Since a few days my battery charges only to 74% although it still shows green and charging. But the % does not go higher then 74%. Anyone experienced the same? Anything I can do? I had my battery discharged to 0% just before since yarbo was stuck in the evening and I did not notice. Any advise?
Or would the % be wrong. Any way I can reset this? Unplug de battery or so? Thanks
Unplug the battery for 4 hours and it will reset the BMS and report correctly.
Too bad we can’t do that in reverse. Force the battery to be “full charged” at say 80%. For those of us not mowing 6 acres, we might prioritize battery life over run time. Also charging to 100% and holding there (over 4.2V per cell) is a bug, in my opinion. Can’t believe that they haven’t fixed this one.
Tim
Thanks for sharing your thoughts!
Once the battery reaches 100%, the BMS system automatically switches to a trickle charge mode afterward to help maintain battery health.
And I’ve passed along the suggestion about allowing users to set a preferred charge level to the team for consideration. We’re always looking for ways to improve, so your feedback is truly appreciated!
@Ella, first of all lithium chemistries should NEVER be trickle charged. That was a thing back when we had lead acid traction packs, but no more. All lithium battery engineers and scientists agree on this topic. Second, lithium batteries like Yarbo uses (NCM chemistry) should never be left at or near 100% for long periods of time. Even overnight will degrade life of the battery. BAttery scientists and engineers agree on these rules too. If you really want to charge to 100% and leave it there, consider changing chemistries to Lithium Iron Phosphate (LFP) which will accept 1000’s of cycles between 0-100% state of charge. NCM is 100’s of cycles (0-100% range), so you can quickly see the order of magnitude difference. Right now, charging to 100% and leaving it there is a bug and should be fixed asap.
Third, the little message Yarbo has when it is “trickle charging” is funny. “Battery is nearly full…” when the battery is sitting at 100%. Now your just insulting our intelligence. I’ve measured Yarbo battery pack at 100% and the cell voltage is over 4.200 VDC. There should absolutely be no charging after that point. Shut it off and leave it off.
Please for the love of dog, give us an adjustable “full charge” percentage from 60-100%, so that WE can decide when to prioritize run time over battery life. This is a primer on charging and discharging lithium batteries for EV’s, and Yarbo is just a little EV. Do I Need to Charge My Car to 100?
Thank you very much!
Tim
There have been other threads requesting this.
Anyone with familiarity with Li-Ion batteries and NMC specifically know how bad it is to leave those batteries at 100% for extended periods of time. And if they really are at 4.2v per cell and maintaining a trickle charge, that is extremely concerning.
I’ve asked for confirmation on the floating cell voltage at 100% before. We need to better understand their charging strategy.
Thanks Bryan. That did the trick.
I just had this same issue. Here is the official yarbo support reply if anyone is interested.
These steps did reset it to reporting 100%.
We have found that the issue with charging is due to the charging coefficient that remains very low and the battery level does not increase despite continuous charging is most likely cause. To help the battery adjust and self-correct, please follow these steps:
-Continue charging the unit for an additional two hours.
-Turn off the device completely and let it stand for two hours.
-Restart the device to see if the charging recovers.
These steps are designed to help the battery adjust itself. If the issue still persists after these steps, kindly let us know so we can assist you further.
I’ve measured the pack at 100% reported SOC on the app. The tool used was a Fluke 87 in recent calibration. Output voltage was 42V, and the pack is a 10S or 10 series configuration. The nominal voltage is 10*3.6 or 36V, but they are being charged to 42.000V or 4.200 volts per cell and being kept there, by a “trickle charge”. That is a bug, and one that is designed to shorten battery life.
Tim
Ouch. 
Not good. Especially when sitting out in the hot summer sun.
Ok. Now I’m curious to see what the other robot manufacturers are doing with their batteries. I’ll check my other bots at the stated 100% charge level and report back.
Just look at electric vehicles. Which is now in a mature product design phase, and Yarbo is just a little autonomous EV. They give the user control over the SOC, so that we (not the company) can decide how much battery life we want. All EV let you set the max charge rate from 50-80% or whatever you want practically. When you go over 80% you usually get a warning about potentially affecting battery life. This is settled science!
And yeah, especially all true at higher temps with Yarbo sitting in the sun! And sitting overnight or longer at 100%!
Tim
Well this battery issue has come back. My battery won’t fully charge. I’ve already attempted the shut it down and unplug it for a couple of hours process with no luck this time. So its in the middle of a job and won’t charge back to 80% to go back out.
Updated my ticket we’ll see what they say this time.
Chris
Are you using the “No Charge Period”? I thought I read there is a bug in there.
Nope haven’t messed with that at all.
You can lower the threshold for charge to go back out under working preferences or just hit resume
@tallman.brew Sorry for the inconvenience!
We’ve checked your case under ticket #120566. The case has already been escalated to our technical team for deeper diagnosis. Once they provide feedback or additional steps, we’ll follow up with you right away.
Thanks for your patience and understanding while we work to get this resolved.
”using the “No Charge Period”?”
Totally off topic but I had to chime in…
This is a powerful tool, and the only one available from Yarbo to actually stop the battery from cooking at 100% overnight and multiple days. This is bad for a battery and every respecting battery engineer has an option for reducing the max charge to 80% or less. Yarbo has adding this “no charge “ feature which you can use to not charge overnight and let the battery charge “float” down to 80% or less. This is not a good substitute for proper lithium ion batteries, but it’s a start. I highly recommend everyone use it at least for a few hours every night. Yarbo has to fix this huge battery eating bug!
Tim
Does anyone know why my battery only charged to 64% since last night at 9:30 pm now it is 8:45 am and still not charged 100%? I used the snow blower couple of times and it recharged one or twice fast, but now it is not charging
Try disconnecting the battery from the core unit (drive unit) for 4 hrs. The BMS for the battery needs to reset it’s self
See details on this link
Thank you! @w.borhauer. I will try it today. Thank you for the reference link
