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Inmotion Factory 1.5A Charger Not Cutting Current


WARPed1701D
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So I have finally had time to mess around with my charge doctor and wanted to to a baseline charge log from what the V8 considers empty (tiltbact and shutdown) to full charge. I sat up last night waiting for the charge to complete and the currrent to drop to 0 and it seemed to take forever. I ended up going to bed and leaving it. I woke up this morning and the charger was still trickling 0.03A into the wheel. Looking at the Charge Doctor website the inventor mentions that his Firewheel charger did this and it is well known that Li-Ion should have the charge stopped unpon completion. Trickle charges are not good for the cells. I've attached the charging graph below. Is this normal? I wondered if the parasitic draw of the Charge Doctor could be fooling the charger to keep the power flowing but another chart of a Gotway wheel by the invetor shows a clear cut off of power from the charger. Anyone care to enlighten me what is going on here. Is this OK. Is this bad.

Background: This is the first time I have logged a charge with the Charge Doctor. I'm going to do it twice with the 1.5A charger and twice with the eWheels fast charger to learn when and how (V or A) to set the Charge Doctor auto-shutoff for each charger (as the curve and constant current/constant voltage transition will move) so I get the charge level and depth of discharge I want. I will post the results when I have them and expect to repeat this in 6 months to gauge battery wear.

ChargeDoctor.png

Additional Info: The light on the charger LED did turn green just before the charge doctor showed 0.05A but it appeared to have no effect on the output.

Edited by WARPed1701D
Additional info about charger LED
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No knowledge, just guesses here:

  • I believe my Gotway charger also shows like 0.02A on the CD after finish.
  • This may also be a tiny current coming from the wheel (Test: does the CD stay on if you keep it in in the wheel and then remove the charger from it?).
  • Maybe it's also due to the CD. As it stops at 1.5A by default, that may not be actually full for the wheel. This is why you should ocassionally charge your wheel fully without a CD (and keep the charger in for 20 mins or so after the light went green) so the batteries are 100% full and can then balance (which they may not do after an incomplete charge which one thought was complete).
  • I don't think this is a problem any way. But I'm removing my charger+CD relatively soon after charging (usually to 85%) or the charger when I charge to 100% without the CD, so it's never in there more than an hour or two at most.
  • The BMSes also should stop overcharging by themselves, shouldn't they? @KingSong69 You're going to know that, don't you?

My guess is, the CD does not actually charge to "full" due to the 1.5A stop, and somehow this results in what you see.

Edited by meepmeepmayer
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6 minutes ago, meepmeepmayer said:

No knowledge, just guesses here:

  • I believe my Gotway charger also shows like 0.02A on the CD after finish.
  • This may also be a tiny current coming from the wheel (Test: does the CD stay on if you keep it in in the wheel and then remove the charger from it?).
  • Maybe it's also due to the CD. As it stops at 1.5A by default, that may not be actually full for the wheel. This is why you should ocassionally charge your wheel fully without a CD (and keep the charger in for 20 mins or so after the light went green) so the batteries are 100% full and can then balance (which they may not do after an incomplete charge which one thought was complete).
  • I don't think this is a problem any way. But I'm removing my charger+CD relatively soon after charging (usually to 85%) or the charger when I charge to 100% without the CD, so it's never in there more than an hour or two at most.
  • The BMSes also should stop overcharging by themselves, shouldn't they? @KingSong69 You're going to know that, don't you?

My guess is, the CD does not actually charge to "full" due to the 1.5A stop, and somehow this results in what you see.

Thanks for the reply Meep. Some answers to the points you raise.

The V8 appears to have a diode in the charging circuit as removing the charger form the CD while still connected to the wheel kills the CD dead. There is no backfeed from the connector ar at least not enough to run the CD on its own. I tested this before I ran the log.

The CD had the auto-cutoff function disabled during this charge specifically so I could log a normal uninfluenced charge to determine the point at which I want to cut-off in the future for my desired level of charge.

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@Keith

You are absolutely right . I didn't understand the process correctly. This awesome explanation answers my follow on question about how could a BMS balance the cells if the charger cut the power at a specified level. I appreciate the effort in your response.

So basically my BMS was likely shunting power around all the batteries all night long.

 

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