Active pre-charge/inrush control

[Jeremy Harris]

Regarding my battery pack which is in a series/parallel switch arrangement - i.e. 32s or 16s2p LiFePO4 (106V or 53V) to power the controller. Can I tap on cell#16 +V and use a 33k gate resistor?
So, either if the battery pack is switched in series or parallel, the gate voltage doesn't change.

Yes, that would work just fine.

 

[Diamondback]

can someone point me at a reputable ebay seller who has genuine 4110's ?

i will use the switch i bought from D8veh and i might try my hand at making one,
if i can find the genuine fet's.

Jason.

 

[Jeremy Harris]

I very much doubt you'll ever get real 4110s from any ebay seller. They retail direct from IR at prices that are often higher than ebay sellers advertise them for, which makes it a dead cert that they will be fakes. It's expensive, but the only way to be sure to get real ones is to buy from an accredited source, such as Element 14, RS, Mouser, Digikey or the like, or maybe buy from a member here that has bought a job lot from IR (methods did just this a while ago, not sure if he has any left, though).

 

[Diamondback]

figured it was worth a shot...

can you point me at a link to the required ones on element 14 ?

i have looked there and fond many different ones with the irfb4110 tag, all with differing extensions after the 4110 part.
im unsure of the correct ones to order...

thanks in advance.

Jason.

 

[Jeremy Harris]

The cheapest are often the IRFB4100PBF ones, but just go for the cheapest ones that are labelled IRFB4110. The last part of the designation only refers to stuff that isn't important for this application, like it being lead-free. Worth shopping around the suppliers and looking at delivery charges and taxes that you might get hit with, sometimes it's worth paying a higher part price to get cheaper delivery.

 

[Diamondback]

thanks.

element14 has them at $4.18 each. and as there's a store within 10km from me, postage will be cheap.

thanks for the info.

Jason.

 

[Diamondback]

i ended up buying 4 genuine fets from another ES member who did a bulk order.

my next question is.....

is anyone able (or willing) to create a PCB mask (for Jeremy's original design) that i might be able to have etched ?
or better still, make a PCB for me (ill happily pay for the time and parts + postage fees)

i have downloaded eagle free PCB maker, but it's over my head im afraid.
im sure if i have a proper PCB, i can build this. im not so confident in using prototyping / vero board for this.

i have all of the required components to build this, with the exception of the PCB.
the enclosure i have bought is 8x5x3cm external.

@ Jeremy
if i mount the whole thing in a small electronics enclosure, will the fets get hot ? (given my application of 20A cont)

also, im going to add a fuse on the positive line, just before the circuit.
it strikes me as strange that the vast majority of ebikes / conversions i see, are running no fuse.

i intend to add plugs on either side of the circuit so the switch can be removed from the trike should it ever fail in the middle of nowhere.

here's where im at with it at the moment...









Jason.

 

[Jeremy Harris]

The FETs will run very cool at just 20A, each will be dissipating around 0.112 W at 20 A continuous, which is barely enough for you to detect by touching them, so they'll be fine inside that plastic box. You probably don't need a circuit board, as the circuit's simple enough to make on a bit of stripboard, veroboard or similar.

 

[Diamondback]

thanks for the info on the temps.

im really not that great a circuit builder.
i have made a few "kits" in my time, but those have lots of pics and instructions and a pre made PCB.
I've never been able to make anything using veroboard etc.

Jason.

 

[winkinatcha]

WOW Awesome!

Thanks Jeremy and all who have contributed here, Perfect timing as I was just starting to fiddle about with similar.

Joe

 

[d8veh]

my next question is.....

is anyone able (or willing) to create a PCB mask (for Jeremy's original design) that i might be able to have etched ?
or better still, make a PCB for me (ill happily pay for the time and parts + postage fees)
Jason.

I've got one last bare pcb left over. If you want it, send me your address by pm. It looks like this - about 50mm x 18mm:

 

[Diamondback]

thanks for the offer, but i think ill have a go at making a suitable PCB from prototyping board.


Edit.

Jeremy, when you get a chance, can you please look this layout over and tell me if that would work ok ?



excuse the rough paint picture... hope it's ok.

edit 2....

just realized that R2 was in the wrong spot (connection wise)



hope this is better.

edit 3.... DOH !

the cap was also wrong....



Jason.

 

[Jeremy Harris]

Looks fine to me Jason. Good luck!

 

[NeilP]

Subscribed to the thread..I need to make someting like this

 

[Gregory]

No Jason, you've got the drain and gate pins on the FET mixed up.

Looking at an actual FET (which on your diagram I assume are "facing" to the left) it goes Gate-Drain-Source, which confusingly is not like it's schematic symbol.

Move the controller black wire to the middle and the middle one connected to the resistors up to the top.

Does that make sense?

Greg

 

[Jeremy Harris]

No Jason, you've got the drain and gate pins on the FET mixed up.

Looking at an actual FET (which on your diagram I assume are "facing" to the left) it goes Gate-Drain-Source, which confusingly is not like the schematic

Move the controller black wire to the middle and the middle one connected to the resistors up to the top.

Does that make sense?

Greg

Well spotted! I missed that...............................

 

[Diamondback]

thanks for the info.

so like this ?



also, which way (assuming i have the fets vertical) should the metal heatsink with the screw hole be facing ?

ie like 1 or 2 in this pic ?


see i told you all i was no good at this stuff....

Jason.

 

[Gregory]

Number 2 .
Cheers.

 

[Diamondback]

Thanks heaps for the info and patients with such a noob !

Hopefully it works first go.

I will post my results after this weekends attempt.

Jason

 

[shinyballs]

This should handle 40A @ 130v now time to find a case at the dollar/thrift store.

 

[migueralliart]

I want one! It's been a while since I've done a pcb plus I don't have enough time :s

 

[migueralliart]

I know this thread has been dormant but reading thru some other threads I came up with the following idea;

How about we send ourselves this circuit schematic and make a pcb that people can buy and solder the components themselves.

This website was references in another thread here
http://dorkbotpdx.org/wiki/how_to_get_involved

maybe we can make this easily and then order some fets in a group buy or something and build a bom list for a 36V,48,60V and 72V

 

[cal3thousand]

I know this thread has been dormant but reading thru some other threads I came up with the following idea;

How about we send ourselves this circuit schematic and make a pcb that people can buy and solder the components themselves.

This website was references in another thread here
http://dorkbotpdx.org/wiki/how_to_get_involved

maybe we can make this easily and then order some fets in a group buy or something and build a bom list for a 36V,48,60V and 72V

Sounds great. Let's do it!

 

[migueralliart]

So just to make sure this attached dwg from Jeremy will serve the purpose. We need to figure out a pcb that can fit 3-7 fets for low to high currents that people can add fets if they up the current. Also some surface board mount Anderson pins.

 

[Diamondback]

that's the circuit.

i would like to see a board that has the positive line pass through the pcb also.

so you could build it into a small box, and have the battery on one side and the controller on the other side.
like this.....



i am in the middle of building this for my trike, but i absolutely suck at scratch building circuits.

i can follow instructions and assemble basic kits though.

i posted pics of what i had in mind for mine back on page 3 of this thread.
i have all of the parts to make the circuit (except the PCB) if i had a pcb made for this, i would be all good to go.

Jason.