Thought I would relate what I decided to do about cutting power to my Balmar MC-614. To recap...my equipment
is a 12 volt nominal 4P4S 400 Ah Lithium Battery
made up of 16 100 Ah 3.2 volt prismatic cells manufactured by Sinopoly. I use CleanPowerAuto LLC's HousePower BMS Control Board with four Mini BMS Boards on the Battery. I have a 270 Ah Second Alternator dedicated to charging
this battery..doesn't do anything else...the MC-614 regulates this alternator.
I have the HPBMS Control board wired to a EV200 Contactor that isolates the entire battery to Protect it from an over voltage condition when any individual cell reaches a High Voltage level of 3.65 volts. The issue was the need to kill the Alternator so it wouldn't be damaged when a Protection event occurs and isolates the battery.
The HPBMS Control Board also has a circuit on it which can be used to cut power to a charging
source. This circuit is activated at 3.6 volts. Important to note that this is a second "Warning Level" circuit...referred to as the HVC circuit by CleanPower.
After a lot of back and forth with CleanPower, Balmar and Main Sail I learned that the HVC warning circuit is "always" activated at least 50 seconds before the Protection circuit. So even if there is rapid charging into a dangerous high voltage situation there will be 50 seconds between when the HVC Warning Circuit is activated, shutting down the Alternator, and when the Protection Circuit isolates the battery.
The speed with which the alternator stops producing power depends on, as we have been discussing, whether the HVC Circuit is cutting power to the Brown Ignition wire or the Red B+ wire or even the Blue Field Wire.
In my set-up, with Protection separately enabled at 3.65 volts, I am comfortable cutting power to the MC-614's Brown Ignition wire at 3.6 volts. To do this you have to be comfortable that your battery will not be damaged during the milli-seconds it takes for a normal Brown Ignition Wire shutdown. I was because of the 50 seconds between that event and when the battery would be isolated at 3.65 volts or 14.6 volts.
I do this because my Battery Manufacturer specifications speak to 3.65 / 14.6 volts as the maximum voltage. So cutting alternator charging at 3.6 works for me...and I can use the Brown Wire without a problem. FYI, I have the MC-614 Charge setting at a maximum of 14.0 volts / 3.5 per cell based on Maine Sails
advice and experience.
After going through all of this I came to the realization that some folks might be only wiring
the HVC Circuit and not the Battery Protection Circuit. In that case, you are making the judgement that 3.6 volts is the absolute maximum voltage you want on your battery and you want to cut any charging immediately. Thus wiring
the HVC Circuit into the Red B+ makes sense. In discussing with CleanPower and others I am comfortable that my threshold for damage is 3.65, so I can take the Brown Ignition wire route
, which shuts down the regulator / alternator in the same manner as when I turn the engine
Hope this helps.
FYI, because I had several exchanges with CleanPowerAuto and Balmar I wrote up what I learned including how to test the HVC Circuit. Can't attach it here because of restrictions this forum has in place. But, I'll send it to anyone who sends me a PM with your e-mail.