Lithium Battery Management System Disconnecting While Charging?

Question:

One big thing I've learned from you (Seattle boat show seminars) is to beware of switched loads. I've noted that several manufacturers today are offering Lithium batteries with an internal battery management system (BMS) that can disconnect charger outputs while they are charging. Victron also publishes schematics with external BMS that do this as well. I'm trying to avoid this by using external BMS to turn off chargers rather than disconnect their output. It appears that Victron thinks this is not necessary. Your thoughts please? - Paul

Answer:

Your concerns about a BMS disconnecting a lithium battery while charging circuits are running is a legitimate issue. Choosing a battery BMS without a separate charging and load bus can create lots of problems in the event of the Lithium BMS disconnecting the battery while an alternator is recharging the battery.

We recently had a very interesting discussion with Nigel Calder about this, https://www.pysystems.ca/resources/videos/lithium-batteries-for-you-boat-with-nigel-calder/

- Jeff