Can charging my bike be made easier?

Batteries, Chargers, and Battery Management Systems.
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nrvwaters   100 µW

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Can charging my bike be made easier?

Post by nrvwaters » Aug 23 2020 7:57pm

Hi,

I need help refining my battery charging procedure on a light weight prototype e-motorcycle I made. It is similar in scale to the LMX and Sur-Ron.
Proto Bike.JPG
Proto Bike.JPG (105.21 KiB) Viewed 267 times
Like my fenders? :). I made them from strips of black plastic cut from a trash can.

My battery is essentially 5 "Mighty Mini-Cubes" from Luna Cycle wired in parallel. Each Mighty Mini has its own built in BMS and I've tied them together using XT 90 connectors. These are 14S, 2P units and here's a link for all the data:
https://lunacycle.com/52v-mighty-mini-c ... -3-pounds/

To charge the Mighty Minis I've been disconnecting them from one another and individually charging all five batteries before reconnecting. What a pain! I want to safely speed up my charging process while not harming the batteries or myself. Clearly this battery set up is the result of me getting impatient and just ordering something that had built in BMS for safety, good power output and could be made fit in my frame... this is not the way one would do a production bike. Regardless, I want to make the most of what I have. To figure this out I need help from someone with far more knowledge than me about batteries. My main questions are:

1. Can I just leave them connected together in parallel and plug my two chargers into two of the five charging ports and let all five charge up that way? Safely? I mean if they are all connected wont they all just charge up or will the battery management systems prevent that? I'm using the Luna Cycle smart charger that is recommended for this battery. If I can just leave them connected I might even buy another charger so that I can get the recharge done in two cycles instead of three..
2. If I must continue to disconnect them and then charge individuals can I just disconnect the positive or negative (but not both) terminals or must I completely disconnect each battery from the pack?

By the way, maybe this is the wrong section on the forum for this question but I wonder if anyone can help me with throttle response issues. I've adjusted the thing as much as possible and it still feels kind of like an on off switch. I let a wheelie master friend of mine have a go. He can wheelie anything for days and is a master of the downhill slow wheelie but he confirmed my throttle is just not what it needs to be. It's too on/off. No subtle control. Any ideas? I have a Kelly KEB7280 controller. Did I pick a bad controller?

Thank you,
Stefan

Pedrodemio   100 W

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Re: Can charging my bike be made easier?

Post by Pedrodemio » Aug 23 2020 9:18pm

I would parallel all charge plugs and plug both chargers in parallel there

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Matador   100 kW

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Re: Can charging my bike be made easier?

Post by Matador » Aug 23 2020 9:41pm

You could charge all five batts left parallelled with ONE charger. That would be no problem. charge current to each small batteries would be 1/5 th the output of the charger.

BUT, my concern is if you want to use BOTH chargers at the same time, then you PROBABLY need to modify the second charger and ISOLATE it from the common AC ground (there are tutorials on youtube for this).

My concern is that if you parrallel two chargers plugged on the same battery (really it is acting as one battery made of 5 small parralleled ones ) and with shares AC ground, you will possibly short one of your charger (and possibly the battery). One way around this is to plug both chargers in different mains plug socket making sure each mains plug socket is on a different circuit braker.

Do not count on BMS to isolate the chargers from ground. They won't.

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Re: Can charging my bike be made easier?

Post by Pedrodemio » Aug 23 2020 9:47pm

Matador wrote:
Aug 23 2020 9:41pm
You could charge all five batts left parallelled with ONE charger. That would be no problem. charge current to each small batteries would be 1/5 th the output of the charger.

BUT, my concern is if you want to use BOTH chargers at the same time, then you PROBABLY need to modify the second charger and ISOLATE it from the common AC ground (there are tutorials on youtube for this).

My concern is that if you parrallel two chargers plugged on the same battery (really it is acting as one battery made of 5 small parralleled ones ) and with shares AC ground, you will possibly short one of your charger (and possibly the battery). One way around this is to plug both chargers in different mains plug socket making sure each mains plug socket is on a different circuit braker.

Do not count on BMS to isolate the chargers from ground. They won't.
Isn't most chargers already isolated? I never tested, but the ones I've disassembled the PCB was clearly isolated, with just the transformer and an optocouple bridging mains and DC side

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Matador   100 kW

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Re: Can charging my bike be made easier?

Post by Matador » Aug 23 2020 9:56pm

Possible. I know server power supply are not isolated. But maybe ebike chargers are.

PCB might not be touching anything. I'm just wondering if it's a problem that both chargers are connected at the same time to the same mains and the same battery. Could that short one charger ?

I personnally wouldn't risk it and would check on youtube if anyone attempted it before and if they had a good or bad experience.

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Re: Can charging my bike be made easier?

Post by Pedrodemio » Aug 23 2020 9:58pm

Good point

The thing that I would do is never connect the chargers in parallel first because of small differences in voltage

Connect first one to the pack and then the second

I want to try that for a long time, if I do will post here

john61ct   100 GW

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Re: Can charging my bike be made easier?

Post by john61ct » Aug 25 2020 2:59pm

Most decent chargers have no problem being connected in parallel to get faster C rates.

It is only when simultaneously charging serial-connected packs that isolation becomes a concern.

Grin Satiator is fine with either or both.

The BMSs being connected while charging like this may be another issue deserving testing, or at least caution and observation.

The ideal would be putting all the balance wires in parallel and using fuse protected balancing boards and hobby chargers purposefully designed for exactly these scenarios.

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serious_sam   1 kW

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Re: Can charging my bike be made easier?

Post by serious_sam » Aug 27 2020 5:32am

nrvwaters wrote:
Aug 23 2020 7:57pm
a light weight prototype e-motorcycle I made.
Sweet looking bike. Nice job.

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Overclocker   10 kW

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Re: Can charging my bike be made easier?

Post by Overclocker » Aug 27 2020 7:52am

serious_sam wrote:
Aug 27 2020 5:32am
nrvwaters wrote:
Aug 23 2020 7:57pm
a light weight prototype e-motorcycle I made.
Sweet looking bike. Nice job.

agree. and very similar to the one i made

nrvwaters, what's the motor? you go a build thread?


VID_20200824_164448~2.mp4_snapshot_00.08_[2020.08.27_20.46.58] (Medium).jpg
VID_20200824_164448~2.mp4_snapshot_00.08_[2020.08.27_20.46.58] (Medium).jpg (331.02 KiB) Viewed 166 times

nrvwaters   100 µW

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Re: Can charging my bike be made easier?

Post by nrvwaters » Aug 27 2020 5:27pm

Wow. Nice build there Overclocker.
I didn't do a build thread.
Motor is a Cyclone 7500w
What did you do for throttle and controller? I did Kelly KEB7200 and some 0-5v throttle off Ebay. Even after dialing on it a bunch it's only somewhat better than an on off switch.

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Overclocker   10 kW

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Re: Can charging my bike be made easier?

Post by Overclocker » Aug 28 2020 10:30am

nrvwaters wrote:
Aug 27 2020 5:27pm
Wow. Nice build there Overclocker.
I didn't do a build thread.
Motor is a Cyclone 7500w
What did you do for throttle and controller? I did Kelly KEB7200 and some 0-5v throttle off Ebay. Even after dialing on it a bunch it's only somewhat better than an on off switch.


that's weird i do have a few kellys (KLS) and their throttle response were ok for the most part. are you sure you got the "TPS type" right? you should pick "hall" type if you got a hall-effect sensor style throttle not a potentiometer based

but on this bike i'm using the Votol EM100 and a wuxing thumb throttle

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skeetab5780   10 MW

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Re: Can charging my bike be made easier?

Post by skeetab5780 » Aug 28 2020 10:39am

Ya nice build man! i have no experience with the KEB(thing is huge) but i've owned KBS and KLS kelly controllers and they all have good throttle control. Could be throttle? or a setting in the GUI

Votol controllers seem to be the new craze now since QS mid motors hit the market. Not sure how any of them will run a cyclone though...never had one of those

I just ordered a D9000 for another dirt bike build from Eastgem, although i probably should have tried the QS since the design is far superior...i like to try something different than the pack. I may run that motor on a KBS or the new Votol-100 i have collecting dust

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skeetab5780   10 MW

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Re: Can charging my bike be made easier?

Post by skeetab5780 » Aug 28 2020 10:44am

Did you really buy 5x $299 mini batteries?

that seems expensive but then again it must be a powerful pack at 30ah

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