***HELP*** CA-HC Shunt

Hi Guys,
I am in the desperate need of some technical help and advise regarding the choice of shunt for my CA and current setup.
Firstly I have my self to blame as I mistakenly ordered the HC model and now need a shunt in order to wire in my new toy.

I understand that there is a calibration setup with CA but first I need to know if the shunt I was advised will suit my application.
I am not a electrical technician and have been pushing my knowledge and learning a heap since starting my first ebike.

Motor
1000 watt rear hub motor (Chinese special)
Controller
48 Volt 30 Amp no LCD just a twist throttle (Chinese special again)
Batteries
2 x 22 Volt 6 cell Multistar LIHV from Hobby King. Which I charge to the higher LIHV specs

The shunt I was advise from my local Jaycar specialist was a 6-50A 50MV shunt, I am not sure if it will be able to be reliable and was the correct choice...

Any help would be greatly appreciated

W1R3D said:

The shunt I was advise from my local Jaycar specialist was a 6-50A 50MV shunt, I am not sure if it will be able to be reliable and was the correct choice...

Click to expand...

Not sure what the leading '6' is about, but the 50A shunt rating is certainly adequate for your system. As far as the CA is concerned:

You appear to have a 1mOhm shunt (0.050V/50A = 0.001ohm ) which is fine for the CA and should require no calibration. If you have doubts or get really wonky readings after zeroing the current, take a look at"Appendix A. Calibrating the Cycle Analyst RShunt Value" in the CA V3 [strike]Un[/strike]official Guide (here).

Although your shunt looks 100% compatible, you might have had a simpler time by ordering the standard external 1mOhm 50A shunt from Grin Tech that is designed to simply plug into your CA (either V2 or V3)... (replace the HC cable with a CACable or add a 6pin JST to what you have - or just exchange the CA) - just a thought.
See "Shunt-CA3".


See "Appendix D. Adding a CA-DP Connector to a Generic Controller" of the Guide on how to hook that shunt up should you decide to go that way. In any case you will need to make similar throttle (and optionally hall/Speed) connections to get CA limiting, etc to work.

BTW - if it wasn't clear - all CAs of a given model (2.3 or 3.0) are the same and differ only in the wiring attachments. It's pretty easy to convert one type to the other. See "Appendix B. Add/Remove Wheel Speed Pickup Sensor" in the Guide for some info on that.

Thanks guys this is the info i needed and i can finally really monitor my setup. As in the past i have just been keeping track of the voltage left at the end of the day.
I am really interested in seeing the top speed and range.

I should have ordered the stand alone model but living in the middle of australia delivery times are a killer. If i had returned it i would be waiting for another month...
At the moment by ebike is my only mode of transportation lucky i live in a small town which is quite flat.

One good point is that as i upgrade my system i can also upgrade my shunt if needed. I would love to get a 3 kw hub so if you see any please drop me a line.

Again many thanks for the info, this is what makes a great forum.

I have 1 more question.
The single red wire?? I read that it only takes 10 volt to power the CA up but what if my power is 48 volt? Its such a small wire...

W1R3D said:

I should have ordered the stand alone model but living in the middle of australia delivery times are a killer. If i had returned it i would be waiting for another month...

Click to expand...

Ya - kind of an issue, I guess (BTW - fill in your location in your User Profile to help out getting better answers...). That said, there are CA distributors in AU that can help you out with bits that you need. Contact Grin or post up a 'vendor?' query here on ES.

Just a note:
Your shunt is HUGE and actually a little fragile. The extreme accuracy of a meter shunt comes from the exact dimensions of that resistive bar in the middle that is carefully trimmed and notched. It doesn't take well to getting banged around, so mounting those guys on a bike is annoying. By their nature, shunts dump heat, but at 30A, yours will only dissipate about 1W of heat, so not too troublesome in that regard (another part of the mounting thing...).

W1R3D said:

I have 1 more question.
The single red wire?? I read that it only takes 10 volt to power the CA up but what if my power is 48 volt? Its such a small wire...

Click to expand...

The CA is designed to run on pack voltage - up to about 150V. Don't mess around with another voltage source - that is possible, but you will be getting into unnecessary complications. The size of the wire deals with the current, not the voltage and the CA draw only 0.01A. Just wire it up according to the diagram in the manual.

If your controller has an 'ignition' or small 'power' wire that is hooked to an ON/OFF or keyswitch, then hook the red CA wire to that. This will turn off the CA with the keyswitch. Otherwise, hooking it up to the main battery power is fine if you switch off your bike by switching/disconnecting main battery power.

At some point you may wish to enable the CA throttle control (low voltage cutoff, current limiting, Current Throttle). The CA-HC cable does not provide the throttle wire to do this, but it can be added to the CA PCB if that's in your skill set. These are cool features that make the CA more than just an expensive Wattmeter....

When stripping back the main power and shunt wire i noticed 2 extra wires,from memory a green and yellow. Are these the wires needed to enable tye other features you mentioned?

Yep.
Hmmm - I didn't know those were in there for the HC version.... handy.

• Yellow - (SPD) - This is disconnected inside the CA since yours came with a wheel pickup for speed/distance measurement. This is normally the difference between the CA_DP and CA_DPS models. There is an Appendix in the Guide that describes how to modify one model to be the other. In your case, you might either re-purpose the wire for some other use or follow the instructions in the V3 Guide to remove the wheel sensor and switch to using a hall sensor on the motor to determine speed (assuming you have a DD not gear motor).
  
  
• Green - (ThOverride) - This should be going to the Thd pad on the CA PCB if you have a CA V2.3/2.4 and to the ThO pad for a CA 3.x. For simple limiting, you follow the directions in the Guide I mentioned above and add a 1K resistor to your controller throttle wire, then tie in the green wire from the CA cable. This will enable all the limiting functions available with the CA-DP and CA-DPS models.

The CA V2.3 is sort of a stripped-down CA-V3 with the same basic PCB layout which is why a lot of the V3 Guide can be used for the V2.3/2.4. Anyhow - if you want to pursue any of this and it isn't clear - post back and we can get things sorted.

W1R3D said:

I would love to get a 3 kw hub so if you see any please drop me a line.

Again many thanks for the info, this is what makes a great forum.

Click to expand...

Don't spose you'd be riding near the Darwin Hospital of late? :wink:

No mate I am down in Alice Springs...

I get stopped at least once a day with people interested in my bike and asking a lot of questions.
I even had a guy chain up a Stealth Bomber e bike next to mine this morning lol... my budget build verses a production e bike lol