36V GM Battery charging circut components

[robinphillips]

I have a 36V battery from GM that I've just started using a week ago. When I came to charge it up though, I discovered it won't charge. Opening up the charging side of the battery it was immediately clear that the problem was that one of the large ICs in the middle of the charging board was broken (housing half missing).

My problem is that since the housing is half missing I can't buy a replacement component since I don't know what it is.

There are four of these style chips on the board (I think they are voltage regulators), all of them are held down on the board with screws for heatsinking. Three of them are mounted together and say T400 BE6Z3B on them. The fourth one in the center of the board is the broken one. The half casing that I have says BN 9 (the next character might be a 7) so it isn't the same as the other 3.

Can someone tell me what this component is?

If I had to guess, I'd say this was a regulator to convert the 42VDC from the power supply to something slightly lower to charge the batteries. Do I actually need this since the batteries have about 40V when full anyway?  So maybe I can just bypass it? If anyone can tell me if this is likely to result in smoke or not I'd be most grateful :-)

Thanks! 

[Bikemad]

Hi Robin,

This is the only picture I can find:



But unfortunately there are no sign of any obvious markings on the chip.

I don't know what its precise function is, but I suspect it is either voltage or current related.

This component must be necessary, or there would be no need for it to have been fitted in the first place.

I suggest you send an email to TOM (zhourenli@goldenmotor.com) explaining the fault and see what he suggests.

It might help to include a picture of the failed device as well if you can.

Alan
 

[muzza.au]

I think they are all fets. The three together are for the output stage. The single one is for the charging input. You can see the yellow wire just below it and although its half obscured, I think it says C for charge. If its gone, then that would explain why its not charging. You should be able to replace it with one of similar voltage and current rating.

Muzza.au

[robinphillips]

Hi Alan, Muzza

Thanks - I found that picture as well, but as you say the writing isn't visible. It is indeed the chip above the yellow wire with the C- marked on the PCB that I'm referring to. I find it a bit weird that it is the -ve wire (comes from the outside of the coax connector on the lid), but it does say C- so I suppose that is correct.   I realise all I need to do is replace it - desoldering it from the board was no problem - the question is, what is the voltage & current rating and what is the pin out?

Does anyone recognise the chip manufacturer logo on the other 3 chips (it is the same as on the broken one) - that might help me since I do have part of the chip ID code if I can find the right web site...

I'll post a picture this evening and also try mailing GM directly as you suggest.

Thanks

Robin

[muzza.au]

I don't have the new GM battery with the bms (I have the older bmsless battery), but I got myself a additional 24v booster pack that has a Signalab bms (2nd hand from ebay). I actually blew up all three output fets when I accidently shorted the power wires. I determined that the fets were IRF3805S fets. They were rated at 55v 75a. (The single charging one is the same). I couldn't actually find any locally, but I did find some online, but they were about $12 each. So I looked on ebay, but didn't find the same ones. But I did find similar ones. IRFZ44N fets that are rated at 55v 49a. I figered the max current I would use is 30a as thats what my controller is rated at, so I thought I would give them a go. Plus they were only $5 for five fets. I replaced them all and it worked!  Months later and they are still going strong. 

I don't know if yours are the same, but one thing I did notice was that on yours all three pins are connected, but on mine the middle pin is not used, cut off in fact.

I tried googling your T400 BE6Z3B but all I found was this forum, nothing else. I think you'll have to contact GM.

Muzza.au

[robinphillips]

Here are the images of the board (with chip removed) and the broken chip - this is exactly the condition I found it in when I opened the battery pack. I have no idea if I did this or whether it was delivered like this.






(note that the forum shrinks the pictures - if you right click them and select "view Image" or similar you'll get the full size version).

Looking at the closeup there I think the chip number infact starts with BN9 (and not BN8 as I wrote previously).

Muzza: I too had tried googling the part number (it was because I couldn't find it that I ended up posting here). If anyone recognizes the chip manufacturer's logo that would help - I spent quite a bit of time going through various online lists of logos but can't find it. It can be clearly seen on the picture of the overall board above. I've emailed "Tom", if he doesn't get back to me I'll try your suggested solution.

[Leslie]

Have no idea what those parts are. 

I'll take a stab though.

Suspicion of the charger chip could be a simple linear regulator.  Pin 1 adj, pin 2 output, and pin 3 input.  Small SM resistor for adjust.  If I am right currents over 5 amps will cook it.


Can you provide some pictures of the back traces too, and the number of R09 and or its resistance to pin 1 of the mysterious BN9 part.

It could be a FET but it would needs a switch, flip flop or optical transistor to switch off the input but that may conflict with a charger switch. 

It could be a power transistor tied to that big resistor thing.

[Jazzjerry]

Just to see if I could help you out I opened my 48v Battery,

Looks completely different though.

Here are the photo's.

[robinphillips]

Hi Jazzjerry,

Thanks for making the effort!

I think that might be useful actually as I can identify the chip logo - it's ST Microelectronics (www.st.com). Unfortunately I can't read the numbers in the picture - could you let me know what it says and in particular are the two that are partially obscured by the green cable in your picture different to the other 4?

Although they may not be identical they obviously perform the same function (I bet the bottom 4 are somehow dealing with multiples of 12, hence why I have 3 and you have 4) as mine so once I see the spec sheet for them (and ST has them all on their website) I should be able to figure out what I need to buy to replace mine (even if goldenmotor never reply - which they haven't so far...)

[Bikemad]

It could be a power transistor tied to that big resistor thing.

I thought that S1 (the big resistor thing) might be some sort of thermal switch, deliberatly placed against the heat sink.

[Jazzjerry]

I opened it up again.

Tried making a better picture with macro, But its dark and they are overflashed.

But readable though.

The top 2
is the photo with 1 ....... on it.,

The bothem 4 are of course the 4 in the picture.

So they are all the same......

[Jazzjerry]

I am sure it is this.

http://www.st.com/stonline/products/literature/ds/8451/stp75nf75.pdf

Description

This Power MOSFET series realized with
STMicroelectronics unique STripFET™ process
has specifically been designed to minimize input
capacitance and gate charge. It is therefore
suitable as primary switch in advanced highefficiency,
high-frequency isolated DC-DC
converters for Telecom and Computer
applications. It is also intended for any
applications with low gate drive requirements.

Applications

? Switching application

[muzza.au]

I knew it was a fet! I'd say it is used to switch off the charging in case the bms senses over voltage or current or simply when the battery is fully charged.

muzza.au

[Leslie]

It could be a power transistor tied to that big resistor thing.

I thought that S1 (the big resistor thing) might be some sort of thermal switch, deliberatly placed against the heat sink.

True!

The big S1 is what I missed, meaning Switch 1.  Doh!

I have these power resistors that look just like them, well mostly like them.

If the mystery B9 part is a fet  st75nf75 has plenty of current capability happening there.