Mixing and matching eBike battery / motor / controller...

Electrically assisted bikes, trikes, etc. that are legal in the UK
Manc33
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Joined: 25 Apr 2015, 9:37pm

Mixing and matching eBike battery / motor / controller...

Post by Manc33 »

I want to stick to the legal limit of 250W for a motor, not just because of the law but also because I want to get the most range I can from any battery I end up using. I want a battery with a lot of range like 50 or 60 miles.

Just get the biggest battery I can, right?

Sort of... the 250W motor is 36V and to have a battery with good range, means getting hold of a battery that's 48V (because that's the only one I can find that goes up to 24Ah and thus is a long lasting one).

Judging from the 250W motor I was using around 2016 and the small battery pack on that giving me about 11 or 12 miles (24V/8.8Ah) I worked out on the same Wattage motor should give me about a 55 mile range on a battery thats 48V/24Ah.

The issue is, you shouldn't go plugging a 48V battery pack into a 36V controller box, you can fry the capacitors. :!:

Also, my old 250W motor was only 24V... what happens when 48V is sent to a 36V motor? Yes the RPM is increased but then so is the battery usage - but if you're indeed going at a faster RPM, the mileage should just even out? You're using more power but you are going faster along with it. I just have no idea how to work this stuff out.

So as long as I get a controller box that can handle 48V (a lot of them say "36V/48V" on the label on the controller) and I run that through the 250W/36V motor... apart from that motor possibly spinning a bit faster because it's having 48V put through it instead of 36V, is this setup still fine to run?

If the controller box says "36V/48V" on it, does that possibly mean it will only send 36V to the motor? I'd want it to send even less and make the battery last ages!

I guess it can't be that intelligent that it can know the motor is rated at 36V though right? However, to have a label with "36V/48V" on, I guess it does know the voltage of the battery being plugged in.

I just don't want to go spending £600 on a hub motor, controller and battery then blow it up within 5 minutes :lol:

I wonder if the "36V/48V" listed in this image refers to the battery you can connect to it, the motor, or both :?:

Image
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Jdsk
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Re: Mixing and matching eBike battery / motor / controller...

Post by Jdsk »

Please don't think this rude, but do you have any experience of assembling components in this way, and are you working only from vendors' specifications?

Manc33 wrote: 20 Jun 2021, 1:28amI just don't want to go spending £600 on a hub motor, controller and battery then blow it up within 5 minutes
You do have the option of buying a kit where you know that it all work together.

Manc33 wrote: 20 Jun 2021, 1:28amJudging from the 250W motor I was using around 2016 and the small battery pack on that giving me about 11 or 12 miles (24V/8.8Ah) I worked out on the same Wattage motor should give me about a 55 mile range on a battery thats 48V/24Ah.
I make that a nominal 211 W h and 1152 W h, and if range is proportional to energy storage I'd expect 63 rather than 55 miles.

Manc33 wrote: 20 Jun 2021, 1:28amAlso, my old 250W motor was only 24V... what happens when 48V is sent to a 36V motor? Yes the RPM is increased but then so is the battery usage - but if you're indeed going at a faster RPM, the mileage should just even out? You're using more power but you are going faster along with it. I just have no idea how to work this stuff out.
The relation between required power and speed varies with speed. At fast road cycling speeds on the level you're in a zone where most of the work is against aerodynamic drag which is proportional to the square of speed so that power is proportional to the cube of speed. But the legal restriction on assistance puts a limit on this. I don't know if there's a rule of thumb for this with eBikes.

Please let us know what you come up with.

Jonathan
rjb
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Re: Mixing and matching eBike battery / motor / controller...

Post by rjb »

Is the wire pair labelled Pas for the power assisted steering. :lol:
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
Manc33
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Re: Mixing and matching eBike battery / motor / controller...

Post by Manc33 »

Cheers folks.

An all in one kit is hard to find, because it gets a bit complicated, I mean the web page selling it would need to list dozens of variants on the page. There's front wheel motors, rear wheel, bottom bracket motors, then 24V/36V/48V/52V batteries at this Ah, that Ah, the other Ah, then there's all different controller boxes, whether you want a push button throttle or a twisty one, whether you want an LCD screen and how good you want it.

What I usually see is kits with everything in except a battery, then you have to hunt down a battery to go with it and try to make sure it's got the light purple Samsung cells in it. Then you have to make sure whatever male plug comes out of your controller box fits the female plug on your battery, but I guess it's all mostly standardized these days.

I read that the Chinese sell motors labelled as 250W to stick to UK legal requirements, but they are often way more powerful like 400W! I also read that as long as a 250W motor can be kept from overheating, you can push it (simply by using more Volts) to be effectively way more than 250W. Perhaps that's also why there is a 15.5 MPH limit.

A lot of people have said, if in doubt (it's not labelled) unscrew the controller box and if the capacitors are rated at 63V or more then it can tolerate having a 48V battery. I still don't know what "36V/48V" refers to on those controller boxes, but I assume it must mean the battery.
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L+1
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Re: Mixing and matching eBike battery / motor / controller...

Post by L+1 »

I think if you moved your query to the ‘Electric Bikes’ section on the forum - or at least alerted them to your thread - you would get a more detailed reply.
Someone will know if what you are proposing is possible, or at least suggest where else you can ask.
Manc33
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Re: Mixing and matching eBike battery / motor / controller...

Post by Manc33 »

L+1 wrote: 20 Jun 2021, 7:01pm I think if you moved your query to the ‘Electric Bikes’ section on the forum - or at least alerted them to your thread - you would get a more detailed reply.
Someone will know if what you are proposing is possible, or at least suggest where else you can ask.
I didn't realise there was a dedicated section :oops:

I can't see a way to move it myself.
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Vorpal
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Re: Mixing and matching eBike battery / motor / controller...

Post by Vorpal »

Manc33 wrote: 20 Jun 2021, 7:55pm
L+1 wrote: 20 Jun 2021, 7:01pm I think if you moved your query to the ‘Electric Bikes’ section on the forum - or at least alerted them to your thread - you would get a more detailed reply.
Someone will know if what you are proposing is possible, or at least suggest where else you can ask.
I didn't realise there was a dedicated section :oops:

I can't see a way to move it myself.
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stodd
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Re: Mixing and matching eBike battery / motor / controller...

Post by stodd »

I suggest you ask the question at https://www.pedelecs.co.uk/forum/forums ... ussion.42/
There are a few people on there with very deep technical knowledge about exactly the issues you are asking.

Most legal 250w motors are 250w continuous, most can deliver 400w or 500w peak, many 750w (or course at the cost or range, and only for
short periods).

If you overvolt a motor most will take it, but optimal efficiency motor speeds will increase as well so you may make it less efficient at the speed you want to run it at most of the time.

A whole variety of legal kits complete with larger than typical batteries at Woosh (http://wooshbikes.co.uk/) and excellent customer service; but short supply right now; also not as big battery as your suggested 48v/24Ah (1152wh).

You should get a good idea of range from https://www.bosch-ebike.com/en/service/range-assistant/, designed for their motors but pretty accurate for most 'typical' 250w motors with a little interpretation and linear extrapolation for battery watt-hour. You can really see the difference of different riding styles, different assist level and different road conditions.
Manc33
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Re: Mixing and matching eBike battery / motor / controller...

Post by Manc33 »

Cheers folks and thanks Vorpal for moving this.

EDIT: I worked out on the Bosch website, after setting every detail like "hilly, winter, mostly good asphalt, hybrid tyres" etc, using their biggest battery (625 Wh) the range came out at 42 miles, that's with their 350W "Performance Line CX" in Tour mode, so if I am using a battery with 1152 Wh that's 1.8432 times more than that - in theory the range could be about 77 miles. That would be amazing if it did have that sort of range on it.

Image
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hemo
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Re: Mixing and matching eBike battery / motor / controller...

Post by hemo »

24ah for 50 -60 miles is way over the top unless of course one is going ot use 50 -100% PAS all the time.
In low power mode PAS 1 or 13% of available current I get 25 miles from a 6ah 36v battery, using the cells discharge current the actual available capacity is nearer 5.3ah/191wh.

The dual volt 36/48v controller looks very much like the excellent KT (Kuenteng) one, it will operate on 36 or 48v without issue including using both alternately.

36v 15ah battery has the same capacity as a 48v 11.2ah, 48v gives you 33% more torque and power over 36v.
hemo
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Re: Mixing and matching eBike battery / motor / controller...

Post by hemo »

A hub motor to doesn't care to a degree doesn't care what it sees voltage wise at less the 60v, though it will depend on the extent of current supplied to it. As one goes up the voltage range less current is required for the same torque power.
The KT range of controllers are good as for 36 /48v one can buy 15,17,20,22 & 25a controllers, the beauty of them is that one can limit the current by adjusting this % wise via the display settings to suit the hub used (some hubs can handle current better then others).
hemo
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Re: Mixing and matching eBike battery / motor / controller...

Post by hemo »

48V/24ah battery is going to be heavy it will add about 6 - 6.5kg o a bike alone, One would expect a reasonable fit rider to get well over 100 miles in range.
First though one needs to know if they want to do put in a fair amount of effort or hardly none at all, if the former then one has to ride with as little assist as possible ( lowest PAS level ).
hemo
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Re: Mixing and matching eBike battery / motor / controller...

Post by hemo »

Most controllers and displays can't be mixed and matched, one has to generally pair them up from the same brand as often simple protocols in the programming aren't compatible. With most generic stuff like KT, Lishui, Brainwave and Bafang any generic battery can be used as they are simple to wire V+/V- hook up with no CANbus type extra wiring.
The only Comms is between controller and the display, the software/programming isn't universal between generic brands so one has to stick to the same pairing from the same maker. Nearly all are compatible with any 9 pin hub motor as the 9 pin wire sequence from the hub motor is generic and most use the Julet 9 pin waterproof connector, the one example not compatible is the flawed Suntour hub on Carrera bikes.
Manc33
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Re: Mixing and matching eBike battery / motor / controller...

Post by Manc33 »

Hemo cheers, that's a lot of useful info.

I was working out my range going off using a 24V/8.8Ah (211.2 Wh) battery in the past, that gave a range of about 12.5 miles (using the motor almost constantly) on a light bike with me probably 40 lbs lighter.

These days I'd be on a heavier bike (+40 lbs) so that's another +80 lbs compared to the previous setup. I thought if I were to use that same old kit now, I'd probably get about 10 miles out of it. I want to get 60 miles from a battery so I just multiplied whatever that old battery was by 6 to come up with needing about 1,250 Wh or rather, a battery thats 48V/24Ah (1,152 Wh).

The weight given for that battery is 5KG.

Code: Select all

https://www.aliexpress.com/item/1005001863748354.html
I didn't notice before but it says that thing has got 91 cells :lol:

That's not far off my estimation if I work it out from how many cells my old pack had (14 cells), to multiply that range by 6 I would need ~84 cells. With 91 that's 7 more so that's maybe another 5 miles bringing it to about a 65 mile range. This is using the motor almost all the time and deliberately going up hills everywhere I go.
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hemo
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Re: Mixing and matching eBike battery / motor / controller...

Post by hemo »

How many cells a battery has depends on the call mah capacity rating.
For 48v there are 13 cells in series.
A 24ah battery using 3000mah cells would have 8 in parallel so 104 18650 cells, each cell is about 48g so 4.99kg plus case weight, bms, nckel interconnectors wiring . It all adds up and 6 kg wouldn't be far out.

With 2600mah cells it would have 117 18650 cells.

Though some might use li-po pouches.
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