You need a HOT AIR GUN. Heat the pcb and pins and the FETs will just fall out. Imho that's the only proper way to desolder them.
Then use a solder pump to clear the pcb holes, put in new FETs, solder them and you're done.
Search found 4909 matches
- Oct 21 2019 9:44am
- Forum: E-Bike Technical
- Topic: Kelly Controller has no torque, jerks motor
- Replies: 27
- Views: 899
- Oct 09 2019 1:37am
- Forum: E-Bike Technical
- Topic: Kelly Controller has no torque, jerks motor
- Replies: 27
- Views: 899
Re: Kelly Controller has no torque, jerks motor
Yeah. Unfortunately genuine ones have their price. And that also makes clear that a ten pack for $2 can't be real.
You won't regret that purchase!
You won't regret that purchase!
- Oct 04 2019 2:09am
- Forum: E-Bike Technical
- Topic: Kelly Controller has no torque, jerks motor
- Replies: 27
- Views: 899
Re: Kelly Controller has no torque, jerks motor
Just checked the video. This IS the correct way to do it. And he's not using continuity mode (open/closed loop), but diode testing mode.
- Oct 04 2019 2:08am
- Forum: E-Bike Technical
- Topic: Kelly Controller has no torque, jerks motor
- Replies: 27
- Views: 899
Re: Kelly Controller has no torque, jerks motor
I checked the FET you posted. IMHO one of the best replacements is the well trusted IRFB3077. An excellent FET with almost the same specs (Vmax=75V), but WAY lower RDSon of 3mO compared to 8mO. That means is dissipates about A TENTH of the heat the RJK type does. So your controller will stay cooler ...
- Oct 04 2019 2:01am
- Forum: E-Bike Technical
- Topic: Kelly Controller has no torque, jerks motor
- Replies: 27
- Views: 899
Re: Kelly Controller has no torque, jerks motor
No the method is fine. It will detect a DEAD FET. It's no proof that a good one is still good, but if one shorts it's dead for sure. A correct test would be to test forward voltage in diode testing mode of the desoldered FET. But they will be good for 99.9%. If you can't find the correct time you ma...
- Oct 03 2019 12:39pm
- Forum: Battery Technology
- Topic: BMS balance wire shorted. Likely damaged BMS, or still good to go?
- Replies: 7
- Views: 230
Re: BMS balance wire shorted. Likely damaged BMS, or still good to go?
How would this CAP test look like? Could you post a schematic? I don't see how connecting a capacitor between two balance wire would do anything helpful to test the BMS.
- Oct 03 2019 6:44am
- Forum: Battery Technology
- Topic: BMS balance wire shorted. Likely damaged BMS, or still good to go?
- Replies: 7
- Views: 230
Re: BMS balance wire shorted. Likely damaged BMS, or still good to go?
Most likely this will still work. But i wouldn't trust it w/o testing it in real life. A BMS you can't trust is worth NOTHING. 

- Oct 03 2019 6:42am
- Forum: E-Bike Technical
- Topic: Kelly Controller has no torque, jerks motor
- Replies: 27
- Views: 899
Re: Kelly Controller has no torque, jerks motor
Your experience clearly proofes that it was the wrong phase/hall combination as amberwolf told you. Now that you killed the controller you will not make the motor run again properly w/o repairing the controller first. Most probably two phase wires touched, or you touched one of the battery wires wit...
- Sep 30 2019 8:57am
- Forum: Motor Technology
- Topic: How to limit current of controller?
- Replies: 14
- Views: 546
Re: How to limit current of controller?
Putting a resistor into the phase wires would be a bad idea.
They power used would still be the same, and the BIIIIIIGGG resistor would just produce a lot of heat.
There are two correct ways:
.) program the controller and reduce the power output that way
.) upgrade wires to thicker ones

There are two correct ways:
.) program the controller and reduce the power output that way
.) upgrade wires to thicker ones
- Sep 23 2019 10:04am
- Forum: E-Bike Technical
- Topic: Loud clicking noise MAC 12T hub
- Replies: 17
- Views: 607
Re: Loud clicking noise MAC 12T hub
+1 on a broken bearing as well.
- Aug 30 2019 2:40am
- Forum: E-Vehicles General Discussion
- Topic: Problem with Nextdrive Scooter
- Replies: 2
- Views: 498
Re: Problem with Nextdrive Scooter
Thanks markz. Didn't read your post, but this is how I did it 8) Took out the battery (clever design, it's hidden in the steering tube, it's a 7s2p design all made very nicely. Then I wiggled it around while measuring the output voltage, which unsurprisingly changed from 27V to 23V, giving an indica...
- Aug 30 2019 2:23am
- Forum: Stand-up E-scooters and E-skateboards
- Topic: 10kW stand-up scooter with air suspension
- Replies: 208
- Views: 25967
Re: 10kW stand-up scooter with air suspension
- Aug 30 2019 2:22am
- Forum: General Discussion
- Topic: How to identify antennas?
- Replies: 25
- Views: 1135
Re: How to identify antennas?
If they are not having any markings it would be difficult and you should go for any test equipment to know the frequency of antennas. Thanks. Yes, they do have markings (double rings), but ALL of them have them. Seems they use the same plastic cover for all kinds of antennas. I now just test each o...
- Aug 26 2019 3:14am
- Forum: E-Vehicles General Discussion
- Topic: Problem with Nextdrive Scooter
- Replies: 2
- Views: 498
Problem with Nextdrive Scooter
A friend of mine bought one of these super cheap scooter: https://www.lightinthebox.com/en/p/self-balancing-scooter-for-adults-aluminium-shockproof_p6199595.html?prm=1.3.5.7 The issue he has: Once you "shake it" it just turns off. And you can't restart it. Once you connect the charger it can be star...
- Aug 20 2019 4:56am
- Forum: General Discussion
- Topic: How to identify antennas?
- Replies: 25
- Views: 1135
Re: How to identify antennas?
If you have a set that works you could range test the various antennas. The one with the longest range will be the one for that frequency. I was pretty impressed with the range on my 433mHz remote switches. That was the only approach that makes sense in my case. And is the way i do it now. I was ho...
- Aug 19 2019 11:40am
- Forum: General Discussion
- Topic: How to identify antennas?
- Replies: 25
- Views: 1135
Re: How to identify antennas?
433 was used for home automation sensors. I switched to zigbee mostly now - so i need 2.4ghz antennas to replace the pcb printed ones (for those cases where more range is needed).
- Aug 17 2019 8:59am
- Forum: General Discussion
- Topic: How to identify antennas?
- Replies: 25
- Views: 1135
Re: How to identify antennas?
I have some 433 and 2.4 antennas and they look EXACTLY the same. So posting pics will make no sense. 
- Aug 15 2019 3:13pm
- Forum: General Discussion
- Topic: How to identify antennas?
- Replies: 25
- Views: 1135
- Aug 15 2019 9:12am
- Forum: General Discussion
- Topic: How to identify antennas?
- Replies: 25
- Views: 1135
- Aug 15 2019 5:43am
- Forum: General Discussion
- Topic: How to identify antennas?
- Replies: 25
- Views: 1135
Re: How to identify antennas?
Damn. I expected those answers, because it googled at bit before. I don't want (and in some cases even can't) disassemble the antennas. Of course it could just add them to the receiver and see which one works best, but that is a bit to much guess work for me. I hope the "one or two ring theory" is r...
- Aug 14 2019 12:01pm
- Forum: General Discussion
- Topic: How to identify antennas?
- Replies: 25
- Views: 1135
How to identify antennas?
Over the years I bought several antennas from ebay, aliexpress ... Some for 433Mhz projects, some for Wifi (2.4/5.8Ghz). Some for 868Mhz. Of course after some time, if they where not installed, they ended all in one big box. They are all black or white, but other from that they look more or less the...
- Aug 04 2019 3:33am
- Forum: E-Bike Technical
- Topic: Automatic Wheelie control / Launch control module Beta testing
- Replies: 16
- Views: 1201
Re: Automatic Wheelie control / Launch control module Beta testing
Matt posted this on FB today: A friend was filming while we went out for a ride and tested the Wheelie Box/ Launch Control Module a little bit, along with some other toys! (the scooter was given to me, seems like a good project to amp up haha) iove had a few messages about them this week so as a sid...
- Jul 12 2019 3:11pm
- Forum: Motor Technology
- Topic: how to fan cool a controller?
- Replies: 16
- Views: 1503
- Jul 12 2019 11:46am
- Forum: Motor Technology
- Topic: how to fan cool a controller?
- Replies: 16
- Views: 1503
Re: how to fan cool a controller?
I would use two server-computer fans that are designed to run off of 48V (one pushing, one pulling). For a 72V system I would run three 24V fans in series. The centrifugal style will push more air than an axial, and look for a fan model that has ball bearings. Really? One of my first thread in 2013...
- Jul 09 2019 1:08pm
- Forum: Battery Technology
- Topic: Build a mini USV/UPS
- Replies: 42
- Views: 1743
Re: Build a mini USV/UPS
Here are the pics. I also did a 4A load test (~550mA per cell fuse). They didn't get warm at all. So at least they will survive normal operation.
