Should I bypass the BMS with my Solar Charger?

[tetonmtnbiker]

Hi,

Attached I have my BMS Setup, and my complete diagram. I have recently read on the "BMS Common Port vs separate Port" String that Will said,
"Considering the likelihood of over voltage situation from most high quality mppt, and the chance of matched LiFePO4 cells going out of balance is rare (and BMS will correct for cell drift over time), and that LiFePO4 can be over charged to 4.2v per cell before electrolyte degradation... I would say its safe to connect mppt directly to the battery bank, and bypass the BMS entirely. We have been doing it this way for years, but people still want to use a BMS."

I plan on top balancing the cells, and thought it may make more sense to connect the SCC directly to the battery bank and bypass the BMS since at a top balance the SCC charge settings would protect the cells. This way, if my BMS ever took a crap, the SCC would not be damaged. Am I overthinking this? Should I just leave the SCC connected to the bus bar (that is connected on the - side through the BMS)?

Thanks All,
Jeff

 

[Ampster]

I assume you just mean the power lead? That is actually how my BMS works with a separate contactor.
That configuration gives me a two step protection. First the high and low voltage disconnects on my inverter/charger and as a last resort the BMS opening the contactor if those settings fail on the inverter. The BMS disconnects are set just a few tenths of a volt outside the inverter settings.

 

[John Frum]

This way, if my BMS ever took a crap, the SCC would not be damaged. Am I overthinking this?

Is that your only motive?
Will Prowse tried hard to kill an scc by disconnecting it from the battery and was not able to do it.

 

[tetonmtnbiker]

Roger that. I'll charge through the BMS. Thanks!

 

[tetonmtnbiker]

Thanks Ampster. I may look at a contactor in the future