dawrench said:
It shouldn't matter much. It doesn't really take much current.
Active pre-charge/inrush control
- Thread starter boo
- Start date
It shouldn't matter much. It doesn't really take much current.
Did you see this one?:nicobie said:Sure wish I could buy one of these that would switch 100V. A kit would work for me if it came with a bare circuit board.
I'm sick and tired of having to fix my large DC contactor every time some idiot flips the main switch without using the pre-charge button.
http://endless-sphere.com/forums/viewtopic.php?f=14&t=54225&hilit=+alan+b
Is there a way to lock out the contactor switch if the precharge hasn't been done? Relay + resistor might work in a crude way. Relay gets powered by the controller caps and won't pull in until precharge is done. Downside is you have a relay sucking power whenever it's on.
dawrench
1 W
Hum, I seem to find my foot in my mouth.
The circuit has been working fine since last fall on 48v. I use it as my main On/Off switch. Wanting to use it on my 18s pack, I had to change some connectors. Simple enough. I still put them on wrong - swapped B- pack and B- controller. I changed them back and it works exactly as it should - no damage.
Great circuit Fechter, Thanks.
The circuit has been working fine since last fall on 48v. I use it as my main On/Off switch. Wanting to use it on my 18s pack, I had to change some connectors. Simple enough. I still put them on wrong - swapped B- pack and B- controller. I changed them back and it works exactly as it should - no damage.
Great circuit Fechter, Thanks.
OK, good news. Yes, reversing those would make it stay on all the time and probably make the FETs get really hot under load.
dawrench
1 W
Can one of these be used to stop controller sparking as well ? Would only need 1 FET to handle the charging current.
I want to build one of these for use with 30s LiPo using 4115 FETs for my Cromotor build. 200 amps means 20 FETs. Other component values don't change? Would a piece of aluminum flatbar be sufficient as heatsink? Something about 6" x 1.5" x 0.25"thick.
I want to build one of these for use with 30s LiPo using 4115 FETs for my Cromotor build. 200 amps means 20 FETs. Other component values don't change? Would a piece of aluminum flatbar be sufficient as heatsink? Something about 6" x 1.5" x 0.25"thick.
dawrench
1 W
izeman
1 GW
??? that's the main reason to use them. as the topic says: active precharge. this circuit replaces the precharge resistor to avoid sparks. for more convenience an on/off switch was used.dawrench said:
dawrench
1 W
Sorry Izeman, still not over my foot-in-mouth problem. Yes, you're 100% right and that's why I have them with a key switch as well.
What I meant to say was "stop charger sparking". I can leave the pack connected all the time now with secure On-Off and have a tap on the pack for the charger socket. It makes the bike less "science project" and more "engineered product" not having to fiddle with the pack connectors every ride.
What I meant to say was "stop charger sparking". I can leave the pack connected all the time now with secure On-Off and have a tap on the pack for the charger socket. It makes the bike less "science project" and more "engineered product" not having to fiddle with the pack connectors every ride.
izeman
1 GW
lol no worries. i never got a problem with charger sparking. i turn on the charger first and then connect it to the battery. i you do it the other way round there are sparks. but maybe my bms helps as well!?
no worries. i never got a problem with charger sparking. i turn on the charger first and then connect it to the battery. i you do it the other way round there are sparks. but maybe my bms helps as well!?
The body diode in the FET allows the pack to suddenly charge the caps in the charger (spark). It would take back-to-back FETs to prevent this. Turning on the charger first will prevent sparking too. That's what I do.
Brake
100 W
Finally! This is awesome! Thanks Fechter.
Nice layout. Do you have a picture of the other side of the board?
Brake
100 W
Sure! Here is the other side. I may install inside a box. Not sure.
izeman
1 GW
wow. i guess you made a switch for a nuclear power plant those fets are good for a LOT of amps!
those fets are good for a LOT of amps!
Awesome layout.
If it proves to be reliable, it might be worth potting the bottom in epoxy to make it water/vibration-proof.
If it proves to be reliable, it might be worth potting the bottom in epoxy to make it water/vibration-proof.
Brake
100 W
Thanks guys. Madin, I must admit that I copied all of what you and Fechter had already worked on. All the components are basically the same ratings. So far I have run roughly 130 amps through at 84v. I wanted it to handle anything that the adappto max e could pull through it.
Fechter, great idea about the epoxy. I will look in to that. So far I couldn't be happier with the way it has worked so far. Just plug in the batteries and all. Then flip the switch and it powers up perfectly. Takes a few seconds to turn off and I can watch the voltage drain down before the display turns off.
Off to look for epoxy now.
Fechter, great idea about the epoxy. I will look in to that. So far I couldn't be happier with the way it has worked so far. Just plug in the batteries and all. Then flip the switch and it powers up perfectly. Takes a few seconds to turn off and I can watch the voltage drain down before the display turns off.
Off to look for epoxy now.
sacko
10 kW
Diamondback said:
Can anyone spot what I have done wrong?
When it was connected, everything was off; perfect. When I turned the switch on though, 2 fets blew.
All though the solder looks very close underneath, there wasnt any solder that had bridged.
alsmith
100 kW
resistor r1 doing nothing, no cut track
sacko
10 kW
Not sure what you mean to be honest, sorry this certainly isn't my forte
Where do I need to move r1 to?
Where do I need to move r1 to?
Also - cap appears to be a polarized tantalum.
Please pick up this bit of thread.
Please pick up this bit of thread.
sacko said:
Oh my, Photobucket causes my computer to crash in a bad way.
Anyway, the schematic you are using is a proven FET blower. Several members have tried it with the same results. Sometimes repeatedly.
I suggest using the version shown on page 6 of this thread.
sacko
10 kW
Doh.. Thanks both!
If anyone has a picture of their finished board, please post
If anyone has a picture of their finished board, please post
As far as I can see you've done everything right. What voltage are you using and what value are the resistors?
I wasn't thinking when I did mine. The back-plane is connected to the middle leg, so you can lay them flat and get better spacing of the two power wires.. Looking at yours, you've soldered to the thin part of the leg, which will heat up and melt the solder. Much better to solder the thick part.
Here's mine:
I wasn't thinking when I did mine. The back-plane is connected to the middle leg, so you can lay them flat and get better spacing of the two power wires.. Looking at yours, you've soldered to the thin part of the leg, which will heat up and melt the solder. Much better to solder the thick part.
Here's mine:
sacko
10 kW
Thanks Dave.
47k and a 10k resistor.
Running 84v @ 50amps.
47k and a 10k resistor.
Running 84v @ 50amps.
Similar threads
