Originally Posted by Jd1
Please elaborate ....
You already have the cells, I really should not have to..
The BMS relays are not
for charge management
they are for bank protection / insurance
. All your charge sources should be programed for the LFP banks safe charging
range and dialed in specifically for the LFP bank. Then, if there is a failure in one of your charge systems, the relays can do their job at protecting
This is like smashing up your car every time you want a new one. Your insurance
policy is not your ticket to a new car, but you are using it as such. Your BMS is not the proper way to manage
your charge sources but you are trying to use it as such.. They should all manage themselves. The insurance
is there as, well..... insurance. By using the BMS as your charge management
system you have no additional level of protection.
I feel you seem to be losing the forest for the trees.... Forget the lead acid bank and focus on the LFP and how to keep it safe and happy. Really what we are looking at is $2000.00 worth of LFP cells vs. $100.00 +/- of LA battery
....... I certainly know where I would focus my efforts...
Once you've nailed the LFP bank and programming all charging
sources to self manage and also nailed the BMS then you figure out what to do about the LA bank.... Really not a lot to think about.... On a C-36, I owned one, an LA bank is only really necessary as a reserve bank (yes another insurance policy
). It can sit there for months with no charge if you choose an AGM
or GEL.. A GEL will do fine at LFP voltages.
The biggest use for my LA reserve battery
is in the winter when the LFP bank is not on board. The rest of the time it sits there and minds its own business. Every now and then I charge it by combining it with the LFP bank...
It seems like you are under thinking the LFP and over thinking the LA battery.. If you design your system correctly you will not need the LA battery. Keep it as added insurance but like your car insurance just keep it updated, so its there when or if you should ever need it, and that is all you'll need.