openinverter forum

Hi all,

I have a strange problem.
Connected is a TCC/Elcon HK-J-144-23A charger via two 30A fuses directly to the main battery terminals on the controller/inverter.
Charging is working perfectly, no issues at all.

But when driving and using regen the charger fuse on the positive line blows for unknown reason.
Replacing the fuse does restore charging capabilities and all but then again driving and using regen: blows the fuse.

Anyone any idea whats going on ?

prensel wrote: ↑Wed Sep 01, 2021 12:41 pm Hi all,

I have a strange problem.
Connected is a TCC/Elcon HK-J-144-23A charger via two 30A fuses directly to the main battery terminals on the controller/inverter.
Charging is working perfectly, no issues at all.

But when driving and using regen the charger fuse on the positive line blows for unknown reason.
Replacing the fuse does restore charging capabilities and all but then again driving and using regen: blows the fuse.

Anyone any idea whats going on ?

Do you use diode fuse? Why use two fuses for charger?
Where do you connect charger on the positive line? Directly to battery side of DC contactor or on the other side?
Dont forget charger has its own capacitor which could react to voltage drop on positive line. Resulting current could blow the weakest fuse. I see with 96S rated chargers they use 30A fuses for 3kW chargers. You use 48S charger and currents should be twice that.
I recommend you use double rated fuse (or two 30A fuses in parallel) and put it only on positive line only.
If you keep having problems you could use 40A DC relay to separate charger from DC line.

The inverter used is for the Vectrix VX1 motorscooter and has fittings on it for standard spade fuses upto 40A each.
Originally there are two 25A fuses installed, one for each connection. The battery is a 40S setup with max 164V charging limit.
The regen limit is set at 164V also so that should not come to work (but it does because I can use/feel regen when fully charged though....)
There's no DC relay installed, the battery, inverter and charger are connected together all the time.

Interesting thing is that I have a similar battery and software setup on another bike but with only a different charger (TSM2500) and standard 25A fuses that hadn't given any problem for almost two years.

Doubling or enlarging the fuses without changing the wiring between fuses and charger would not be a good idea I guess..

Measuring the output DC terminals of the Elcon charger without battery connected shows an R of almost 180k so how is it possible that there's even more then 30A passing through the charger causing the fuse to blow ??

I'm really interested in the theory behind what is happening because it doesnt make sense at all at this time...

Have you measured the actual voltage at regen? Maybe the charger sees overvoltage and wants to discharge the battery. Does it get powered up in a way that would make this possible?

Well, in any case, one possibility could be that the charger has high enough capacitance at the output and the inverter has low enough capacitance at the input to cause the charger to act as an extra capacitor for the inverter. However, I don't think this is the case because then the fuse should blow at acceleration also.

Just put a diode on the charger output.
Maybe that is built in on your other charger.

joromy wrote: ↑Wed Sep 01, 2021 8:46 pm Just put a diode on the charger output.
Maybe that is built in on your other charger.

Yes I have thought about that but then the charger probably wont see that a battery is connected when starting to charge.
Maybe connecting a diode with a 10K resistor in parallel so it can sense that battery voltage is present but will provide current though the diode when charging ?

celeron55 wrote: ↑Wed Sep 01, 2021 8:29 pm Have you measured the actual voltage at regen? Maybe the charger sees overvoltage and wants to discharge the battery. Does it get powered up in a way that would make this possible?

Well, in any case, one possibility could be that the charger has high enough capacitance at the output and the inverter has low enough capacitance at the input to cause the charger to act as an extra capacitor for the inverter. However, I don't think this is the case because then the fuse should blow at acceleration also.

I'm thinking about something similar as your last statement, When going in regen the chargers capacitors get charged with the higher voltage coming from the motor then it was when in drive mode. And when switching from regen back to drive mode (it is a two-way twist throttle so this happens pretty quickly) all that stored energy is going back to the lower voltage of motor creating a higher current for a very short moment causing the fuse to blow. Thats the only explanation I can come up with at this moment ?

Could it be some sort of over voltage protection on the charger output?

johu wrote: ↑Thu Sep 02, 2021 10:38 am Could it be some sort of over voltage protection on the charger output?

This Elcon charger is capable of charging upto 198Volt so I cant imagine any like that.
Problem is I cant measure the regen voltage and current when the bike is stationary.
So I need to make a CANbus logging when driving and applying regen to see whats going on.

prensel wrote: ↑Thu Sep 02, 2021 8:41 am

joromy wrote: ↑Wed Sep 01, 2021 8:46 pm Just put a diode on the charger output.
Maybe that is built in on your other charger.

Yes I have thought about that but then the charger probably wont see that a battery is connected when starting to charge.
Maybe connecting a diode with a 10K resistor in parallel so it can sense that battery voltage is present but will provide current though the diode when charging ?

Don't think the charger needs to measure the voltage on the battery. It puts out constant current and measure it's own voltage.
The reason chargers are made without diode output, is probably because it should be a separate relay for it.