Now that we've been asked to stay home the GLE will be without use for the next month. Is a trickle charger available for the unit. What about the 48 volt battery what happens with this over time. I sometimes travel for months at a time. Someone know how this works?

 

Sorry I didn't see the thread below about the trickle charger, but I still want to know about the 48 volt battery and how that works?

 

Since the 48V battery is the starter battery, I assume when you charge at 12V it also up-converts to 48 and charges that.

 

I would be surprised if that was the case. On my QX60 Hybrid, which has a 48 Volt system similar to what's in the GLE 450, it works the other way. The hybrid battery will charge the 12V when in the run position, but only the hybrid motor/generator will charge the hybrid battery. I would guess the GLE 450 works the same way.

 

So if the 48v starter battery is too depleted to start the car, explain to me how jump starting from another 12v battery or hooking up a “maximum 14.8 volt” charger would help.

 

When my 12 Volt battery suddenly died a year ago on my QX60 hybrid, I could not start the car even though the hybrid battery had a charge. The 12 volt battery simply would not hold a charge. So the electronic ignition, which uses 12 volt power, wasn’t getting any power...was a weird experience. Jump starting the 12 volt battery provided power to the 12 volt ignition and computer, so it had power to send the command to the starter generator to use the 48volt system to go into electric motor mode, clutch to the engine and spin start it. Once the engine started, the starter motor provided power to the 12 volt system to keep it running. The crazy thing was when I stopped at a stop sign, the freaking computer told the car to go into EV mode and shut off the engine. The 12 Volt battery was still dead, so the damn engine wouldn’t start again. I had to jump start it once more. This time I ran the A/C in max mode so the engine would stay on (A/C in the QX60 hybrid is accessory belt driven) and I made it to the Infiniti Dealer without it going into EV mode again. Infiniti replaced the 12 volt battery and all was well.

Lithium ion battery (the 48 volt power source) state of charge management is an art. When the hybrid battery state of charge indicator shows it is depleted, it isn’t. If you completely drain a lithium ion battery, it will brick...you kill it. So hybrid power management systems only let the hybrid battery state of charge drop to about 30% before the electronics tell the engine to turn on and charge it back up. So when the hybrid battery indicator shows zero charge left, it still has around a 30% state of charge, enough power to start that engine a hundred times....if it has 12 Volt power to run the ignition and computer.

 

Makes sense.

 

I was told never to try and jump start the GLE at my dealership. So again how do you maintain the 48 volt system when the vehicles not in use for a long period of time. How long will the lithium battery hold a charge?

 

That's bull. Yes, you can do it wrong, but the owner's manual has instructions for both jump starting and charging. Most Li-ion batteries lose about 5% in the first 24 hours then up to 5% per month. As noted in post #6, it is more likely the 12V battery that will prevent a car from starting.