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I have a new LiFePo4 battery arriving. It has the BMS a built in, however the means of communication is via this pig tail. I could not copy a picture here, but a link to the description of it is below. I want to hardwire 3 Alarms.

This is my understanding of the wiring I need to do….Using only the A Connect……

Yellow (a3) is common…meaning this will be the ground for each alarm device.
Each of the others are positive to their respective alarm device.

I want to have 3 different alarms

So..I wire yellow (-) and green (+) to the first alarm for current
I wire yellow(-) and black(+) to the second alarm for temperature
And I wire yellow (-) and red (+) to the last alarm for voltage.

The diagram below is from the vendor…oops..it wouldn’t let me Post it….so...this is a link to diagram.

Do I understand this correctly .?


https://www.electriccarpartscompany.com/...k-4-27.pdf
 

James

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The wire colours are correct, however, they are not outputs to wire directly to an alarm.
think of them as switches, I.e. yellow and red are joined together internally when the voltage is abnormal
 
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The wire colours are correct, however, they are not outputs to wire directly to an alarm.
think of them as switches, I.e. yellow and red are joined together internally when the voltage is abnormal
They appear to be output from the battery. The other end is plugged into the BMS internal to the battery. I thought it was saying that the BMS acts as the switch and that turns the voltage on when the conditions are met (switch).

somehow the alarms are connected to this pig tail. How should that be done?
 

Avo Mk8

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They appear to be output from the battery. The other end is plugged into the BMS internal to the battery. I thought it was saying that the BMS acts as the switch and that turns the voltage on when the conditions are met (switch).

somehow the alarms are connected to this pig tail. How should that be done?
I don't agree that they appear to be "output". The second page of the instructions describes how the alarm outputs are switches. The third page of the instructions titled "Related Components", shows a schematic of how to wire an alarm. It shows an additional battery is needed to provide "independent power" to the alarm. It also describes limitations on the voltage used (max 60V) and the max current (1.5A), as per James' explanation.
 
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I don't agree that they appear to be "output". The second page of the instructions describes how the alarm outputs are switches. The third page of the instructions titled "Related Components", shows a schematic of how to wire an alarm. It shows an additional battery is needed to provide "independent power" to the alarm. It also describes limitations on the voltage used (max 60V) and the max current (1.5A), as per James' explanation.
I am confused. The third page does NOT show an additional battery. The 12 pin connector is on the battery itself, and seems to be the output of the battery management system.

my take on this is that each of the wires (except yellow which is ground) carries no voltage until the battery management system sends the voltage to that wire (depending on the condition ie: voltage, temperature, current). Normally there is no voltage anywhere as it would only happen when the condition is “on” and the circuit is closed allowing voltage to flow.
 
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I don't agree that they appear to be "output". The second page of the instructions describes how the alarm outputs are switches. The third page of the instructions titled "Related Components", shows a schematic of how to wire an alarm. It shows an additional battery is needed to provide "independent power" to the alarm. It also describes limitations on the voltage used (max 60V) and the max current (1.5A), as per James' explanation.
The current would flow from the battery (the 12 pin connector) to the alarm.

the question I have is that I want to have 3 different alarms.…
after talks with the manufacturer and the supplier of the pig tail cabling… the only device I can buy is the remote monitor (S connector), no one is offering an alarms device…so I have to hard wire it myself.

so…. Is it legit to wire this the way I described in my first post? …..

yellow as common ground,
so, each alarm would be wired with yellow and the one and only color corresponding to the alarm I want to install.
 

Avo Mk8

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I am confused. The third page does NOT show an additional battery.
To clarify my post, on the third page of the document in your original link, there is a schematic of the "Alarm Speaker Set", showing an alarm symbol in series with what I take to be a battery symbol, or at least illustrating a source of power. The description is consistent with this.
To do what you want to do, you will need to design a circuit that is switched by the pigtails from the BMS, that connects whatever alarm device you want to use in series with a source of power to make that alarm work (if the alarm device is not already self-powered, and just needs to connect to a switch). I imagine you could use power from the LiFePo4 battery If needed.

The 12 pin connector is on the battery itself, and seems to be the output of the battery management system.
I understand it is the output of the battery management system, but the documentation says the "A" connector outputs (which I assumed to be the ones you are interested in) close a connection between A3 (common) and the relevant alarm signal A1, A2, A4. No power comes from directly from A1, A3, A4 as I read the leaflet.

PS. I'm not clear what alarms you intend to use, but if they happen to operate from the same voltage as your LiFePo4 battery, you could (via a fuse) connect one side of the battery to A3 yellow, one side of each alarm to its respective colour as you say, (noting polarity) and then connect together all the other alarm supply sides to the other battery terminal.
 
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