E-scooter build - Advise regarding controller and battery

[Haxerflaxer]

Hey everyone!

I'm a mechanical engineer who recently got access to a full metal workshop and is interested in building my own scooter for traversing to and from work.

My idea is to do a similar look to the newly released 'Husqvarna - Skutta', or 'Husky - Skutta'. The construction is no problem, however the electric, more the battery in question, is. I'm looking at a 48v, 1000w hubwheel with a drum brake. The seller has a motor controller rated 48v, 1000w and 38A current limiting. When calculating range, speed and etc I've come to the conclusion that a 48v, 15Ah battery would work and a 20Ah would be most optimal. However, most batteries I've seen, within a reasonable price, doesn't have a continuous discharge of 40A and when asking Chatgpt, regarding what would and what wouldn't work, it says a battery with 20-25 continuous discharge would suffice. From what I've read on this site, and others, it seems a tad bit low. Even if magic smoke would perhaps look cool and floor heating would bring the electric scooter to a new level, I'd rather keep it on the safe side.

Is it best to focus on having more or the same amount of continuous discharge rate as the controller and therefore go for a controller with a lower current limiter or is it okay to have a battery with lower continuous discharge, but can have instantaneous 40A? There aren't a lot of hills here, but it's in a city, so I would have quite a few stop lights.

Thanks in advance!

 

[amberwolf]

If you have a controller with a certain current limit, the battery has to be capable of handling that amount of current, for however much time the controller ever draws that much current.

If it's a peak limit, and will automatically reduce to some other continuous limit, that's what the battery has to be capable of.

Because batteries weaken as they age, it's safer to get one that is *more* capable in both current capability and capacity than you actually need. Cheap ones weaken faster, and ones used hard also weaken faster.

If a battery has a low current limit, it is usually because it's resistance is high, which means power is being wasted as heat inside the cells (and interconnects and wiring, but mostly cells). Wasted power, aside from the aging the cell heating will cause, means power you can't use in the system, both for watts at the wheel (because voltage drop will reduce those watts), and for range.

Somteimes it's because the BMS is just cheap, and not capable of what hte cells can handle, but someitmes it's the opposite--the cells aren't really capable of even what the low-end BMS is, and the seller options for hgiher current BMSes don't include changing the cells to match, so they're pushed harder and harder with bigger and bigger BMS...but the seller is not going to tell you about this).


Many sellers of batteries will outright lie about them; if the ad seems too good to be true, it probably is. :/ What most people consider a "reasonable price" on a battery is not sufficient to get one that will actually do the job they expect of it, or at least not for very long. The battery is normally going to be the most expensive part of the entire system, as it has to provide all of the power that the system uses--if it can't do it, the whole system fails to do the expected job.

If you link the specific parts you want to use before you buy them, we can look at them and give whatever experience / opinion we have on them, if it's useful to you.


If you go to one of the simulators like those at ebikes.ca , you can use them with your specific riding conditions, etc., to guesstimate power usage, etc., and use that to help ensure you get what's needed, but don't end up buying more than you really need.

You may find that you don't need as high a current limit on the controller, or you may find you need more, to get the acceleration, or the slope-climbing, etc that you need. (keeping in mind that it's a simulation, and because you'll have to use custom parameters to simulate your motor/controller/etc if they aren't in the existing list of simulations, reality will vary a bit from that)

 

[macmac-001]

If you have a controller with a certain current limit, the battery has to be capable of handling that amount of current, for however much time the controller ever draws that much current.

If it's a peak limit, and will automatically reduce to some other continuous limit, that's what the battery has to be capable of.

Because batteries weaken as they age, it's safer to get one that is *more* capable in both current capability and capacity than you actually need. Cheap ones weaken faster, and ones used hard also weaken faster.

If a battery has a low current limit, it is usually because it's resistance is high, which means power is being wasted as heat inside the cells (and interconnects and wiring, but mostly cells). Wasted power, aside from the aging the cell heating will cause, means power you can't use in the system, both for watts at the wheel (because voltage drop will reduce those watts), and for range.

Somteimes it's because the BMS is just cheap, and not capable of what hte cells can handle, but someitmes it's the opposite--the cells aren't really capable of even what the low-end BMS is, and the seller options for hgiher current BMSes don't include changing the cells to match, so they're pushed harder and harder with bigger and bigger BMS...but the seller is not going to tell you about this).


Many sellers of batteries will outright lie about them; if the ad seems too good to be true, it probably is. :/ What most people consider a "reasonable price" on a battery is not sufficient to get one that will actually do the job they expect of it, or at least not for very long. The battery is normally going to be the most expensive part of the entire system, as it has to provide all of the power that the system uses--if it can't do it, the whole system fails to do the expected job.

If you link the specific parts you want to use before you buy them, we can look at them and give whatever experience / opinion we have on them, if it's useful to you.


If you go to one of the simulators like those at ebikes.ca , you can use them with your specific riding conditions, etc., to guesstimate power usage, etc., and use that to help ensure you get what's needed, but don't end up buying more than you really need.

You may find that you don't need as high a current limit on the controller, or you may find you need more, to get the acceleration, or the slope-climbing, etc that you need. (keeping in mind that it's a simulation, and because you'll have to use custom parameters to simulate your motor/controller/etc if they aren't in the existing list of simulations, reality will vary a bit from that)

Good day, can I ask if it is okay to replace a battery with 20A discharge current with 10A discharge current? considering the voltage is 48v, and motor power is 1000w

 

[Haxerflaxer]

@amberwolf

The only specific parts I've looked at so far, got no link, is a motor from Lunyee. Since I've seen pictures of their motors spread across different websites I got in contact with them directly. They don't seem to be selling the wheel I'm after on their website any longer, however, after contact with them they still have some. Since they manufacture mostly motors it feels like it shouldn't be all garbage, and the reviews I've seen all seem positive. It's a 1000w nominal, 200x90 hubwheel with drumbrake. The controller the seller wants me to buy as well is a:

"Brainpower motor controller
Volts: 48v
Power: 1000w
lower volts: 42v
Current limiting: 38A
Degreebrake: low (Which I'm not all sure what it means)
Angle: 120/60
Item no. KSDPU42"

A controller which I guess is not of top quality, but could be wrong. The motor wattage and voltage should be an amp pull of 20.8, which made me start to scratch my head and think that a 38A limit is a bit too much. It also seems to be more or less impossible to find a battery that can supply more than that continuously as well without going to astronomical sums of money and or weight and size. I'm guessing a 1000w nominal motor can pull more when in hills and etc and that maybe a 25A controller would be enough and also make my search for a battery easier.

It's very flat where I am and the biggest "hill" I can think of in my surroundings is a bridge tunnel. Within the city there are a lot of traffic lights, but outside (to and from work) it's mostly just straight bicycle roads. It's roughly 9km one way, so I would like the scooter to at least be able to manage that so I can charge it at work. if it could do 20km it would be even better. I doubt I will go faster than 35km/h and would only be on the 'dead stare into the horizon'-roads, else the normal speed would most likely be around 25km/h. The weight of the scooter is still unknown, but will probably weigh a bit since it will be steel and not aluminium.

Battery wise it would be nice if it was open and not in a bicycle cartridge, since I will incorporate it into the base of the scooter.

I would love suggestions for motor controllers and batteries

 

[macmac-001]

If you have a controller with a certain current limit, the battery has to be capable of handling that amount of current, for however much time the controller ever draws that much current.

If it's a peak limit, and will automatically reduce to some other continuous limit, that's what the battery has to be capable of.

Because batteries weaken as they age, it's safer to get one that is *more* capable in both current capability and capacity than you actually need. Cheap ones weaken faster, and ones used hard also weaken faster.

If a battery has a low current limit, it is usually because it's resistance is high, which means power is being wasted as heat inside the cells (and interconnects and wiring, but mostly cells). Wasted power, aside from the aging the cell heating will cause, means power you can't use in the system, both for watts at the wheel (because voltage drop will reduce those watts), and for range.

Somteimes it's because the BMS is just cheap, and not capable of what hte cells can handle, but someitmes it's the opposite--the cells aren't really capable of even what the low-end BMS is, and the seller options for hgiher current BMSes don't include changing the cells to match, so they're pushed harder and harder with bigger and bigger BMS...but the seller is not going to tell you about this).


Many sellers of batteries will outright lie about them; if the ad seems too good to be true, it probably is. :/ What most people consider a "reasonable price" on a battery is not sufficient to get one that will actually do the job they expect of it, or at least not for very long. The battery is normally going to be the most expensive part of the entire system, as it has to provide all of the power that the system uses--if it can't do it, the whole system fails to do the expected job.

If you link the specific parts you want to use before you buy them, we can look at them and give whatever experience / opinion we have on them, if it's useful to you.


If you go to one of the simulators like those at ebikes.ca , you can use them with your specific riding conditions, etc., to guesstimate power usage, etc., and use that to help ensure you get what's needed, but don't end up buying more than you really need.

You may find that you don't need as high a current limit on the controller, or you may find you need more, to get the acceleration, or the slope-climbing, etc that you need. (keeping in mind that it's a simulation, and because you'll have to use custom parameters to simulate your motor/controller/etc if they aren't in the existing list of simulations, reality will vary a bit from that)

Does this means you cannot use a battery with 10A discharge current on a 20A rated brushless controller although they are both 48v? my motor is only 1000w, 48v. Thanks!

 

[macmac-001]

Good day, may I ask also if this battery specification can be used to replace my old battery (20A)? I cannot find the same exact power rating matching my old battery until now. my motor hub is rated 1000W, and my brushless controller is rated 20A (picture below.) all three are 48 volts. thanks! I am desperate but don't want to end up burning my device. Thanks!

 

[Haxerflaxer]

Good day, may I ask also if this battery specification can be used to replace my old battery (20A)? I cannot find the same exact power rating matching my old battery until now. my motor hub is rated 1000W, and my brushless controller is rated 20A (picture below.) all three are 48 volts. thanks! I am desperate but don't want to end up burning my device. Thanks!

If I have understood everything correctly; If the battery has same voltage and more continuous amps than what the motor controller is rated for it works fine. However, the battery specs you have sent seem to be a made up battery. 48v 60ah should have a power of 2880W, but says it has 1000W power. Fast charge with 5A with 60ah should be 12½ hours, not 2½ hours.

 

[macmac-001]

Thank you @Haxerflaxer for the answer. That's okay for me if I will wait long for the charging hours. I can breathe now that I know it will not burn my scooter.

One thing that caught my eye, the battery is 2880W, while my motor is only 1000W, will it now be a huge no-no because the battery is almost 2.9 times more power than the motor? thank you very much!

 

[Haxerflaxer]

Thank you @Haxerflaxer for the answer. That's okay for me if I will wait long for the charging hours. I can breathe now that I know it will not burn my scooter.

One thing that caught my eye, the battery is 2880W, while my motor is only 1000W, will it now be a huge no-no because the battery is almost 2.9 times more wattage than the motor? thank you very much!

No, that's the amount of power in the battery. Is this battery from amazon, aliexpress, alibaba or some chinese site? I wouldn't buy that battery since it's most likely a scam and most likely does not have any of those specs and could burn your scooter. A quick search shows that a 48v battery with a capacity of 60ah weigh around 18-20kg and cost a fortune.

 

[macmac-001]

No, that's the amount of power in the battery. Is this battery from amazon, aliexpress, alibaba or some chinese site? I wouldn't buy that battery since it's most likely a scam and most likely does not have any of those specs and could burn your scooter. A quick search shows that a 48v battery with a capacity of 60ah weigh around 18-20kg and cost a fortune.

sadly, I only saw China brands which is cheaper, and looking at the specifications seems promising, although I am just looking only for some compatible battery to keep my device going.

 

[Haxerflaxer]

sadly, I only saw China brands which is cheaper, and looking at the specifications seems promising, although I am just looking only for some compatible battery to keep my device going.

Well from forums, videos and comments all those China batteries will end poorly for you. Either that it dies, because the cells they say they are using are something else, or it destroys your scooter or it causes a fire. Should also note that a battery fire is not easy to put out, burns hot and fast and gives off toxic fumes. Sadly, there aren't any cheap batteries and you're going to have to be ready to settle for a smaller capacity battery and put in the money. The ones I have seen that are "guaranteed" to be the specs they say (of the specs I'm looking at) of a 48v 15-20ah battery cost between 280-600$. Maybe someone here on this forum knows of cheaper batteries, but what I have found is that the only way of maybe getting a cheaper one is to build one yourself, but that's also a dangerous task if you don't have electrical knowledge.

 

[Haxerflaxer]

@macmac-001, @amberwolf is more adept in this and could perhaps give you more exact answers than my speculations. I am new here as well. Would actually love if this thread could go back to my post

 

[slaphappygamer]

I’m not sure about those BrainPower controllers. I was looking at lots of them when selecting one for a scooter that I was bring back from the dead. I looked at lots of display manuals. I got a kit with the S866 display. I noticed that all of the manuals stated the max current limit is set to 22 amps. I had a 30 amp controller. I couldn’t get more than 22 amp current draw. It appears that the S866 can not be set higher than 22 amps. The other displays were noted, in the manual, has having a current limit range 0-20 amps.

 

[Haxerflaxer]

I’m not sure about those BrainPower controllers. I was looking at lots of them when selecting one for a scooter that I was bring back from the dead. I looked at lots of display manuals. I got a kit with the S866 display. I noticed that all of the manuals stated the max current limit is set to 22 amps. I had a 30 amp controller. I couldn’t get more than 22 amp current draw. It appears that the S866 can not be set higher than 22 amps. The other displays were noted, in the manual, has having a current limit range 0-20 amps.

Hm, interesting. Did you go with it or did you find another controller more suitable?

 

[docw009]

That particular battery label is mostly lies, You can't build a 39 cell 48V lithium pack with 18650 cells that exceeds 10,5AH. They claim 60AH. You can't pull 90A out of those cells either. Yo cannot charge at -20C. The cells are frozen and will ne ruined. Don't blame this on bad translation. Call it lying,

In general, a battery with 10A discharge (if that's true) is too small for a 20A controller. When over the lowest assist level, it will sag in voltage at half charge and probably shut off. There are exceptions, but most battery specs are optimistic, If they say 10A, you likely don't have a 20A in disguise.

 

[slaphappygamer]

Hm, interesting. Did you go with it or did you find another controller more suitable?

The battery I had has a 30 amp continuous bms, so I stuck with the 22 amp limit. I was thinking about getting a KT controller l/display combo for that scooter, but I’m parting it out. I got a better scooter to replace it.

 

[Chalo]

That particular battery label is mostly lies, You can't build a 39 cell 48V lithium pack with 18650 cells that exceeds 10,5AH. They claim 60AH.

Customary (and misleading) capacity rating by Chinese sellers of cheap crappy battery packs is to claim the sum total Ah of all the cells in the pack. So 60Ah ÷ 39 cells = about 1500mAh, which is most likely the cells' nominal rating.

It makes no logical sense doing it the way they do, but it results in larger numbers-- the better to sell to people who don't know anything whatsoever, but know they "need" hydraulic disc brakes and fat tires.

 

[Haxerflaxer]

The battery I had has a 30 amp continuous bms, so I stuck with the 22 amp limit. I was thinking about getting a KT controller l/display combo for that scooter, but I’m parting it out. I got a better scooter to replace it.

I see. Well, I guess I'll skip on that controller and look into KT controllers. Got any good recommendations for batteries with 25-30 continuous discharge? As soon as I start searching for those specs I just find the fishy ones that most likely end in a fire.

 

[slaphappygamer]

I don’t have any battery recommendations, but as Chalo pointed out, doing the math while choosing a battery pack will quickly help you weed out the worst ones. Math doesn’t lie.

The battery I got was a Hailong 36v 20ah from Amazon. Some will say it’s garbage. Maybe it is. I haven’t had enough battery packs to know EXACTLY to expect from a particular cell arrangement, but It worked fine for my recreational scooter. I traveled maybe 1000 feet a day a couple of times a week. It didn’t have awful battery sag or run out of capacity quick. It didn’t get hot while charging. I did toss the charger because it only had 2 prong AC cord and would spark when I plugged it. I didn’t like that. I opted for a 3 prong AC plug and charger with an aluminum housing. Even a little fan too. Some will say that the charger I got is trash and don’t ever get one with a fan. The fan is nice, because when it stops, I’ll check the charger and see if it’s crapped out or just finished charging. It always finished charging.

Aside from math checking the cells, you’ll want to dig into what BMS the pack has. It’s continuous and max amp ratings. Also, cell balancing. Some packs don’t offer that due to BMS limitations (lack of the feature).

 

[slaphappygamer]

Also, the KT controllers. Some are listed as “not for e-scooter “. I think that is because the KT controller doesn’t have reverse or alarm connections. Also scooters typically don’t have a PAS sensor. Maybe there are other reasons, but I would go that route.

 

[Haxerflaxer]

I don’t have any battery recommendations, but as Chalo pointed out, doing the math while choosing a battery pack will quickly help you weed out the worst ones. Math doesn’t lie.

The battery I got was a Hailong 36v 20ah from Amazon. Some will say it’s garbage. Maybe it is. I haven’t had enough battery packs to know EXACTLY to expect from a particular cell arrangement, but It worked fine for my recreational scooter. I traveled maybe 1000 feet a day a couple of times a week. It didn’t have awful battery sag or run out of capacity quick. It didn’t get hot while charging. I did toss the charger because it only had 2 prong AC cord and would spark when I plugged it. I didn’t like that. I opted for a 3 prong AC plug and charger with an aluminum housing. Even a little fan too. Some will say that the charger I got is trash and don’t ever get one with a fan. The fan is nice, because when it stops, I’ll check the charger and see if it’s crapped out or just finished charging. It always finished charging.

Aside from math checking the cells, you’ll want to dig into what BMS the pack has. It’s continuous and max amp ratings. Also, cell balancing. Some packs don’t offer that due to BMS limitations (lack of the feature).

I have quite a bit further I'd like to travel, and every day more or less. I saw some polish company advertising on this forum making battery packs. Price wise they seem to cost like an extra 50 euros from some of batteries you see on pwpower or what the site is called. Thinking of going that route and get a battery pack I know will work from the get go. Searching and going through all specs takes time too. Yeah, started reading up on different BMS's, but that feels like an even deeper jungle

Thanks for the warning regarding the controller

 

[DaLanMan]

Sitting on my desk right now is a battery I was asked to look at, with I kid you not "We got it off aliexpress for like 50 bucks, we knew it was gonna be sad and lame, but it doesn't even want to stay on the charger"

It is listed as a 100AH battery pack, 36v, which I can easily lift with one hand...

It is however Sanyo cels and it is 3p... tight lil unit and is WAYYY better than I expected. The issue they were having is I told them to buy the good charger. They did, and plug it in after a hour or so riding and it only charges for a few hours, not like the old one (lead acid 3x) which took something along the lines of 800 Bajillion years.

I need to find who is making these.. I am putting a real BMS on it for them, because this one is uhm.. I have no idea, my foreign language skills requires I have something to look up.

 

[amberwolf]

Good day, can I ask if it is okay to replace a battery with 20A discharge current with 10A discharge current? considering the voltage is 48v, and motor power is 1000w

My previous post, which you quoted, already answered this.

 

[Haxerflaxer]

Sitting on my desk right now is a battery I was asked to look at, with I kid you not "We got it off aliexpress for like 50 bucks, we knew it was gonna be sad and lame, but it doesn't even want to stay on the charger"

It is listed as a 100AH battery pack, 36v, which I can easily lift with one hand...

It is however Sanyo cels and it is 3p... tight lil unit and is WAYYY better than I expected. The issue they were having is I told them to buy the good charger. They did, and plug it in after a hour or so riding and it only charges for a few hours, not like the old one (lead acid 3x) which took something along the lines of 800 Bajillion years.

I need to find who is making these.. I am putting a real BMS on it for them, because this one is uhm.. I have no idea, my foreign language skills requires I have something to look up.

That's quite interesting. If you find who makes them please share, might be a good bargain. Slap on a new BMS and get a separate charger.