Hi there! Trying to fix a Joycube charger - MOSFET puzzlement!

[MarkSD]

Hi all - I’ve owned a Carrera Crossfire e for 5 years and covered 1.6k miles. I’ve read many of the Pedelec posts on the annoying 'cutting out' issue and the mythical quest to find a cheat mode.

Anyway, the battery charger has packed up and my best guess (YouTube is your friend) is that a MOSFET shorted out and blew the fuse in the process. I have managed to de-solder the offending parts but when I Google the MOSFET numbers stamped on it I can’t find an exact match.

AUK H77516 SMK1060M

I think AUK is the manufacturer and H77516 possibly their part or serial number. I can find parts with SMK1060 but not with M on the end. I can find SMK1060F and don’t know whether that would be ok.

Any advice on replacement parts would be very welcome. I’m trying to repair rather than throw away and pay £65 for a replacement :-/

 

[Nealh]

The maker is Kodenshi, I expect one can fit a P variant and all will likely be ok. the mosfet is semiconductor and the current rating and specs will be much the same.
H77516 is liklely a factory date code.

 

[StuartsProjects]

my best guess (YouTube is your friend) is that a MOSFET shorted out and blew the fuse in the process.

If the MOSFET did really go short and blow the fuse, you might try a resistance test with a multimeter, that should show a short on the MOSFET if there is one.

 

[Nealh]

The reason for not findng an m series one may be that the made a customer spec batch for joycube.

 

[lightning]

The device will likely have failed because some other component has failed, such as a capacitor or resistor.

lf you just replace the mosfet it's likely to
fail instantly when you plug the charger in. You could give it a try though, you never know you might get lucky.

 

[StuartsProjects]

The reason for not findng an m series one may be that the made a customer spec batch for joycube.

Possibly cheaply bought parts that were not quite up to the full spec of the SMK1060F.

 

[MarkSD]

Thanks - I have tested the MOSFET with a multimeter and it is toast. I can’t be certain it hasn’t taken out any other components with it (other than the fuse) but I’ve seen a few vids where replacing the MOSFET has worked but it’s definitely a gamble.

I've looked up some specs and the major difference between the F and P variants is Maximum Power Dissipation - the F variant has a Pd of 40W and the P variant has a Pd of 120W. I can’t find any specs for an M variant.

I cannot tell from the Joycube label whether the F rating of 40W would be OK. Any thoughts?

 

[Nealh]

The reason I mentioned the P variant was because of the higher pd of 120w.
The charger is 36v nom x 1.8a so approx.64w or 75w given the max 42v charge raring.
The 40w imv will not be sufficient, being that the M variant or what ever it is my logic says the P being an improved or better variant opposed to the F.

Good to know you have your thinking head on with this one and also are trying to look up the component specs.

 

[StuartsProjects]

I cannot tell from the Joycube label whether the F rating of 40W would be OK. Any thoughts?

Where was the MOSFET fitted, i.e. was it on a heatsink ?

The max power rating would likely only be relavent if there is heatsink involved.

 

[MarkSD]

Where was the MOSFET fitted, i.e. was it on a heatsink ?

The max power rating would likely only be relavent if there is heatsink involved.

Yes, it was bolted to what I believe is a heat sink. See photo - not brilliantly clear but you can see where it’s bolted through.

 

[StuartsProjects]

To dissapate 40watts, the MOSFET would need to be on a heatsink of 3c per watt, or better. See picture below of a typical 3c per watt heatsink.




With the heatsink being the alluminium box only, I would guess the effective heatsink is maybe 10c per watt, so the MOSFET would only be able to handle 12 watts or so.

 

[MarkSD]

Well I’ve Googled SMK1060P and would have been very happy if I could easily find one to buy but it doesn’t seem that easy I’ll have to continue looking and possibly find an alternative make

 

[lightning]

Beware of fake parts being sold on popular internet auction sites. l've had loads of issues with fake parts that either don't work at all, or fail within a short time.

 

[StuartsProjects]

Beware of fake parts being sold on popular internet auction sites. l've had loads of issues with fake parts that either don't work at all, or fail within a short time.

Definetly.

If your trying to fix stuff you need to be real sure the parts you are using are the real thing.

 

[MarkSD]

I’m struggling to find a suitable replacement - I can't find anyone selling Kodenshi other than dodgy looking 'from China' suppliers and I spent an hour last night looking at various alternatives but none of the numbers marry up exactly and I’m not knowledgeable enough to know what would be suitable. Frustrating!

 

[Woosh]

I’m struggling to find a suitable replacement - I can't find anyone selling Kodenshi other than dodgy looking 'from China' suppliers and I spent an hour last night looking at various alternatives but none of the numbers marry up exactly and I’m not knowledgeable enough to know what would be suitable. Frustrating!

your charger is standard 36V Lithium ion charger made by SANS Electronics.
You can use another SANS charger with the same connector.
They cost about £30-£40 on the net.
SANS is about the best brand for this kind of products.
I wouldn't be tempted to spend time and effort repairing a charger.
With a repaired charger, the risk of damage to the battery is much higher than with a new charger.

 

[Nealh]

One can get a snas or similar model for 10- 20 quid, they are quite easy to find .
My last one I got off AliExp and it arrived quickly for my 12s/44v battery and it is fan cooled.

 

[MarkSD]

I’ve looked at getting a new charger - because this bike uses a 5 pin connector there are not many about and I have not found one cheaper than £60 which seems very expensive, plus I was hoping to repair/re-use rather than just throw away but I do appreciate the warning about damaging the battery

 

[lightning]

You think £60 is expensive for a charger try buying a replacement one for a Bosch or Shimano ebike

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[Woosh]

I’ve looked at getting a new charger - because this bike uses a 5 pin connector there are not many about and I have not found one cheaper than £60 which seems very expensive, plus I was hoping to repair/re-use rather than just throw away but I do appreciate the warning about damaging the battery

charging a Lithium-ion battery goes through two phases: CC or constant current phase, 2A for small capacity 36V (3A or 4A for larger capacity), the charger modulates the output voltage to keep the charging current constant.
it is followed by CV constant voltage phase 42V for 36V batteries.
The change over point is usually 40.5V-41V. At over 42V, the battery will likely burn.
There is simply not much room for error. That's why I would not recommend repairing your faulty charger.