 weeks ago. Due to the present zombie apocalypse it doesn't get driven much so I use a M-B badged CTEK 5.0A charger which is rated as suitable for slow charging both lead acid and lithium ion batteries. I understand the 12V and 48V batteries cross charge via a DC/DC converter. I left the charger attached to the engine bay points for 4 days and the full charge/float light was lit. I took it for a drive and the MBUX Info "engine" display showed 12.2V. After starting the engine, it showed 14.8V for about 20min driving then it changed to 12.8V. It stayed at 12.6 - 12.7V for rest (45min) of highway drive. On returning, I reattached the charger and it only showed the first light (~50%) but changed to 80% after a couple of hours. Four hours later it still shows 80%.
Does this make any sense? Does anyone have any information about the battery management in the GLE 450? My thoughts are that the 12V battery cross charged the 48V lithium battery in the background and then the voltage dropped to the lead battery operating level. If so, why the apparently low level on reconnection after a reasonably long drive?
Does this make any sense? Does anyone have any information about the battery management in the GLE 450? My thoughts are that the 12V battery cross charged the 48V lithium battery in the background and then the voltage dropped to the lead battery operating level. If so, why the apparently low level on reconnection after a reasonably long drive?
Last edited by stan911; Aug 27, 2020 at 04:22 AM.
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Joined: Jan 2020
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2020 GLB 250 4Matic
I'm no expert in this matter, but I think you have it the other way around. I think the generator supplies the full 48volt charge to your 48volt battery and it also has a step down charger that lowers the voltage to charge your 12volt battery. Every time you step on the gas at a stop light, that 48volt battery gets used, not so much the 12volt battery. When you trickle charge the battery, you are only really charging the 12volt battery. That's my understanding at least....
