max safe limit when overvolting/amping a 48v 1000w brushless gearless hub?
- Thread starter jimmyhackers
- Start date
thanks for the info.
i have a few ideas bubbling in my head. your probably right i will end up wanting more. acceleration is fine but i would like a bit more top speed right now.
i still havn't gotten an estimate for a new top speed running at 60v
35- 40mph? what do you think? possible on 60v?
im tempted by my other idea for a 60v boost button, the more i think about it the better it gets.
itd have a two stage power curve (hope that make sense)
so id be able to negate the low rpm causing heat issue by initially running at 48v and then switching to 60v when im going fast enough or when im desperately in need of a bit more umpff.
thanks again for the help/info
jim
i have a few ideas bubbling in my head. your probably right i will end up wanting more. acceleration is fine but i would like a bit more top speed right now.
i still havn't gotten an estimate for a new top speed running at 60v
35- 40mph? what do you think? possible on 60v?
im tempted by my other idea for a 60v boost button, the more i think about it the better it gets.
itd have a two stage power curve (hope that make sense)
so id be able to negate the low rpm causing heat issue by initially running at 48v and then switching to 60v when im going fast enough or when im desperately in need of a bit more umpff.
thanks again for the help/info
jim
Maybe 35mph, you could so a simulation of your set up Here but is hard to be exact as you don't the the exact specs of your motor and controller?
If you want to stick with your LA pack then just pick up another 12v plug it in and see.
It doesn't quite work like that; More volts are not the problem for heat, more amps are
You may be better installing a 3 speed switch, if your controller has a connector for one?
It sounds like your best option, would be to actually buy one of these controllers. along with the plug and play 3speed/cruise throttle and programming cable. The phase/hall connections should be the same as your motor. Or the 12 Fet version?
All the options that you require will easily implemented and it will be future proof, if you decide that you want even more volts or amps.
Get you head around the programming software and you can have full control over your 3 speed power levels and many other things.
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Indeed, I'm eighty next year, lungs fine, heart fine and although from some mild easily controlled blood pressure rise, much fitter than many 10 to 20 years younger. And I eat butter, salt, red meat and all the other things that were supposed to have killed me years ago! I don't drink alcohol though.Just stumbled across this flecc,
"77th year and after smoking and inhaling at least 700,000 cigarettes"
Doing well I'd say
I have an ambition to reach 92 years old, since that would mean I'd had 38 working years and 38 retirement years. If I make it I'll write a letter to the prime minister and pensions secretary of the day to inform them of that just to depress them. ( I hate politicians).
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Use this calculator for speed.thanks for the info.
i have a few ideas bubbling in my head. your probably right i will end up wanting more. acceleration is fine but i would like a bit more top speed right now.
i still havn't gotten an estimate for a new top speed running at 60v
35- 40mph? what do you think? possible on 60v?
im tempted by my other idea for a 60v boost button, the more i think about it the better it gets.
itd have a two stage power curve (hope that make sense)
so id be able to negate the low rpm causing heat issue by initially running at 48v and then switching to 60v when im going fast enough or when im desperately in need of a bit more umpff.
thanks again for the help/info
jim
http://www.hembrow.eu/personal/kreuzotter/espeed.htm
2kw gives 60 to 90 kph depending on bike and position.
But road surface has a considerable effect at these speed and power levels.
It very much depends upon motor winding as well.
You're unlikely to be able to pedal at speed unless you change your gearing.
Your motor is probably closest to the 9 continents range in the simulator.
So at 60V with your standard 25a controller you only actually have a 1500w input (not power output, this will be less)
At these levels
The fastest winding 9c motor (2806) has a top speed of 31.2 mph
The slowest winding (2808) has a top speed of 27.2 mph
You're unlikely to be able to pedal at speed unless you change your gearing.
Your motor is probably closest to the 9 continents range in the simulator.
So at 60V with your standard 25a controller you only actually have a 1500w input (not power output, this will be less)
At these levels
The fastest winding 9c motor (2806) has a top speed of 31.2 mph
The slowest winding (2808) has a top speed of 27.2 mph
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5mph = 22w
10mph = 68w
15mph = 163w
20mph = 333w
25mph = 601w
30mph = 993w
35mph = 1532w
40mph = 2247w
45mph = 3147w
50mph = 4280w
10mph = 68w
15mph = 163w
20mph = 333w
25mph = 601w
30mph = 993w
35mph = 1532w
40mph = 2247w
45mph = 3147w
50mph = 4280w
Interesting thing about the above figures, is that 1000w will get you to 30mph but it takes another 900 to get from 40 to 45mph.
Yes, the exponential nature of resistance with speed.
It's sobering to reflect that the human powered speed championship record on the flat at Battle Mountain in the USA is about 83 mph on a streamlined recumbent. The pedalled power input over the timed stretch is probably far below 1000 watts, some of the record holders being by no means exclusively race cyclists, designer Sam Whittingham being a good example.
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source: http://en.wikipedia.org/wiki/Drag_(physics)
The required power is proportional to the cube of the speed as per this formula:
Yes that is! My working span was from 14 to 54 when I retired, but I took two whole years out on sabbaticals during that 40 years. From the age of 16 I'd been determined to retire early.
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I see that none of the established pedelec "experts" (if I may respectfully call them that) have come in on this thread.
One area you may be mixing up is the difference between the power drawn from the battery and the power available at the rear wheel. Quite a lot is lost in iefficiency, friction and heat.
One area you may be mixing up is the difference between the power drawn from the battery and the power available at the rear wheel. Quite a lot is lost in iefficiency, friction and heat.
Hi averhamdave, Not sure if that's directed at me, if so read my previous posts.
Regarding
I'm trying to offer advice on a thread for over volting a motor. This I have done many times so thought the info may be helpfull to some. If the info that I have posted is wrong in any way then I'd love a Pedelecs expert to point this out, this is how we all learn, including myself.
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I just realised that you are the one saying things like
Which makes me think that you don't know what you are talking about.
D
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Aĺ the figures mentioned look about right to me, but they have to be based on assumptions since OP hasn't mentioned the actual winding speed of his motor and the current from his controller. If the bike can do 30 mph as it is, then it would be reasonable to predict that it'll go a bit faster with 60v, which would give it 25% more power. Personally, I think that the estimate of the present 30 mph is a bit optimistic. Not that it matters because we only need it for comparison.
One thing we can say is that for sustained speeds of over 30 mph, the battery will go down very fast, and I hope OP has good brakes and tyres. I seem to remember a song about a machine that an engineer made, for which there was no way of stopping it. The point I'm trying to make is that you have to upgrade the whole bike if you want to go fast. I found that I lost adhesion many times when I tried a bike that could go over 25 mph, and that was with a relatively light battery and motor.
One thing we can say is that for sustained speeds of over 30 mph, the battery will go down very fast, and I hope OP has good brakes and tyres. I seem to remember a song about a machine that an engineer made, for which there was no way of stopping it. The point I'm trying to make is that you have to upgrade the whole bike if you want to go fast. I found that I lost adhesion many times when I tried a bike that could go over 25 mph, and that was with a relatively light battery and motor.
ooooo its getting a bit heated, calm down chaps
is counting the windings a case of disassemble and count? the motor has no markings on it and the seller is nigh on useless as a regards to further information :S how usefull would this be in knowing the limit of my motor?
not sure how to tell what amps im actually drawing without an ammeter and a shunt. is there another way?
i have a multimeter so i can check voltages.
only real world figures i have are the 48v (really 54v in sla) and the 32mph flat and 35mph downhill speeds.
the guessed/assumed figures are the 1000w for the controller and subsequently its amp draw.
which gives me an estimate somewhere between 20 - 25 amps draw
my speed is from a bike speedometer and is pretty accurate so the 32 and 35mph figures are real world and not "optimistic" so
dont worry i have good brakes and tyres.
another thing people seem to worry about is my range.... im getting about an hours ride (25miles or so uphill downhill and flats) out of each charge and the battery still shows 2 bars out of the three (bike meter) or a good 52ish volts (mulitimeter) after im done.
this range either mean one of two things. my batteries can output 20ah or im taking a lot less than 20ish amps on avergage
is counting the windings a case of disassemble and count? the motor has no markings on it and the seller is nigh on useless as a regards to further information :S how usefull would this be in knowing the limit of my motor?
not sure how to tell what amps im actually drawing without an ammeter and a shunt. is there another way?
i have a multimeter so i can check voltages.
only real world figures i have are the 48v (really 54v in sla) and the 32mph flat and 35mph downhill speeds.
the guessed/assumed figures are the 1000w for the controller and subsequently its amp draw.
which gives me an estimate somewhere between 20 - 25 amps draw
my speed is from a bike speedometer and is pretty accurate so the 32 and 35mph figures are real world and not "optimistic" so
dont worry i have good brakes and tyres.
another thing people seem to worry about is my range.... im getting about an hours ride (25miles or so uphill downhill and flats) out of each charge and the battery still shows 2 bars out of the three (bike meter) or a good 52ish volts (mulitimeter) after im done.
this range either mean one of two things. my batteries can output 20ah or im taking a lot less than 20ish amps on avergage
I am calm,i am calm
I linked you to a plug and play amp meter in a previous post.
You wont be using 20 amps all the time. More at start off, then the volts will kick in.
Btw what bike is it going on?
Not very with your set up, there's not much you can do about it without buying a new motor, so maybe learn about it in the future once up and running. Your motor will take it at the levels you intend. may have to mod it if wanting to go higher.
I linked you to a plug and play amp meter in a previous post.
You wont be using 20 amps all the time. More at start off, then the volts will kick in.
Btw what bike is it going on?
jimmy, you use the bike at pretty much what the motor is meant to do. The only drawback with your present kit is the weight of the SLAs. I think you pull on average close to 18A-20A when riding at 25-30mph. Your motor is very efficient at that sort of speed. Adding another 12V SLA may kill the controller not counting the time you'd spend charging them.
The obvious improvement is as someone has already said, is to save up and get a 48V 20AH LiFePO4 battery. You'll get a nicer bike to ride, nice range, simple charging, consistent performance but not necessarily faster.
I reckon at present, your kit costs £200 + £30 for the battery. A record by itself.
The obvious improvement is as someone has already said, is to save up and get a 48V 20AH LiFePO4 battery. You'll get a nicer bike to ride, nice range, simple charging, consistent performance but not necessarily faster.
I reckon at present, your kit costs £200 + £30 for the battery. A record by itself.