Tesla V2, Overcharging downhill, does it downhill damage battery?

[cucurac]

Hello, I have a Gotway Tesla V2 1020Wh unicycle purchased in Oct 2020 that works great. I live on a pretty big hill and charge it at night. The next day towards the bottom of the hill it will frequently give warning beeps and tilt back. I presume this is from overcharging, and I'm happy that they included this overcharge warning. My response is to ride very slowly the down short remainder of the the hill. My question is whether doing this repeatedly will damage the batteries. I'm fairly terrified of the batteries going bad and exploding, especially with Gotway / Begode's sketchy safety oversight.

Anyone have advice? Should I always drain some of the battery before heading down the hill? I'm usually in too much of a hurry to do that.

 

 

  

[.....]

Not a good idea to constantly hit over-voltage beeps. I sometimes do on my Sherman during e-stop practice. Its a little hard on the batteries i think, but the real worry is if it decided to cutout because of it. I for one dont want to land on the back of my soft noggin'. Perhaps do a little practice before the long downhill?

Edited August 11, 2021 by ShanesPlanet

[Alex-l]

Don't go downhill with a full battery. I had a cut out on my v8 going downhill after I went uphill and no warnings!

[meepmeepmayer]

Just go up the hill for 100m and then back down again when the beeping starts.

[cucurac]

Ah thanks! So according to Alex-I's experience, I should consider the overcharge warning to mean that a cutout is eminent even if I then go up a hill or ride on flat, I guess until the battery gets drained past some (mystery) level. 

[.....]

4 minutes ago, cucurac said:

Ah thanks! So according to Alex-I's experience, I should consider the overcharge warning to mean that a cutout is eminent even if I then go up a hill or ride on flat, I guess until the battery gets drained past some (mystery) level. 

Yup. Beeps are beeps. I keep it nice and simple. ANY beep means danger danger. I dont know about you, but being on one wheel that is WORKING is enough danger for me. Do like meep suggests. Work on going down a little, whip it around and go back up. OR, down a little, ride backwards back up....

You could also use a charger that charges to less than 100%. Altho this opens another maintenance reminder to balance cells regularly, and you lose a little range. Over voltage beeps doesnt mean the batteries are FULLY charged btw. I can hit over VOLTAGE beeps starting at 90% charge. Once I quit the hill or power braking, state of charge returns to near 90%.

Edited August 11, 2021 by ShanesPlanet

[Alex-l]

What happened to me is that I went uphill first, then walked for maybe 1.5 miles with my wheel and I think it was enough to recharge it too much. Also the hill I was going down was really steep. But I didn't get any overcharge warnings. I wish I did, would have been better for my elbow's skin. But yeah, I would avoid riding with these warnings. What I do now is check euc world when I go downhill with my battery close to full.

[.....]

1 minute ago, Alex-l said:

What happened to me is that I went uphill first, then walked for maybe 1.5 miles with my wheel and I think it was enough to recharge it too much. Also the hill I was going down was really steep. But I didn't get any overcharge warnings. I wish I did, would have been better for my elbow's skin. But yeah, I would avoid riding with these warnings. What I do now is check euc world when I go downhill with my battery close to full.

Wow, I wouldnt have thought it would drop you, under those circumstances either. No warnings? OUCH! I also use eucw and its not uncommon for me to see voltage above 101v during e-stops. Hasnt dropped me yet, but its not like I'm not expecting it. Does trolleying a wheel recharge it? I would think that if you dont have to FORCE the wheel to roll, its not charging. SOmetimes I envision holding my wheel outside my car door down the highway to see if I can get a quick 60mph charge. Still not sure how to turn it on and get it rolling w/o dropping it tho..

[The Fat Unicyclist]

On 8/12/2021 at 5:20 AM, ShanesPlanet said:

SOmetimes I envision holding my wheel outside my car door down the highway to see if I can get a quick 60mph charge. Still not sure how to turn it on and get it rolling w/o dropping it tho..

Please video this once you have worked out the logistics...   

Edited August 14, 2021 by The Fat Unicyclist

[meepmeepmayer]

1 hour ago, cucurac said:

Ah thanks! So according to Alex-I's experience, I should consider the overcharge warning to mean that a cutout is eminent even if I then go up a hill or ride on flat, I guess until the battery gets drained past some (mystery) level. 

If you hear the beeps, you can go up a hill or in the flat until they go away. Somehow you have to discharge the battery. Just don't do anything to charge the batteries further, or the wheel has no choice to shut down eventually when the voltage goes too high.

With the bigger Tesla battery size, no need to be worried of the wheel shutting down without warning. Just stop going downhill immediately if you hear the overvoltage beeps.

As regenerative charging never is 100% efficient, you can always turn around and go up where you came down (and recharged), and then turn around again and continue down further. The beeps will appear later. Repeat until you're at the bottom of the hill.

Riding very slowly the remainder when you hear beeps already is playing with fire.

[alcatraz]

Charge with a simple timer. Once you get to 80% the charging speed levels off quite a lot so it's not hard to hit 90-95% with the timer.

Now it's worth noting that if you attempt to descend aggressively you will be hitting the batteries hard and could still go over 4.2v temporarily. Meaning, the higher the charge level, the more gently you need to descend. And if you're at 99% then there no speed slow enough that won't overcharge the batteries.

Edited August 14, 2021 by alcatraz

[Chriull]

On 8/11/2021 at 6:21 PM, cucurac said:

Should I always drain some of the battery before heading down the hill?

Yes!

Quote

I'm usually in too much of a hurry to do that.

It should be less than a minute to do some uphill runs for discharge evertime it beeps - or you will know by time when and how long to go uphill.

Or 1-2 minutes all in all...

So maybe you think of organizing/ slowing down your live down a bit if every sevond counts and make you miss your appointments! Imho it's not always the safest thing to participate in traffic beeing in a hurry.

6 hours ago, alcatraz said:

Charge with a simple timer. Once you get to 80% the charging speed levels off quite a lot so it's not hard to hit 90-95% with the timer

Then @alcatraz's proposal could seem very tempting for you! Afair some people regularly starting from a hill do it like this.

Unfortionately your batteries will _never_ get balanced by this and so have good chances to degrade quite fast.

 

Edited August 14, 2021 by Chriull

[cucurac]

Thanks all. I will drain it some by going uphill during the down hill from now on. I also didn't know that charging only to 80% can damage the batteries.

[Nostris]

I also live 800 meters up a hill, it ha a 100 height difference top to bottom. Like Alex I ride a V8, but mines a V8f. I have had the beeps and tilt back at the bottom of the hill before, plus the audio warning of ‘ Overload….Please get off’. Which I did. The wheel didn’t just switch off and dump me like Alex’s. Maybe it’s a newer model?  I lifted the wheel and let it spin a couple of times, then it was fine. It was definitely an over charge situation, so now I just pay attention and ride a bit around my yard for a minute or two, before I head off down the hill. 

[LanghamP]

My guess is that since most wheels seem to charge at around 100-150 watts going downhill (the equivalent of 8 or so amps), then recharging from the top of a hill is faster than the fastest charger. That's a situation just begging to dump you.