This is perhaps one of the most often asked questions I get from people looking to build or buy their first ebike. There are many different electric bicycle power ratings out there which can be confusing to a beginner.
250 watt, 500 watt, 1,000 watt, 36V, 48V….. what does it all mean?!
Well the first thing to know is that not all electric bicycles are created equally. Even two ebikes that both claim to be the same power or ‘wattage’ level can actually be fairly different ‘under the hood’. I’ve written specifically about the myth of the ebike wattage, but I’ll cover it briefly here.
Generally speaking, the higher the wattage, the higher your electric bicycle power will be. However, many ebikes are labeled differently than their actual power level, whether it be for marketing gimmicks, to sneak higher powered ebikes past laws and regulations, or a whole host of other reasons. You’ll want to check with the manufacturer to determine the actual wattage of an electric bicycle, which will come down to two numbers: the voltage of the battery multiplied by the peak current limit (in amps) of the controller.
A common electric bicycle setup is a 36V (volt) battery and a 15A (amp) controller. Wattage is just voltage multiplied by current, so 36 volts x 15 amps = 540 watts. In this case, we are looking at an ebike of approximately 500 watts. Do the math just like this on any electric bicycle to determine just how much power that specific ebike is capable of delivering.
But how much electric bicycle power is necessary?
How much ebike power do you actually need? The answer will mostly depend on two factors: your weight and whether you will be riding up many decent-sized hills. The heavier you are, the more power you need to accelerate the ebike. The steeper and longer the hill you are trying to climb, the more power you need to get up the hill.
My wife, for example, is quite comfortable on her 24V, 250 watt ebike. This is a very low powered electric bicycle, but she only weighs about 110 lbs (50 kg) and we live in a flat city, so she doesn’t have to worry about hills. If we lived in a hilly area, she’d likely need closer to 350-400 watts of power, which could better be achieved by an ebike with a 36V battery. An electric bicycle with a 36V battery and 12A controller would output a peak power of 432 watts (36V x 12A = 432W) which would be plenty to scoot her up a decent sized hill.
I weigh about 150 lbs (68 kg) and my wife’s 250 watt electric bicycle feels a bit sluggish to me. A 500 watt ebike, such as an ebike with a 36V battery and 15A controller would be about the minimum comfortable level for me, assuming I’m on flat ground.
Of course, I enjoy a sportier, faster accelerating ebike so I ride an ebike with a 48V battery and 20A controller, giving me about 1,000 watts of power to my direct drive hub motor. That’s more than I need at my weight in a flat city, but if I lived in a really hilly city, that would be a quite appropriate power level. As it stands, in my flat terrain city, 1,000W leaves me some wiggle room for strong accelerations and occasionally towing a bicycle trailer, though I generally don’t use anywhere near 1,000W for my daily driving needs.
Power requirements go up quickly for folks weighing over 220 lbs (100 kg). In a flat area, a 750 watt ebike should be plenty, though acceleration will be notably slower. In a hilly area, a 1,000 watt ebike would be the minimum. Heavy riders climbing serious hills might even have to push past a 20A controller to 25A or 30A combined with a 48V battery to get 1250-1500 watts of power, depending on the specifics of their weight and terrain. Once you start getting above a 1,000W electric bicycle, over heating issues can start to come into play on especially long uphill rides.
The best way to know for sure what electric bicycle power level you need is to do a test ride on a few ebikes of different power levels and determine what feels best. On flat ground an underpowered ebike won’t really be too much of an issue; it will simply result in sluggish performance. Trying to ride an underpowered ebike up a steep hill, especially with a heavy rider, can risk causing damage to the ebike by burning out the motor or connectors. If you feel like your power is disappearing as you ride up a hill, that’s a sign the ebike is working too hard you need a higher power setup.
Lastly, think about cargo. A loaded backpack shouldn’t be an issue, but if you want to carry child seats or pull a trailer, consider bumping up to the next higher power level to ensure you have the power you need when it counts. I personally like to err on the higher power ebike side. If you don’t use the extra power all the time, that’s fine of course. But when you really need it, you’ll be happy that extra power is there.
Yea, you’re going to need more than 250 watts…
Greetings Micah, I’m building a trike with a 48 volt 1000 watt front hub and will use a 48 volt 15 or 20 ah lithium battery. My hope is to be able to put my wife on the back and take her for a whirl. The total weight including bodies, bike, battery and all gear will be around 400lbs. My question is whether you think this is an appropriate setup for what I’m trying to do. 90% of the time it would be just myself at around 170 lbs. minus trike and gear. I have an option of upgrading to a 1500 watt or higher rated hub but cost wise things are getting pretty crazy. I sincerely appreciate your time and thoughts helping me/all of us, understand these things.
Thank you! christiian Ps I’m using a high end fat tire hub with a really nice street tire for this build, can’t wait!
I’m back! Hi again Micah, So now I have a bigger question and really hoping I might hear back from you. I got a great deal on two Vpower lithium ion 48 volt 10 ah battery packs and need to know once inside, where to make the parallel connections to get the increases I’m hoping for. The only other question would be how to charge…to disonnect and charge separately, they each come with 6amp chargers, or charge them in parallel. I would be happy to to make a donation towards the sites maintenance or a few cups of java for you if there’s any way to do that, please let me know…I would be honored! Shalom!
Hi Jc,
You could parallel them by removing the BMS from one battery and connecting each parallel group of cells in parallel. For example, if they are lithium-ion packs, you’ll probably have 13 parallel groups in each battery. You’ll want to make 13 connections, one between each group. But you remove one BMS as the new larger pack only requires a single BMS.
Alternatively, you could simply connect the discharge wires in parallel when you want to use them together, and then disconnect them for charging separately. If you go that way, just make sure you never plug them in parallel when they are at different states of charge. A good method would be to only parallel them when they are both full.
Perfect! The alternative method seems to be the easier way to go but just want to be clear, the packs stay in tact with their individual BMS’s, right, and creating a 48 volt 20 ah power sorce? I appreciate the heads up regarding seprate charging and the importance an equal, “full” charge. Thank you Micah, you bless us all with your kindness and knowledge. {~`Jc
Ps I’ve been writing from a small tablet and will lend support when I get home this weekend and back to my iMac by buying a copy of your electric bicycle ebook. Blessings!
It can likely work, but the performance might not be what you’d hope. The problem is there is very little weight on the front of a trike, and when you add more gear/passengers to the back, this imbalance gets even worse. Imagine a pickup truck with front wheel drive and the bed with a full load of rocks. You’ll have serious traction issues with a full load. And with that high level of power, you’ll really need to feather the throttle to keep from doing burnouts every time you start driving. Lastly, most trike forks aren’t meant to handle that much power, so you’ll want to use a beefy torque arm, likely on both sides of the axle.
dear Micah
I have selected e-bike as my final year college project and we are producing it for a person who weigh 50 kg and have target to achieve max. speed of 18km/hr.
But i’m having confusion regarding the” motor power and battery voltage”.
will you please suggest me to use the right accessories for the project.
I’m having the project cost of the ”US $200 and I’m using dry lead acid batteries” as the power source.
$200 is on the low end of what is possible. If this is just a proof of concept, finding some used batteries and building a custom friction drive using an old DC motor will likely be a good option. Look up “friction drive ebike” and you’ll find many examples.
Any ready-to-go ebike kit is going to break your $200 budget, so you’re left with building something custom.
Hi micah
First tnx for your useful website
can i ask you how much energy can produce an e bike with generator?
I’m not sure I understand the question. If you run a generator off of an ebike, you’ll probably end up getting back around 75% of the energy that was stored in the battery, after efficiency losses. The second law of thermodynamics is a cruel mistress…
Hi Micah,
Greetings from New Zealand. Loved your website and every bit of it very informative and useful.
I am converting my son’s mini quad bike (40cc) to electric at the moment.
I am planning to add a 36v brushed DC motor with 1000w. He is around 40 kg 8 years old. But i would like him to use it until he is 12 years old up to 60kg.
I am adding 3 x 12v 7.2Ah/ 20hr SLA batteries (cheap option) and a charger 36v with 12amp charging current.
I would like to have your advice if anything wrong with my project ? any recommendations are much appreciated !
I don’t understand what you mean by 7.2AH/20hr batteries. Are they 7.2AH or 20AH? 7.2AH isn’t much, especially for SLA’s where you shouldn’t really discharge them more than 50% if you want long life out of them.
Other than that it seems like a good plan. Brushed motors and SLA is old school, but it’s worked for decades.
Please be safe though…where I live you have to be 16 to ride an electric bicycle…
Thanks for the response.
The battery pack will have 3x sla batteries. Each are 12v – 7.2 amp.
The 2ohrs as per the manufacturer that need charging 20 hrs to get 7.2amp. Link below. So i assume 7.2amp × 3 = 21.6 amps total ?
https://www.jaycar.co.nz/12v-7-2ah-sla-battery/p/SB2486
I know old skool but not keen to spend alot on his project so far ( on a budget ).
He is going to use off road in the farm with protective gear. So he should be fine.
Still need your advice about the charger please. It will be 36v charger 12amp.
Hi Micha, first of all thanks for sharing e-bike ideas through your great website!!
I am planning to mount an electric kit (like the 8fun mid drive) on my mtb in order to go to work on bike more often. In my case it is 35km one way consisting of a mix 1/3 kinda hilly gravel roads and 2/3 bike lane. I wonder about my power requirements, yet being a newbie I am still a bit confused about the figures in this discussion, since it is not always clear if they are pertinent to “pure throttle mode” or to “pedal assist mode”. I am mostly interested in the latter.
For instance in your response to Carlos W you say “A 100kg total (bike and rider) setup with a 250W motor and 36V battery would get 20 km/h on a 5% grade, but only 7 km/h on a 10% grade. On the 5% grade, the motor would overheat in 6.5 minutes, and on the 10% grade the motor would overheat in 1.4 minutes!”. I take the overheating figures are meant without pedal assist, so how would this scale with pedal assist? Any comment welcome.
Cheers, Kris
Hey Kris,
Those figures are all assuming 100% throttle and zero pedal assist. It’s hard calculate exact figures when using pedal assist because everyone pedals at different power levels… If you assume you’re doing half the work of the motor then you’d effectively double your range, but who knows exactly how much work you’re actually doing? Unless you’re a really serious pedaler, I’d assume you’re not going to be doing more than 1/3 of the work, which would be a good basis to start from. You can head on over to the ebike simulator at ebikes.ca though and play around with the numbers for your battery and motor setup to see what figures you get. That’s how I calculated all the figures you referenced.
I am a 95 kg man and looking for my first ebike. Do you consider 250w 36A will not be enough for my weight? Not many hills where I might use it but since it´s a folding one I would like to take it when travelling. Should I opt for the 350W instead?
Thanks or sharing
36V 250W will work for you, but it’s going to feel a little underwhelming in terms of acceleration. If you want a nice, slow and easy going ride, 250W will do it. Keep in mind that most humans generate less than 250W when pedaling. But if you want something that feels sportier, 350-500W is the ticket.
Hi Micha,
I have just started to repair my 2-seater e-scooter with lithium ion battery pack, which had lead acid battery earlier. I want to change all; battery, controller and the motor. I’m confused with a question: How to define permissible load for a dc electric motor? For example, if I have a 500 W motor, what would be max power and how to relate with load?
Thanks anyway for your helpful blog.
Basically, you want to make sure your controller isn’t higher powered than your motor, since it’s the controller that limits power in the system. So if you have a 500W motor, you’ll want to pair it with a 500W or less controller. What will happen if you used an 800W controller, for example? If you’re a fairly lightweight person and/or don’t climb many long hills, chances are you’d be fine (and notice some nicer acceleration). But using more power than the motor is rated for in long durations (like accelerating a larger person or climbing a long hill) could burn out the motor.
Hi Micah,
Many thanks for your earlier discussion. I came back with two further doubt.
(1) Can I use 18650 Li-ion cells to built a 5 kWh battery pack? I am basically curious about what to do while scaling up the system.
(2) If I want to drag one ton of total load (lets say a 3 wheeler) in a nominally flat road, what kind of motor (watt) should be used? (average speed: 30~35 km/h)
Thanks in advance.
Sourov
What do you think about a BBS02 8fun Bafang motor 750w with a 48V – 10.4 AH SANYO battery, i’m 82kg of weight. I live in a place full of hills.
Is this kind of battery appropriate?
There are a few Sanyo batteries out there so it’s a bit hard to say, though most are rated for at least 2C. Basically, 10.4 AH is about the minimum for that motor kit. It will definitely work, but you’ll be pushing the battery closer to its maximum power draw level, meaning it just won’t last as long as a larger battery.
Hello Mecah,
Can i use a 350W motor with 300W source power?
Thank you in advance.
Generally speaking you do not want to use a stronger motor than your power source (battery) is rated for. However, the more important figure would be your controller. If you have a 300W controller or less, than it should be fine for that battery.
I have been looking all over YouTube for something like this. Thanks a lot for the information, I have a little problem I just want to verify with you pls.
So I bought mountain bike from Walmart.
just ordered 1000watts 48v e-kit
ordered (4) 12 volts 7ah batteries (makes it 48×28= 1344, I think)
-I weigh 168lbs (5’9) and carry a 5lbs school backpack to school everyday
-from my apt to school is 1.9mile
-always this slide hill (though I’m a new biker still able to ride it) but always tired afterward and little knee pain. ( that’s why I bought the e-kit)
1. do you think with the e-kit and battery power can push me up the hill ?
2. if the watts from my battery is 1344watts but the e-kit is 1000watts, will that mess it up or damage it?
3. the battery fully charged, can it take me to school and back at a constant 48v?
note: the 1.9mile to my school isn’t all hill just like 0.2mil.
That all sounds reasonable, the batteries can definitely handle that 1,000W motor and they should be able to drive you 4 miles with a slight hill no problem at all. The 7AH isn’t a lot and the lead acid batteries are a bit old school, but it will all work. Your math is a bit off though. Your battery is a 48V 7AH when you combine those 4 bricks together (the voltage adds since they are in series but the capacity does not add unless they are in parallel). So you’ve got 48*7=336 watt hours. Not a ton, but you’re also not going that far either. Lead acid batteries can also handle a lot of power – much more than lithium batteries. That is one of their advantages – one of their only advantages actually…
hi
i want to make an e bike in my university
at first i decide to use hub motor for my e bike but there is a problem
in my country this kind of motor are very expensive so i decide to use DC motor (250) watts ( i am 65 kg ) and there is two choice for DC motor
first : BLDC
second: DC
i don’t know the difference of these motors and the usage of them
please tell me the best motor for ebike and then tell me why ?
thank you
Micha,
Can you recommend a good e Bike store in Jerusalem?
Thank You
Ofanayim
Sorry, but I don’t know too much about the retailer scene in Jerusalem. It’s so hilly that I know most the 250W ebikes (the legal limit in Israel) can struggle on those hills. I wish I could be of more help to you! There are some good Facebook groups for ebike riders in Israel, so you might have better luck searching there for a recommendation on a specific Jerusalem vendor.
A person riding a bike cannot usually output more than 200-250 W of power for more than a minute or so. If you use the motor only as an assist, I think that 250 W would suffice even in hilly terrain and for a 100 kg person. Can you please explain why my reasoning is wrong?
A 250W motor can suffice for many people, but a 100 kg person on hills would find the performance to be very underwhelming.
I used the hub motor simulator (an awesome tool!) over at ebikes.ca to run a few quick simulations. http://www.ebikes.ca/tools/simulator.html
A 100kg total (bike and rider) setup with a 250W motor and 36V battery would get 20 km/h on a 5% grade, but only 7 km/h on a 10% grade. On the 5% grade, the motor would overheat in 6.5 minutes, and on the 10% grade the motor would overheat in 1.4 minutes!
These motors are fine for flat ground, but they just can’t handle the hills. A normal rider going up a 5% or 10% incline would get tired and as their legs filled with lactic acid, they’d be forced to stop. A motor, on the other hand, just keeps going and progressively heating up, which increases its resistance which makes it even less efficient which makes it heat up even more and the cycle continues until it eventually destroys itself…
Hi , thanks for the article ..
I want to buy an E bike , big wheels .
I weight 210 lbs and I live in Jerusalem , and as you know Jerusalem has some hills but I will be peddling easily to “help” the bike .
What e bike should I choose ?
Thanks ..
Hi Khalid,
In Israel I know that the company Greenbike has some good quality bikes and good service. Most of their bikes are the smaller folding bikes but I believe they have some standard size bikes with larger wheels as well. Jerusalem is pretty hilly as you noted, so I’m not sure how well they will work. They’ll get you around, but the performance will be a little underwhelming on those big hills…
Dear Micah, I was quite happy to discover your site and was surprised about the amount of information that you make available.
I would love to build two new battery packs for our two bikes.
The bicycles are Gazelle Easy Glider made in The Netherlands around 2008…
They are equipped with a Brushless Panasonic motor and powered by a 10Ah 26V Li-Ion Mn battery type NKY233B02.
Forgive me if I overlooked your information concerning he use of LiFePO4 cells.
Apparently, these cells offer nothing but advantages though their voltage is significantly lower…?
I would welcome your ideas on the replacement of the present battery and hope to be able to achieve a bigger capacity.
Could you please advise me what BMS I would best buy and possibly also the type/brand of cell and their connection S7 or S8 ?
What about using 19670 Vss 18650 ? Does this protection make a difference?
Any spot welder recommendation?
Thank you for all possible hints !
Kindest regards,
Hey Micah,
First, thank you for sharing your knowledge on electric bikes. There is a lot to think about before installing a conversion kit. Pity I did not find your page (my bad) BEFORE I ordered and installed a kit.
My questions are regarding Torque: How to know, or calculate torque power delivered? The manufacturers tend to give a higher torque on the specs than the real one, it seems. How to be sure I get what I am paying for? I would like my next build to be stronger, as my 500 w/ 20 A/ 36V gets quite warmed up when I pulling trailer with two kids in it. Living on the west side of Norway, the next hill is not far away! And 1000 w seems a little much to me, as max power allowed on the roads in Norway (EU-regulations) is as little as 250 w.
How can I maximize my torque, in short?
Best regards
Jan
Calculating the actual torque is pretty difficult without a custom dynamometer for your ebike. I actually built one for a senior design project for my mechanical engineering degree, but it’s not a simple build. Generally speaking, a motor with a wider stator is going to be torquier, but with motors that are similar sized it can be hard to compare. Many manufacturers supply a torque graph with the motor, and I’d recommend searching around for one. Here’s a somewhat shady one for a goldenmotor hubmotor showing a max of about 9Nm of torque at full power: http://www.goldenmotor.com/hubmotors/BLT-800W%20Performance%20Curve.jpg
The best bet is to try and locate the performance charts like these for each motor before you buy to compare. When you’re stuck with a 250W motor, there’s not a lot you can do to maximize torque though. You can aim for a lower speed motor which won’t have more torque, but you’ll feel like you have more effective torque because the motor will not heat up as much when towing as it is staying in a more efficient rpm range. Other than that, 250W are pretty much known for not being so torquey. You can always overvolt your motor (swap in a 36V battery instead of 24V or 48V instead of 36V) which will give you a boost in power and torque.
sir i want to build a ebike with 100ow motor and how much power battery does it needs? bike wiehgs 80kg and man weighs 70kg
I’m a 5’9″ 246 lbs person who is losing weight. I’ve been checking out ebikes and have ridden four different ebikes by 3 different manufacturers. The only one I’ve been able with peddle assist to get up 20 mph was a Pedego Interceptor. I’m looking for something for commuting 21 miles round trip that can move my heavy body easily at 20 miles per hour for 11 miles with either pedal assist or throttle depending on how lazy I’m feeling at the time. Can you advise the minimum watt motor I should have to meet my needs?
Wattage isn’t the biggest concern here, though anything less than 500W isn’t going to be great for your purposes. 750W would be best. But more important is capacity of the battery in AH. 10AH is the minimum you want if you can charge in between the two legs of the trip. Assuming you can’t, or planning for the odd day that you forget to charge, 20AH would be best to ensure you’ve got enough juice to get there and back on throttle alone.
Hello,
I have a 48 volt battery and a 500 watt motor. Will a 48 volt 1000 watt controller work with these, or will it burn out the motor??
Thanks
It really depends on riding conditions. Generally this combination would be a bad idea, but if you’re fairly lightweight and you don’t go up long hills, the motor won’t be pulling the full 1,000W offered by the controller very often. You only pull full power under peak loads (e.g. Heavy acceleration and hill climbing).
I AM SAUD FROM INDIA,
I am an electrical engineer.
I am going to build an electric motorcycle for a competition.
I just want to know that I have to consider both the vehicle and driver’s weight or just driver’s weight for the selection of motor.
And please suggest the ratings of motor and battery for 70kg of driver and 60-80 kg of vehicle to drive in a muddy road and to claim through 30 degree elevation.
Hello back from Israel!
You definitely want to consider the weight of the rider as well. Unlike cars, for electric bicycles and motorcycles the weight of the driver is a big percentage of the total weight. I’ve never built an electric motorcycle so it’s hard for me to estimate the power you’d need, but you’re looking at seriously powerful components not normally used in ebikes… likely 5kW minimum.
I live in Istanbul, Turkey in a city with hills. Eventually I will return to the USA but I would like to buy an e-bike to ride while I’m here. I’m not sure how to address the 110 vs 220 current issue. I’m familiar with the brand Pedego which I like because it’s perky. I weigh about 112 lbs. I’m thinking 36 volt lithium battery 12 amps. Also, I like a quiet bike and not that loud humming sound. Any advice would be appreciated.
The 100v vs 220v isn’t really an issue, you just buy a different charger if it isn’t multivoltage.
If you have big hills, you’ll want a powerful direct drive or a mid drive. A geared motor is smaller but they are usually weaker and also are a bit louder, which you said you’d like to avoid.
sir I want make a ebike to carry a cargo with the weight nearly 100 kg and me 100 kg. how much power motor and battery I needed to built a e bile
That’s hard to say because it also depends on many other factors including type of motor, battery, riding terrain, speed, etc. You’re looking at an absolute minimum of 1000 watts though. I’d aim for a slower winding of motor and you’ll be able to get away with less power. It will also be safer.
With that much weight, make sure you’ve got good brakes.
will a 12 v battery do for a boy weighing around 40 kgs. If it will, what should be minimum Ampere ?
12V isn’t going to provide enough power unless you’re pulling a crazy amount of current, which can be dangerous. Aim for 24V at a bare minimum. My wife weighs 50 kg and her bike uses 24V 10AH battery with a 14A controller.
thank you . And what power motor do i need?
And did u mean that throttle should be of 14A ?
hi my name is meysam I study in Iran and my major is Mechanical engineering I want to make Ebike and I don’t know if I choose motor’s 500 waat how much is the weigh of bike ?
tank you
hello I am meysam .
I want to know can I use battery of laptops to make an Ebike?
Yes you can, but it isn’t the best method. It’s hard to know what quality of cells you can find in old laptop batteries. Plus, mixing different types of cells will give less than optimal results.
tank you
It really depends. Most 500 watt motors will weigh between 4-6kg, but the weight of the finished bike will depend on the other parts you include and the type of bike.
hi my name is helmy. i am planning to make diy electric bike .i have an old 700cc bicycle . my weight is 100kg . my target speed 25km/h . how much watt motor is needed? what type of motor to use? how many volt battery to use? how to charge the battery electric bike using alternator? how far it can go ? i hope you can help me. TQ.
Hi Helmy, you’ve got a lot of great questions that require specific answers based on your own needs. Your questions are so broad and diverse that I recommend you check out the book I wrote to help people like you plan and build a custom ebike at http://www.UltimateEbikeEbook.com
Hi Micha, my name is Shalom, and i live in Tel Aviv, Israel. I have been building a diy ebike for some time now but with the laws in israel on ebikes being so tough its hard to get parts. I managed to get a 750w brushless motor (China) on a 750w 36v controller on a 36v 11ah battery. I have a lot of power taking off but then after 10mph or so it wont go any faster. Its quite embarrasing as 36v 250w bikes pass me all the time. I recently got a 48v 13ah battery and a 48v 800w controller. Will i kill my motor if i use this and do you think that i would still be able to use my 36v 11ah battery if needed?
Also is there anyway to tell how much max amp my controller is. I am trying to do the math like you easily explained in a different page (thanks for that) to figure out the actual wattage of my bike now and if i were to switch the setup. Thanks
Shalom Shalom,
Was the motor meant for a 26″ wheel and you put it in a smaller 20″ wheel? Unless it was already meant to be a really slow wind, then that could be the reason it’s going so slow. 10mph, or 16 kph, is very slow for a normal 36V motor. You should be fine with using 48V on that motor with a new 48V controller, but that will only increase your speed by about 33%, to about 21 kph.
There’s a chance that your original controller had a speed limiting function. This is often a set of single wires that can be disconnected with a single wire connector. Or it could be an issue with your controller. If you switch to the 48V battery and controller and suddenly your speed doubles, then that is a sign that it was actually a problem with your 36V controller.
To determine the max amp of your controller, I recommend using a watt meter like a Cycle Analyst or Wattsup meter. There’s also the Battman meter that is sold in Israel. Connect that between your controller and battery to see exactly how much current your controller is pulling at any moment. The current it is pulling during acceleration or when climbing a hill will be the max amps of the controller.
Firstly may I say that this is a brilliant site. Especially for a layman who does not know negative from positive in electrical terms, having been in the financial markets for the most of my life. For my sins I purchased a bike hire company and like all good corporate characters have expanded (read this as very busy loosing money) to include more areas and exotics like the Worksman Chariot which I have electrified using a Dillenger ebike 250w kit which is the legal limit for Western Australia. I have now purchased 4 derelict Pedicabs, 2 Chinese specials and 2 VeloCity Cruisers, you can see the difference in quality. The specifications for the latest Velocity cruisers is a 250w 48v motor with a 39ah battery. My model had a 20ah battery. The current batteries and state of the wiring is “had it” and I have no way of testing the motors, so I would like some advice on how I could check if the motors are OK. Secondly do you know where I can purchase a replacement kit with a 20ah battery, or should I go with a 250w 36v 12ah setup which I can get for under $500-00. These are heavy pedicabs, 190kg with a gross of 300kg. However the terrain is as flat as a pankake.
I’m not familiar with the VeloCity cruiser ebike (or is that one a pedicab too?) and didn’t find it in a quick google search. Do you have a link or more info on the motor (brushless, brushed? etc?) that can help me advise you on checking the motor?
Regarding a 40AH battery, are we still talking 36V? That’s a big battery for a bike, but if it’s for a pedicab, you might even consider lead acid batteries. Generally I advise against them for ebikes, but since a pedicab is stable and the extra weight isn’t a deal breaker in a flat area, it’d be a cheap way to get a lot of battery. If you can afford it though, there are some big batteries on Aliexpress that could be good for you. Lithium is of course more expensive, but it will last longer too. Here’s a 36V 40AH and here’s a 36V 25AH for comparison, both LiFePO4 batteries so they should last well over 1000 cycles – years even if you’re doing a complete discharge every day at your business.
I’m not sure what wheel size you’re looking at. Assuming it’s a standard 26″ kit, something like this would get you everything you need except the battery for about 200 USD.
My Volto is 37 Volts/14 Ah = 514 Watts. It just copes with me on most of my riding as I’m over 100kg. What I have just been reading about, enables me to understand the juddering and complete stop of the motor on 1 or 2 places I’ve been. ( Hot weather also.) This seemingly repaired itself after a long downward gradient.
I’m not sure that I would want a more powerful motor at this stage as I’m appreciating the extra exercise, unless I decided to trek over some of the much rougher and steeper roads inland. (which may happen in the future)
So thanks for that.,
Pat.
Hey Pat,
I’m glad to hear that you’re enjoying your Volto. Remember though, the power equation is Power=Volts*Amps, not Amp Hours. Amps (or more accurately “current draw”, measured in amps) is determined by the controller, not the capacity (AH) of the battery. I’d suspect that your controller is somewhere in the range of 15A, meaning that your Volto is still pulling a bit over 500 watts.
That judder you are experiencing can be caused by a few different things, one of the most common is a bad or weak connection between the motor and controller wiring. Sometimes the connection is just weak enough to cause issues during heavy loads, such as climbing a steep hill. When things heat up it can also increase the symptom. You might just examine the connectors from the motor to make sure the sensors and phases are in good shape and haven’t melted together.
Happy riding!