2009 Buddy City-Jet-6, 12V systems seems ok but it do not run.

[SveinHa]

Yesterday, I bought my first Buddy. I knew it didn't run and the owner told me that he had been driving it one day, parked it and the next day it didn't run. It then sat for a year before I bought it with charger connected.

So far, I've been reading quite a lot on a few forums but so far, I have not been able to locate the problem with my car.

When I got it home on a trailer and after fiddeling a bit around in the dashboard and in the rear compartment, I suddenly heard a distinct click in the rear end and found that the main 72V contactor had activated. I was able to drive it for 20 meters, reverse a bit and then it died again and have been dead ever since. By "dead" I mean that the main 72V contactor is off and of course then the motor is not running. The rest, all 12V systems, work fine.

So far, this is the status:
All 12V systems seem to work fine.
All 13 fuses on the passenger side is ok.
One 10A fuse in the rear is ok.
When turning ignition on, the first (uppermost) relay behind the glove compartment energizes (72V ignition on?) end the third relay energizes (12V ignition on?) and instrument panel lights up indicating one LED on the speedometer and full battery.
When pushing the throttle pedal, one green LED lights up on the ECO meter.
I have 2 spare Car Controllers but they all works the same.
Main battery is 76V and utility battery is 13.6V

I only have electrical diagrams for City-Jet-5 but hopefully, they are not too far off... Sadly, they are scanned in a too low resolution
so they are partly unreadable...

I've been told that the car should be able to run without the Car Controller present but I guess i have to make a scortcut here and there to make that happen. The main purpose with any car is to transport me from A to B whenever I want to so if anyone have a recipe to make it run in "emergency mode", I would really appreciate some info about that as well. Of course, my main goal is to be able to make the car run as it was designed to do...

Any ideas would be greatly appreciated.

 

[matzetronics]

I've been told that the car should be able to run without the Car Controller present

No, it won't run. And yes, to run it without the CC you would have to bridge quite a few cables. But this here doesn't sound like a problem with the car controller but a problem inside the rear electric box or with one of the security switches..

The green LED on the panel shows that there is current consumption on the motor circuit. As a help, you could set the Jumper JP1 on the car controller board to show voltage, temperature and motor current on the panel display.
If its an older Buddy, most of the circuit should match the Citi-Jet 5. You may have a newer controller board but the connectors are still the same. Make sure all connctors are firmly seated in the car controller and that the board is free from moisture and other debris.
Try this circuit diagram from my site:

https://kewet.de/downloads/kewet5-schaltplan-gro.pdf

When pressing the speed pedal you should first hear a powerful click from the rear (Main Relay).

Please also note that most of us Kewet drivers are not very goos informed about the Buddy. We never could buy it here.

 

[SveinHa]

There is a crucial line missing on that diagram but it is visible on schaltplan-kewet-5-speedbox.pdf

With relay K6 open/unplugged, i have 76V over the contact which should tell me that the "NOT-AUS" circuit is ok.

Next contact below, is that the microswitch on the throttle? If so, it may not last long with current to contactor KM or may there be a relay in between? I have only 2 wires to that microswitch but the diagram show 3.

I listed the battery data today and they don't look good but I plan to install LiFePO4.

I did a battery reset and a few other resets with jumpers on the CC but it seems that battery data still remains...

 

[matzetronics]

I did a battery reset and a few other resets with jumpers on the CC but it seems that battery data still remains...

Its important to follow the procedure to the letter. First unplug JP1 from the car controller to switch it fully off. Now place 2 jumpers over S8 and S9. Plug in JP1 to power the controller and turn the ignition key to thr 'Run' position. a few relay klicks can be heard if you're lucky.
Turn off the ignition key and unplug JP1 from the controller. Remove jumpers over S8 and S9. Plug in JP1 and print a report. Capacity should be at 100%.
Btw. there's no way to tell the car controller about larger batteries. It will always start with 116.8Ah. For this reason i manipulated the current measuring in the CC to get better readings with my 314Ah LiFePO4 setup.

If so, it may not last long with current to contactor KM or may there be a relay in between?

No there's no extra relay but the switch is a quality switch and lasts in my El-Jet 4 now for more than 30 Yrs/31000km.
If you don't hear the main relay though, there's a problem.
Btw, the misuse counter shows suspicious values. It seems that the former owner fully discharged the batteries very often. It might be that they are no longer capable of delivering sufficient current to run the motor. You could lift the rear and try to free-run the motor. When the green LED is lit it tells about a little current to the motor but the yellow and red LED should light up if you accelerate with the speeder.
If that never happens it could be weak batteries.

 

[SveinHa]

Its important to follow the procedure to the letter.

I think I did. Didn't notice any relays clicking...

If you don't hear the main relay though, there's a problem.

Yes, that is also my conclusion. The couple of times I have heard the main relay, the car is driveable.

Btw, the misuse counter shows suspicious values.

I also noted that. 2 batteries (#5 and 6) are recently replaced with ordinary Biltema Start batteries

When the green LED is lit it tells about a little current to the motor...

The green LED lights up even when the main relay is out...

 

[Norbert]

Bilder sagen mehr als viele Worte Fährte er im Notfahrmodus / mit ganz gedrehtem Zündschlüssel gegen / Über die Federkraft wie z.b. einen Verbrenner zu starten ?
A picture is worth a thousand words: Is it being driven in limp-home mode, or is the ignition key turned all the way—working against the spring tension—to start it, much like a combustion engine? ( Gogl translate )

 

[SveinHa]

After a good night sleep, I got a bit further.

With ignition on and throttle depressed, I have +76V on the positive side of the main relay KM coil.

The negative side is one blue wire going directly to the multi connector on the SepEx.

According to the electrical diagram, the negative side of the coil should go directly to battery negative. For testing, I made a temporary connection from KM coil negative to chassis and the main relay works as expected but still no driving...

I think I have seen a flashing yellow light on the SepEx a couple of days ago but now it is dead...

Conclusion so far: The +72V side of the KM-coil is ok, the negative is not... SepEx is not working or have some safety feature kicking in...

Found this Curtis SepEx manual https://cdn.curtisinstruments.com/products/manuals/1268_manual_en.pdf Not for the exact same controller but the connections look identical so probably they are the same...

 

[matzetronics]

That looks like a lot of corrosion there. Read about the problems of another user of the buddy in this thread:

Kewet Buddy City-Jet 6 Restoration - Elektroauto Forum

Hello , I bought a Kewet one week ago(roughly) and thought I wanted to share some information about the car and show the progress. I am planning on restoring as much as possible on the car to a nicer condition but primary goal is to get it up and running and get it passing inspection...

elektroauto-forum.de

This car suffered from very bad crimping on the cables. It might be a good idea to contact him about the buddy.
Make sure that all cables (especially the thick ones) are properly crimped and not corroded.
The left bolt on the main fuse e.g. looks suspicious (all black bolt and nut?). There's a thin red cable from one of the motor connections which looks like it has been suffered on the insulation.

 

[SveinHa]

I've been working with industrial electrics/electronics for four decades and have not seen any obvious bad crimps or bad connections, no signs of heat. Didn't notice the black bolt though, guess I assumed it had a black plastic cap but it have not... Crimps/connections is not a priority right now as I have power on my 72V system. When the throttle is pressed, I would hear the whining electronic noise long before any serious power is pulled from the batteries but I hear nothing (except for the couple of minutes where I actually could drive the car).

Not all connections in the SepEx found in the Curtis document is present in my car but I've found one suspicious one: The throttle pot.meter is supposed to be fed with +5V in J1-13 but I only measure +0.43V both to ground and to J1-14. Even with the throttle pot.meter disconnected, I only measure 0.51V both it the SepEx and in the connector by the throttle.

I planned to do another battery reset on the CC today but the report already said 100% on all batteries so it seems to have worked yesterday after all...

 

[matzetronics]

If the Logic enable and the Logic Power inputs have the correct voltages, it might be a good idea to temporarily supply a regulated and current limited 5V (via a resistor) voltage to the pot high connection. Or feed a regulated votage to the pot wiper.

 

[SveinHa]

I just tried that, fed 3V from a battery between J1-14 (-) and J1-15 (+ Wiper) while holding the throttle a bit down but nothing happend...

I have a spare (used and obviously opend up some time in the past in unknown condition) SepEx so I installed it and that one is behaving exactly the same, KM not activated and about 0.2V on J1-13...

The fault LED is also dead so I assume there are some internal systems in the SepEx that don't work. By only taking off the SepEx cover, I couldn't see any fuses or burnt components... When I by-passed the KM negative side, I would expect a 3,2 fault: Welded main contactor.

 

[SveinHa]

I opened up the second SepEx and found 2 MOSFETS blown up (literally)...

 

[tewek]

what ist this poti for?

 

[SveinHa]

what ist this poti for?

I believe it is to set throttle response and maybe also the amount of regeration. I've seen it in some documents, need to look it up...

 

[matzetronics]

and found 2 MOSFETS blown up

That doesn't look good. If the controller came from the same car, i'd check the motor for short circuits. You probably have also noted the main fuse being slightly deformed under the black nut and bolt.

what ist this poti for?

Its also present in the Buddy from the other thread and connects to the same mysterious little plastic case with two wires. It probably sets the amount of regenerative overspeed protection and breaking. Its not meant for this kind of environment, though.
Throttle response is set with the Eco/Sport pot in the cockpit.

 

[SveinHa]

what ist this poti for?

Adjust Economy-Normal-Sport mode

 

[SveinHa]

That doesn't look good. If the controller came from the same car, i'd check the motor for short circuits. You probably have also noted the main fuse being slightly deformed under the black nut and bolt.

This controller is the one that sat in the car when i bought it.

The fuse deformation seems to be due to the white plastic around the fuse.

Its also present in the Buddy from the other thread and connects to the same mysterious little plastic case with two wires. It probably sets the amount of regenerative overspeed protection and breaking. Its not meant for this kind of environment, though.
Throttle response is set with the Eco/Sport pot in the cockpit.

I have not found any pot in the cockpit but there is a multicable with no connections both near the motor controller and the steering wheel (looks like the same cable) so I guess the pot is supposed to be in the cockpit but for some reason it is moved...

 

[tewek]

It looks like the green cable from the poti goes to pin 21, yellow to pin 20 in the controller plug J1