I am happy to report that my Lithium system is up and running perfectly!
I am using 700 Ah batteries from Balqon and the HousePower BMS system. I am using three Tyco 200 relays which I found for a bargain of $60 each (!!!) on ebay (they have much smaller gauge wire than the full priced version you buy in the store but otherwise are identical). One of the relays is configured as the 'holy ****' relay cutting off all battery access. It is controlled by a reset switch so manual intervention is required and is tripped by individual cell voltages being too high or too low. The other two relays control the charge and load bus to the batteries and are activated by the HousePower BMS based on pack voltage. These will activate and clear by themselves for unattended operation. I have a lead acid battery system as a backup (my old house batteries) and the connection to the alternator
is there all the time which means I can disconnect the charge bus to the lithium pack without worrying about blowing the alternator
I have a Cellog8 display that gives me individual cell voltages in case I am curious or want to check if I should be re-balancing the cells. Presumably this will not be required but it's nice to be able to see the voltages. I do not use the relay functionality of the Cellog8.
Last but not least, I am using a BMV-700 SOC meter to tell me what the current
state of the lithium bank is (volts, amps, instantaneous watts and of course SOC). This little gem of a meter has all kinds of intelligence built in, it has a buzzer and it has a relay output! It also has a serial
port output that blurbs out all of it's data every second which I hope to eventually use once I figure out how to send the data out over wifi
This meter and it's smarts is really the cat's meow! for now I am using the built in relay for additional control of the battery charge bus. I have configured it to activate charging when the battery SOC hits 50% and to turn charging off when SOC goes up to 90%. This assumes that the HousePower BMS has allowed charging.
With the charging controlled by the battery SOC, I can rest assured that the system will even be safe with my charger
running while docked. The Lead Acid bank is trickle charged and the lithiums are automatically disconnected when required and will not sit at 100% all the time which is reportedly bad for them.
I am very pleased with how everything works so far but only time will tell if everything works as well as I am expecting.
The one thing that remains is to fix up the wire spaghetti in the one locker that has all the smarts in it. For now, the lid gets closed and the system gets used