Battery decision

[Andy-Mat]

You quoted 44.4 volts for your battery:-

My cut off speed is set to 25 km/h
My battery is 44.4v nominative (EN15194 specifies 48v)
So I am well within the limits of the law.

I looked at the document you referenced and could not find a mention of ANY nominal Battery values. See here:-
http://12686946-873973833989121800.preview.editmysite.com/uploads/1/2/6/8/12686946/norme_en_15194.pdf
This is EN 15194 Mai 2009 :-
If you were referring to another version, could you post a link here for us all please?
I found the following on an e-bike web page, it fits in perfectly with my knowledge, but not with yours:-

Voltage: most ebike kits are rated for a specific voltage range. A typical 36v ebike needs a battery that delivers power between 42v to 30v. A 36v pack, at 42v is fully 100% charged and holding as much energy as it can and at 30v it should shut down and stop giving power before causing permanent damage..

The common " 36v" number is an average operating voltage or sometimes called nominal voltage.

Electric-Find.com says: "Voltage, Nominal. A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (e.g., 120/240 volts, 480Y/277 volts, 600 volts). The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment.May 28, 2009"

Some ebike kits have a wide operating range like 36v or 48v, so be aware and pick accordingly.
Most ebike kits with displays that show battery charge levels with a series of LED lights can only work at that voltage, if in doubt, ask the vendor!

But until you are able to do that, I am taking the generally accepted nominal values, which are 48 and 36 volts respectively!
44.4 v is not a nominal value.
But if we stay with the nominal values for example, we are talking about a 12 volt difference.
If we stay with a full charge, the 36 volt will measure 42 volts.
A 48 volt battery fully charged will be around 54 volts , but again a 12 volts difference!!!
Where do you get your 10 volts, or was that simply a "guesstimate"? Its not in the literature quoted as far as I can tell....

A 12 volt difference with regard to say a 36 v motor is 33.34 % more voltage!
If we take your 10 volt guesstimate as a value, that is still almost 28% more!
Where are you "coming from" and where are you "going to?"

Very little of what you post is true!!!

To quote you yourself:-

You really do have issues...

Awaiting some far more exact and easily verifiable comments from you in the future!!

Have a great day!

 

[Deleted member 128]

Not necessarily true.
In the case of these electronically commutated motors, the current is limited in the controller.
Increasing the voltage ***allows*** more current to be fed to the motor, but the current is only increased if you change the current limit settings (software) or tamper with the shunt (hardware).

Indeed, but then what's the point of increasing the voltage if the current isn't increased via software or hardware?

 

[Nealh]

We all can argue the toss about over volting hubs all day long, what may not be theoretical to do and what practically can be done are two different things. For many years hub have been over volted some do fail, usually because to much power(watts) have been put through them. Cwah has a few times stated he has ruined a hub, not by over volting but feeding to many amps/watts through his hubs.
It is not the voltage that is of concern but the actual amps you intend on putting through the hub, if you are sensible the hub will not have any issues. Push the boundaries to far and they fry a bit, end of the day if a hub fries you replace it as they aren't very expensive in most cases.
I have overvolted 4 of my hubs and none have had issues with up to 20a max , max power isn't used continuously as this affects battery range so for the savvy power is used accordingly to manage range and give the extra high torque/power when needed for inclines. An over volted hub continuously run at high amps in the short to mid term will most likely suffer but used carefully the crash and burn that has been alluded to doesn't happen.
I'm happy to do so as are quite a few other members who successfully have had no issue's, it's about control and being sensible with the power. Some of the decent hubs which there are quite a few have a limit as to how much power they can handle and that is about 1000w max before heat and serious issues lead to failure.
.

 

[Nealh]

Current doesn't need to be increased, simply by overvolting 36v to 48v not only increases hub/bike speed if required but also increases the watts output by 33% at the wheel so gives a nice bonus/increase in torque for inclines esp when used with 5 levels of pas.

 

[Sturmey]

You quoted 44.4 volts for your battery:-

44.4 v is not a nominal value.

Hi. 44.4v (or sometimes called 44v) I presume refers to the 12s battery (12 groups of 3.6 volts in series) and is a standard, and chargers are readily available for same e.g. https://www.amazon.com/50-4V-Charger-Li-ion-Battery-Auto-Stop/dp/B07BFPYYSM

 

[Deleted member 128]

Current doesn't need to be increased, simply by overvolting 36v to 48v not only increases hub/bike speed if required but also increases the watts output by 33% at the wheel so gives a nice bonus/increase in torque for inclines esp when used with 5 levels of pas.

Hi Neal
If the current isn't changed then surely the power into the motor, crudely speaking it's proportional to I^2R, won't change, the controller will limit the voltage it applies in order to keep the current the same.
By the way, increasing the voltage from 36 to 48V without limiting the current would increase the power consumed by 77% not 33%, its roughly proportional to V^2, not V.

 

[danielrlee]

The only thing that makes a brushless motor rated for a particular voltage is the fact that its winding pairs nicely with a commonly available battery voltage to give a specific legislatively limited speed, e.g. 25kph in the EU, 20mph in the US, etc. This voltage rating is purely for the purposes of marketing and is not a physical motor limitation.

Any motor can be destroyed at any voltage - you just need to introduce a stall condition at any reasonable power level and the windings will melt within 60 seconds due to 0% efficiency at 0RPM.

Increasing the voltage fed into a brushless motor (NOT motor controller - this will have a much lower voltage limit determined by the input/output capacitors and MOSFETS) will proportionally increase its no-load speed. Damage will not occur until the breakdown voltage of the motor windings/phase wires are reached (usually in the region of 100’s of volts). As long as the breakdown voltage is not reached, the only physical limitation is that of heat.

Heat is generated in a motor from two types of losses, copper and iron. Copper losses are directly related to the amount of current passed through the motor coils to generate torque and iron losses are directly related to motor RPM. Generally speaking, unless you are running silly speeds, iron losses are relatively low to not be of concern in this discussion. That leaves copper losses (I^R).

If a motor is used at the same performance specifications (torque & speed) as prior to a voltage increase, no additional heat will be generated by the motor.

If the extra speed gained from the voltage increase is utilised, extra heat will be generated by the motor due to the extra power required to overcome increased air resistance at higher speeds. As long as the extra heat is managed and the temperature is kept below an absolute limit (varies by motor type, construction and materials used) the motor will continue to run without issue.

Ultimately, anyone involved in EV performance modification in 2018 is "standing on the shoulder of giants". Those before us have tested the limitations of individual components with their own resources and as a result, we all benefit from this knowledge.

 

[anotherkiwi]

You quoted 44.4 volts for your battery:-

My cut off speed is set to 25 km/h
My battery is 44.4v nominative (EN15194 specifies 48v)
So I am well within the limits of the law.

I looked at the document you referenced and could not find a mention of ANY nominal Battery values. See here:-
http://12686946-873973833989121800.preview.editmysite.com/uploads/1/2/6/8/12686946/norme_en_15194.pdf
This is EN 15194 Mai 2009 :-
If you were referring to another version, could you post a link here for us all please?
I found the following on an e-bike web page, it fits in perfectly with my knowledge, but not with yours:-

Voltage: most ebike kits are rated for a specific voltage range. A typical 36v ebike needs a battery that delivers power between 42v to 30v. A 36v pack, at 42v is fully 100% charged and holding as much energy as it can and at 30v it should shut down and stop giving power before causing permanent damage..

The common " 36v" number is an average operating voltage or sometimes called nominal voltage.

Electric-Find.com says: "Voltage, Nominal. A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (e.g., 120/240 volts, 480Y/277 volts, 600 volts). The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment.May 28, 2009"

Some ebike kits have a wide operating range like 36v or 48v, so be aware and pick accordingly.
Most ebike kits with displays that show battery charge levels with a series of LED lights can only work at that voltage, if in doubt, ask the vendor!

But until you are able to do that, I am taking the generally accepted nominal values, which are 48 and 36 volts respectively!
44.4 v is not a nominal value.
But if we stay with the nominal values for example, we are talking about a 12 volt difference.
If we stay with a full charge, the 36 volt will measure 42 volts.
A 48 volt battery fully charged will be around 54 volts , but again a 12 volts difference!!!
Where do you get your 10 volts, or was that simply a "guesstimate"? Its not in the literature quoted as far as I can tell....

A 12 volt difference with regard to say a 36 v motor is 33.34 % more voltage!
If we take your 10 volt guesstimate as a value, that is still almost 28% more!
Where are you "coming from" and where are you "going to?"

Very little of what you post is true!!!

To quote you yourself:-

You really do have issues...

Awaiting some far more exact and easily verifiable comments from you in the future!!

Have a great day!

Preface of EN15194:

"This document specifies the safety requirements and test methods for evaluating the design and assembly of electrically power assisted bicycles and sub-assemblies dedicated to systems using a battery voltage up to 48 VDC or an integrated battery charger with an input of 230 V. It specifies requirements and test methods for engine power management systems, electrical circuits including the charging system for the assessment of the design and assembly of electrically power assisted cycles and sub-assemblies for systems having a voltage up to and including 48 VDC or integrated a battery charger with a 230 V input."

I am using a 12S battery which is 44.4v nominative (3.7v nominative per cell) and which I charge to a maximum of 4.15v per cell for a peak voltage of 49.8v (my LVC is 43.8v).

44.4v - 36v = 8.4v however I rarely run the battery down below 46v and hey look:
46v - 36v = 10v isn't that amazing!!!

Why would I want to run a 36v mid-drive motor at a higher voltage?

- Because I spin quite fast and doing so ups the RPM to between 95 rpm and 105 rpm which suits my riding style better
- It gives me a peak power range between 735 and 690 Watts, about 150 more Watts which come in quite handy where I live now
- Faster acceleration away from the lights, safer riding in trafic
- I no longer sag to below LVC climbing the last hill home

Notice there is no mention of illegal speed in my list...

 

[Andy-Mat]

Current doesn't need to be increased, simply by overvolting 36v to 48v not only increases hub/bike speed if required but also increases the watts output by 33% at the wheel so gives a nice bonus/increase in torque for inclines esp when used with 5 levels of pas.

Someone who understands electricity at last!!!
Well put.....
regards
Andy

 

[MartinsBart]

Yes I totally agree that current doesn't need to be increased, simply by overvolting 36v to 48v not only increases hub/bike speed if required but also increases the watts output by 33% at the wheel so gives a nice bonus/increase in torque for inclines esp when used with 5 levels of pas.

 

[RoadieRoger]

Intel I have the Pro Rider Flare with the Dapu mid drive and similar battery Ah and you should get your 30 miles range out of it . As has been stated the Woosh machines offer long range batteries and I can vouch for the battery quality of Woosh . My Brother has a 6 year old Woosh and it still gives excellent range . Another to look at that gets excellent reviews for a good price are the NCM Ebikes , supplied by Amazon but coming from Hanover . I have 3 Ebikes , the Mid- drive , a front wheel hub drive Folder and a Fat Tyre Folder with a rear wheel hub drive . The mid - drive has superior hill climbing but on the flat in the cruise the rear hub is better . Having said that , the Fat Tyre in Full assist is equally good in the climb . The Motor marked as a 250 watt but in the brochure 250/350 Watts is putting out 470 Watts in Full Assist . The 3 layers of the KT - LCD 3 handlebar controller are more interesting than watching TV, as well as requiring an Apprentice Genius to work it all out !

 

[Eagle]

RoadieRoger,
I had never heard of NCM Ebikes until I read your post.
Their Milano gets very positive reviews:
https://www.amazon.co.uk/NCM-Trekking-Das-Kit-Battery-Mechanical/dp/B07CKXW6C3/ref=sr_1_1?qid=1553608892&refinements=p_89:NCM,p_72:184323031&rnid=184305031&s=cycling&sr=1-1

 

[vfr400]

RoadieRoger,
I had never heard of NCM Ebikes until I read your post.
Their Milano gets very positive reviews:
https://www.amazon.co.uk/NCM-Trekking-Das-Kit-Battery-Mechanical/dp/B07CKXW6C3/ref=sr_1_1?qid=1553608892&refinements=p_89:NCM,p_72:184323031&rnid=184305031&s=cycling&sr=1-1

DAS Kit is the same guy as who supplied the electrics for the previous Oxygen MTB and the last Oxydrive kits. They have a German brand with the same bikes called Leisger. He then came up with a new design, which he called Foo bikes. The bike in your link is identical to the setpthrough Foo Bike. Notice the similarity to the Oxygen S-cross, though they're not the same.
http://www.foobike.com/

NCM have other models that match the Foo Bike range.

Be careful what you read in reviews. this is what comes up when we check NCM. That's not to say that it's a bad bike. At 48V it should be quite powerful. I'm pretty sure they're good bikes. the only drawback is where you're going to get a new LCD or controller from if you need one. I've seen them on German Ebay, but quite expensive.

https://reviewmeta.com/brand/ncm

 

[RoadieRoger]

My Batribike Quartz Folder has Leisger stamped on the Controller Cover and in 9 years I have had no problems with it . That Milano looks nicely balanced and the motor/battery combination looks good . I was drawn to it last July but it was out of stock at the time on Amazon, so I went for the Pro Rider Flare mid motor when they dropped the price £200 .