Wide Wheel aging battery diagnosis and first intervention

We (mostly) all know that as things age they stop performing at peak levels, sometimes replacement is the best solution, but perhaps other times intervention can fix the issue. I'm not one to shy away from a surgical intervention if needed, but if another therapy can work then all the better.

Background

So, while the WW was going well these last few years I've been using it less (favouring my bicycle for shorter trips in and out of town) and its had a few small issues that I've needed to fix (like the seized rear motor, exacerbating the not using it as much).

I noticed however that the battery was "sagging down" more in voltage sooner than I thought it should do as I was riding (you know, that volt meter on the handlebars does have a useful purpose right?) and began thinking that it may be something more than just expectable aging.

I always check the "Watt Hours" (Wh)  shown on my charge monitoring tool (that always remains plugged in between the charger and the scooter), and the Watts needed to recharge are less than what I'd have expected were the battery depleted down to that level of "remaining charge" (as represented by the voltage when riding). For reference, this is the Watt meter I use:

It conveniently shows how many Amps are flowing, the battery Voltage and on the bottom row cycles the left number through 

• Amp hours (Ah)
• Watt hours (Wh)
• Peak Amps (Ap)
• Voltage maximum  (Vmax)
• Peak Watts (Wp)

the right number shows just the current situation of Watts flowing. Its a great tool and I would strongly recommend everyone with an eScooter or an eBike have one of these; you learn a lot from them.

I mean unless you're stupid, then you don't learn anything ....

First step

So I decided to pay attention to the last part of the charging cycles and come on in at the end; glancing at it as I went about my doings around the house.

I noticed that it was 0.18A (that's also 180mA) at one point, then suddenly became 0.00A ... that's wrong as before I've seen it taper nicely down to 0.01 Amps (because I like to watch these things, just like I like to watch the food I'm cooking so I don't burn it).

"Riigghhhttt" I thought, "the BMS is cutting off before balance has completed" ... first step was to turn off the charger (at the wall, in Australia power points have switches on them) and leave it plugged into the charger (so I can monitor the actual charging point voltage as well as the "take off end" that  shows on the handlebar, yes they are different voltages) and wait a while (about half an hour) and then turned it back on ...

bam ... started charging at 0.56A and I thought yep, diagnosis looks right: BMS is shutting down, the full cells settle (after charging) lowering the difference between pack cell groups. The role of the BMS (among other things like discharge protection) is to ensure that charging is stopped before any cell (bundle) is over charged (think fire risk) and to help fully charged cells bleed over to the less charged cells (although different BMS's do this with different levels of quality).

So clearly it was shutting off before the other cells were fully bled.

Not wanting to stand there all day I decided to automate this with a simple "clock work" power timer I had lying around ... 

I set it to provide power for 15 minutes and not provide power for 15 min. I can "turn it on" for the first bulk charge (to save time) using the switch on the side:

in the up position its providing full time power (ignoring the settings) and in the down (blue/green arrow) position its on the timer.

Lastly

I've put together this quick video showing all this and discussing the same points above but in a slightly different angle. 

I hope that together this makes things clearer

I'll follow this up in the coming weeks with what happened and if this simple solution means I don't need to do pack surgery and replace the BMS (with a spare which I'll probably already have on hand from last time).

See Ya