Local LEGEND Jaykup coming in with the awesome test results! So cool!
If only you had the 100v ubox - these XLR deaths make complete sense now. If the 75v ubox can kill a 715wh battery in 100 days left at 50% charge, it is EASY to see how XLR’s die when their owners let them sit for 6-8 months like the two I’ve had personal contact with
#DataIsBeautiful
Are discreet antispark switches the MOSFET type or the buck type?
Logically, I would think they’d be mosfet for the most part
The external ones you can buy? They are mosfet based ones, since the buck is on the ESC there really isn’t a way to control it like that.
But even those can be broken down into two varities.
High side switching, where it switches the positive battery lead. This is more complicated but better because everything stays grounded. It’s more expensive because you need a decent mosfet driver IC. It’s also harder to get right. The Unity had a lot of problems with this, but the Stormcores were much better.
Low side switching, where it switches the negative battery lead. This is simpler and cheaper. I’ve seen this built into two different Flipsky ESCs, and the problem is that they barely get a volt or two at the gate, when it should be 10+ volts above source. This means the mosfets don’t fully turn on, and have a higher resistance. They run fine at low battery currents, but burn up at high battery currents like when climbing a hill.
I have two different models I’ve been meaning to take a look at.
Your conclusions do not check out.
For one the 100v version is a v2, so we are looking at double your days.
The XLR should have ~3kwh, so even at 50% / storage our ref data is 1500wh.
All in all this would be two full years before reaching ~3v aka empty charge (not dead battery).
Hm didn’t think about that part
Yeah I guess we would be looking at an additional drain source then to reach the same amount of time
He did mention the drain is worse the higher the voltage though, so it’s reasonable to think at 20s on the v2, it might be higher
If anyone in the US wants to part with a 100v ubox for a week or two shoot me a PM and I’ll get it tested / included in the results.
I think it’s going to be similar. The logic board seems to be similar for both versions, but the power stage is different
Some additional results for a higher voltage battery. Even though this 16s battery has twice as many cells as the 12s battery, the time to discharge is the same because the Ubox pulls more current at higher voltages
I’m pretty sure you know this, but for anyone else reading, part of why this testing was done is that the low voltage shutoff on the vesc is only for the power stage, aka driving the motor. There is nothing to prevent an idle vesc, on or off, from continuing to draw current until the battery is at 0v.
Things like the Robogotchi and rESCue are devices with sound alerts to let you know that the battery is too low after sitting for a while. Of course they have to be powered to work, and you have to be somewhat nearby to hear it.
the beta ubox 75v v2 had different logic boards but they switched to the red ones on the production models
Yeah I am aware, what I do not know is how fast 3v drops to 0v for cells (aka how fast “empty” goes to dead).
A LOT faster than full to 3v.
There is very little capacity for most cells between 3 and 0 and even less between 2.5 and 0. Maybe @Battery_Mooch can chime in on this
…and @Skyart…it depends on the chemistry and cell but around 5%-10% is left between 2.5V-3.0V. There is verrry little available below 2.5V.
IMO we should consider 3.0V (or so) as “empty” and 2.5V as “dead” though. Yea, it’s nit-picking but we need to avoid any conversation regarding going below 2.5V as that always leads to wanting (or learning how) to revive a pack…which should never be done.***
***We can choose to revive any pack of our own, I’d never try to prevent someone from choosing the level of risk they wish to take. But I strongly urge everyone to never advise anyone else to do it or to even mention that you do it. We’ve got enough battery issues to worry about already.
Should this also mabe be tagged in safety, product warnings and Esk8 Dev?
There isnt a wikki as such is there? Excellent research @jaykup , as a result of this ill be adding a loop key on my flux.
Mad respect for getting measurements in the uA range!
This is exactly what I’m talking about! Your contributions are endlessly appreciated.
So we tested the ubox v2:
The resistor is 56K+2.2K, drawing current will be 72/58.2k=1.24mA for one ESC. Two ESC is 2.48, the rest 20uA is from the setp down circuit.
