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Old 08-09-2020, 09:21 AM   #81
MrBritGolfFan
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Default Re: RXV HV/LV BMS Shutdowns

Quote:
Originally Posted by Sergio View Post
You may need a smaller load for P1 if your normal voltage ranges are that low.

The original values I chose were based on a Leaf cell chemistry, it was a compromise between keeping the relay coil cooler by using less voltage across the coil but still allow the relay to click at low pack voltage.

Once closed that relay will hold the contacts until around 5v so no chance of dropping under load.

The guaranteed turn ON voltage is 36v but usually they close with less voltage.

There is also a "fudge" factor on those 12v lights as different manufactures use slight different resistors depending on the brightness they want, and different LED colors provide a larger "constant" voltage drop that affects its interaction with the circuit as the pack voltage drops.


Anyway, the best thing to do is to measure the voltage between:
  1. Solenoid Big Post on Controller side to BMS C-
  2. Measure the voltage between the relay coil terminals (1/4 quick connectors).

Once we know how much effect that 12v light is having in the circuit we can make adjustments.
Thanks Sergio

Checking now. My pack is 35v to 46.8v. Nominal is 42.8v.
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Old 08-09-2020, 09:26 AM   #82
MrBritGolfFan
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Default Re: RXV HV/LV BMS Shutdowns

Quote:
Originally Posted by Sergio View Post
You may need a smaller load for P1 if your normal voltage ranges are that low.

The original values I chose were based on a Leaf cell chemistry, it was a compromise between keeping the relay coil cooler by using less voltage across the coil but still allow the relay to click at low pack voltage.

Once closed that relay will hold the contacts until around 5v so no chance of dropping under load.

The guaranteed turn ON voltage is 36v but usually they close with less voltage.

There is also a "fudge" factor on those 12v lights as different manufactures use slight different resistors depending on the brightness they want, and different LED colors provide a larger "constant" voltage drop that affects its interaction with the circuit as the pack voltage drops.


Anyway, the best thing to do is to measure the voltage between:
  1. Solenoid Big Post on Controller side to BMS C-
  2. Measure the voltage between the relay coil terminals (1/4 quick connectors).

Once we know how much effect that 12v light is having in the circuit we can make adjustments.

1- 42.57v
2 - 26.05v

Re: the led is a 12-24v one I just checked.
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Old 08-09-2020, 09:42 AM   #83
Sergio
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Default Re: RXV HV/LV BMS Shutdowns

The 12v/24v rating on that light is part of the problem, it has a higher value resistor than a 12v light so it can also work at 24v.

A typical 12 LED would be dropping around 8v at that pack voltage.

At those voltage ranges all you need is a plain LED and no resistors, or no LED at all in the circuit.

Sometimes the resistor is easily spotted in the light wires and you can just by-pass it, otherwise you can use without the indicator light.
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Old 08-09-2020, 10:21 AM   #84
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Default Re: RXV HV/LV BMS Shutdowns

Quote:
Originally Posted by Sergio View Post
The 12v/24v rating on that light is part of the problem, it has a higher value resistor than a 12v light so it can also work at 24v.

A typical 12 LED would be dropping around 8v at that pack voltage.

At those voltage ranges all you need is a plain LED and no resistors, or no LED at all in the circuit.

Sometimes the resistor is easily spotted in the light wires and you can just by-pass it, otherwise you can use without the indicator light.
Ok thanks Sergio. Testing now.
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Old 08-09-2020, 10:58 AM   #85
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Default Re: RXV HV/LV BMS Shutdowns

Quote:
Originally Posted by Sergio View Post
The 12v/24v rating on that light is part of the problem, it has a higher value resistor than a 12v light so it can also work at 24v.

A typical 12 LED would be dropping around 8v at that pack voltage.

At those voltage ranges all you need is a plain LED and no resistors, or no LED at all in the circuit.

Sometimes the resistor is easily spotted in the light wires and you can just by-pass it, otherwise you can use without the indicator light.
Ok thatís works Sergio! And now I have black wires not red! :)

Thank you for all your help!

How can I test that it works? If I were to jack the back up and get the wheels spinning if I then shut down my battery with my big disconnect switch would that simulate it?
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Old 08-09-2020, 11:12 AM   #86
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Default Re: RXV HV/LV BMS Shutdowns

Don't disconnect the pack, you need to disable the BMS to test the Controller lockout function.

Does your BMS have Bluetooth or any other switch to disable it?

The BMS is what needs to be tested since you already know if that relay does not close the cart will not move.
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Old 08-09-2020, 02:28 PM   #87
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Default Re: RXV HV/LV BMS Shutdowns

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Originally Posted by Sergio View Post
Don't disconnect the pack, you need to disable the BMS to test the Controller lockout function.

Does your BMS have Bluetooth or any other switch to disable it?

The BMS is what needs to be tested since you already know if that relay does not close the cart will not move.
No Bluetooth I am aware of for the bms.

If the power is cut completely does that mean the RXV locks the brake? Eg if I cut the power off at the battery etc?
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Old 08-09-2020, 05:01 PM   #88
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Default Re: RXV HV/LV BMS Shutdowns

That is my understanding, removing power will lock the wheels and apparently some Controllers are also more susceptible to settings corruption if power is removed while to Controller is working.

Without being able to temporarily change the settings to force a shutdown, I don't know of any safe way to cause the BMS to trigger on LV or HV.

You need to check any manuals or with the place you got the pack to understand the procedure to unlock the BMS if it does shutdown.
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