I've been given a 10aH 36v LiFePO4 battery to repair. I found the problem as a blown output mosfet. There are only two mosfets on the PCB: One for output and one for input. The body of the mosfet is burnt and cracked, but I can make out numbering something like TP98N. Underneath is 075T..... I guess it needs to handle 30 amps at up to 50v, which seems a lot. Can someone recommend a suitable replacement?
Suitable Mosfet
- Thread starter d8veh
- Start date
dnmun
1 PW
30A is a lot for a 10Ah pack but you can get the irfb3205 really cheap on ebay.
powersupply
100 W
I agree that ebay is not a reliable source for FETs.
Especially when coming from far east.
Though one individual on this board calls it racism if one complains about shady and unscrupulously and unethically business styles from them.
But the facts are the facts and being called racist won't do away these simple facts.
Anyhow, save your 4110s, considering you need TO-220 I recommend these here:
http://www.newark.com/nxp/psmn5r0-80ps-127/mosfet-n-ch-80v-100a-3-to-220ab/dp/70R7972
Saw that yours are 75V 98A, so the ones I recommend are just a little better.
But again, if the battery pack was from those mentioned sources, that FET could very well be fake, too.
For $1.08 each and (unfortunately) $5.60 shipping (make sure to select USPS) it is the best I could find.
I read that when you call Digikey they might put some in an envelope (lower shipping costs). I tried several times, and it didn't work for me.
But I had good luck with samples, maybe that's an option for you, too.
I got a few to try out for free (shipped overnight!!!).
Did you find out why it got damaged at all?
Especially when coming from far east.
Though one individual on this board calls it racism if one complains about shady and unscrupulously and unethically business styles from them.
But the facts are the facts and being called racist won't do away these simple facts.
Anyhow, save your 4110s, considering you need TO-220 I recommend these here:
http://www.newark.com/nxp/psmn5r0-80ps-127/mosfet-n-ch-80v-100a-3-to-220ab/dp/70R7972
Saw that yours are 75V 98A, so the ones I recommend are just a little better.
But again, if the battery pack was from those mentioned sources, that FET could very well be fake, too.
For $1.08 each and (unfortunately) $5.60 shipping (make sure to select USPS) it is the best I could find.
I read that when you call Digikey they might put some in an envelope (lower shipping costs). I tried several times, and it didn't work for me.
But I had good luck with samples, maybe that's an option for you, too.
I got a few to try out for free (shipped overnight!!!).
Did you find out why it got damaged at all?
Thanks for your suggestions. Do I understand it right then that the important parameters are max current, max voltage and Rds(on), so any one above 60v with Rds(on) about 4mOhm and current above say 75 amps should be OK, but the lower the Rds(on) and the higher the current, the better, or is them some other important parameter?
powersupply
100 W
Did you ever find out why it failed to begin with?
Was it a short or overheating or what?
It might have failed because of a bad/cheap FET, but then why after it worked for a while?
Yes, higher current, higher voltage and lowest Rds(on) are desirable with these.
One problem with them is derating, meaning that FI at higher temperatures than the 25degrees the max amps are lower.
So the lower Rds(on) = less heat is generated = less derating.
Derating of the current is well documented, however the derating factor of voltage is notoriously not (I'm struggeling with that myself right now).
There are also dynamic issues, like surge voltage and currents (avalange etc).
And don't go just by the battery voltage, you might have brief differences in potentials in excess of that which could cause a breakdowb, too.
It is always good to leave much headroom.
75V and 98A and max 10mOhm ist the minimum I would stick to. Even that failed (if the FET was not a chinese knock off).
attached..View attachment IXTP98N075T.pdf
Was it a short or overheating or what?
It might have failed because of a bad/cheap FET, but then why after it worked for a while?
Yes, higher current, higher voltage and lowest Rds(on) are desirable with these.
One problem with them is derating, meaning that FI at higher temperatures than the 25degrees the max amps are lower.
So the lower Rds(on) = less heat is generated = less derating.
Derating of the current is well documented, however the derating factor of voltage is notoriously not (I'm struggeling with that myself right now).
There are also dynamic issues, like surge voltage and currents (avalange etc).
And don't go just by the battery voltage, you might have brief differences in potentials in excess of that which could cause a breakdowb, too.
It is always good to leave much headroom.
75V and 98A and max 10mOhm ist the minimum I would stick to. Even that failed (if the FET was not a chinese knock off).
attached..View attachment IXTP98N075T.pdf
dnmun
1 PW
people make a big show about how they know all the 'chinese' mosfets are knockoffs.
i have bot the 3205 on ebay and other transistors and never had a fake part. you can buy whatever you want. mouser has cheaper prices than newark by far.
i have bot the 3205 on ebay and other transistors and never had a fake part. you can buy whatever you want. mouser has cheaper prices than newark by far.
powersupply
100 W
dnmun, I have not seen you actually prove that the 3205s you got off ebay are genuine.
You should do so by testing their specifications with a voltmeter and ampermeter.
Until you do that your claim is not established IMO.
You should do so by testing their specifications with a voltmeter and ampermeter.
Until you do that your claim is not established IMO.
dnmun said:
dnmun
1 PW
you people are the ones who said that all the parts on ebay are fraud, not me. yet you have no proof just bigoted opinions because you think everything on ebay is chinese. those yellow people.
powersupply
100 W
dnmun, first of all nobody claimed that "..all parts on ebay are fraud..", typical you, twisting things and deductiing a judgement off that.
Second, you are constantly asking for proof and establishing facts, this was just a joke, but even that you did not notice.
Lighten up! This is just a hobby board.
Anyhow, back to the issue, d8veh should first try to find out why the FET got blown, then maybe call in for samples or buy some from a vendor or maybe even use one of his own 4110.
Second, you are constantly asking for proof and establishing facts, this was just a joke, but even that you did not notice.
Lighten up! This is just a hobby board.
Anyhow, back to the issue, d8veh should first try to find out why the FET got blown, then maybe call in for samples or buy some from a vendor or maybe even use one of his own 4110.
Thanks for all that info. I don't know why it blew. I'm fixing it for someone else as a favour. I think he said it blew at first use. Maybe he connected it the wrong way round.
I know about counterfeit FETs from Ebay. I've bought two lots of IRFB4110s, but I also boght a load of genuine ones firect from IR.
I know about counterfeit FETs from Ebay. I've bought two lots of IRFB4110s, but I also boght a load of genuine ones firect from IR.
