BMS and battery arrangment for motorcycle

[dirtbike]

Hello
I have searched the internet for the best setup for LiFePO4 battery and BMS to make a compact battery and BMS arrangement for a custom bike I am building.
I have gone for the two parallel sets of batteries, each with four batteries in series, and using two Daly BMS with separate port to charge each series bank.
What Im not sure about is the charging side of the arrangement. Like a car the battery's prime use is to start the engine, the alternator then powers the electrics and charges the battery.
I have come up with the attached a pdf arrangement and would welcome comments.
Thanks for letting me use this forum.
Tom.

PS - I am also going to add a 10way rotary switch (8 batteries + main output + off) with connections from each battery and the main output to a small voltmeter to monitor charge voltages.

 

[HRTKD]

If your Daly has bluetooth, you can monitor the cell voltages with your phone.

As with a car alternator, there is concern that the voltage will be too much for a LiFePO4 battery. Yes, the BMS is supposed to cut off charging at a certain voltage. But if the alternator provides too much voltage, the battery may not get correctly charged. A DC-DC charger is often used to solve this.

 

[dirtbike]

Hi Jim thanks for your reply.
Or I could but a forward diode from the charging cct to drop the voltage by 1.2volts.
What do you think about the rest of the charging arrangement?
Tom

 

[HRTKD]

I remain skeptical that this plan will be good for your cells. I don't charge my LiFePO4 from an alternator, but if I did, I would have a DC-DC charger with a LiFePO4 charge profile.

 

[dirtbike]

Thanks Jim.
Could you recommend such a DC-DC charger
Tom

 

[HRTKD]

If I were to put one in, it would from Victron. But I doubt that these are small enough to fit into your compartment.

https://www.victronenergy.com/upload/documents/Datasheet-Orion-Tr-DC-DC-converters-isolated-100-250-400W-EN.pdf