Ohm of OEM connections

[IamIan]

I was wonder if anybody already happens to know what the Ohms are in the IMA OEM battery pack connections outside of the battery itself?

The two I am mostly interested in ... are the + & - terminal connection coming off the whole IMA battery out to the junction board on the side that faces the MDM... not the two that feed to the MDM ... but the two that actually pull out from the battery itself out to the junction board.

If no one happens to know... I might have to put it on my list of things to check / test when I next pull my IMA battery out.

I'm suspecting very low of course... But I am wondering for a project I'm thinking of ... how low... like below 0.1 mOhms kind of low... or much much lower than that?

[Mike Dabrowski 2000]

You need a special 4 lead ohm meter to directly measure anything less than an ohm with any degree of accuracy.

If you pass a measured relatively high current through the connection, you can compute resistance by measuring the voltage drop across the connection as measured with a good DVM.

[retepsnikrep]

Why do you need/want to know? Intrigued.

Very Very low would be my guess.

[JimIsbell]

Originally Posted by IamIan

I'm suspecting very low of course... But I am wondering for a project I'm thinking of ... how low... like below 0.1 mOhms kind of low... or much much lower than that?

As Gilda always said, "Nevermind." I calculated that wrong because my head was up my ........its only one watt.

[IamIan]

Originally Posted by Mike Dabrowski 2000

You need a special 4 lead ohm meter to directly measure anything less than an ohm with any degree of accuracy.

If you pass a measured relatively high current through the connection, you can compute resistance by measuring the voltage drop across the connection as measured with a good DVM.

Thanks... I am suspecting I might have to try and do something like that... but My Meter won't do it on its own ... and I'm not sure exactly how I want to regulate a high enough current accurately enough to be able measure it safely... I'll have to think about that a bit.

Originally Posted by retepsnikrep

Why do you need/want to know? Intrigued.

Very Very low would be my guess.

A friend of mine gave me as a gift one of the new Cycle Analyst.

I had been planning on adding some additional instrumentation to display additional IMA battery information ... although this is originally built for E-Bikes and Low power EVs... I think it might work instead of my original idea I had of trying to make something from scratch... especially because I have it now anyway... Instead of putting it on my 36V E-Bike... where I think it would be over kill.

Instead of using a conventional Shunt... I was wondering if the resistance of those battery to junction board connectors had enough resistance to work ... that way I wouldn't have to introduce any additional resistance into the system... 0.5mOhm is recommended for 100Amps, but it does adjust down to a bit under 0.1 mOhms... I didn't know how the BCM and stuff would like additional resistance causing larger dV from current flow... and getting a shunt to fit in there might be kind of tight.

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The Unit I was given does the following:

Large OEM Display model with Back Light.

Volts 20V up to 200V

Amps by +/- 200mV Shunt from 0.0728mOhms up to 9.99mOhms... for 100Amps 0.5mOhm Shunt is recommended.

Watts

Counts cumulative Ah & Wh... drained from battery and regen back to battery

If speed sensor is provided it will do Speed Max and Average , Distance, Time , and Wh/km or Wh/Mile

Peak Currents forward and regen.

Minimum Battery Voltage Sag point.

Battery cycles

Battery life time Ah

It can be programmed to send out a signal to other devices based on programmable speed limits, or current limits, or minimum Voltage level.

Saved data is maintained with no power drain

And it comes with a USB output and software for data logging to a PC.

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Alternatively I could just try to move further ahead with my plan to re-design / re-build the IMA battery box.

Alternatively I could go back to my idea to build something from scratch and make use of the Hall Effect Current sensor already there for Current sensing without the need for a Shunt.