Help identifying these components

[made2hack]

Hi all,

These two components are from a NiCd battery pack (9.6V - 8 1.2V cells in series).

I'm pretty sure the red component is an NTC, and I think it is a 6.8k. But I wanted to check with you guys if I read it correctly. At room temperature, it reads around 7.5k - 8k. It might be just old and out of spec. Can it be a higher value? The marking seem to say 6k8k.

As for the square component, is it a cap? Markings 100 , 1826, 9513. Some kind of poly or foil cap?

Thanks

[Fraser]

Nicad and Ni-Mh batteries normally contain one or more thermal safety devices in series with the battery. The thermal protection devices fitted are usually a bimetallic self resetting cut-out and a non resetting thermal fuse that is a last ditch defence against serious overheating if the bi-metallic protector fails. Some batteries only have one thermal protection device fitted.

Thermal monitoring is different as it cannot itself stop the battery temperature rising, but it can provide thermal information to a charger or appliance that is using the battery. The thermal monitoring device can take the form of a thermistor, thermocouple or even just a simple diode. The temperature monitoring device usually has one pin connected to the negative terminal of the battery and the other end connected to a dedicated contact on the battery case. This is sometimes marked with the letter T. NTC Thermistors are very common in battery packs but I have often found them to be 10k types. There is no rule that they cannot be other values though.

The location of the component in the batteries electrical circuit will tell you either it is an over current protector or a thermal monitoring device.

If you tell us where these devices are located we may be able to comment further. Are they in series with the battery or does at least one leg go to a dedicated contact other than + or - ?

Fraser

[Andreas]

Hello,

the green part is a Roederstein capacitor series 1826.
polyester film capacitor
http://www.farnell.com/datasheets/15284.pdf

Is there any marking on other sides of the component?
The capacitor value should be on the top side.

with best regards

Andreas

[made2hack]

Hi,

The devices are monitoring devices as they span the Negative and "T" sense contact. They are not active current limiting.

[made2hack]

@Andreas - on the top it is marked 0n J

[made2hack]

Can I replace the film cap with a X7r ceramic cap of same capacitance?

[made2hack]

Anyone know whether I can replace the film cap with a X7r ceramic cap of same capacitance?