Accidental ebike newbie with controller and battery questions

[hdw123]

Hello hello. I got my first cargo, disc and ebike all in one package the other day. I was aware of the first two specs but not anticiapting having a MXUS 250w 36v front hub motor involved. According to the previous owner, hub works but he gave up trying to sort out a new battery/controller.

So my plan is to get a new battery and controller to get the motor going again. My limited understanding and research has led me to believe I need

- a controller rated at 250w 36v
- a battery rated at 250w 36v

Is this right? For the battery amps, should I go for a 10ah or more? The bike doesn't have peddle assist, just throttle and brake sensors, does this limit my controller choices as I'd like to reduce the amount of rewiring I'd have to do?

I'm only planning on taking my arthritic dog to some local parks with so don't need anything too extreme, for now.

Appreciate any advice and help

The ride

 

[e-beach]

What you need is a battery and controller that doesn't burn out your motor. Since your motor is 36v, a 36v controller will match. However, 250w is a small controller. (250w / 36v = 6.9 amps.) I would go with something bigger. Maybe 500 watts. However then you will need a battery that can handle the 500 watts or about 14 amps. (500 / 36v = 13.88 amps)

That is a smallish amount of amp draw BTW, so most 36v batteries will be able to handle it. It depends on the battery chemistry as different lithium chemistry's have different energy densities.

If you chose a LiFePO4 battery, make sure it is at least a 7 ah battery.
Pretty much any battery built with 18650 cells will have the "C" rating to run that motor.
(http://www.batteriesinaflash.com/blog/battery-c-rating-explained-and-demystified/)

And, with RC lipo at 20 C these days, a small lipo battery will move that motor with a 500 watt controller.

Caution! Most lithium battery can catch fire if misused.
LiFePO4 is very inert compared to other lithium batteries. I use it because I feel safe leaving it charging in my garage over night.

The various chemistries that 18650's are built from are mostly safe, but on rare occasions can catch fire....
https://endless-sphere.com/forums/viewtopic.php?t=87975

RC lipo, though small and relatively inexpensive is very volatile and should be watch while charging and stored in a fireproof bag or box.

Some trusted battery sellers around here are:

ebikes.ca
Ping Battery
EM3EV

There are probably more but those come to mind.

 

[spinningmagnets]

If you add a temp sensor to the stator on the inside of the motor, you can run a surprising amount of watts through it, as long as it's only a temporary peak.

The amps cause the majority of heat in a motor, and the motor you have can likely be run with 48V. That would give you slightly more power without a significant increase in heat.

If that interests you, then you would need a 48V controller, along with a 48V battery and charger.

Do you have a model number for that motor? There should be a cable with five very thin wires coming out of it for the hall sensors, and also a cable with three slightly fatter wires, which would be the motor phase wires.

 

[motomech]

My first hub motor was a MXUS like that one (over 10 years ago) and it was great. Aside from a added sensor, I doubt it has changed.
I used to run it at 20 Amps and 48 Volts, but had it as high as 25 Amps and 56 Volts. That was a bit much, as that much power would hammer (make it knock) the poor motor. It also ran fine sensorless (without Halls).
Since there is no PAS, there is little reason to use a sine wave controller and a simple square wave will do.
To make really simple, you could use a sensorless square wave like this one;https://www.pswpower.com/products/36v-48v-500w-brushless-dc-square-wave-controller-ebike-electric-bicycle-hub-motor-controller-with-right-output-30
You will also need a simple LED display (on/off and 3 speed settings);https://www.pswpower.com/products/24v-or-36v-or-48v-electric-bicycle-kt-led-890-control-panel-display-electric-bike-parts-52
That is a "soft-start" controller which makes start smooth and protects the motor gears.
I would certainly test the batt. before laying out the money to replace.
Although I prefer the controller from PSW Power, BMS Battery probably has the best battery packs for the money;https://bmsbattery.com/63-ebike-battery
The MXUS motor is very sturdy, but you will still need to take care on hills. Don't try and climb hills where the climbing speed falls below half the top speed, for at that point the motor starts to make more heat than locomotion. If you have to, jump off and push.
It should do 23 to 24 mph without pedaling on 48 Volts and that is a good top speed for that bike.
I also recommend drilling some air holes for the dog

 

[hdw123]

Thanks for the great tips and links guys. Really sucks about that garage fire and will definitely check what I'm buying and run a tight ship for charging. I've learnt never to mess with concentrated energy no matter what its form!

I've got an option to buy a new 36V10AH 250-350w Li-ion bottle cage battery for £100 ($130) which I might take up then. Seems like a good deal for UK prices.

The bike does have a throttle and simple 3 led indicators which I guess I could keep but, I should still be able to use a sensorless square wave controller, right? In that case should I go for this 500w controller https://torquetech.co.uk/collection...0w-9-fet-20a-kt-square?variant=11815425572911 or this 250w one https://torquetech.co.uk/collection...6-fet-15a-kt-sine-wave?variant=11815406403631? I'm guessing the 250w will be enough for that battery and motor? Is there a downside to having a small controller?

I've taken the lid off for the doggo so plenty of fresh air!

 

[E-HP]

I've got an option to buy a new 36V10AH 250-350w Li-ion bottle cage battery for £100 ($130) which I might take up then. Seems like a good deal for UK prices.

There are no good deals when it comes to batteries. Getting what you pay for is as good as it gets. However, there are plenty of bad deals. $130 for a 36V 10Ah batteries, guarantees generic Chinese cells of unknown origin, so just set expectations accordingly.

 

[e-beach]

...... Is there a downside to having a small controller?

Yes, a really powerless bike. It is better to have an overpowered bike and use less throttle then have a bike that doesn't really do much so you have to pedal hard anyway. IMO a 250w to 350w controller is a waist of money.

 

[hdw123]

...... Is there a downside to having a small controller?

Yes, a really powerless bike. It is better to have an overpowered bike and use less throttle then have a bike that doesn't really do much so you have to pedal hard anyway. IMO a 250w to 350w controller is a waist of money.

But surely that depends on the battery size and the motor? I thought the controller just controls whatever power it's getting. I guess my question is, if I have a 250w motor and a 250w battery, is there a penalty to having a 250w controller vs a 500w controller? Is it actually possible/recommended to run a 500w controller on a 250w-350w 35V10AH battery?

 

[hdw123]

If you add a temp sensor to the stator on the inside of the motor, you can run a surprising amount of watts through it, as long as it's only a temporary peak.

The amps cause the majority of heat in a motor, and the motor you have can likely be run with 48V. That would give you slightly more power without a significant increase in heat.

If that interests you, then you would need a 48V controller, along with a 48V battery and charger.

Do you have a model number for that motor? There should be a cable with five very thin wires coming out of it for the hall sensors, and also a cable with three slightly fatter wires, which would be the motor phase wires.

I'll check model number and all the wiring tomorrow and post.

 

[hdw123]

I've got an option to buy a new 36V10AH 250-350w Li-ion bottle cage battery for £100 ($130) which I might take up then. Seems like a good deal for UK prices.

There are no good deals when it comes to batteries. Getting what you pay for is as good as it gets. However, there are plenty of bad deals. $130 for a 36V 10Ah batteries, guarantees generic Chinese cells of unknown origin, so just set expectations accordingly.

I mean there are occasionally good deals. Averaged out, probably not. But I get what you mean. This is the same dude that sold me the bike, honest enough guy, says he bought the battery for new £165 ($226) and it looks identical to one sold here https://www.ebay.co.uk/itm/12451619...klv-Be78EhHVCWE5aFY1yKjszNw_QPdwaAq0FEALw_wcB. Happy with the risk as long as I don't discover an experiment gone wrong has cooked the motor or something!

 

[e-beach]

But surely that depends on the battery size and the motor? I thought the controller just controls whatever power it's getting. I guess my question is, if I have a 250w motor and a 250w battery, is there a penalty to having a 250w controller vs a 500w controller?

Battery size, battery chemistry (C rating), controller watts, motor size, wiring gauge, tire type, size and pressure, bicycle and rider weight compounded by cargo weight, not to mention aerodynamics, hills and weather conditions. Just to mention a few things to think about with an EV.

But to your questions. Where your motor is involved, the controller takes the input voltage and amps from the battery and converts it to a phase voltage for your motor. If your controller has a lot of mosfets, it could take 36v and pump out high phase voltages. Aka 36v 1000 watt controller vs a 36v 250 watt controller. The 1000 watt controller will use more energy, but it will give you more motored assistance then a 250 watt controller. It will also generate more heat. Too much heat will burn your motor up. A small controller, something like a 250 watt controller for a big bike your size would be almost useless. It will also heat up the motor as it struggles to pull your bike.

Is it actually possible/recommended to run a 500w controller on a 250w-350w 35V10AH battery?

35 x 10 = 350 watt hours usable energy, more or less. Around here 25 watts used per mile (usa) is the rule of thumb. So yes, a 350 watt hour battery is possible for your bike, but a bigger battery will be of more use. And with a bike your size, IMO, a 36v 15ah battery would be the smallest I would run.

 

[spinningmagnets]

If you plan to actually haul cargo in that large cargo box, you would definitely be better served by a mid drive motor, so the motor has some gears to work with. The smallest I would use would be the 48V BBS02, and if you think you wouldn't get into trouble, a slightly larger 48V BBSHD would be ideal.

Of course, don't do anything that would be illegal in your country.

 

[hdw123]

Thanks again guys.

So it seems I'm running the XF07 mxus 250w motor and I've snapped a picture of the motor wire ends. Would this 250w sensorless controller still work (assuming the 36v10ah battery)? https://torquetech.co.uk/collection...0w-6-fet-15a-kt-square?variant=11815425540143

Definitely not planning to haul cargo in this, and it won't be going on longer journeys than 10-15miles. Just fairly flat cruises to the parks.

 

[hdw123]

But surely that depends on the battery size and the motor? I thought the controller just controls whatever power it's getting. I guess my question is, if I have a 250w motor and a 250w battery, is there a penalty to having a 250w controller vs a 500w controller?

Battery size, battery chemistry (C rating), controller watts, motor size, wiring gauge, tire type, size and pressure, bicycle and rider weight compounded by cargo weight, not to mention aerodynamics, hills and weather conditions. Just to mention a few things to think about with an EV.

But to your questions. Where your motor is involved, the controller takes the input voltage and amps from the battery and converts it to a phase voltage for your motor. If your controller has a lot of mosfets, it could take 36v and pump out high phase voltages. Aka 36v 1000 watt controller vs a 36v 250 watt controller. The 1000 watt controller will use more energy, but it will give you more motored assistance then a 250 watt controller. It will also generate more heat. Too much heat will burn your motor up. A small controller, something like a 250 watt controller for a big bike your size would be almost useless. It will also heat up the motor as it struggles to pull your bike.

Is it actually possible/recommended to run a 500w controller on a 250w-350w 35V10AH battery?

35 x 10 = 350 watt hours usable energy, more or less. Around here 25 watts used per mile (usa) is the rule of thumb. So yes, a 350 watt hour battery is possible for your bike, but a bigger battery will be of more use. And with a bike your size, IMO, a 36v 15ah battery would be the smallest I would run.

Thanks for the explanation. I checked out the battery prices and I'll be doubling my costs by going even for the most basic 36v15ah battery. Seeing as I'm just dipping my toes into the ebike world and want to keep cost down for now, I'll most likely see what I can do with the 10ah battery.

 

[motomech]

Seeing as I'm just dipping my toes into the ebike world and want to keep cost down for now....

But you want to buy a $70US controller that forces you to buy an expensive display and there's freight on top of that???
The PSW Power link I provided sells the same controller for $19. And they offer the inexpensive 890 display.
Really the only reasons an Ebike, much less a cargo bike, uses a puny controller like those is to meet the restrictions against fun or if it is an "assist" bike with power levels so low as to force the rider to pedal. And that cargo bike is not going to induce anyone to pedal. But if you want an ebike with all the zippiness of a speedy glacier that's your choice and besides, if you want to swap in a more powerful controller later it would be no big deal.

Here is a controller from PSW Power's Ebay UK store;
https://www.ebay.co.uk/itm/36V-48V-250W-14A-6FET-ebike-Electric-Bicycle-Brushless-Motor-Controller-with-LED/222373438955?hash=item33c67d65eb:g:SuQAAOxyaTxTUWbp
They come with the 810 display and are less than 30 Pnds w/ free ship, but is the sensored type. But I think the connectors even match.
But if the Halls don't, you could buy and use a crappy crimp-on brass connector kit of different size bullets and insulator sleeves. No need for soldering, heat shrink, etc. Just electrical (crimp) plyers.
Pretty sure the controller wire colors (phases and Halls) will match the motor wires.
A 10 Ah batt. (which I would get from BMS Battery) will be pushing it at 15 Miles. Figure 1.5 miles per Ah, and that would be with you pedaling. To do a 15 mile round trip, I think you would need at least a 12 Ah batt.
With lot's of mounting options, you really don't need a water bottle batt. The highest capacity to cost ratio are the shrink-warp batt.s like this one;
https://bmsbattery.com/ebike-battery/664-16401-high-c-rate-polymer-li-ion-battery-heat-shrink-battery-pack-battery.html#/8-voltage_capacity-36v_15ah
That would be 22 miles of no-anxiety range.
Could doggo share the box? The warmth could be good for his arthritis.

 

[hdw123]

Thanks for the link mate. I was going for the $70 one only for sensorless compatability, UK stock and led indicators compatability but if I can find UK stock of one like yours at half the price, that would be sweet.

Yeah slow works for this bike. It's quite difficult cycling with a dog in the front with wonky weight distribution, so glacial sounds great actually Pedal assist would've been ideal but maybe for a later project. I come from the road cycling side and have some pretty zippy machines so it's nice to have a more relaxed set up. I'm thinking more barge boat than speed boat for this one.

So, my plan of action then for project glacial dog bike is to buy a new 36V10AH 250-350w battery (40% off, no shipping), and unless I can find something compatibile and UK stock, this sensorless 250w controller https://torquetech.co.uk/collection...0w-6-fet-15a-kt-square?variant=11815425540143. If this setup simply works, then that would be good to know. Based on everything above, it seems it would, but would be slow af.

 

[05silgto]

Looking through this thread, I feel like there is a few things that I should say that might have been missed or overlooked but I'm not sure how helpful it may be to the thread starter if he's on a budget.

First off, a 250w motor doesn't nessarly need to be run at 250w. If you powered that "250w" motor with a 1000w controller, you would be sending 1000w to the motor and the motor will use 1000w. Now the watt rating is typically what the motor is rated to handle at a typical voltage. So let's say it originally came paired with a 36v controller. 250w/36v= about 7 amps. Usually amps/current is your limiting factor because it is what causes heat. You don't start runing into issues with voltage with cheap ebike motors until you go over 100v assuming it's a brushless motor and not geared.
So, a good practice, in my opinion, is to go high on voltage and low on amps. You can get a decent controller and limit amps in the display usually.
So let's say you get a 72v battery/controller. Run it at 7 amps. 7 x 72= 504w and your not actually sacrificing really any relability. Problem with this is that 72v batteries aren't too common and therefore aren't cheap. If your really into and want to save money you can look into making your own battery. Someone told me about a site called batteryhookup.com where you can get cheap quality cells. I've tried them once with good luck. If you go this route, then make sure you do your hw and choose a cell with a high enough discharge rating for your goals.

Moving on, one more thing to mention, voltage plays a direct effect on your top speed. Voltage directly affects the max rpm of the motor. I could have a 10,000w motor with 10v but 1000 amps but I might be limited at 5mph. You can usually find the rpm of the motor per voltage listed somewhere, then you need to take into account the size of your wheel and tire to come up with your top speed for whatever voltage you use.
So, voltage sets your top speed, but your gonna need enough watts to get there in the end.
As a reference. I have a large fat bike with a heavy Chinese hub motor. With 72v and 45 amps I was able to hit a little over 40mph. Then I limited my controller to 30amps, cause honestly 40mph was too fast for that bike and my pas was too sensitive, with 30amps my top speed was reduced to about 33mph. So all in all is just depends on your goals, your budget and the amount of time you plan on spending. However, I feel it's important to see the big picture to get an idea of what to expect and your goals before spending money and getting results different than what you expected. I've increased by voltage 2 times just trying to hit a top speed that I was happy with.

 

[hdw123]

Thanks for posting, it's always good to understand these things more. As things stand I haven't gone for the 10ah battery from my previous post. I'm looking at a 36v15.6amp hailong battery at the moment and was wondering if it would work with this https://torquetech.co.uk/products/e...0w-6-fet-15a-kt-square?variant=11815425540143 250w controller rated current 7amp max 15 +/-1 amp? I read that battery should preferrably be able to supply more amps than the controller pulls at max, but is 0.6 enough?

 

[Blacklite]

Thanks for posting, it's always good to understand these things more. As things stand I haven't gone for the 10ah battery from my previous post. I'm looking at a 36v15.6amp hailong battery at the moment and was wondering if it would work with this https://torquetech.co.uk/products/e...0w-6-fet-15a-kt-square?variant=11815425540143 250w controller rated current 7amp max 15 +/-1 amp? I read that battery should preferrably be able to supply more amps than the controller pulls at max, but is 0.6 enough?

That battery spec will be 15.6 AmpHours capacity, not a 15.6A max draw for the battery. The units make a huge difference. You need to check what the actual continuous and peak draw capabilities are.

 

[MxusMick]

Nice thread! I have 2 ebikes and both use 36v 10ah lithium, the small bike with $15 350w controller goes as fast (20 mph)as the big ebike with $40 1500w controller. I can't imagine wanting to go faster on a trike, sounds sketchy. Buy both size controllers so you have a spare, and when a larger battery comes your way you won't be waiting on the mail. I love ebikes and encourage your project!

 

[alan0048]

*bump* was the XF07 Front Motor compatible with a sensorless controller? Or did you buy a sensored (9-pin) instead?

 

[E-HP]

*bump* was the XF07 Front Motor compatible with a sensorless controller? Or did you buy a sensored (9-pin) instead?

Description appears to indicate so.
“hall sensor and sensorless compatible”

MXUS 36V 250W XF07 Front XF08 Rear Freewheel XF08C Rear Cassette Electric Bicycle Brushless gear Hub Motor

MXUS 36V 250W XF07 Front XF08 Rear Freewheel XF08C Rear Cassette Electric Bicycle Brushless gear Hub Motor

pswpower.com

 

[alan0048]

Description appears to indicate so.
“hall sensor and sensorless compatible”

MXUS 36V 250W XF07 Front XF08 Rear Freewheel XF08C Rear Cassette Electric Bicycle Brushless gear Hub Motor

MXUS 36V 250W XF07 Front XF08 Rear Freewheel XF08C Rear Cassette Electric Bicycle Brushless gear Hub Motor

pswpower.com

I made an order a couple minutes ago just wanted to make sure but I noticed OP hasn't been online for 3+ years ^^'
Gonna have to spoke/build a 28" 700C wheel, so next step is finding out what thickness and length of the spokes to buy for the XF07 :S

pspower says 36H*13G, but that has to be for a particular size. I cant imagine 20-28 having the same spoke length.

 

[E-HP]

Chalo is the resident expert on mechanical bike stuff, so he may chime in. I used Sapim E-strong single butted 12/13 gauge spokes when I laced my hub motor, but Chalo usually recommends 14 gauge in order to obtain the right amount of tension. If I were to do it over, I’d follow that advice, but it requires using washers, since the hub motor spoke holes are usually drilled for 12 gauge spokes.
Length will depend on your lacing pattern and the dimensions of you hub and rim.

 

[99t4]

Gonna have to spoke/build a 28" 700C wheel, so next step is finding out what thickness and length of the spokes to buy for the XF07 :S

This great Grin tutorial was a wonderful help for me in determining the correct spoke length:

How to Measure Hubs and Rims for Perfect Spoke Lengths, Ebike Hub Motor Wheelbuilding

They also have a good tutorial on (hubmotor) wheelbuilding and also a good spoke calculator.

These are the spokes to use:

Sapim Strong Single Butted J-Bend Spoke

A butted spoke is drawn to its specific profile, which defines its high strength. The strongest spoke in Sapim’s product range, the Strong is developed for specific and heavy usage such as tandem, e-bikes or heavy load use. In case of large hub holes, the Strong is the recommended choice...

wheelbuildingparts.com

And if you need washers for overly large hub flange spoke holes:

Sapim Spoke Head Washer

Spoke washers help adjusting bending better to the hub. This washer adds additional reinforcement at the neck of the spoke.

wheelbuildingparts.com