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how to get the most battery life out of a euc


Shad0z
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5 minutes ago, Chriull said:

Driving around half of lift cut off speed could give good efficiency = longer range. Did not think through this in detail, but max power is available at this speed, motor efficiency raises with speed (?and drops again somewhere at the end?) and air drag raises with the square of the speed. So the sweetspot should/could be somewhere in that range?

Inclines should be taken with as much speed as possible - by going up a steep incline slowly efficiency is terribly low.

By this gets one near to overleaning the wheel -> faceplanting :(

So preventing (steeper) inclines should help :D

Keeping steady speeds, slow and seldom accelerations, crouching oneself to reduce airdrag, keep oneself balanced so the wheel has less balancing work,...

Also have the wheel calibrated ?to ones riding style/positioning? could help - this came up as reason for low range in one of the discussions. Don't know if this was just a rumour/hypothesis or real practical knowledge?

Treat the batteries nicely so they keep up their capacity! No storing of especially a fully charged wheel in hot places! 

From http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries  :

"In terms of longevity, the optimal charge voltage is 3.92V/cell. Battery experts believe that this threshold eliminates all voltage-related stresses; going lower may not gain further benefits but induce other symptoms"

So just charge the wheel to 3,92*20=78,4V for 84V wheels or 62,7 for 67,2V wheels directly after each ride and fully charge it before you go for a ride.

This are "saturation" voltages - so one has to charge to a bit higher voltages and then the cells should settle to this voltage.

If you know beforehand that you don't need the whole range you can also "topcharge" before riding to just 80-90%.

This part charging is imho best achieved with a charge doctor (or two - don't know how comfortable it is to change voltages)

And every know and then one should give the wheel a full (saturation) charge so the cells keep balanced!

Edit: PS: but most important is to have fun ruding the wheel! If one overdoes the "treatments" and not rides anymore all the measures are counterproductive!

i will look more into the calibration thing 

especially just for comfort but what do you use? straight foward or backward leaned? 

and how do i use a charge doctor?

it looks like a good idea and its not that expensive

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3 minutes ago, Shad0z said:

i will look more into the calibration thing 

especially just for comfort but what do you use? straight foward or backward leaned? 

and how do i use a charge doctor?

it looks like a good idea and its not that expensive

Ps.: I hid your duplicate of this topic

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3 hours ago, Chriull said:

These are "saturation" voltages - one has to charge to a bit higher voltages so the cells settle to this voltage (after 15-30 minutes).

So what voltage do you think/guess is an appropriate cut off on the Charge doctor, so that it settles back to the ideal resting voltage?  67.2V and 84V  estimates.

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43 minutes ago, Smoother said:

So what voltage do you think/guess is an appropriate cut off on the Charge doctor, so that it settles back to the ideal resting voltage?  67.2V and 84V  estimates.

@WARPed1701D reported a voltage drop directly after charging from 83,9V to 82,5V within ~20 minutes for his V8 (20s2p?)

So as a first try for the 20s packs one could set the charge cut off voltage this 1,4V higher (for 16s 1,4V*16/20 :)) and look at the reported voltage of the wheel afterwards if some adjustments are needed. With few iterations you will find the "perfect" voltage for your wheel.

From readings at BU this voltage settling are dependend on the different cells, their state and the charging current.

So if you have a 20s4p configuration maybe +1,4V * 2 / 4 could be a better first try?

Ps.: If one wants to really make it right the accuracy of the voltage reported by the wheel should be checked - as for example some ks14 serie was way off...

Edited by Chriull
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You have to use WheelLog to figure out where you consumption is. I got a tip from @Marty Backe to link wheellog to cell phone and buzz me when I exceed consumption. However, just because one uses a lot of power all at once doesn't mean one is using up a lot of power.

My suspicion, without ability to confirm, is heavy usage of the following.

--Speeds above ~18 mph (~30 kph).

--Quick acceleration from stops. Use a skate board push off instead.

--Braking hard instead of coasting because you don't get the benefits of regeneration braking.

And of course weighing less.

I would think hills would kill EUC range, but no, I cannot tell any change in range. I even wonder if hills increase range. Impossible, of course, but I wonder.

In practice so long as you avoid acceleration, and ride just fast enough to start feeling the wind against your eyes and cheeks, you can achieve extraordinary mileage. This is useful if you find yourself at 40% and need to turn back, and don't want the "limp home" mode.

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21 minutes ago, LanghamP said:

You have to use WheelLog to figure out where you consumption is. I got a tip from @Marty Backe to link wheellog to cell phone and buzz me when I exceed consumption. However, just because one uses a lot of power all at once doesn't mean one is using up a lot of power.

My suspicion, without ability to confirm, is heavy usage of the following.

--Speeds above ~18 mph (~30 kph).

--Quick acceleration from stops. Use a skate board push off instead.

--Braking hard instead of coasting because you don't get the benefits of regeneration braking.

And of course weighing less.

I would think hills would kill EUC range, but no, I cannot tell any change in range. I even wonder if hills increase range. Impossible, of course, but I wonder.

In practice so long as you avoid acceleration, and ride just fast enough to start feeling the wind against your eyes and cheeks, you can achieve extraordinary mileage. This is useful if you find yourself at 40% and need to turn back, and don't want the "limp home" mode.

Whenever I've ridden the paved mountain trails I get ~1/3rd more range out or my wheel. It's significant. All of the downhill parts of the ride regenerate the battery. Of course you would think that going up the hills would take even more power out of the battery, but somehow the power drain (going up) verses the power gain (going down) is not equal.

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Regeneretive braking... I think I heard that before

definertly interesting  

the guy who got the idea is a genius and implemented it in a euc  braking=battery

EDIT: I feel kind of stupid that I thought this:P

 

Edited by Shad0z
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It's not invented and implemented, it happens with every electric motor due to physics. You use a current to make a magnetic field (which moves the magnets), but also moving magnets (= magnetic field) will produce a current. You can't have an electric motor without regenerative breaking.

Basically it works like this:

  • flat road = you need battery to ride
  • going downhill = you get battery back (regenerative breaking) = you can go on forever (until your battery is full, then you have to stop or ride flat or uphill again)
  • going really steep downhills = you almost get no battery back because it has to brake too, so it's more or less neutral
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7 hours ago, meepmeepmayer said:

It's not invented and implemented, it happens with every electric motor due to physics. You use a current to make a magnetic field (which moves the magnets), but also moving magnets (= magnetic field) will produce a current. You can't have an electric motor without regenerative breaking.

Basically it works like this:

  • flat road = you need battery to ride
  • going downhill = you get battery back (regenerative breaking) = you can go on forever (until your battery is full, then you have to stop or ride flat or uphill again)
  • going really steep downhills = you almost get no battery back because it has to brake too, so it's more or less neutral

i see i tohught if there was a part or someting...

it was back then u when I was in the mini pro forums one asked if the mini had regenerative braking and then I thought it was like a feature.. Or something

turn out physichs got me again.:innocent1:

Edited by Shad0z
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1 hour ago, LanghamP said:

I would think hills would kill EUC range, but no, I cannot tell any change in range. I even wonder if hills increase range. Impossible, of course, but I wonder.

 

1 hour ago, Marty Backe said:

Whenever I've ridden the paved mountain trails I get ~1/3rd more range out or my wheel.

I've read that efficiency of the BLDC motors is about 80%-85% overall with the constant change in demands on the motor and the fact that they are more efficient at higher speeds.  The losses materialize as heat in the controller and motors and also exist when it is acting as a generator (during regenerative braking).  This aligns pretty well with what Marty has stated with his observations.

9 minutes ago, meepmeepmayer said:

Basically it works like this:

  • flat road = you need battery to ride
  • going downhill = you get battery back (regenerative breaking) = you can go on forever (until your battery is full, then you have to stop or ride flat or uphill again)
  • going really steep downhills = you almost get no battery back because it has to brake too, so it's more or less neutral

If you go downhill on a full battery you risk the chance of the BMS (battery management system) shutting off the EUC.  Meaning that the wheel is trying to put current into an already full battery and at a certain voltage above 4.2V, it will trigger the over voltage protection circuit to minimize the chance of a battery fire.  

I'm not sure what you mean with the 'going down really steep hills' explanation with it being neutral and am perhaps just misunderstanding what you are stating.  :) The only real power dissipation a battery has is through powering the motor and in regenerative braking mode, it isn't drawing much power.   There is a limit on how much regenerative braking you can have because the batteries can only handle so much current being pumped into them at once.  This is the limitation of hybrid and electric cars as well which is why they also have to have mechanical brakes assisting the regenerative brakes much of the time.

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1 hour ago, Cranium said:

I'm not sure what you mean with the 'going down really steep hills' explanation with it being neutral and am perhaps just misunderstanding what you are stating.

I just noticed that you're basically at +-0% battery when going down steep hills, while you can get significant charges from going down less steep hills.

I'm imagining it like that (just a theory): in general, the less the wheel has to work while the tire is still being rotated, the more charge you get from the regeneration due to the rotating motor/magnets. So ideally you'd just roll down the hill like the wheel was off (only work is the balancing, which is a small energy requirement). On really steep hills (15% or 20% or so) the wheel has to brake all the time (which costs energy) so less regeneration.

But maybe it's just that you're slower on steep hills and so you get barely any regen? Just because the tire rotates much slower? I don't know. Would have to do actual measurements to be sure what exactly happens in the first place.

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12 minutes ago, meepmeepmayer said:

I just noticed that you're basically at +-0% battery when going down steep hills, while you can get significant charges from going down less steep hills.

I'm imagining it like that (just a theory): in general, the less the wheel has to work while the tire is still being rotated, the more charge you get from the regeneration due to the rotating motor/magnets. So ideally you'd just roll down the hill like the wheel was off (only work is the balancing, which is a small energy requirement). On really steep hills (15% or 20% or so) the wheel has to brake all the time (which costs energy) so less regeneration.

But maybe it's just that you're slower on steep hills and so you get barely any regen? Just because the tire rotates much slower? I don't know. Would have to do actual measurements to be sure what exactly happens in the first place.

The efficiency of regenerating depends on speed of rotation, just as the efficiency in motoring mode.

Example 1: If you do a braking to 0 speed on down hill and stand still, there is no generation, and the battery has to send current to motor to hold the position. So, the regeneration efficiency in this case is actually negative. The current is not doing work to change your mechanical energy, and hence all dissipated as heat. Thus, stall at a down hill/ uphill situation for long enough time will burn the board or the motor.

Example 2. Therefore, when you go down hill at very slow speed, the situation is not much different from Example 1, by continuity. Thus, the regeneration efficiency is low if not negative.

Example 3. Thus, the regeneration efficiency can be good enough only if breaking at higher speed. Probably higher the better.

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I'm wondering if it is possible to lose energy by going down a really steep hill or braking really hard. Where the energy spent to support that is bigger than what you get back from regeneration.

Or do you always have some kind of regeneration in every deceleration situation?

If you went down a very steep and long enough hill really fast, eventually you'd also have to brake to not get too fast. So the wheel constantly brakes while you're at 50km/h or so. Would you get regeneration then, or not?

Not going to try this one:efeebb3acc:

Edited by meepmeepmayer
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1 hour ago, EUCMania said:

The efficiency of regenerating depends on speed of rotation, just as the efficiency in motoring mode.

Example 1: If you do a braking to 0 speed on down hill and stand still, there is no generation, and the battery has to send current to motor to hold the position. So, the regeneration efficiency in this case is actually negative. The current is not doing work to change your mechanical energy, and hence all dissipated as heat. Thus, stall at a down hill/ uphill situation for long enough time will burn the board or the motor.

Example 2. Therefore, when you go down hill at very slow speed, the situation is not much different from Example 1, by continuity. Thus, the regeneration efficiency is low if not negative.

Example 3. Thus, the regeneration efficiency can be good enough only if breaking at higher speed. Probably higher the better.

Example 1 can't really be considered part of regenerative braking once you aren't moving.  Regenerative braking is only being applied when you are actively decelerating the EUC.

I will be doing some more research on this because it is very interesting to me.  But from my readings so far that there is a minimum amount of energy required to overcome losses from the inefficiencies of the motor and electrical system.  Even friction from bearings, tire friction, and air resistance work against you during regenerative braking because they are taking away energy that could have been used to put back into the EUC.  So at some point it would indeed be ineffective if you aren't able to regenerating enough power to compensate for the losses. But we can't say going down a hill at a slow speed isn't good regenerative braking because it depends on the grade of the hill.  The higher the grade hill, the more potential energy the EUC has due to gravity which can then be converted back to electricity for the batteries. 

So if your EUC was low on power, you could recharge it by walking up a hill and riding down many times.  The speed of the EUC would determine the efficiency of regeneration to the battery and the grade of the hill and length of the hill would determine how much would be put back in the batteries with each trip (I would personally just call an UBER).  

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2 hours ago, meepmeepmayer said:

I'm wondering if it is possible to lose energy by going down a really steep hill or braking really hard. Where the energy spent to support that is bigger than what you get back from regeneration.

Or do you always have some kind of regeneration in every deceleration situation?

If you went down a very steep and long enough hill really fast, eventually you'd also have to brake to not get too fast. So the wheel constantly brakes while you're at 50km/h or so. Would you get regeneration then, or not?

Not going to try this one:efeebb3acc:

Because I live on top of a hill, and since I have several optional hills going to and from work, I've experimented going up and down moderate and semi-steep hills with my MSuper (but not with my other wheels).

If you just coast downhill, being neutral on the pedals, your energy usage is extremely low but I do not think it is regenerative braking. Basically you just free-wheel down the hill until you hit an equilibrium between air resistance and speed. 

If you brake a little bit going down this same hill then the energy usage reads negative on WheelLog, but the energy is extremely spiky and high, swinging dramatically between neg and positive. I'll see something like -400 watts then a split second later see +800. It's all over the place. The most I think I've seen is a -2800 and an 1800, watt or whatever flashed up. Not sure; kinda hard to check phone while riding at 28 + mph.

My observation is if you "freewheel" down a hill and then go up a hill rather slow, then you can get extraordinary mileage. It might be higher if I went faster going uphill buuuut...I faceplanted going uphill when my wheel slowly and gracefully gave away so I'm leery going uphill at much faster than wind-resistance speed.

 

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46 minutes ago, LanghamP said:

My observation is if you "freewheel" down a hill and then go up a hill rather slow, then you can get extraordinary mileage. It might be higher if I went faster going uphill buuuut...I faceplanted going uphill when my wheel slowly and gracefully gave away so I'm leery going uphill at much faster than wind-resistance speed.

I can't argue one bit with your observations.  :)  And you certainly have to take into account the limits of the wheel in both power output and regenerative current input to avoid those face plants.  

This image came from a student's masters thesis titled "Evaluation of a BLDC drive line and energy analysis for an electric Ultra Light Vehicle".  I linked the thesis below.  It shows the changes in efficiency for driving a BLDC motor and its relationship to the torque (page 17).    

ieeefa.jpg

This next image (from page 31) shows the effect of regenerative braking compared to not using regenerative braking (the dashed red line is non-regenerative braking).  SOC is "State of Charge" for the battery (red lines).  And the blue lines show speed.  He started with a battery charged to 90% and then loaded it simulating a standardized drive simulation designed to use for vehicles traveling in urban environments with frequent stops and starts over a 10.4Km distance (called Braunschweig City Driving Cycle and linked below). 

 

smxfe8.png

 

The limitation of the regeneration simulation is that it is on flat ground (as stated on page 23).  But we can infer from the efficiency graph that the steeper the slope, the more torque the motor will require (or generate depending on if you were going up or down the slope) and that for a given rotational speed, there is a sweet spot in torque for efficiency (and vice versa).  As an example using the efficiency graph, at about 220RPM the motor is most efficient at about 22Nm of torque.  

http://publications.lib.chalmers.se/records/fulltext/163436.pdf

https://www.dieselnet.com/standards/cycles/braunschweig.php

So what does all this show?  For regenerative braking, it shows it works (no real surprise).  But for how hills and speed affect the efficiency of driving a EUC or regenerative braking in the EUC.....it depends.  It depends on the characteristics of the motor design and the hill and the speed.  We are unable to apply a general statement about any observed EUC's behavior on a given hill at a given speed and have it be applied for anything other than that EUC on that hill at that speed.   I thought there would be a more concrete answer than this but after going through this paper as well as some others, it isn't black and white.

If anyone finds any research that defines EUCs better or even that goes against the conclusions from this one, please post it.  Science should be able to hold up to scrutiny and be able to be replicated.  

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On 1/19/2018 at 12:08 AM, Shad0z said:

how to get the most battery life out of a euc?

besides slowing down of course :D

is there any changes i can do in riding style?

or any other things?

Slowing down has the biggest effect. When I ride my Monster normally, I get ~65-miles. When I rode it where I limited my speed to ~15-mph, I achieved 95-miles!

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On 1/23/2018 at 12:25 AM, Marty Backe said:

When I ride my Monster normally, I get ~65-miles. When I rode it where I limited my speed to ~15-mph, I achieved 95-miles!

I just finished a 30 mile trip on my 1600 Monster today and the battery was at 30%, with the 80/20 alarm coming on at speed. I was speeding the whole time pushing the wheel with steep hills. Temps were 45-50 F. Top speed was 28 mph..

Im kind of disappointed... I guess I should add another pack to the wheel?

Once the 80/20 alarm starts in its kind of a drag riding..

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1 hour ago, Mrd777 said:

I just finished a 30 mile trip on my 1600 Monster today and the battery was at 30%, with the 80/20 alarm coming on at speed. I was speeding the whole time pushing the wheel with steep hills. Temps were 45-50 F. Top speed was 28 mph..

Im kind of disappointed... I guess I should add another pack to the wheel?

Once the 80/20 alarm starts in its kind of a drag riding..

Speed kills the battery :D I can push my 2400wh Monster pretty hard and get 65-miles, but my top speed is 25-mph. At your speeds, with steep hills, sounds about right.

Add another battery and even with your crazy riding you should be able to get 45-miles :)

I agree, it sucks with the alarm kicks it. One reason to avoid KingSong ;)

Edited by Marty Backe
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