TechDirect BYD BMS in pre-built units: Can anyone read this Chinese label?

[GVSolar]

Thanks again to both of you. As you can probably see, the reason I got these pre-built units is because of my unfamiliarity with LFP/BMS procedures. Old school lead-acid guy. I figured it was enough for me as a start to get my CC's and Inverter specs tailored correctly. And I'm also AC coupling - which throws another set of variables into the mix. Really appreciate the heads up.

 

[GVSolar]

That's not correct.

The correct procedure:

- turn off circuit breaker
- unplug balance leads connector
- measure cell 1 voltage between pin 1 and pin 2 of the connector
- measure cell 2 voltage between pin 2 and pin 3 of the connector
- measure cell 3 voltage between pin 3 and pin 4 of the connector
...
- measure cell 8 voltage between pin 8 and pin 9 of the connector
- replug the connector
- turn on the circuit breaker

It doesn't matter which way around you put the voltmeter leads, the only difference will be a sign "-" on the screen but we don't care, we just want the voltages

Previously I didn't say to turn off the circuit breaker and to unplug the connector because you can do the measurement without unplugging the connector but it's a bit more complicated if you're not familiar and there is greater risk to make a short-circuit between the connector pins with the voltmeter leads, so yeah, don't go this route.



Yes, but you need to find the same connector which is used here and do the Y yourself.

Bidule, I started to follow the directions as stated, but first took a careful look at the connector. There are only 8 pins on the connector, not 9 - first pin being the red wire. How does that affect "- measure cell 8 voltage between pin 8 and pin 9 of the connector"? And how does "main negative" figure into the equation? Wanted to make sure I wasn't off base. Thx.

 

[BiduleOhm]

Ah, then they must use the B- for the first cell. That's not super good for accuracy.

So the procedure is the same but for the first cell you need to measure between the big black wire coming from the battery and the first wire of the 8 pins connector.

The first cell should be opposite to the red wire on the connector. But it can also be the red wire. There's no way to tell without measuring the voltage; if you measure almost battery voltage then it's the last cell, so start at the other side of the connector, if you measure about 3 V then you're on the correct wire.

Then follow what I described in my previous post for all the other cells

 

[Darkstar]

Ah, then they must use the B- for the first cell. That's not super good for accuracy.

So the procedure is the same but for the first cell you need to measure between the big black wire coming from the battery and the first wire of the 8 pins connector.

The first cell should be opposite to the red wire on the connector. But it can also be the red wire. There's no way to tell without measuring the voltage; if you measure almost battery voltage then it's the last cell, so start at the other side of the connector, if you measure about 3 V then you're on the correct wire.

Then follow what I described in my previous post for all the other cells

I don't think they get first cell positive from the B-.

I think maybe they have 8 leads, one for each cell and the negative line is the main neg?

At least that is what my testing of a stand alone Techdirect BYD BMS showed.

 

[Darkstar]

Bidule, I started to follow the directions as stated, but first took a careful look at the connector. There are only 8 pins on the connector, not 9 - first pin being the red wire. How does that affect "- measure cell 8 voltage between pin 8 and pin 9 of the connector"? And how does "main negative" figure into the equation? Wanted to make sure I wasn't off base. Thx.

Be careful measuring "Between the pins" if you short 2 pins you could have some trouble.

On the bottom side of the connectors there should be a little bit of exposed metal corresponding to each pin. Put the neg probe of your DMM on the main battery neg and the positive probe on one of the little metal bits on the bottom of the BMS connector to get the cell voltages... At least that is what I do. YMMV. Verify with an electrical engineer before following my advice though...

 

[BiduleOhm]

First cell = lowest cell = cell on the negative side of the battery.

I think maybe they have 8 leads, one for each cell and the negative line is the main neg?

That's exactly what I described in my previous post actually.

 

[Darkstar]

First cell = lowest cell = cell on the negative side of the battery.



That's exactly what I described in my previous post actually.

Was not clear to me.

 

[GVSolar]

Thank you both. Good advice. Now lets see if I can follow it...

 

[Darkstar]

I am finding this chart useful for my BYD packs...

Rule of Thumb State of Charge voltages for Various BYD LiFePO4 series configs attched.

 

[GVSolar]

Any chance one of the resident design wizard on this forum could design a Y cable configuration with a bluetooth reader/sender to monitor cell voltages on these pre-built BYD units?

 

[wyrdone]

Does anyone know if these units have header for CAN bus communication off them? Victron indicates that they support some BYD units for direct monitoring.

 

[jasonhc73]

Does anyone know if these units have header for CAN bus communication off them? Victron indicates that they support some BYD units for direct monitoring.

The 12 pin connector is a can bus connection. 2 pins are 24V for the fan, the rest are unknown, completely. Several have tried to figure it out, some have read data, but as for "control" sorry, nobody has cracked that nut.

BYD BMS

A no cut, no splice, plug-n-play. It has a screen, Bluetooth, and more settings in the app than we know what to do with. Will already reviewed this BMS. The Inside wires: The Outside Wires: Conclusion: Molex Micro-Fit 3.0 430251000 10POS 3mm Molex Micro-Fit 3.0 or 1729521001...

diysolarforum.com

 

[wyrdone]

More interested in knowing if the Victron will "see" the battery and monitor it within ColorControlGX. Similar to the way they can for Battleborn and even the ByD B-Box BMS units. Guess I should just pony up and buy one and test it.

Victron & BYD [Victron Energy]

www.victronenergy.com

 

[FlyinBrian]

Does anyone know why the BMS wouldn't reconnect? I have a friend with 5 of these wheeled units and the voltages dropped down low enough the disconnect via the BMS. Only one turned back on when 24v was applied to the load side. How do I get the rest to reconnect?

 

[FlyinBrian]

Heres a picture of his system when it was working correctly. Now he's only running off of one.

 

[wyrdone]

So I bought one of the TechDirect BYD BMS units. I see it show up on Bluetooth. Anyone have a link to the App/Software for it?

(I emailed TechDirect but no response and none of my searches turn up anything.)

 

[nwillitts]

So I bought one of the TechDirect BYD BMS units. I see it show up on Bluetooth. Anyone have a link to the App/Software for it?

(I emailed TechDirect but no response and none of my searches turn up anything.)

very interesting.

 

[GVSolar]

So I bought one of the TechDirect BYD BMS units. I see it show up on Bluetooth. Anyone have a link to the App/Software for it?

(I emailed TechDirect but no response and none of my searches turn up anything.)

When I read about you getting a bluetooth signal I tested my units - no discernible pairing signal on my phone or iPad. Of course the BMS is buried in a metal case on my pre-assembled units... details about your matching protocol? ID? Pairing device?

 

[GVSolar]

Does anyone know why the BMS wouldn't reconnect? I have a friend with 5 of these wheeled units and the voltages dropped down low enough the disconnect via the BMS. Only one turned back on when 24v was applied to the load side. How do I get the rest to reconnect?

I have 4 of those units in parallel. Working flawlessly. Might I suggest applying a charge to them one at a time? You can use the circuit breakers to disconnect/reconnect them - assuming they are wired correctly. Also, not clear about what you mean by the "load" side...

 

[wyrdone]

When I read about you getting a bluetooth signal I tested my units - no discernible pairing signal on my phone or iPad. Of course the BMS is buried in a metal case on my pre-assembled units... details about your matching protocol? ID? Pairing device?

I connected the BMS while watching my phone in discovery mode. Saw a mac address pop up, but it wouldn't let me connect or pair.