This is once work is done and it returns to charge.
Traditionally, lithium ion batteries simply get damaged if left at 100%, and the battery charging station does a great job at getting it there. But I don’t want it there, I want to have a healthy battery. Traditionally, that means not to leave a charge at 100%.
Can we have a max charging percentage when NOT working setting?
I agree. We’ve discussed this before. Needs to be an option.
Or, if Yarbo (the company) can confirm that 100% charge in the app is really only 90% based on cell voltage, I’d be ok with that too.
FYI, I keep my electric vehicles at 80% max state of charge for this same reason.
They have told me and numerous others on numerous occasions that the BMS is maintaining the optimal SOC for the battery. I can only trust that is the case. Based on my observations, it will quickly drop from 100% when in a work plan. I think when it equalizes and stops dropping quickly that this was the true SOC and not the “dumb user 100%” SOC. I honestly think it’s not a true 100%. Some have disagreed with me on this based on measured voltages, but I just assumed that there are sacrificial cells and extra buffer that isn’t advertised that would account for this discrepancy. Not my area of expertise, just a knuckle dragger making observations. Could totally be wrong here. Nevertheless, the company said the BMS has got it under control and the battery is warrantied for 2 years. I think they wouldn’t warranty it that long if it wasn’t managing it effectively. I also know other PPP who have been using batteries from the early 2022 proof of concepts testing models that still work to this day.
Hi Shanie,
We totally understand your concern about battery health. Yarbo is equipped with a battery management system (BMS) that carefully controls the charging process to help protect the battery over time. So it’s perfectly okay to let it charge to 100%—in fact, the BMS ensures it’s not overcharging beyond safe levels.
Thanks for sharing your thoughts!
@Yarbo-Forum- Charging to 100% isn’t the problem. I want a full charge when it’s headed out to mow. It’s the sitting at 100% for long periods of time, especially in extreme temperatures, that heavily stresses this battery chemistry.
I have suggested a Max Charge level previously as well. It could be manually ramped up on cutting days. Ideally, it would also be tied to the Scheduler to auto “top-off” to 100% a couple hours before a job start.
There is known “happy” range for Li-ion batteries. Extreme high and low SOC accelerate degradation. At $1,100US replacement cost, I want to be nice to it.
This curve also closely mirrors my attitude on most days 
Hi @Yarbo-Forum,
Though I agree that these devices have a BMS (as most lithium products do), I also have an EV, I also have other high-capacity devices, and none of them suggest holding a 100% charge for any length of time. As @cobradunn shows, a typical Lithium-Ion EV battery hates being fully charged (but is fine if you’re imminently about to go on a trip!)
I don’t see how holding a charge at 100% for long periods of time in a Lithium Ion device makes sense. Please have an option to charge before first setting out and that would make me very happy!
If you have a battery team, I’d love to hear their thoughts.
Displaying 100% may not mean the battery is actually at 100%.
That is purely speculation on my part.
It should display the actual SOC. If it’s not charging to 100% they’re leaving a lot of capacity on the table. I’d be surprised if that were the case. BMS most important function is cell balancing. I’ve not heard it used do something like this.
Aren’t there reports of it dropping from 100 to 90 pretty quickly, or did I dream that?
For me it was sitting at 100% for a 1/4 of the job then dropping quickly to where it should have been.
So if say 80% to 100% shows as 100%, wouldn’t that be your case?
Again, I speculating.
This is what I was speculating above.
Caveat:
Cell balancing, at least for many systems, only takes place at (whatever full charge is) and can take a long time. Especially if the bms just uses simple diodes+resistors to bleed everything down to the same level.
The balancing method for the Yarbo’s winter battery is unknown to me, however. But with the typical BMS that I’m familiar with, charging to 100% a few minutes before take-off means you’ll never balance the cells.
YMMV, clearly.
It may well be the case that’s it’s just a “dumb” system that can only balance near 0% or near 100%. But, there are systems that can calculate the requirements and do at almost any SOC. Telsa is probably the most advanced example of it.
That said, I still don’t care for my battery sitting at 100% for days.
Another thought is this, Yarbo manufactures the batteries as far as I know. And they make the BMS as far as I know. If you’re in the business of making batteries and BMSs you likely know something about batteries.
It’s a pretty safe bet that you’ll get at least 2 years out of the current battery as that is how long the warranty covers. And according to @bryan.wheeler some of the PPP have 2022 batteries still in operation. So that’s what 2-3 years?
My neighbor (I think I stole that from @steve) owned a couple of Priuses (or Prii). Their battery was warranted for 10 years. First one made it 13 years. Second one is over 12 and counting. I suspect Toyota knows a thing or two about batteries.
Batteries aren’t my area of expertise. I definitely won’t be making a replacement battery or BMS for Yarbo.
If someone makes a replacement battery for Yarbo and warranties it for more than 2 years and it cost less that the $1,199.00 price on the Yarbo store, I may be in the market in 2-3 years.
Correct me if wrong, but these were winter only machines until recently. The batteries haven’t seen high temps like this before.
I agree with being able to set an upper limit. Most “smart” devices now a days will automatically keep the maximum charge at around 80% and track battery stats, and either after a certain amount of time or other concerning pack data will trigger a full charge to 100% and do balancing as required.
I believe you are correct. And they went through the wringer when customers complained about not being able to charge. And in the end, the solution they came up with seems to have quieted the masses.
Or maybe they just turned on zero turn to divert our attention. 
I’ll be honest. Unless Yarbo tells us something different, and provides data to support what they’re telling us, I am concerned about the batteries and will start restricting the charge to ~80% like I do with all my EVs.
It’s obvious that with Yarbo originally being designed and optimized for winter use, the summer heat and prolonged storage at 100% SOC will degrade the batteries over time.
As a counterpoint, I have owned multiple Husqvarna Automowers for years, and their batteries are still going strong. No noticeable decline in runtime. My Lubas still also seem to have the same run time as new, but they aren’t nearly as old.
