Sadly that one also appears to only be sold by in lots of 5000.
ah, missed that.
I updated post 326 with more clear instructions on Ruv1/Ruv2, assuming LVP in the IC won't be used for now. I've realize that if used, this needs to be setup for very high hysteresis, so if it turns off, it stays off until a power cycle, and furthermore you would need to have low to high mode order to have any hope of getting it to come back on. I guess the same is true for the mcu LVP though.
I also added some words about Coff, but I'm kind of thinking now any attempt to give math or explanation for tuning any of these things is probably more information than most people want to even see. Edit: Created an "adjustments" section for Rsense and soft transitions, and "expert tuning" section for everything else.
I will probably soon work up a calculation sheet with Vf correction (because it matters near direct drive) specifically for this build, just for fun. It could be good to start adjusting the OP, but wouldn't hurt if I had a second post. I don't know if it's possible for mods to insert a post. I doubt it (would change all post numbers).
Question:
How does the bleeder resistor situation work for this board? For a typical board, it bleeds current from batt+ to case "ground" and that case current returns to batt- through a tailcap led. However on this board the bleeder resistor connects directly from the batt+ contact to the batt- contact. It's just a battery short. There is no case path in the middle. I haven't looked yet, but I wonder how this works on the Texas Avenger too.
I haven't looked at how a lighted e-switch would work. It's a momentary so it won't short out an led like a tail cap switch will. I guess they're either always on or they'd need software control, but just speculating.
One thing I realized when working out new values for th Ruv1 and 2 is that the pad the via comes from not only never goes to batt-, but it's always at 8.4V above batt- in both 4S and 2S. Because of that the voltage divider (if ever used at all) would never need to be reconfigured. I never noticed because I wasn't considering to leave a voltage divider on anyway, and I'm still not sure I like the idea of pulling current (voltage is fine) off a middle voltage. It could unbalance cells over enough months. It could be something to have in mind though, maybe even for R1 for other SRK boards.
The bleeder in this case is not needed and most likely would not be used but there was room for it so why not. It could also be used for an indicator as well.
Although in this case you are correct, it is simply a short since the tailcap is not connected to ground. You could still wire it up but there is no need as you could directly tap the positive and ground at the tailcap. In fact I might add this to my tailcap MCPCB come to think of it.
In this particular case it’s most likely use would be an indicator LED installed near the switch for when the light is off. Something that could easily show you the button location. In fact I really like this idea and will have to see if it could be implemented on the BLF GT. Finding the side switch to turn a light on is always the hardest part.
The most important thing for the average person when it comes to the component list is an easy to follow list for 2s input and 1s or 2s output along with 4s input and outputs of 2s and 4s. Those are the most common uses I see.
The only real change most would make besides that is the sense resistors, which a simple to follow calculation or a simple list would do for that. Anyone building one of these should be able to figure out what they need with a few reference points or a basic calculation.
That's actually the direction I was going with it in my head, in almost the same steps.. yeah, could wire to tiny 0603 pads, but, why not...
The thing that seems slightly harder with e-switches is, well, with a clicky the switch shorts the tailcap light and turns it off. With a momentary, it doesn't. So if you want it to turn off when the light's on, I guess you need another control mechanism? Of course it could just stay on.
I figure the .05ma that the indicator LED would use pales in comparison to the 12,000 that is being shined out the front lol.
There is a spare pin available for a controlled indicator LED but why not have options? Plus it is easy accsess to both positive and ground for anything else that might be needed.
I guess it just seems less slick, but it's not really. Always on is fine.
So actually I was thinking a + pad next to Rsense on the driver board. Slightly dangerous for case shorts. Could put it after (right) of rsense, but it gets in the way of the star of Texas, or could make a hole. The tailcap won't actually have direct access to batt+, only to 4.2V in 2S and to 4.2V and 12.6V in 4S, and the quality of the ground connection depends how well the ground ring gets connected to the case. Also ins't it easier to wire the switch light from the driver compartment than the tailcap?
I will be honest, I have no idea what you are talking about there. Talking about an extra + pad added?
Far as a lighted tailcap, it would only need 4.2v anyways.
Yes, we were talking about where to get voltage from to wire an extra circuit for a light. You can add a plus pad on one side or the other of Rsense and could piggy back on the LED - pad.
I thought the SRK lights usually go at the side switch so you'd need wires there somewhere, and include your own resistance inline on your wires probably or at the light.
Right for a light at the back end 4.2V would do it. It would unbalance cells though over the course of a some months, which could then result in cells getting over-depleted even with LVP engaged. This is ultimately an issue with the 1-batt mcu idea on the avenger too.
For the e-switch that is what the switch pads are for. For an LED output there is the pad next to the MCU for control an indicator LED and the bleeder resistor gives options for a uncontrolled LED. Not sure there is a need for anymore?
I see. I wondered if it could power through the switch contacts. Didn't know if the mcu put out enough juice. The BR pad is a bit small, but yes, it works.
Oh, power the LED through the switch wires? Hmm, not sure about that. Kind of doubt it. Generally you run the LED to another pin anyways on both the switch and PCB, which is what the pad next to the MCU is for.
Come to think of it, there is enough room to enlarge the BR, so I might as well do that, either 0805 or if it will fit 1206.
Yeah, but if that's the reason for enlarging it, there are probably easier places to make a big batt+ pad. Either way though. On the other hand if you forget the ground pad on BR, there's even more room to just get a hot. It's all good.
Oh my shopping list still has a JMP in it I think or at least my text does. At some point I thought I should remove it, then realized, one jumper is needed for the 4S battery connection anyway. Not sure if that's still a good size, or if wire is better anyway. Wire is surely fine, so it's not a big deal anyway you slice it, but we could include a few reasonably sized jumpers in the list.
Yeah, I need to check and see what size is needed to make the jump effectively. Although basically anything will work, the ones you listed will surely be large enough and if cheap they should be fine.
$0.14 each and $1.20 for 10. I wouldn't call that very cheap. 1206 are $0.24 for 10.
Just checked it and the 1206 should work fine, or 1210.