OK to run my OEM 24V EVG at 36V?

[cor]

... the 3 schottky diodes on that heat sink. no idea why they are there, maybe part of the voltage regulated output for the lights.

The diodes are part of any DC controller, they carry the motor current while the transistors are off. (Basically it is a Buck converter with the motor as inductor).

 

[cor]

about using the 24v controller at 36v for accessories, from my experience the short answer is no. I used an old dead controller at 36v (it wouldn't power a motor any longer or give warning beeps etc. but it still worked just to run the lights and horn). my findings were: the horn developed problems at 36v. the rear LED light burnt out some resistors and quit working and the headlight melted the plastic reflector after a month or two, diminishing it's beam. DC

I have a stock 24V EVG as well, the controller cannot take more than a peak of 35V, not only because of the caps being 35V but also because the voltage regulators cannot take more, they will die if you try it with a battery that is giving more than 35V. I am running it with 8s LiPoly cells, so the peak voltage that I use is 8 x 4.2 = 33.6V and this is as high as I dare to push the bike.
The only thing that completely died on me is the horn, when I tried using it the sound kept going for much longer, then slowly died with a whiff of smoke.
Later I found out that the relay controlling the horn is too sensitive and wired in a weird way: the current through the light-on LED will always run through the horn relay. If the pack voltage is above 30V then the current is high enough to keep the relay engaged after you release the horn button, so the horn keeps going (and dies) until you switch off your lights....
Also, I lost one row of taillight LEDs. Since it is sealed, I don't know if a resistor died or a LED or a solder joint. It sees quite a bit of shock and vibe because I moved the light from the seat to my rack, which is a one-arm clamped to the seat post. This avoids that I accidentally cover the light with the laptop bag that I often carry.
I plan on upgrading the bike and controller to higher voltage by adding a DC/DC and higher rating MOSFETs and diodes.
At this moment the bike is very usable, but I often pedal faster than the stock motor at 30+Volts can go.

 

[cor]

Curious thing that maybe you guys can shed some light. I am currently riding my other EVG - 36V stock machine.
It climbs fine with enough battery. But, will eventually give the 3 Beeps every 20 seconds and, if, you keep going, it begins to just wind down on its power (current limiting I suppose) regardless of the battery state. When I stop, I check the motor temp to the touch - not hot. I assume this is an overheat protection for the motor but I understand the 36V Heini does not have a thermal sensor in the motor.

This is the "lugging" or "current limit" protection of the controller.
So, this has nothing to do with heat (I believe there is a separate temp sensor in the controller which may also kick in at some point) but it is the controller that measures the current and if the current is above a threshold for some period of time, it will warn and expect you to reduce throttle. This allows you to take off fast (lift the front tire on take off with very high current draw) but when you continue to draw high current that could overheat and damage the controller or motor in the long run, it will warn you and expect you to reduce the current (throttle). The way the controller measures this is by feeding the current measurement into a RC circuit with long time constant, so only if the current is high for a long time will the level go above the warning threshold. The higher the current draw, the faster it will start warning, until you reduce current. I was also questioning the beeping when I was climbing a local mountain, but just dividing the power between motor and pedaling (climbing faster than the semi-pros on their road bikes going up) I was able to reach the top (gaining 2700 feet) and use less than half of the 20Ah (8s2p) LiPoly pack. I reduced throttle every time it started beeping (I did not want to burn up the controller or motor).

 

[cor]

I used an old dead controller at 36v (it wouldn't power a motor any longer or give warning beeps etc. but it still worked just to run the lights and horn).

OK, you were essentially only using the glass fuse on the main board, not the plug-in controller cards. You will find that you can save some weight by removing those from the controller. If you are interested, I can have a look at the controller card and see if it can be repaired or else I can use it for my experiments in upgrading this controller.
Cor.

 

[DCMotorworks]

@ Cor: Ya, I did remove 2 of the cards now that you mention it. been a while since I set that bike up. good catch. I thought I needed one of the cards in there to run the lights/horn. the smallest one from the pics above w/ the 100V DC fuse. maybe it was unnecessary to leave it in.

Has anyone tired running a 36v evg controller at 48v? they are fully potted so you can't really look at the voltage ratings of the caps and I never had a dead one to tear apart and investigate.

and Cor, my 2 non-functioning 24v evg controllers seem to have bad chips. did you ever figure out how to replace/reprogram them?

DC

 

[cor]

Hi DC,
I heard (but have not checked myself) that it is the processor that dies, because it is run at 6V while it is a 5V device. Another reason why it may die is because several inputs and outputs are wired directly to different parts of the bike, these might be subject to ESD (Electro Static Discharge) or other noise that freely flows into the processor and kills it. Inputs such as key switch, brake switches, light and horn and outputs such as the LEDs.
My own controller is still stock and I am contemplating reducing the processor voltage closer to 5V while adding a voltage shift to drive the MOSFETs (which is the reason the processor runs at 6V, to guarantee to be able to switch the motor drive FETs on.)
Most these days I do not even connect my battery pack and ride my EVG as a regular bike, so it is a nice exercise to commute...

I have not dealt with a bad controller myself, but when looking up the processor spec I see that it can be locked from external reading of the programming, which means that it is likely that the program is hidden inside and it cannot be copied.
Unless you know someone that has intimate knowledge or access to the original EVG software it will not be easy to get your hands on the program that needs to go into this controller, even if you can get the unprogrammed controller itself.
If you want I can have a look at your processor boards to see what they do or don't do, but I also still have a NiMH pack here that I need to deal with and two dead chargers and the transmission of my electric truck just started leaking, so only send something that you are not in a hurry with...