Lithium Ion Batteries

[Sean]

Tom,

Yes, sorry if I was not clear.  The principle functions of the per-cell BMS on a lithium battery are to cut off charge when the cell is full and to cut off discharge when the cell is empty.  Without this functionality the cell will be destroyed.  So from this perspective, the BMS on the Corvus and similar batteries does "control" the charging.

That said, you still need to provide the single set of terminals with a voltage that the BMS can use for charging.  On the Corvus and many other batteries that's going to be 16 volts (32 for a nominal 24-v system).  Many RV-type chargers or inverter-chargers can't even produce a voltage this high.  Certainly setting your engine alternator to this level will produce unwanted results, such as cooking the lead-acid chassis batteries and shortening the life of the chassis lamps and other components.

FWIW.

-Sean
http://OurOdyssey.BlogSpot.com

[pvcces]

Hi, Sean.

I guess that was looking at the charge curve in a different way.

What I was seeing was that the resting voltage of the battery extends outside the normal charge and discharge settings that we use on our coaches. That made me think that the battery might remain midcharge most of the time if it was used in a stock system. If that were true, we would have only part of the capacity available most of the time.

For a regenerative braking system like on an EV, that might serve pretty well, but I can see where it would aggravate the high cost of the battery if you could never use the designed capacity.

I was reading the minimum to maximum voltage as 10.8 to 16.8 and thought that we would only use the range between 11.5 and 14.5 volts. That would cover around 2/3 of the designed capacity.

I couldn't tell if you were saying that we would be needing to use a BMS separate of the battery so that it could track the full voltage of the battery. I noticed that the setup in the RV article above used some kind of panel like that.

Thanks, Sean.

[TomC]

Guess I'll just stick to my Lifeline L16 AGM's. Using 4-6vdc batteries wired for 12vdc, that gives me 800 amp/hours.  Even with using only 50% which is 400 amp/hours, that will give me close to 2 days of battery before recharging.  Good Luck, TomC

[Brassman]

Here is a link to someone who is trialing a lithium battery in a RV:

            http://www.amsolar.com/home/amr/smartlist_22/lithium.html