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The eBike thread

unkel

A quick look seems that this doesn't really seem to fit in the cycling forum. So starting a thread here about all things eBike

I'll get the ball rolling. I have zero experience with eBikes. But I was going to build myself a battery anyway, for various reasons (like in bringing with me in my EV as a "petrol can")

I'm going to buy a solderless kit to make the battery (with 18650 cells I have removed from dead / old laptop batteries). This kit cah handle 20A max, and I would like the battery pack to produce 1kW constant. P=V*I so 1000W = 50V * 20A

This dictates that my battery needs to be nominal 48V (was thinking of making a 24V battery pack, but that won't be able to charge my car)

A quick browse on eBay and Amazon shows that you could buy a powerful 1000W bike conversion kit with everything needed except the battery for about GBP120 (a bit more from Amazon but peace of mind)

What to buy though, front wheel or rear wheel kit? Pros and cons? Any other advice?

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SCOL

Just pass the 70HR mark riding by Bafang mid Drive commuting to work.

I wonder how much it has save me on fuel for the car

Magzire

WoollyRedHat wrote: »

Does anyone know a good place to buy a mobile phone holder?

https://www.amazon.co.uk/gp/product/B072XNFFH3/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

using this one, its great

WoollyRedHat

Does anyone know a good place to buy a mobile phone holder?

jamesieliz

cc wrote: »

On my R1 there's a little plastic cover that seals over the charge port on the frame.

On a side note, it looks like if you press the up and down buttons at the same time for a couple of seconds you can adjust the max speed assist up to about 40 kph. Haven't had a chance to test it out yet properly.

Have you been able to get the assist working up to 40kph ?
I tried what you did and pushed up the number from 25 to 40, but I still think the motor stops assisting at 25 ?

Thargor

SCOL wrote: »

you could use a actual drink container, fill it with the tools you need.

Magzire wrote: »

Since i have rivet nuts under the frame i was thinking it be a good spot to have a spare tube and tools. Anyone know something like a bag holder that will go into a drink holder mount?

I see what looks like a tool bag that fits in an included bottle holder in Aldi this week, lots of good bike stuff there anyway...

https://leaflets.aldi.ie/view/876489109/6/

WoollyRedHat wrote: »

Thanks, it's actually the pin port on the bike frame I'm referring to that the battery clicks into.

On my R1 there's a little plastic cover that seals over the charge port on the frame.

On a side note, it looks like if you press the up and down buttons at the same time for a couple of seconds you can adjust the max speed assist up to about 40 kph. Haven't had a chance to test it out yet properly.

WoollyRedHat

Skill Magill wrote: »

Could you expand a little? Perhaps a photo of the battery port? Mine is detacheable and has a cover that you just press over the charging port to stop water ingress. This is what mine looks like

Thanks, it's actually the pin port on the bike frame I'm referring to that the battery clicks into.

JimmyCorkhill

Out of interest (say taking the Kuma R1 for example), how much would a new battery cost and how often would it need to be replaced? Is it every couple of years or after say 20,000km for example?

In relation to the wheels/tyres - are they normal bike wheels/tyres? Or are they more expensive?

Skill Magill

WoollyRedHat wrote: »

Does anyone know?

Could you expand a little? Perhaps a photo of the battery port? Mine is detacheable and has a cover that you just press over the charging port to stop water ingress. This is what mine looks like

WoollyRedHat

WoollyRedHat wrote: »

Can anyone recommend a good cover for battery port, to prevent water damage?

Does anyone know?

unkel

the_amazing_raisin wrote: »

I suspect there's a few ebikes that are regularly put on charge on Sunday and left until the following Saturday. Do that for a couple of years and you'll definitely see some battery degredation

Oh of course, no argument there. My point is that if you spend huge money on a big expensive battery from say a shop, you'd want to treat it well to make it last 4-5 years. Personally I'd rather spend 75% less, don't care about the battery, abuse it, and still get 2-3 years out of it

the_amazing_raisin

@unkel, yeah fair enough, no need to agonise over whether you charged the battery when it's at 20% or 40%. If you need to charge then charge.

I wouldn't fully trust the BMS to protect the batteries longevity, it's more designed to stop immediate damage.

I wouldn't want to regularly run the bike down to 0% if I can avoid it, but at the same time I'm not going to lose any sleep over it

Good point about charging indoors, it should be safe if the battery and charger is from a reputable company, but given some of the garbage that's going around these days better to play it safe if you can. Definitely wouldn't leave it charging while I'm asleep, too much energy stored in that battery

I guess I'm trying to get the idea that if you get into some good habits then you'll get 5 years easily and maybe more. I think that's a reasonable lifetime for an ebike battery

I suspect there's a few ebikes that are regularly put on charge on Sunday and left until the following Saturday. Do that for a couple of years and you'll definitely see some battery degredation

unkel

@the_amazing_raisin - you have some general logic right, but I disagree with a lot of what you are saying there.

Don't charge inside your house if you can avoid it. Not very safe. Also all shop bought batteries have a BMS. It will not let you discharge the battery to dangerously low levels causing harm. And even if you didn't have a BMS, the bike's controller also has a fairly safe low voltage cut off. It's also no problem to charge a lithium battery to 100% and leave it sit for a bit, a few days is no problem at all

And the story about the phone batteries is that you usually have only one cell, it's a numbers game, a lot of phones have multiple cycles per day, so after 3 years they would have had 1000-2000 cycles, which means a severe reduction in capacity. Does that matter? Of course not, the phone is pretty much obsolete after 3 years and most people would have upgraded well before then

Same with bike batteries, but for most people even daily commuters, 1000 cycles (pardon the punch) would mean 4-5 years or even way more. Do you really want them to last 20 years? Waste of your efforts really. And in particular I find that with discharging. Do you really want to carry a 1kW battery with you if you want 1000W power out of your bike regularly? Of course not. The battery will be toast anyway after 4-5 years, much better to buy a 500Wh battery and discharge the hell out of it, and just buy another 500Wh battery after 2-3 years. Cheaper this way and lighter too...

the_amazing_raisin

Mousewar wrote: »

Thanks for the posts. Very useful.
I don't have a shed though so I'll have to carry on charging in the house. Won't leave it over night though anymore.

I guess as Unkel said, top up as you need to, if you're using the bike for commuting then it'll probably need a charge every day or so

There's not much point in not charging one evening because you've 40% battery and running out of battery the next day

If the bike is for weekend spins, then probably best to try and get the battery to 50% after the weekend cycle and then top it up before the next cycle. This'll avoid it sitting too high or low during the week

So how you charge depends a lot on how you use the bike

Mousewar

Thanks for the posts. Very useful.
I don't have a shed though so I'll have to carry on charging in the house. Won't leave it over night though anymore.

the_amazing_raisin

Mousewar wrote: »

Absolutely burned past a couple of those rental ebikes on a big hill today so my kuma must be half decent at least.

What's the deal with charging ebike batteries? I always try to run it down before charging. Should I do that or can I just top it up as needed?
Or does it not really matter at all?

I'm assuming you're using lithium batteries, if not then you should probably disregard what I'm about to tell you

This is based on best practices for using and charging an electric vehicle but the principles should be the same

Lithium batteries have a certain cycle count before they begin to lose a significant amount of capacity.

Depleting the battery and charging to full will give you something like 600 cycles before it's badly degraded. This should sound familiar if you've ever had a smartphone where the battery is wrecked after 2-3 years

Depending on how you use the battery, you can dramatically extend the lifetime of it. For example electric vehicle batteries can last 8 years without significant degredation now

The two best things you can do would be to not deplete the battery to zero before charging, and not leave the battery fully charged

If possible, try to recharge the battery when it's still not 20% left to avoid a deep discharge

Also, if you can stop the charge at 80% that will increase the lifetime. If you need to charge to 100%, then try to do it just before you use the bike so the battery isn't sitting at full charge for a long time. Don't leave the battery connected to the charger after it's charged

Similar to people, batteries don't like being too hot or cold. I'd recommend bringing the battery inside if the bike is kept outdoors or in a shed. Makes it less likely to be stolen as well

Discharge rate can also affect battery lifetime, especially in cold weather. How much power you can safely draw from a battery depends on the cell type, but to be conservative you should probably not try to draw more power than the battery capacity.

So if you have a 100Wh battery, then you'll want to try and avoid drawing more than 100W for an extended period of time

In other words, try to back off the assistance levels as much as you can. It'll be good for your health as well as your battery health

EDIT: One last thing, if you're ever leaving the battery for a while unused (a week or more) it's probably best to get it to 50% charge. This is how they're stored in warehouses for long periods of time

unkel

Mousewar wrote: »

What's the deal with charging ebike batteries? I always try to run it down before charging. Should I do that or can I just top it up as needed?

Top up as needed is theoretically better. Lithium ion battery cell only ever charged between 25% and 75% SOC at a constant ambient temp of 21C will last 50-100 years and still have near half the original capacity

Mousewar wrote: »

Or does it not really matter at all?

See my answer above, it matters very little really unless you want your battery to last 20 years

unkel

Skill Magill wrote: »

always charge when the battery is cooled down and indoors. Once charged, I unlug the battery from the charger (rather than leaving it attached to the charger and unplugging that from the wall)
Think thats best practice, but I'm open to correction

You will need some correction. There is no need to unplug the charger when charging is finished. Unlike lead acid, lithium chargers only charge up to the full voltage and never any more. When the batteries are full, there is simply zero current from the charger to the batteries. Same as it not being connected at all

I wouldn't charge indoors though, if you mean inside your house. Lithium ion 18650 battery cells are pretty unsafe things that can cause fires. I charge mine in the shed.

Skill Magill

I never let the battery run down to zero if I can help it and always charge when the battery is cooled down and indoors. Once charged, I unlug the battery from the charger (rather than leaving it attached to the charger and unplugging that from the wall)
Think thats best practice, but I'm open to correction

Actually this paraphrases what they say on the Brompton site

Worth a quick look through

WoollyRedHat

Can anyone recommend a good cover for battery port, to prevent water damage?

Mousewar

Absolutely burned past a couple of those rental ebikes on a big hill today so my kuma must be half decent at least.

What's the deal with charging ebike batteries? I always try to run it down before charging. Should I do that or can I just top it up as needed?
Or does it not really matter at all?

Padre_Pio

Magzire wrote: »

I managed to get a cable and got it all working, got it up to 54km/h. Ridiculously fast, that's only the 750watt version. That's plenty enough for me. A lot smoother than i expected. Overall definitely worth it.

54km/h is a dangerous speed for anyone wearing cycling gear.
Take care of yourself.

Where are people getting batteries from nowadays?
I want to build one from scratch with a BMS.

Any reputable sources for 18650?

Magzire

I managed to get a cable and got it all working, got it up to 54km/h. Ridiculously fast, that's only the 750watt version. That's plenty enough for me. A lot smoother than i expected. Overall definitely worth it.

unkel

yousifm wrote: »

If you're planning to use it quite a lot, I would definitely look at a battery size of at least 12Ah.
You should be able to find an ebike with a decent sized battery for about 1400 or 1500 or, if you already have a bike, you can make it electric with a conversion kit (they usually come with decent sized batteries).

Depends completely on what you want with the bike. Sure if you have a huge commute and need a (very) long range and / or use it as a "motorbike" without wanting to do much in the way of pedaling yourself, sure get a big battery

For a lot of people a smaller battery would be a better option. It is substantially cheaper and lighter.

yousifm

jc bamford wrote: »

Just wondering if you got the Kuma and how it worked out. I am looking at the R1 myself but the the battery looks a bit small at 8.7 AH

If you're planning to use it quite a lot, I would definitely look at a battery size of at least 12Ah.
You should be able to find an ebike with a decent sized battery for about 1400 or 1500 or, if you already have a bike, you can make it electric with a conversion kit (they usually come with decent sized batteries).

Magzire

Skill Magill wrote: »

This will do the job, cheap and has good reviews too :

https://www.wiggle.co.uk/lifeline-tool-storage-bottle

great idea, thanks

Skill Magill

This will do the job, cheap and has good reviews too :

https://www.wiggle.co.uk/lifeline-tool-storage-bottle

SCOL

Magzire wrote: »

Since i have rivet nuts under the frame i was thinking it be a good spot to have a spare tube and tools. Anyone know something like a bag holder that will go into a drink holder mount?

you could use a actual drink container, fill it with the tools you need.

Magzire

Thargor wrote: »

That looks great there, underneath the downtube was a bit dodgy looking.

The power controller is right there were the tire would hit, that would end in disaster

Magzire

Since i have rivet nuts under the frame i was thinking it be a good spot to have a spare tube and tools. Anyone know something like a bag holder that will go into a drink holder mount?