stephengoldberger Posted January 29, 2013 Report Share Posted January 29, 2013 Over the period of a month or two, what needs to be done to maintain the lithium battery? I gather that the vehicle has a conventional starter driven by the 12 volt battery, and I am familiar with the exercise of attaching a float charger to maintain that one. Does the lithium battery self discharge to a dangerously low level and, if so, how long would that take at typical summer time garage temperatures? Should one install exhaust fans to keep the garage temperatures down? Quote Link to comment Share on other sites More sharing options...
valkraider Posted January 29, 2013 Report Share Posted January 29, 2013 The exhaust fan might be a good idea. I have no idea about the high voltage battery. Quote Link to comment Share on other sites More sharing options...
Bob999 Posted January 29, 2013 Report Share Posted January 29, 2013 I gather that the vehicle has a conventional starter driven by the 12 volt battery, and I am familiar with the exercise of attaching a float charger to maintain that one. Does the lithium battery self discharge to a dangerously low level and, if so, how long would that take at typical summer time garage temperatures? Should one install exhaust fans to keep the garage temperatures down? The 12v battery is strictly for the computer, relays, control circuits and some other things like the radio. The CMAX has no conventional starter. Instead one of the motor generators in the transaxle functions as the starter and it is powered by the high voltage battery. "Starting" the CMAX is primarily a process of connecting the high voltage battery via relays powered by the 12v battery. The owners manual has a section addressing medium/long term storage and talks about maintaining the 12 v battery but does not address the high voltage battery. that suggests to me that the high voltage battery discharges very slowly but I suggest you read the section and form your own conclusions. Quote Link to comment Share on other sites More sharing options...
MikeB Posted January 29, 2013 Report Share Posted January 29, 2013 Unlike NiMH batteries, most Lithium chemistries have a negligible self-discharge rate. They can probably sit for years safely, as long as they are disconnected from any parasitic load. People have had problems with the Tesla when left sitting empty for months, but it only has the one lithium battery and there are some electronics that draw from it. For our cars, there's a relay to disconnect the high voltage battery, so you are probably best just attending to the 12v one as usual. Quote Link to comment Share on other sites More sharing options...
Bill-N Posted January 30, 2013 Report Share Posted January 30, 2013 And you could always simply disconnect the high voltage battery pack. Quote Link to comment Share on other sites More sharing options...
Bob999 Posted January 30, 2013 Report Share Posted January 30, 2013 And you could always simply disconnect the high voltage battery pack.When the CMAX is shut down the high voltage battery is automatically electrically disconnected by relays. No action by the owner is necessary. Quote Link to comment Share on other sites More sharing options...
stephengoldberger Posted February 6, 2013 Author Report Share Posted February 6, 2013 Thanks to all who replied. I guess the concern I have is that lithium batteries in small devices (like bluetooth earsets) seem to go flat over a month or two. Perhaps the ratio between capacity of the battery vs. the energy needed to restart the car is large enough that it can tolerate a substantial self discharge and still work fine. Quote Link to comment Share on other sites More sharing options...
Dawa Posted July 6, 2021 Report Share Posted July 6, 2021 My C-Max Energi is in standby since nealy 2 years now. What are the consequences on HVB properties/capacities ? Is it loosing performancies if not used ? ... what is the shelflife on storage procedure? Anyone have datasheets/manual on fomoco HVB ? Quote Link to comment Share on other sites More sharing options...
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