imo it’s pretty obvious what’s up.
The first battery clearly had some cell issues, probably some p-groups over discharged. The BMS still works, as you can see in the video. He plugs in the charger and the esc can be powered up.
This is actually the voltage of the charger, thus the remote shows full battery.
The second battery has a dead bms (doesn’t charge or discharge). Maybe it died while charging and the power bursts and braking current gave it the rest. The cells are probably fine.
Just to be precise. I rode for roughly 1-1.5 km without (or with minor) braking, was thinking that should be enough to start riding ‘properly’ (fast braking and acc) again.
I triple-checked the data again.
1st battery: while on charger (only works when connected to charger) charger shows red light (indicating charging). remote shows all 4 bars. voltage 41.7, measured with multimeter.
2nd battery 46.8V. I cant get the remote to show anything on the 2nd battery, as board does not start even with charger connected. as stated, most likely BMS.
The remote displays the battery voltage at it’s current state, not what the input is.
What i also would like to know is if meepo sent the wrong charger. @ridiculed check the backside of your charger. Does it say 42v or 50.4v?
Both chargers (Meepo sent a second one with the first replacement battery) are 50.4V. I measured both, voltage on the first is 49.7V, on the second charger 49.5V. I am using the replacement charger, just because it was newer lol.
Ok so we can rule out the wrong charger. The 42v 8A one looks identical to the 50.4 one so they could’ve sent the wong charger. That’s off the table.
NO! You have to drain the battery for at least 10%…so the bigger the battery the more you should ride before braking
Theoretically it should, yeah. But remember, without the charger connected, the battery won’t power the esc. I think the charger can’t really charge the dead battery and the output of the battery is the voltage of the charger.
He can measure this too by connecting the charger to the first battery and probing the voltage on the output of the battery. It should be about the same as the charger.
I’ve never heard this said before. What is the reason for this? If you’re not braking more than you’re accelerating there is no way you’re putting more energy back into the pack than you took out so you’re not going to overcharge the cells as far as energy. I can see why you would run into trouble if you charge to 4.2 V per cell and go down a hill braking. Otherwise I don’t understand why there would be some catastrophic issue. Also, the charger isn’t going up to 4.2 V per cell, it’s going to 4.125 V, so there should still be some headroom potentially, depending on the BMS setup. This is using a discharge BMS, isn’t it? In that case, it shouldn’t even be possible to overcharge due to braking. The BMS should shut things down before that happens.
@chr1spe That’s what I thought as well (without the exact statistical background). I’d say the BMS is supposed to do exactly what you said, shut things down before anything bad (a.k.a overcharging) happens. The first (or two) kilometers (roughly 3-4% of battery) of riding ‘soft’ is done by me just to have an additional ‘backup’, even though it should not be necessary. Thing is, I do remember pushing things very hard in terms of braking and accelaration, (basically max/max, racetracking) right before the shutoff, so it feels to me that the BMS being damaged by that intense use makes sense. As for the future, I’ll just wait some more time after a full charge before I start racing the board, just to be sure, but still.
with the charger plug in, what’s the voltage on the XT60 connector?
are both ur charge port mosfet module still intact?
Yes but not when the battery is practically empty.
49.5V. Exactly the voltage as on the charger itself.
Think so, everything looks fine.
Well, not sure, what do you mean? Board was fully charged (at least it said so on the remote) when it happened (minus the 1-1.5km), and acceleration was strong (unlike when the board hits below 25%, where it is obv less). I did ride the board until the remote vibrated (indicating low battery) BEFORE that last charge, but even then, the BMS should shut the board down before any damage can happen (before total emptyness, right?).
Or did I understand you wrong?
I have heard that rule of thumb once somewhere years back in this or the other forum and I never had a problem but a friend of mine had bc of ignoring it.
He ruined more than 3 Boards with braking to “early” so thats my mindset.
Maybe you are right, but Im going this route for years without issues.
Im no battery expert so bms things here or there isnt my game, you have to trust battery builders like @Simeon or other proffessionals.
I would still bet its the cause.
Europe
He’s gonna visit me on Sunday and bring the board over ^^
I’ll take both batteries apart and hopefully build one working battery out of that.
10% of such a battery is probably 5km, how can you ride for five kms without braking?
And I remember that meepo had over charge protection, but I may be wrong…
Yes, looking forward to having a go at the Prototipo and eFoiling in Dresden on the same day @Simeon 
And meanwhile, Meepo has looked through all the vids and explanations I gave them an decided… well 
Ok then. Tell us the truth.
