Tranzx 24V battery output voltages

johnRN

Pedelecer
Jun 7, 2022
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Still trying to fix problems with my previous post ....I am looking to try and identify the output voltages (see pic) from a Tranzx 24V BL03 battery.
Currently, the output from -ve (black) left conn to both second (white) and third (blue) connectors is showing as 0V.
I suspect that it should be much higher than this, as it could be used as a power supply for display/pedal sensor/torque sensor etc.
Black/red ....white/red....and blue red show a predictable 26V -29V.
Any thoughts?24v-tranzx-2_1280x1280bc.jpg
 

thelarkbox

Esteemed Pedelecer
Aug 23, 2023
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oxon
@about 2 1/2 mins thet describe the power port. and why you should not undo the screws beside it ;)
 

johnRN

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Jun 7, 2022
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Thanks for that ..I have reviewed this several times, and it does not really address the output voltages (blue, white wires) ...looks like it may be a Tranzx secret ..or it may be a bms issue
 

saneagle

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Oct 10, 2010
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Thanks for that ..I have reviewed this several times, and it does not really address the output voltages (blue, white wires) ...looks like it may be a Tranzx secret ..or it may be a bms issue
I haven't watched the video, but if they're data wires, they don't have any voltage.
 

cyclebuddy

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Nov 2, 2016
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Beds & Norfolk
This may not help as these images are from a TranzX rear-rack battery but 36v BL07's BMS of about the same vintage as the BL03. You can see the white/blue wires run from the BMS (unfortunately the PCB print/marking is obscured) and ARE meant to be connected at the output. Also, the label attached - this battery recorded the number of cycles and that counter can be read/reset externally, so it did "plug in" and my guess would be that's the function. It doesn't explain why having those connected made that battery unbalanced though.

TranzX BL07 circuit.jpg

i2c_Reset.gif


Also, he's right about only needing a +/- on the charge port, but a third wire IS being used on the official TranzX chargers and I'd guess it's a temp sensor.
 

johnRN

Pedelecer
Jun 7, 2022
29
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Looks like the blue and white wires do occur on both 24V and 36V batteries, and are connected to the BMS at the same location.
On my battery, as mentioned previously, there is a zero voltage showing when connecting a multimeter between the left 'black' negative conn, and either the blue or white outout conn. I suspect that the BMS has a problem here, because the same ports show a voltage of 39V/40V on a re-built/re-celled battery that I have borrowed ....I have not attempted to install this battery since I am cautious about the 39V/40V voltage magnitude !!
 

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