[brainzel]

I made a detection, which I would like to share.

Since 2009 I use a Zivan NG3 charger to charge my battery pack.
I used a Curtis 1221C, than updated to a 1231C Motor Controller.
The charger (sometimes two NG3 in parallel) was connected to the battery every time (output) and pluged in (AC) when I had to charge.
No problem.

Since one month now I had to change the controller and installed a Soliton Junior.
Great device, everythings OK, but this:

Leaving the Zivan NG3 connected to the pack causes some issues.
High frequency whistle, light smell and the charger warms up while driving.

Evnetics recommends to disconnect the charger during the drive and I can confirm this advise.

So disconnect your pack from charger, while driving.

Michael

 

[Tesseract]

You can leave the charger connected to the pack all the time if you insert an inductor in between it and the pack, same as for the input to the dc/dc converter, but the inductor for the dc/dc converter usually only has to handle a couple of amps, while the one for the charger almost always has to handle at least 10A, and perhaps 25A or more, hence it needs to have a significantly larger core to support a sufficient number of amp-turns.

But since you typically don't drive and charge at the same time - indeed, you typically want some form of interlock to prevent driving while the charger is plugged in - it makes sense to install a switch on the charging port that breaks power to the controller when the port is open/in use, and which interrupts the connection between the pack and the charger when it is closed/not in use.

 

[brainzel]

If for some reason someone wants to use the inductor, how would you calculate the inductor size.
The amps is easy, but the µH/mH would be a challenge, I think.
Michael

 

[Tesseract]

If for some reason someone wants to use the inductor, how would you calculate the inductor size.
The amps is easy, but the µH/mH would be a challenge, I think.
Michael

The minimum amount of inductance depends on the ESR and capacitance of the output capacitor on the affected device. The reactance of the inductor forms a voltage divider with the reactance/ESR of the capacitor. If the ESR of the capacitor is 0.1Ω at the controller switching frequency then an inductor with a reactance of 1Ω will cut the ripple fraction through the capacitor by 11x. At 8kHz you only need 20uH to get to 1Ω of inductive reactance. Whether that will be enough depends, again, on the amount of output capacitance (and its ESR).

And since I don't know the value/ESR of the output capacitor in any particular application, I can't offer a specific inductance value. Rebirth Auto sells a "generic" 100uH/25A inductor that should cover just about any dc/dc converter and charger rated for 3kW or less, but outside of that range you are on your own.

 

[brainzel]

Addendum: opened the case yesterday to replace the charge curve chip and saw a bloated capacitor.
Function of the charger is OK, but the cap (220µF / 200V) seems to be proposed for a replacement
Picture will be submitted later.

 

[ElectriCar]

If for some reason someone wants to use the inductor, how would you calculate the inductor size.
The amps is easy, but the µH/mH would be a challenge, I think.
Michael

I used this to make mine. I put a 12uh coil on my DC-DC and Cycle Analyst based on this online calculator but not on my charger, an NG5.

I used a 1.25" PVC conduit as a form and used a 14ga wire I believe but the wire has to be sized to carry the amps you need. For 20 amps I would use a #12 and for 30 use a #10.