Safe charging battery on the bike?

General Discussion about electric bicycles.
SkipperDK   100 µW

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Safe charging battery on the bike?

Post by SkipperDK » Sep 08 2019 9:09am

Hi guys,

So i've got this middrive kit from bafang with a 36v std. shark battery included.

How do you guys go about charging? Is it alright to leave the battery on the bike while recharging?
I'm using the charger that came with the battery.

Best regards,

john61ct   100 kW

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Re: Safe charging battery on the bike?

Post by john61ct » Sep 08 2019 9:29am

Yes.

But to really be safe with LI, never unattended, and in a location where a fire won't be a problem, never in the living space.

LFP and LTO are the two exceptions, but less energy dense.

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Re: Safe charging battery on the bike?

Post by SkipperDK » Sep 08 2019 10:26am

Yeeaaah, so none of the above is really an option. I live in a flat and commute everyday. The only option for me is to charge at night in the flat while sleeping.

I've placed a firealarm above my chargearea as a precaution as well as placing the charger in an area where the possibility for catching fire by sparks are small.

Any other suggestions for staying safe?

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Re: Safe charging battery on the bike?

Post by hypertoric_amplituhedron » Sep 08 2019 11:42am

It is not recommended to charge while sleeping. It sounds like you are trying to alert yourself if there is a fire. But, keep in mind that this is a fire you cannot extinguish. you can only smother it with stone dust, to the point where it smokes, but it's still 'on fire'.

So, if the alarm goes off, you have to figure out how to relocate this unstoppable fire after being harshly woken in the night. Also yeah, that smoke is out of this world toxic. You will have to hold your breath while handling a fire close to your body in the night, with the alarm going off, along with one hell of an adrenaline rush. I hope I've painted the right picture. I skirt this by using a fast charger, but that requires a BMS that can handle it.

Since you can easily remove the battery, that's your best option. I'm sure there is some place discrete to charge off the bike.
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donn   1 kW

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Re: Safe charging battery on the bike?

Post by donn » Sep 08 2019 11:55am

I read that for example the Germans bought 1 million electric bicycles last year, about a quarter of bicycles sold, and similar story in the Netherlands etc. At this rate practically everyone in Europe will have one. Are they all running cords out to remote outdoor charging stations?

SkipperDK   100 µW

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Re: Safe charging battery on the bike?

Post by SkipperDK » Sep 08 2019 12:23pm

hypertoric_amplituhedron wrote:
Sep 08 2019 11:42am
It is not recommended to charge while sleeping. It sounds like you are trying to alert yourself if there is a fire. But, keep in mind that this is a fire you cannot extinguish. you can only smother it with stone dust, to the point where it smokes, but it's still 'on fire'.

So, if the alarm goes off, you have to figure out how to relocate this unstoppable fire after being harshly woken in the night. Also yeah, that smoke is out of this world toxic. You will have to hold your breath while handling a fire close to your body in the night, with the alarm going off, along with one hell of an adrenaline rush. I hope I've painted the right picture. I skirt this by using a fast charger, but that requires a BMS that can handle it.

Since you can easily remove the battery, that's your best option. I'm sure there is some place discrete to charge off the bike.
I do indeed get the picture, and would, if i saw that possible change the way to charge. Great idea regarding charging at greater amps, I don't know the C-rating of the BMS. At the moment i'm charging at 2amp. I have considered buying a 4A charger since that would allow me to charge it within the evening and attended.

Thanks for the reply

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Re: Safe charging battery on the bike?

Post by john61ct » Sep 08 2019 1:30pm

So to reduce fire risk in that scenario, no garage, basement, laundry room, back shed?

if you really can't convert to LFP or LTO,

buy packs from known-trusted vendors, made only from brand new grade A recent mfg date cells, of a long-term proven top-quality model.

charge to 4.05-4.10Vpc rather than any higher*

find a way to balance cells that does not require sitting at top voltage point for ling periods of* time

charge at a slow current rate, like 0.1-0.2C*

make sure you have a **reliable** HVC cutoff set at bulk amps equivalent of 4.2Vpc

regularly capacity-test your pack(s) SoH with a precisely timed CC-load discharge test

and discard / recycle before SoH% falls to 75%

* all these extend longevity as well as improving safety

Charge in a battery safe, fireproof container you can throw out the window (kidding?).


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Re: Safe charging battery on the bike?

Post by 999zip999 » Sep 08 2019 3:47pm

It greatly reduce the potential problem if you buy a quality battery and it should last longer. A good vendor will tell you the exact battery cell inside the pack. With pride. Ebike.ca or em3ev ect.

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Re: Safe charging battery on the bike?

Post by john61ct » Sep 08 2019 4:04pm

Yes but all batteries are consumables

Even the best is just delaying the point at which it becomes not-yet-exploded ordnance in the foyer.

So I'd in fact recommend starting with the mediocre (not default shitty no-brand cheapie) packs

have a bit more money for the required test/monitoring gear, and

**more quickly** develop the knowledge on spotting approaching EoL.

Also learning how to slow down declining SoH with good care protocols before paying the required big premium pricing for The Good Stuff.


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Re: Safe charging battery on the bike?

Post by dilkes » Sep 08 2019 4:42pm

To reduce the amount of time the charger is running while unattended, I use a simple countdown timer like this:
https://www.amazon.com/Woods-Countdown- ... ay&sr=8-43
and set it for 1, 2, or 4 hrs depending on how much I want to put in. Then perhaps topup if needed before setting off on a ride

AHicks   100 W

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Re: Safe charging battery on the bike?

Post by AHicks » Sep 08 2019 6:47pm

Call me reckless if you like, but my bikes are charged in the attached garage. I'll roll the dice on the potential for fire. I generally don't go too far out of my way to avoid being hit by lightning either.

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Re: Safe charging battery on the bike?

Post by 999zip999 » Sep 08 2019 8:16pm

What you get scared when you walk under the Neighbors motion sensor light. Yes any battery is full of potential energy. Just some chemistries are more volatile. And some builder's just scare me. As I will be looking for a 72v 20 - 30 ah battery and trying to balance things out. What cell ?
One guy in Reno was hit five different times by lightning.
Last edited by 999zip999 on Sep 08 2019 8:33pm, edited 1 time in total.

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MadRhino   100 GW

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Re: Safe charging battery on the bike?

Post by MadRhino » Sep 08 2019 8:17pm

LiCo is the most dangerous chemistry. Not so long ago, its usage on vehicles was limited to a few performance freaks. Now, manufacturers have developed some ‘’safer’’ LiCo batteries, protecting them with a round casing and most of all, severely limiting their C-rate specs. So, some cheap ´intelligent’ charger and low power controller are supposed to keep them safe by demanding very little of their potential reactivity. But, enclosing highly reactive chemicals is changing fire hazard into explosion hazard.

LiCo is everywhere now, and cheap Lico cells are a much greater risk. The safest LiCo cells are prismatic with low impedance/high C-rate. You will never set fire to a LiCo battery that you are watching, because it does warn you with heat, smell and gaz long enough before starting a fire. High C-rate LiCo can be charged faster than smoking a cigarette, then you are not tempted to leave them charging alone.

When you choose to charge slowly, while you are sleeping, a much more stable battery chemistry should be purchased. That is because intelligent machines can turn dumb anytime, and any cell can wear and leak anytime.
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Re: Safe charging battery on the bike?

Post by john61ct » Sep 08 2019 8:27pm

Quite a few members of these, and of related forums have indeed had catastrophic thermal runaway incidences, including burning down the house.

I think it will be increasingly likely that insurance will deny payouts citing recklessness using these chemistries indoors.

Of course by them the next hotness will have come along.

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Re: Safe charging battery on the bike?

Post by e-beach » Sep 08 2019 8:30pm

e-bike battery fires are not common. You don't hear about them every day like a house fire or a car fire. But they can happen. And they have happened to some of the best around here. So, if you work hours that make you charge while you sleep, put your battery in something that is fire proof. A heavy can that is made for solvent and oil rags maybe? I run LiFePO4 so I can sleep while I charge and balance.

Another option is to charge at work if you can so your home charging time is less.

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Re: Safe charging battery on the bike?

Post by donn » Sep 08 2019 9:50pm

MadRhino wrote:
Sep 08 2019 8:17pm
LiCo is the most dangerous chemistry.
Is that because LiPo is too rare to be an issue? Aren't 90% of the incendiary accidents LiPo?

I like (and use) LiFePO4, which I think is what john61ct means by "LFP"? (So what's "LTO"?) It's supposed to be a little less apt to burst into flame in a recharge, it lasts longer, fewer environmental issues etc. But LiCo as you point out is everywhere - not just in bicycles - and while there's a risk, if it were a giant risk I think we'd be hearing more about it. Like I mentioned above, millions of ebikes in northern Europe, all use LiCo, don't they? and the owners don't read endless-sphere to find out about all the safety precautions and high end chargers they need to know about. They plug 'em in and come back later. Europe isn't in flames.

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Re: Safe charging battery on the bike?

Post by e-beach » Sep 08 2019 10:15pm

donn wrote:
Sep 08 2019 9:50pm
..........They plug 'em in and come back later. Europe isn't in flames.
It is uncommon, but it does happen. viewtopic.php?t=87975
You do your thinking, pay your money and take your chances. Life has on guarantees.

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Re: Safe charging battery on the bike?

Post by 999zip999 » Sep 08 2019 10:16pm

Can we have a link to the battery ?

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Re: Safe charging battery on the bike?

Post by john61ct » Sep 08 2019 10:22pm


donn wrote:
MadRhino wrote:
Sep 08 2019 8:17pm
LiCo is the most dangerous chemistry.
Is that because LiPo is too rare to be an issue?
LiPo is not a specific chemistry, just means gellified electrolyte and ultra-light flexible containing materials.

Which makes them very easy to puncture or pop from squeezing.

Most LiPo are LCO / LiCoO2 these days, but could be

LiMN / LiNiCoAlO2, aka NCA, or
NMC / LiNiMnCoO2, aka INR,

and still be called LiPo.

Yes LFP is LiFe aka LiFePo4.

LTO batteries you can google, as I said, not relevant here, just the only other safe LI chemistry variant.

> if it were a giant risk I think we'd be hearing more about it

Everything is relative. People with higher disposable income and who learn the care basics, as above, will find it easier to be safe.

As are those choosing LFP if their use case allows for half the energy density.

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Re: Safe charging battery on the bike?

Post by fechter » Sep 08 2019 10:37pm

One option would be to remove the battery every time you charge it and place it inside a fire resistant metal box for charging. You would still have lots of smoke in the event of a fire but less chance of burning your place down.
Sounds like a pain.
I charge in my garage on the bike. I understand the chances of fire are low but not zero.
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Re: Safe charging battery on the bike?

Post by AHicks » Sep 09 2019 8:12am

You know, something not mentioned (or if so I missed it). When it comes to fires, my bet is the percentages drop way down when it comes to production batteries sold with matching chargers. As regarding homemade batteries being charged by questionable chargers, possibly with no BMS installed, THEN the percentages go way up. Abuse, whether intentional or not (possibly through ignorance/lack of due diligence), would also increase the chances dramatically.

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Re: Safe charging battery on the bike?

Post by john61ct » Sep 09 2019 10:52am

No, the issue is quality gear, well designed to prevent disasters.

The packaging of high-quality battery packs and high-quality charging / protective / balancing gear is a great idea in theory, but only necessary for those who don't have the knowledge to select the right components themselves.

Unfortunately, the scammers dominating this market niche take advantage of such ignorance, by selling cr^p gear, which of course greatly increases the risks.

Most people just want to shop on price, so most kits are cr^p.

The good stuff costs triple or ten times the price, and thus it's worth climbing the learning curve so you can sort out what's what yourself.

A good pack at high capacity can easily cost more than all the rest of the drivetrain put together.

A quality BMS can cost nearly as much again as the pack.

Making do with a cheap BMS and balancing gear, and a cheap charger, but still being **safe**, requires additional test/monitoring gear and the **knowledge** to use it.

Which you end up needing anyway, with a crappy bank you just need it sooner.

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Re: Safe charging battery on the bike?

Post by MadRhino » Sep 09 2019 12:23pm

donn wrote:
Sep 08 2019 9:50pm
MadRhino wrote:
Sep 08 2019 8:17pm
LiCo is the most dangerous chemistry.
Is that because LiPo is too rare to be an issue? Aren't 90% of the incendiary accidents LiPo?
RC Lipo are LiCo chemistry, and so are most of the round cells used in vehicles today.

RC Lipo was responsible for most of battery fires, now the cheap LiCo round cells are. In Europe, most ebikes sold now are 250w pedelecs with small batteries made of quality cells, thus unlikely to burn the house. The bigger the battery, the higher the risk, because most batteries are built with parallel banks and that doesn’t make it possible to monitor every cell. Yet, many modern BMS are monitoring temp, and that is making them much safer. Still, the safest way to charge LiCo cells is to watch them charging, for no BMS is as safe as someone watching.
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Re: Safe charging battery on the bike?

Post by john61ct » Sep 09 2019 3:28pm

LCO/LiCoO2 is certainly higher specific energy, so that chemistry dominates propulsion use cases, and yes, very risky thermally

My impression is many if not most cylindrical cells (that what you mean by "round"?)

not used for propulsion

are NMC /LiNiMnCoO2, which

largely superceded LMN/LiMnO2, new vs "old spinel"

In any case, they all have the same care requirements and fire prevention strategies.

LFP and LTO, at lower density and much lower risk (likely favorably comparable to lead) are completely different, each their own thing.

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Re: Safe charging battery on the bike?

Post by Tommm » Sep 09 2019 5:11pm

What's the big deal. When your bike is in your apartment, remove the battery and charge it in a fireproof ammo box or safe with a hole drilled for the wire. Put a handle on it. If things go south chuck the whole thing out the window. Done.

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