Motor Check

[geekygrilli]

Just had a report from Electrofit Zapi, I have blown quite a few MOSFETs and resistors in my H2 600. They are knidly fixing under warrenty as they cannot say if its faulty components or my fault.

I'll be getting it back on Monday.

I really want to check that my motor is OK, and make sure it is not the source of the problem before I run the car again. I have hooked up the motor to a 12v battery and it still runs fine. The car ran fine until the controller stopped. Though I did have the current set to max, it would easily wheel spin in 1st, 2nd and 3rd from standstill. I was pulling away very slowly in 1st when it stopped.

1. Is there anything I can do/measure?
2. What size fuse should I have in place btwn the controller and motor? There is a 325A fuse btwn the batteries and the controller.

Thanks in advance

[electricvehicles]

To be perfectly honest, I have in the past had a few H2 Controllers suddenly go pop for no reason. But if it was me I would get the motor checked out before connecting it up to the controller. EMR in wembley are a good port of call. Tel: 0208 903 1390.
Good luck and pls keep us informed of developments.

[geekygrilli]

Super, thanks for your reply...I think i just need to look for a current leak at high loads. I have 2 spare motors, I'll get them looked at too, but it'll be a pain to make up another adaptor plate.

It was a bit of a worry that I was repair number 72 of 150 this month at EZ. And they too said that it might just have been faulty components.

I have a guy who does motor checks for some people on my ind. estate, and the fork lift people who I got the motor from should be able to have a look at it (but I don't really trust them , cos one of their engineers suggested I put alternators on the wheels of my car to charge the batteries whilst i drive along, and therefore would never have to charge the batteries from the mains - he couldn't understand that this is impossible)

[electricvehicles]

Might have been one of my ex-engineers who came up with that bright idea !! I once did have one who use to go on about it. Needless to say he has since departed my company !!!
On a more serious note:
As far as I am aware the H2 controller is fitted with blocking diodes so as to prevent a controller burnout in the event of a motor short. Set the current limit low and take it in stages. Thats the big dissadvantage with Zapi controllers, when you change parameters you have to scroll all the way back through the menu before the change actually changes. That why im a fan of the Curtis, as soon as you change anything it is changed immediately.
Do keep me informed
Regards
Dave

[geekygrilli]

I did point out that it requires energy to move the car along, even without the alternators, but he still couldn't grasp the concept that perpetual motion is impossible. I gave up.

I really am wishing i bought a curtis now, they seem a lot more popular. Oh well, you live and learn, and get a bit poorer along the way. But its my first build, doing it on a 'budget', and to be fair it was all going well up until now!

According to the EZ engineer, the diodes were all OK.

Its just strange as the didn't get the least bit warm (the controller did), it was running fine for quite a while, and it failed at low currnet draw.

[electricvehicles]

Might have just been a component fault, lets hope so. I installed 20 odd of their H2 controllers, must be 10 years ago. Did have one unit fail more or less immediately, but the others have been trouble free, only problems that we have had has been with the contactors. We are running full speed management whereby we use a speed sensor on the motor and should the vehicle start to overspeed the opposite contactor comes in and applies power to the motor in reverse mode. Also if one of the daft drivers leaves the vehicle on a incline without the hand brake being applied it wont run away. Forward or reverse contactor will switch in and hold the vehicle where it is. All clever stuff. It was my fault regarding the contactors, tried to use ones with smaller tips and they dont stand up so well as the 15mm diameter ones.
When you get round to it I would love to see some pics of the project
Regards
Dave

[geekygrilli]

I spoke to a guy from Nelco, most helpful chap. He said i need to carry out a 'Mega' test by putting 500v through the motor and looking for leaks.

I went round to the Forklift place and asked if they did this test. Explained why - want to check the motor is OK, but they don't understand. But i was speaking to the perpetual motion guy again, so I stood no chance!

I've just spoken to EMR, I'll drop off all my motors to them ASAP to get checked, all the staff there were really nice, and enthusiatic. If the one I am using is no good, i'll have to swap for another...

[EVguru]

The stress on the Mosfets is high at low duty cycles, so a failure at low speeds is not uncommon. You need a pretty serious motor fault to blow a controller (like the brushgear flashing over). If it ran smoothly it should be fine. A leakage path from field coils to frame or even one or more armature coils should not have damaged the controller.

If it wasn't just an assembly fault or a faulty component in the controller, then check your battery connections carefully. The inductive 'kicks' caused by the controller are absorbed by the filter caps and the battery pack. If you have a poor connection in the battery circuit then one of those 'kicks' can exceed the voltage ratings of the components, but it usually only happens at high load.

[geekygrilli]

Thanks Paul

So even if the motor tests OK in the MEGA test, it might have a brush gear flashing thing going on. Hmmm.

Well, I'll have to strip it down to check.

It did run smoothly - it was brilliant, until it stopped.

[EVguru]

A brushgear flashover is usually only a result of excessive voltage and current simultaneously.

Generally it's only our dragracing friends in the US that have problems with flashovers, although it can happen if you let excessive amounts of carbon build up in the brushgear.