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jordanbigel · 01-04-2022, 13:59

I'm considering these batteries from BestGo (https://www.electriccarpartscompany....-battery-packs) and I have a question about how to use the BMS signal from this battery to control my Balmar voltage regulator/alternator.

For those not aware of these batteries (which I learned about here on this forum) they are a hybrid drop-in battery which has a built-in BMS but also has external control signal wires which go closed-circuit when the internal BMS detects various out of range values (voltage, temp, current) See docs at link below if interested. I've also attached (what I think is) the relevant portions of said docs below.

The way I understand it, when wired together, the BestGo signal wires for voltage, temp and current are all combined to make 2 leads (+/-) which provide 2 signals - too high/too low -- in this case, we don't know (and don't care) if it means temp is too low or too high, or if voltage is too high or too low, etc., etc.

My understanding is that these signals are programmed to trigger before the built-in BMS will shut-down the battery.

From the Victron forum, I have determined that I can wire this to the Victron Multiplus (AUX1 I think) so that the battery BMS can tell the Multiplus to stop charging/inverting (using the "two-signal assistant").

My question here is how can achieve the same thing with my MC-614 regulator?

I've heard of various different approaches using either the regulator's field wire or the regulator's power (B+) wire - I believe the idea in each case is to interrupt the circuit to shut down the alternator.

Being an amateur electrician (ie. only on my own boat) I am trying to figure out what to connect where in order to accomplish this.

I think the solution will involve some kind of a relay, which as I understand in this context would be a device which can accept a signal from the battery's BMS (which closes the circuit and powers the relay when the battery battery BMS detects a too low/too high situation) and then in turn break the current in the regulator's B+ - or field wire - does this make sense?

Assuming that I am on the right track so far, my questions are:

- how do I find the correct relay which will do this - I know almost nothing about relays and how to select the right one
- which approach should I use for controlling the regulator, interrupt the field wire circuit, or cut power to the regulator by breaking the B+ circuit?

THANKS in advance!
Jordan.

BestGo external signal documentation:
https://www.electriccarpartscompany....-pack-4-27.pdf

In parallel configured system, operator should combine all battery pack’s A1, A2, A4 together as one node, combine all pack’s A3 together as another node, then detect the "on-off" status between those two nodes to tell main circuit act accordingly (like disconnect the main circuit). Operator can even installing an upstream LED light on each A1, A2, A4 before they are combined will also provide an indicator to determine which individual pack triggered what alert.
(Here is an important notice in parallel configured system. If one pack has the biggest current pass and triggered the switch, it means this battery pack is the best one. Operator have to deal with the worst battery pack which offering the smallest current when in parallel config, by replace the worst battery pack or add some resistance to the best pack, to keep the current value of every battery pack is in the good range suit to A4 to A3.) 
Those pins and wires can allow max 60V voltage and max 1.5A current pass shortly. The A1, A2, A4 to A3 can be used as individually, or can be used as bind together, in both charging and discharging conditions, act as switches as resistance change between max and zero.

goboatingnow · 01-04-2022, 14:59

The BMS alarm output is arranged in what is commonly known as a volt free contact , basically a switch contact.

Balmar recommend shutting down the 614 by interrupting the brown ignition wire.

Hence the easiest way to do this , is as you say wire a relay into the BMS contact. Feed the battery voltage into one side of a relay with a coil rated for your system nominal voltage ( 12v) , feed the other side of the relay into the BMS switch , ground the other side of the BMS switch to complete the circuit. Make sure whatever battery voltage is driving the relay isn't itself disconnected by the BMS !! . The relay should have enough switch contact to switch whatever charging devices you have. One set of relay switch contacts will have the ignition wire fed through those contacts such that the contacts open when the relay is triggered by the BMS.

jordanbigel · 01-04-2022, 16:24

Quote:

Originally Posted by jordanbigel

The way I understand it, when wired together, the BestGo signal wires for voltage, temp and current are all combined to make 2 leads (+/-) which provide 2 signals - too high/too low -- in this case, we don't know (and don't care) if it means temp is too low or too high, or if voltage is too high or too low, etc., etc.

I think I mis-spoke here when I said the 2 signals are too high/too low - when you combine the 3 signal wires from the battery, basically you have either open circuit = all is fine, closed circuit = stop now, so there is actually only 1 signal, a binary, circuit open or circuit closed, which is 1 signal.

jordanbigel · 01-04-2022, 16:43

Quote:

Originally Posted by goboatingnow

The BMS alarm output is arranged in what is commonly known as a volt free contact , basically a switch contact.

Balmar recommend shutting down the 614 by interrupting the brown ignition wire.

Hence the easiest way to do this , is as you say wire a relay into the BMS contact. Feed the battery voltage into one side of a relay with a coil rated for your system nominal voltage ( 12v) , feed the other side of the relay into the BMS switch , ground the other side of the BMS switch to complete the circuit. Make sure whatever battery voltage is driving the relay isn't itself disconnected by the BMS !! . The relay should have enough switch contact to switch whatever charging devices you have. One set of relay switch contacts will have the ignition wire fed through those contacts such that the contacts open when the relay is triggered by the BMS.

Thanks for the reply!

Using the ignition wire (brown) seems to be the key, not the power wire (red) - makes total sense. That way the regulator still has power to control the alternator (ie. shut it down gracefully). I think if I were to wire it the other way so it cuts the power wire it might even damage the regulator (based on something I read on HowTo about wiring a service disconnect switch).

"Make sure whatever battery voltage is driving the relay isn't itself disconnected by the BMS !! ."

WRT, the battery docs state that the signal will close the circuit "before" the BMS will self-disconnect. It does not specify how much "before".

I feel like I have a clear path and confirmation that my plan will work. So thanks a ton for that!

The only question now is about this relay. I see a lot of stuff meant to be mounted on an IC board. Any hints or pointers would be welcome!

Thanks again.

jordanbigel · 01-04-2022, 19:18

And then I found this and I was ready to celebrate!

Using this relay to control an alternator in a Lithium Battery system with external BMS

...but then I read the details and it seems to work exactly backwards to the way these batteries signal.

This relay can be used to turn on and off a 12 volt alternator regulator on the control of the BMS. It isnt sold by Balmar with this purpose in mind but we found it an effective way of achieving this result. We are assuming the BMS has an "Allow to charge" signal that is +12 volts. The power consumption of the coil is 140 mA. Here is the pin configuration that is used:

This relay seems to make the connection on the ignition wire to the regulator when the BMS signal wire is closed-circuit.

But the way I read the specs for the BestGo, it's the opposite, the battery is "allow to charge" when the signal circuit is open, and the battery signals to stop charging by closing the circuit.

So, this won't work. Is there a way to make it work? I don't think so.

https://shop.pkys.com/Balmar-ULR-Uni...ay_p_2813.html

goboatingnow · 03-04-2022, 09:21

Quote:

Originally Posted by jordanbigel

And then I found this and I was ready to celebrate!

Using this relay to control an alternator in a Lithium Battery system with external BMS

...but then I read the details and it seems to work exactly backwards to the way these batteries signal.

This relay can be used to turn on and off a 12 volt alternator regulator on the control of the BMS. It isnt sold by Balmar with this purpose in mind but we found it an effective way of achieving this result. We are assuming the BMS has an "Allow to charge" signal that is +12 volts. The power consumption of the coil is 140 mA. Here is the pin configuration that is used:

This relay seems to make the connection on the ignition wire to the regulator when the BMS signal wire is closed-circuit.

But the way I read the specs for the BestGo, it's the opposite, the battery is "allow to charge" when the signal circuit is open, and the battery signals to stop charging by closing the circuit.

So, this won't work. Is there a way to make it work? I don't think so.

https://shop.pkys.com/Balmar-ULR-Uni...ay_p_2813.html

Doesn’t matter. Use a relay with both normally open and normally closed contacts you can then wire them up correctly whether the default state is the relay is powered up or not

jordanbigel · 03-04-2022, 13:34

I think this will work! It has both NO and NC circuits!

https://www.amazon.com/gp/product/B0..._saved_image_5

smac999 · 03-04-2022, 16:51

you want to cut the ignition wire to the balmar reg. you probably need to use a relay. so the bms opens the relay and cuts power to the regulator ignition input