What Is Peak Power & How Does It Work? | EMTB Motors Explained

[@embn]

Do you set & go OR dial & tune your EMTB!? 👀 👇

[@nomad-pq4yw8iy7v]

I dial &tune the bike and use the factory settings on the motor. Another words there is so much you can due to the bike it self. The motor comes with 5 setting don't find my self looking to adjust yet.

[@rgd1977]

I can’t be bothered to phaff on with apps. I have my Bosch powered bike in EMTB 90% of the time and put it in turbo for the really steep stuff.

[@mcridr08]

Great explanation and looking forward to the next chapter.

[@embn]

Thanks for the support! We're glad to hear you loved the video! Stay Tuned! 👀

[@willian.direction6740]

Thanks for the insight I look forward to talk about how my power settings help my battery take me further on my Levo.

[@embn]

No problem! Thanks for watching and keep safe!

[@garth62]

So what I glean from this, is that the 250W limit is a bit of a farce, They will provide far more power/assistance for short periods. So to stay within the current legisaltion, any manufacturer could state it's "nominal" power to be 250W but could peak at 3KW (but of cause limited to 25kph assistance). Or have I missed something?

[@CarkeekW]

the 250w is a continuous power rating and yes it is nominal because if you stall any dc motor it will peak way above that maybe in future motors will be dynoed to make sure they are under 100nm to pass the standard who knows

[@JohnRushworth]

It’s not a farce the 250W rating. It’s what a motor can do on a test rig usually over about 30 minutes where the motor reaches a thermal equilibrium. The short term peak is much more, maybe 600W after losses. The point is the motors would burn out if they were to hold peak power for a long time, hence we talk of rated or continuous nominal power of 250W for legal eMTBs classed as bicycles in Europe.

[@JohnRushworth]

I think it important to say that the peak power discussed assumes you can only pull in Amps the Ah rating of the battery times the nominal battery voltage. If that’s the case we say the battery has a 1C rating at 25 Centigrade. Battery capacity varies with temperature. Some lithium batteries subject to the chemistry and the number of cells in series and parallel can pull more than 1C, so continuous power from the battery depends on the battery pack C rating. Peak power will depend on the C rating and a given short time, usually a few minutes. It’s also important to note this is not the actual power output of the motor at the crank as we have to take into account the losses (from friction/heat) from battery, wires, controller and motor. That’s an overall combined efficiency map which could vary for example from 60 to 80% efficiency. In other words we could lose from 20% to 40% of that battery power on the way to the bicycle crank output.

[@casualcarl8460]

More great detail John. Thanks 🙏. This confirms my suspicion how after market motors like Befang will promote their 1000 watt motors but that says nothing about the efficiency of the motor and the overall system. If it generates a lot of heat, a higher watt motor is not necessarily a better choice. I run a Bosch system that has a low watt rating. However I suspect it’s a well engineered system because it never overheats and provides a consistent overall experience. Cheers

[@JohnRushworth]

The reservoir is in Wh (stored energy), the instant power is in W (Volts x Amps drawn). The potential power from the battery depends on the C rating of the battery. In this instance you are assuming 1C discharge where C is the capacity in Ah x the nominal voltage. Not all lithium batteries have a 1C rating. Some can do more, some less. It all depends on the series/parallel setup of the cells and type of lithium chemistry. On eMTBs the cells are usually NMC due to low volume and weight. Note capacity also varies with temperature, hence less range in winter. Nominal battery capacity is usually stated at 25 Centigrade. Don’t you just hate pedants…

[@casualcarl8460]

Great details John. I have a Bosch system. How do I find its “C” rating? Cheers

[@dingbatbell01]

I notice something on Saturday. I’ve got an S Works Levo SL (it’s not just the lower price point bikes that have the standard display by the way). I was riding using the range extender, which was set to discharge first, before the main battery. I noticed I was struggling on a climb, the range extender was on the last bar and was it was fully discharged and the bike switched over to the main battery, which was fully charged, the power came back on and it felt like I was riding down hill. You mentioned that as the battery drains the power drops off. Would that be the reason I was struggling on the almost empty range extender? Great video by the way.

[@casualcarl8460]

You are correct in your thinking Alan. In addition, the battery management of these systems can require multiple battery ‘cells’ to burst/boost to maximum power output. Towards the end of the battery drain you may not have enough cells to produce the peak power. So it feels a bit sluggish. I believe Specialized is one of the few systems with bottle cage range extenders. I wish Shimano and Bosch would introduce this as well. Cheers

[@dingbatbell01]

@@casualcarl8460 Thanks for that. Would changing the settings in Misson Control so that both main and range extender batteries drain at the same time? I'm guessing it would, until both batteries where drained.

[@lewiss66]

So to resume the 250W nominal power is restricted unlike the peak power which is not! That's why EMTB mode is present on bosch motor for instance.

[@casualcarl8460]

Great question! This is my read on this as well.

[@ThePhilliesYou]

Seems that the best way to learn is by just adjust the settings as you go. Also you should mention that you can have presets so you can have certain settings depending on the trail or type of trail.

[@jestt600]

Great explanation, it was easy to understand, thanks

[@embn]

Thanks! 🙌 Glad you found this useful! Steve and Ady did a great job of breaking down and explaining peak power! 👍

[@JoseCastillo-cn4dc]

please clarify, if I select 50% of peak power then I will have to put more effort to move forward but in return I can get more distance out of the battery?

[@grahamsmith9788]

Correct; with PP at 50%, say 280W, you're going to burn less battery than if PP is 100% 560W, and faced with that lower peak power either you go more slowly or you put more effort in.

[@embn]

Hey Jose! That's completely right! The weaker the assistance you have, the longer battery life lasts! 👍

[@john_enx]

Hi, the motor does it need service and how much does it cost? are there service kits? I'm thinking of buying a new enduro bike, I don't mind the extra cost for the initial buy but I would like to know more about the life of the motor and battery, does an ebike battery last more than 3 or 5 years? Thanx in advance!

[@seanknight9898]

Never mind Peak Power, I think you better elaborate on that Pee Power there Steve. Like an aging battery, as I get older I to find a loss of power behind a pee. 😜

[@embn]

We think we'll leave Steve to answer this one! 😂

[@tsalesto]

Actually, since the nominal power of the motor is determined by the cooling capacity of said motor, by running at above the nominal power (especially in hot weather) you will reach the max allowed temp. The firmware will then throttle (limit) the power output.

[@FattyOn2Wheels]

i have a 48v 17.4ah battery would i be able to size up and go for a 48v 50ah ?

[@JohnRushworth]

That battery would be significantly physically larger. Larger Ah means greater capacity for the same pack voltage and providing you have a correctly sized controller you could pull more amps from the pack and if the motor had a higher rating you’d get more power out of the motor. This assumes you can only pull 1 x the Capacity rating of the battery. Depending on the cells configuration of series/parallel and the type of chemistry we can often pull more than 1C.

[@lozetchells9164]

The mission control app is pretty poor for explaining the tuning for each mode, but it's straightforward once you understand you're entering a percentage of the motor's peak power, not of rider input power. The tuning part of the app is really good, but the ride recording is annoying. The Bosch bikes record all rides regardless of whether you're paired with a phone (with the exception of GPS data). But the mission control app needs you to be paired, connected and actively click Start Ride before it'll record. Also viewing the ride after is pretty limited. The actual bike, however, is batshit bonkers brilliant. I've dialed my eco back to 20% for long treks, but otherwise stock.

[@giddyup3451]

Would using an internal belt (like in the Brose) be more inefficient than gears or direct drive at going from 'battery' energy to mechanical energy?

[@jcheco59]

What is the relation with torque power, do we drain the battery faster with a 90nm than a 70nm?

[@oumu]

A bit late to answer, but motor torque does have a relationship to motor power: power = torque * RPM. So, if you're in a situation where more torque is necessary (e.g. climbing a hill), you'll use more power to maintain the same RPM. More power translates to faster battery drain. However, a 90nm motor isn't always applying 90nm of torque. Everything else equal (including efficiency), a bike will not drain more power just because the motor has a higher torque rating. If you already know power (watts), that's the goal here; you don't need to know torque.

[@thewrx2600]

good info, lets keep digging on this topic and dig more into the innerworkings of ebike drive systems and power supplies; maybe even start discussing how all these systems communicate on a canbus network. I would also be interested in what the SL and other mid/low-power ebikes might look like in this conversation. Last, I think having a sticky linked spreadsheet of this info for the common motors, that riders could try and calculate their total power output, and battery consumption based on their unique use cases. (even plotting those on a graph so you cold compare also) Personally, that would be more interesting than the ebike newb videos on range, lame product evals, or general maintenance that are not ebike specific (unless they were model specific).

[@leeteemtb9587]

I charge my legs up at night when I sleep, then I'm fully set for a proper ride 😂

[@embn]

Haha! That's always the best way to get charged up! 😂⚡️

[@Ruffest]

So if I set my assist at 50% I only need to give 75w to get that assistance if its set at 100% peak power. If I set it at 50% peak power I only need to give 37.5% to get the 50% assistance from the motor

[@JohnRushworth]

Assist is rider input plus the level of assist set. So if you input 100W and have support at 300%, that’s 100 + 300% = 400W combined power. However I think that is referring to the support from the battery not the actual power at the crank after system losses. System losses are a serial efficiency equation from battery to controller to motor output. Motors vary in efficiency as it’s a map not a fixed number. Suffice to say the power you take from the battery may be 60 to 80% of what is taken by the time it outputs at the crank so your 100W input plus 300% support from the battery could now be (if 60% losses) 100 + (300 x 0.6) = 280 Watts output after losses. In fact this is a conversation I’m having with Bosch at present about is my Kiox showing power output before or after losses. The sums suggest Bosch are using power taken from the battery which is misleading.

[@joggerke5295]

Here we go again with the control app. first make sure it works on every phone because here in Asia it doesn't work i can't get my levo connect with the app.

[@joeblaney684]

Three things great channel love it. Two it’s so good to hear a regional accent,( in this case a lovely welsh one.). It’s one of the great collateral benefits of internet broadcasting. A battery stores energy a controller which is the interface between that and the engine and finally the engine itself. There are other inputs to the controller such as the torque on the pedals ie how hard u push and inputs the rider does to setup how the controller delivers via the screen. The early e bikes had crude simple exchanges between all these, the modern bikes with software and sensors increasingly more sophisticated. There is a lot of smoke and mirrors from manufacturers in an attempt to differentiate but what common between them is greater that what’s different. The only way to tell what’s best for your style is to ride them in a similar situation to where you ride. My only complaint is that the actual cost of the bike at reasonable scale is very low regardless of brand. But marketing builds margins and will ultimately make it unattainable for most. Research and development whilst it absorbs capital initially is relatively minimal once amortized over a significant production volume , so can’t justify the margin.

[@adriannash755]

There's two welsh accents there, North and South West... the lovelier one is the North 🤣

[@embn]

Hi Joe! Thanks for the support, it means a great deal to us! You make some very valid points. All the best and safe riding! 👍

[@110markb]

I wish manufacturers like Specialized would apply newer battery technology to the older generation of batteries. I love my 2019 Kenevo but have got fed up with the limited range with the 500 watt battery but I can’t justify the cost of a newer one. I know everyone wants to sell new, but I fear that one day there will be bad publicly aimed at e bikes for not being sustainable in the same way a modern car is likely to be scrapped before they get to ten years old due to parts failures and cost of repairs.

[@casualcarl8460]

Have you looked into the bottle cage battery extenders?

[@graemenelson4068]

As far as I know specialised systems are 48 v not 36 as stated. And Mtrs are all rated at 250 watts output and through electronics software ca. Go up to 500 watts or more depending on systems. That’s get them pass govt regulations.

[@craigweightman799]

Well that's my brain frazzled 🤪

[@acelectricalsecurity]

What is misleading is calling a bike turbo which gives the impression that bike will have more power and be faster than a bike that doesn't have the word turbo in it, when in reality all legal ebikes have the same speed and power limits.

[@simonchaddock3694]

Electryfying

[@embn]

⚡️

[@Tasteful_Living]

First here

[@embn]

🥇

[@molak34]

2:20 watts-hour.. 2:31 this motor can draw 720 w from this battery FOR ONE HOUR 2:58 amp-hours is not the same as amps... battery capacity is not power!!!!!!!

[@JohnRushworth]

If you are going to correct, at least use capitals correctly. 😏 Wh, Ah etc. But yes folk do get confused between Energy, Power and Capacity.

[@molak34]

is this an april fool joke ? or you really don't get the diference between Wh and W ?

[@bobpoor6348]

The whole premise of this video is wrong. People who say they have a XXXw battery bugs the crap out of me. It is XXXwh's which is volts x Ah's = watt hour's not watts. Watts = volts x Amps and has nothing to do with the battery but describes the maximum amount of watts a motor is able to put out. Watts draw from the battery to power the motor and under use the voltage drops and you are losing wh's incrementally as you ride. It doesn't effect the power noticeably until you are close to the low voltage cutoff of the BMS, battery management system, that is in the battery to protect the cells from discharging too far causing them harm over time. Many articles and videos online that explain this better than this one.

[@1brokenspoke189]

Never piss on a ebike especially Shimano ep8

[@embn]

Haha! Yeah, we certainly wouldn't recommend doing that! 😂

[@johannkruger3530]

Tell us again which one is the battery and the motor. Looks like I got it wrong all these years. Never knew the battery is actually the motor.

[@embn]

Hey Johann, The battery is always on the down tube of the bike and the motor sits between the cranks where the bottom bracket is. Hope this helps! 👍

[@terencegreebz7744]

so then more support less distance? less support more distance? # more # less # or #@$$.lame.

[@embn]

Yeah, you're right! The more support the bike is giving you, the less distance you'll travel with electrical assistance. 👍

[@molak34]

5:50 75% efficient motor ... that's a heavy insult to Brose engineers ...

[@rgd1977]

Not really, petrol engines are about 30% efficient.

[@molak34]

@@rgd1977 Your comment is SO irrelevant, a decent Brushless motor is 85% efficient, chinese knock off are 80%, a Tesla motor has 95% peak efficiency. The 75% claimed in this video is wrong as many of the shit they are saying

[@casualcarl8460]

You ok?

[@malanalan1]

Jeez! No mention of torque at all! Torque is what matters most not power! Somewhere in the middle of the video you veered off course and gone bonkers. Just read through comments. Everyone mumbles power in confusion! You sent people off track.

[@SimonBauer7]

tune it up way high so the stupid belt in the brose motor fails even faster. there are many reports from brose riders where the belts failed and destroyed the entire motor including the tensioner. if you want longevity id go with a gear driven motor like yamaha bosch or shimano.

[@sklivello]

Dynamo stand? Accurate measurements? No, a lot of buzzwords and marketing!