Will a 250w 24v controller run a 120w 24v motor

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Aug 3, 2019
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As above

Do I have to match my controller or is it okay to over rate the controller for further upgrades?

Tia

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Run it? sure, if they're both the same kind (brushed vs brushless)

But you'll be putting more than twice the power thru the motor than it was designed for, so it may not last as long as it would have with the right controller, especially if it's under higher loads a lot. It'll get more than twice as hot as it should.
 
Thanks for the reply. What about running through a 7a breaker on a 24v system?

I kinda thought that the controller rating was based on the max amp vs the voltage of the device?

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Geneticallymodified said:
Thanks for the reply. What about running through a 7a breaker on a 24v system?
A DC rated breaker? That should protect the thing OK. However, breakers are for control and protection from shorts - not for protection against thermal overloads.
 
billvon said:
Geneticallymodified said:
Thanks for the reply. What about running through a 7a breaker on a 24v system?
A DC rated breaker? That should protect the thing OK. However, breakers are for control and protection from shorts - not for protection against thermal overloads.
Yeah DC from another 24v scooter. Do you think the breaker will kick in when throttling at max? Or just just under extreme load

In my thinking the 7a would kick in if peak draw exceeds 168w. But the question is really; will the control try push more than this through the motor when fully open

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Geneticallymodified said:
Yeah DC from another 24v scooter. Do you think the breaker will kick in when throttling at max? Or just just under extreme load.
The breaker will trip when its rating is significantly exceeded.
However, it is important to point out that a breaker will NOT protect you from overheating.
 
billvon said:
Geneticallymodified said:
Yeah DC from another 24v scooter. Do you think the breaker will kick in when throttling at max? Or just just under extreme load.
The breaker will trip when its rating is significantly exceeded.
However, it is important to point out that a breaker will NOT protect you from overheating.
Right, but the load shouldnt run the system too hot if kept under 7a max draw?

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Unless your controller has a 7A current limit, there's nothing in the system to keep it under 7A.

The breaker won't do that. The breaker will just cut power entirely after enough overcurrent has flowed thru it long enough to heat it up enough to trip. You'd have to look up the breaker's specs based on whatever's printed on it to see how much and how long that is. It could be as much as 15-20A for a minute or two, or as little as 8-10A for 20-30 seconds, you won't know unless you look it up and / or test it with measuring equipment on the bench.

It's possible, even likely, that you could easily put enough current thru the motor long enough to cook it before the breaker pops.

If you have a current meter on the system, where you can watch it all the time you're riding (can easily be dangerous to do so, though), then everytime you see the current go over 7A, you can let off throttle till it stays below that. But you wont' have your eyes on the road, and you're either going to have a problem because of that, or you're going to have your eyes on the road and not on the meter, and end up pushing it overcurrent enough for long enough to overheat things.

The controller would do this automaticlaly for you if it has a current limit appropriate for that motor at that voltage.

If you never (or seldom) put much of a load on the system, it won't draw enough current to cause overheating...but what would be the fun in that? ;)
 
amberwolf said:
Unless your controller has a 7A current limit, there's nothing in the system to keep it under 7A.

The breaker won't do that. The breaker will just cut power entirely after enough overcurrent has flowed thru it long enough to heat it up enough to trip. You'd have to look up the breaker's specs based on whatever's printed on it to see how much and how long that is. It could be as much as 15-20A for a minute or two, or as little as 8-10A for 20-30 seconds, you won't know unless you look it up and / or test it with measuring equipment on the bench.

It's possible, even likely, that you could easily put enough current thru the motor long enough to cook it before the breaker pops.

If you have a current meter on the system, where you can watch it all the time you're riding (can easily be dangerous to do so, though), then everytime you see the current go over 7A, you can let off throttle till it stays below that. But you wont' have your eyes on the road, and you're either going to have a problem because of that, or you're going to have your eyes on the road and not on the meter, and end up pushing it overcurrent enough for long enough to overheat things.

The controller would do this automaticlaly for you if it has a current limit appropriate for that motor at that voltage.

If you never (or seldom) put much of a load on the system, it won't draw enough current to cause overheating...but what would be the fun in that? ;)
Awesome. Thanks very much for taking the time

I think the plan will be evolving quickly, as I'm kinda looking towards making some kind of touring style scooter [emoji1696][emoji1696] just gonna be alot of money in batteries it looks like [emoji28] but once I've got a finished plan (atm 36v 250w chain drive for the rx, which means some minor upgrades), then I can start sinking some money into batteries and maybe building them instead if all goes well (10s3p or 10s4p [emoji2369])

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Touring scooter?

I think before you go any further, you should describe exactly what you want the scooter to do.

How fast does it have to go?

How far does ti have to go?

How quickly does it have to accelerate to what speed?

WHat kind of terrain will it be used on? (hills, etc)

What kind of weather (winds primarily) will it be used in?

What is the total weight of you and the system expected to be?

Any and all other details may be important to figure out what will be required to do what you want it to do.


I suspect that what you're trying to build won't do it....
 
amberwolf said:
Touring scooter?

I think before you go any further, you should describe exactly what you want the scooter to do.

How fast does it have to go?

How far does ti have to go?

How quickly does it have to accelerate to what speed?

WHat kind of terrain will it be used on? (hills, etc)

What kind of weather (winds primarily) will it be used in?

What is the total weight of you and the system expected to be?

Any and all other details may be important to figure out what will be required to do what you want it to do.


I suspect that what you're trying to build won't do it....

Rightio. The plan is for 2 long ish range (maybe 10-20miles per battery pack) but as long range as possible (using multiple battery packs) low ish watt scooter. For myself and my daughter

Fast is really not important, ideally 15.5 mph will be more than enough for us I believe. But a good firm torque as hills are more than likely but again it doesnt need to be fast. Long term I would hope to attach a lightweight trailer to both so again high torque is more important

Weather, will be most weather conditions up to light rain.

So I was going to mod a razor rx200 for the daughter as she can already ride it comfortably but it does pull abit as it's still standard throttle (planning to change it to 250w 36v variable speed) and something like a viron 36v 800w (or something like that). Both 36v so we can share battery packs

I weigh about 65kg without a back pack. And the daughter cant be more than 25-30.kg max

So yeah ideally there will be paths and tracks on our adventures but planning for some dirt tracks and stuff a little off road ability will be good

Over all weight I need the daughters scooter to be lighter than mine. Like maybe 12-15kg max for the rx200 and the larger, maybe 20-40kg total laden weight?

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Geneticallymodified said:
The plan is for 2 long ish range (maybe 10-20miles per battery pack) but as long range as possible
At a guess, it's going to take around 10wh/mile or maybe less, to go on flat ground, no headwinds, etc, at up to 15mph or so. So not a huge battery pack to do that, perhaps 300wh (46v8Ah) (to allow for pack aging, occasional headwinds, etc) to get you 20 miles on that. 200wh (36v5Ah) would be right on the edge of the ability.

But...it'll have to be bigger to handle more power like for hills, etc. and still get the same range.

If you're thinking multiple packs, perhaps carried in the trailer when not in use, that may work, but it can be easier on the packs to simply have bigger ones or parallel smaller ones.

Fast is really not important, ideally 15.5 mph will be more than enough for us I believe. But a good firm torque as hills are more than likely but again it doesnt need to be fast. Long term I would hope to attach a lightweight trailer to both so again high torque is more important
I don't think the 120w motor will survive that on a scooter, especially upped to 250w+. On a bicycle where you're doing half the work or more pedalling, and it's just helping you some, it might.

Depending on the hills, and the weight, you're probably going to need up to several times that power, since the motor must do *all* the work.

You'd also want to be sure it's geared to the right speed, so it isn't running at a high load at a low motor speed. If you have to crawl up the hills vs the speed it's geared for, the motor will overheat.

If you didn't need hill climbing power, you could get away with less power (possibly a lot less). You'd have to walk the scooters up hills so they don't overheat, in this case.

You'd just need enough power to keep you at 15.5mph with no winds. (if you need to keep moving against headwinds, then you need however much more power it takes to go as fast as your speed plus the headwind speed).
Weather, will be most weather conditions up to light rain.
Pretty easy to weatherproof stuff for then. Keep in mind that the wheels will splash stuff up and any gaps or cracks will let water in, so you'll want to seal what you can against that, and maybe put drain holes in the lowest corners of the battery box, etc, to let the water that does get in drain out.


So I was going to mod a razor rx200 for the daughter as she can already ride it comfortably but it does pull abit as it's still standard throttle (planning to change it to 250w 36v variable speed) and something like a viron 36v 800w (or something like that). Both 36v so we can share battery packs

I weigh about 65kg without a back pack. And the daughter cant be more than 25-30.kg max


Over all weight I need the daughters scooter to be lighter than mine. Like maybe 12-15kg max for the rx200 and the larger, maybe 20-40kg total laden weight?
At a guess, a scooter that will do what you want with batteries for the range you want may be 25kg or more, depending on the kind of batteries you use and the size of motor you end up having to use. Her battery can be smaller (or the same size pack would last longer), since she weighs less, so her scooter will weigh less with less batteries in it.

Trailer...would guess 10-20kg for a trailer, depending on type; then whatever you're going to carry in it on top of that.

You want to at least guesstimate your total weights that each motor has to push, to get an idea how much power it will take to push that up a particular hill (slope) at a fast enough speed to not be damaging to the motor under that load.

The power you have to be able to use determines the controller and motor, and also the batteyr size, not only for it's capacity and range, but for the battery's ability to provide that power without much voltage sag or heating.

So yeah ideally there will be paths and tracks on our adventures but planning for some dirt tracks and stuff a little off road ability will be good
That's probably going to take yet more power, because you'll likely want fatter knobby tires for that, and they dont' roll as well on the street. Depends on the specific conditions you have to go thru, you might be able to use the regular tires. I'd recommend trying out what you've got on the conditions you expect to encounter and see how well it handles it. If it can't (tires sinking into the surface, bogging down, etc), that's when you have to decide if you can just skip those conditions or if you have to build specifically for them.
 
yeah i think im going to have to start a new thread to save confusion lol

so the RX200 has 200w at 24v which i will up to around 250-300w at 36v and a second scooter for myself at 36v and 500-800w?

The idea of stick with 36v is so that the battery packs dont have to be specific to either scooter. Im already looking into building custom 18650 packs. The kinda pack i was looking to build would be 10s3p of 10s4p depending on what capacity max drain cells i can find at a good price. the batteries ill be aiming for between 36v9ah and 36v11ah

trailer im thinking the lighter the better, even just cutting up a couple old sack trollies to save weight. 100% the extra packs will be in the trailers mainly. ive also got some 3 stage DC rocker switched so i will make one internal battery per scooter but have one external which can be changed without too much hassle i hope

yes the RX200 already has off road knobbly tyres and ill be looking for similar on the adults scooter also

thanks again for all the infor and help bud
 
Just realised you said laden weight of the trailer. So yes probably 10-20kg

So the smaller scooter will be carrying 25kg ish of child and roughly 5kg of batteries on the scooter and a trailer with approx 15kg, say 20kg as better to over estimate usually. So say 50-60kg payload

The larger will have 65kg rider, 5kg batteries and likely a slightly heavier trailer, say 30kg at an over estimate. So say total payload roughly 100kg

Can I assume that working with chain drive is going to be simpler than hub motors? Especially if gearing is going to be playing a major part?

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Uisng a chain drive allows you to use the ratio that gets the optimum speed of motor vs wheel, so yes, easier than hubmotors for that.

To find out what the weight means vs the power you need, you can use any of the various power-vs-hill calculators or simulators out there.

Whatver trailer you use, pick the largest diameter wheels you can, as it will ride better and bounce less and have less drag on the scooter(s). Then put their axles as high on the trailer as you can, so that as much of the trailer's load as possible is below the axles, so it is more stable, and less likely to tip over under any conditions.
 
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