Jeremy Harris wrote:Looks very neat indeed. Only observation I'd make would be to use PU rather than epoxy for potting. Clear PU remains slightly flexible and tends to move enough to allow components to expand and contract without cracking. I had problems years ago when I encapsulated some power stuff in epoxy, so tend to now use the flexible potting stuff whenever I can.
methods wrote:(sometimes I forget that you guys dont know everything that is bouncing around inside my head...)
heathyoung wrote:Also - where did you get the board mount andersons? Or did you make these up yourself with solid copper crimped to them?
methods wrote:since I am on my soap box... I used to be a die hard solder guy - but now I crimp every chance I can get. There is nothing better than a professionally crimped connection that comes from a properly tuned ratcheting crimper. (IMHO) Airplane guys will disagree (I mean real airplanes) and that is the one application that I would actually solder too.
acuteaero wrote:Looking good, my man! I'm always a proponent of machined aluminum bits.
If I were designing/machining the box I would put radii on the outside corners just to make it a little less likely to poke anything around it- depending on how the box was fixtured (can't quite tell from the photos) this might require more steps, or it could be totally free. If the latter, I would do it. If the former- eh, maybe.
I will ask him - or I suppose he will probably read this
Methods- for that new revision, you know, the "screw the parts count" version... I'm sure you've realized you've pretty much built the "soft-start main power switch" here too. If this could do both LVC/HVC breaker function and soft-start on/off the money would FLY out of my pocket for it. Seems to me you could do that just by adding another momentary button that "trips" the breaker- then you have an off button (the trip switch) and an on button (the existing reset switch)... I think that would be really handy.
Never crossed my mind since I rarely disconnect my battery from my controller. I like it though - good idea and easy. The capability is already built in and ready to go. All you have to do is tap in a button between the LVC_GND line and LVC_Signal line. I suppose I could put an extra pair of holes in the PCB or maybe offer a custom wiring harness with this pair coming out as a JST SM. I actually have a cap on the board that is in parallel with the gate of the fets that would add a nice slow rise time - but I dont populate that cap. Rise time is quick - but once the connection is made that should be fine.
Thanks for the idea
I really appreciate it when folks point stuff like this out. I guess my head is just in the clouds these days... but that is definitely a feature we should further incorporate.
Hm, point of clarification- will the current design working as a HVC breaker be OK running bidirectional current from a regen controller? It just won't trip if the HVC limit is hit under regen?
The HVC breaker is only between the pack and charger so even if it did hit it would not affect discharge. I have HVC set to a lofty 4.29V which is pretty high... I highly doubt anyone will go that high with regen. I mean - it is ok to hit that kind of dynamic voltage so long as the resting voltage is within reason... I just did not think anyone actually would.
Getting more to your point - when the mosfets are activated they can pass current in either direction equally well. The only nasty bit is that if they are triggered (lets consider the unit between the battery and controller) they can only *block* current in one direction. So in this case if somehow LVC tripped while in regen then regen would continue to happen right through the body diode of the fet. That wont hurt anything (for short periods) and it is sort of good in that a person wont suddenly lose their regen braking without warning
Now... on the second version this would not be the case. If LVC were tripped (say - via noise or via an inadvertent button press) then regen would instantly terminate. I dont think we need to worry about that for now though. The way I designed it - the HVC and LVC are completely isolated circuits.... and that is why I have a mess of 6 wires running down my daisy chain (instead of 2 or 3).
As for the good old to crimp/to solder debate- a good crimp wins- solder will wick into the strands of the cable and make the joint more likely to fatigue and fail. A well crimped joint should be essentially forged/welded together and impervious to internal corrosion. I would expect that real aircraft are wired only with crimped joints, given the criticality of proper attention to metal fatigue in planes. The flight computers for the Apollo spacecraft were not soldered- they were wire wrapped. Since buying proper crimpers for the various different connectors I use I haven't soldered a single connector pin.
I would tend to agree with those statements.
fechter wrote:A slow rise time could be self destructive if there is a heavy load other than just charging some caps. Ideally, you'd want a separate precharge circuit and turn on the main FETs only after the caps have reached charge, thus inhibiting turn on in the event of a shorted controller. This is probably too complicated for how often it would happen. .
docnjoj wrote:I'm sure I need one of those gizmos, just for the box art alone. What did you say that thing does............................................................................................................................ ?
ZOMGVTEK wrote:...Do you have a 200A model?