Topic: Motor thermistor

[jk]

G'day,
My armature thermistor was open circuit so I've removed the heat shrink from it and found that the glass thermistor was smashed, and there was also a 180 ohm resistor in series with it.
Can anyone advise me of a replacement spec thermistor or advise me of its resistance at 25deg
It's pins 1 and 2 of control box connector X6.
The unofficial service manual does state the trip levels of 900 and 1100 ohms, do these correlate to the figure 3 graph levels of 150 and 120deg?
Thanks,
Jason.

[Karl]

I'd love to help mate but your knowledge of electronics is already way above mine 

If no-one else on here can answer your query, try emailing c5martin.

I usually just get round the problem by changing parts over and getting them fixed later by someone who understands electrickery 

[jk]

If someone has a multimeter, and their control box open, could they please measure the resistance between the small grey and purple wires with the connector removed. Could you do this with the motor cold and let me know the temperature of the day. thanks.

This connector:


Between these two:

[PLOD11]

Hello,  well both mine are having a service at the mo, so here are the readings i got from them.

Meter on 20k setting 1st one read 12.54 the 2nd 7.63 

So there you are.

John

PLOD11

[KarlG]

I know the suject is very old, but I thought my findings might be of interest.

My armature thermistor was open circuit so I've removed the heat shrink from it and found that the glass thermistor was smashed, and there was also a 180 ohm resistor in series with it.

Because the glass bulb from my thermistor had been ripped off I decided to see if I could repair it. Although the bulb was missing the connection legs were still present, I stripped the heat shrink sleeving off and low and behold NO resistor.

I removed the good thermistor from my other C5 and checked, by feeling, the first 10 cm from the thermistor and can't detect any addition connection to the thermistor, so I assume the there is also no resistor present. When I find my small diameter heat shrink sleeving I'll check out the second unit to ensure there's no resistor present.

The good unit reads 10K at 25°.

So I'm wondering why the 180Ω resistor was fitted. Has anyone else info on this subject?

[jk]

I ended up getting a replacement thermistor from RS components, stock number 706-2737.
I can only assume that the 180 Ohm resistor is to limit the current through the thermistor and thus protecting the ULA, should the temperature rise too high. Checking the RS data sheet, once the temperature rises above approx 160 deg C, the thermistor resistance falls below 180 Ohms, which may allow too much current to pass.
This still doesn't explain why KarlG has no resistor fitted...
Jason

[C5 ENTHUSIAST + RESTORER]

Hi there I am in contact with Perran Newman the person who designed the electronics for the C5 .If I get in contact with him what would you what to know ..
Chas

[KarlG]

Hi Chas,

it was Perran who was in contact with Phill concerning the ULA parameters, pointing out that not all was correct. The contact was somewhat too late as Phill had already decided that subject was, for him. now closed.

It would be nice to know the model number
Nominal resistace of the thermistor at 25°C
Why some units were not fitted with a (limiter?) resistors and at least one was.
Even better, if a data sheet is available for the original
If not, could he recommend a suitable replacement.

Cheers.   KarlG.

[C5 ENTHUSIAST + RESTORER]

Hi there karl regarding Phills replacment chip I do have two but never tested them .Has anyone got one in use or tested one ....The reason being if I can get someone to make some I do not know if they will work ...(I know that I should test them myself but if anyone has one in use or tested one that would be great)
 please let me know Chas

[KarlG]

Hi Chas,

I think you can take it that Phil has tested all of the units before they were delivered. What Phil will not have done is to program the unit, they have to be set up for normal (i.e. UK) use, or for pedelec mode. Phil may have set them up for UK use, but without asking him there is no other way than to hook them up to a computer and check the settings.

Cheers.  KarlG.

P.S. As I'll be leaving the forum I'd appreciate it if you could email me the results of the thermistor settings. You are free to contact me at any time concerning any subject you would like to discuss.

[C5 ENTHUSIAST + RESTORER]

Hi Karl why ??

[Lancealot]

Karl why you leaving the forum??

Lance

[KarlG]

Let's just say if I write what I'd like to say it'll be removed, so what's the point in writing. Plus this theme (Motor thermisor) is not the place to discuss it.