SRam Sparc -> how does it work (technically, two motors ?)? how in practical use

[kraeuterbutter]

i have the opportunity to maybe get a used sram sparc for few money..
question:

how does it work ?

it is said to have 2 motors with belt-drive inside the internal gear hub..

what motors ? brushed or brushless ?
how are they rated..
i have read, that it is not a strong drive-train, more on the weak side
how noisy is it ?

do you feel a drag of the motor(s) when driving without motor-power ?
or is there a free-wheel unit integrated ?

are the electronics integrated (controller ?)
on the pics on the sram-homepage:
...::: POWERED BY SRAM :::... --> products and then SPARC

it looks so
if it is brushless, and there are two motors: is there one controller (and the phases of the motors synchronized) or are there two controllers.
(i would prefere to use my own controller)

how is it with giving some more than 16Volt to the motors.. would they servive ?
etc. etc.

does the motor use the gearing ? i think no, otherwise that would be a great feature and Sram would have not forgotten to mention that

has somebody more pics of the system..

iam realy interested in it !


thankx !!

 

[coops]

Sorry I don't have any info Kraeuterbutter, except for a mention in the AtoB electric bike Buyer's Guide that you may have seen anyway: look for "Dahon Roo EL (SRAM Sparc power)" about 1/3 way down: this page was updated in April 2007, but that item refers to 2002 and 2005??

Stuart.

 

[flecc]

Be careful on this one Kraeuterbutter. The first generation Sparc was revised as it was very poor and gave trouble. The replacement is supposed to be more reliable, but it's still a low power system. That said, it is a good hill climber, but at low speeds, and has quite a good range with the standard batteries.

I don't have any figures, but that's the summary of past review information.
.

 

[Flying Kiwi]

idoes the motor use the gearing ? i think no, otherwise that would be a great feature and Sram would have not forgotten to mention that

You're correct in that it's not a drive through the gears system and the motors are only connected to the hub through a compromise fixed gear ratio seems like a lost opportunity to me given the gears are already there in the hub. The Sparc has been around for ages now, I would have thought an all new replacement model can't be far away. Perhaps the next model might be sensible enough to drive through the gears, a bonus would be if the new unit incorporates a roller brake.

 

[kraeuterbutter]

hmm.. how much would you pay for it..

i think i will go up to 150Euro.. if he wants more i will forget about it..

i liked the fact, it is said to be very light...

as i have seen, its powered by 16Volt ?
i would want to use a light battery (0.42kg light)
to have after conversion still a very light bike..
(i don´t need 20km range, so 18Volt and 4Ah would be enough for me))

last thing: do you feel the motor in power-offmode ?
does it has a resistance like hub-motors ?
or is there a free-spinning-unit integrated, and i can also drive without power ?

 

[halfmedley]

Thought this info might be of some interest to you...

If you go onto BIKE SHOP UK. Buy mountain bikes, road bicycles, cycle parts, bicycle store. Discount cycling bike shops London and enter SPARC into the search box, a whole load of relevant parts seem to be available, even some 5 speed motors at £450!

 

[Flying Kiwi]

even some 5 speed motors at £450!

As long as people realise the 5 speeds only relate to the input sprocket gearing - from the pedals so in that regard the whole assembly has 5 gears but the motors, unfortunately only one fixed gear.

 

[kraeuterbutter]

450 Pfund ?!?
wow..

well, than maybe 150 Euro would be not that bad of an deal..
maybe i should even pay more...

 

[kraeuterbutter]

well.. bought it for 104 Euro

i think a very good price, isn´t it ?

i have now got the information,that you don´t feel it when pedaling without motor-assistance..

for weight:
its around 2.5kg for the hub-gear-unit

-> normal hub-gears without motor are often over 1kg in weight..

so: compared to this there are only about 1.5kg of added weight (without battery) compared to a normal bike..

QUESTION:
has somebody of yours already disassembled a hub-gear-drive..
is it very difficult ?
will all parts fall out of it when i unscrew it, and will i be unable to put it together again anymore ?

i would like to look at the motors and the controller..
i have seen a pic, and it seems that there are cheap canned motors are used..
if this is true, it should be doable to plant some after-market brushless-motors into it with
1.) higher efficience
2.) more power (2x 250Watt should be nicer)

or is it a no-no to disassamble a hub-gear by yourself ?!?
thx
(100watt)

 

[flecc]

The SRAM P5 hub gear part is easy enough kraeuterbutter, but I don't know about the motors that are fitted in that Sparc unit.

The P5 gear part uses a complete replaceable inner assembly and is effectively unrepairable now since no spares are available other than that.

Thanks for the information on free running and weight.
.

 

[kraeuterbutter]

sorry.. my english my english..

what do you mean with:

The SRAM P5 hub gear part is easy enough kraeuterbutter

easy enough ?
easy to disassamble and re-assamble ?

effectively unrepairable

so, if a part fails i have to replace the complete unit ? (the gears, maybe not the motor + controller)
?!?

the bike-industrie is make me wonder more and more..
how can it be, that when i have a high-quality product (i think the sparc is more in the higher-price-region, so not a china-cheap-300US$-for-complete-electric-pedelec make)

so how can be there no spare-parts..

its like i buy a BMW or Audi, so not the cheapest cars, and when there fails something in the driveline i have to replace the complete motor + gears + clutch

 

[flecc]

Not the whole thing, just the hub gear part, the epicyclic gear core of which is available as a complete spare for around £100 in Britain. That sits inside the shell which is the hub on a bike with this 5 speed hub. This is the hub I speak of:

The electric motors are outside that and inside the outer hub shell, and I've no idea on the spares situation for that. I would think there are spares for that, particularly the drive belt of course.
.

 

[kraeuterbutter]

thx..

how likely is such a hub to fail ?!?
200Watts of the motor + my 300Watt from the legs (maybe 500Watt+ (leg-peaks)) ?

at least i have not seen a hub on the bikes in my neighbourhood fail after years..
hmm..

for the motor:
on the opended picture ont he sram-homepage:
...::: POWERED BY SRAM :::...
--> producte --> sparc

you can see part of the motor..
2 wires, so that are brushed motors

the length can not be that big, maybe 550 or 600er canned motors
(so 55m or 60mm long)
it looks on the picture like a cheap canned motor, you get for 10US$ each in rc-shops..
the power-rating - 100Watt - seems to be right for that too..
12-16V, most likeley 5-polemotors with best efficience in the region of 65-70% (but falling very fast under 50% )

if that is true it should be easy to replace it by a brushless-motor (i think about Lehner, because:
1.) sequmented neodym-magnets, so less eddy current looses at partial load
2.) very high efficience (including controllereff. up to 91%)
3.) i can get this motors in different sizes and each motor in 20-35 different windings... so its a pool of over 1000 motors i can select from
4.) one single motor would be enough (its difficult to run two brushless-motors from only one controller)
5.) power should not be a problem... (a single motor should have at least 2-3times the power of this 2 motors used there)
6.) there are a lot of power/efficience/torque diagramms on the Lehner-Homepage
7.) all motors can be used in Triangle AND Star-configuration...

well.. i think i will disassamble it before i install it to the bike and have a closer look, if i can use one of the lehners..
maybe, when removing the plastic innercase on the picture, its even possible to use a homebuild outrunner.. so i would be able to experiment with the count of windings until they fit my preferences...

 

[flecc]

The SRAM P5 is one of the strongest hubs and only the rider power is going through it in the Sparc, since the electric motors drive the hub directly. If anything it's much less likely to fail than a hub by itself.

I understood the motors that Sachs used in the Sparc were very similar to those used in rechargeable power tools at that time.
.

 

[kraeuterbutter]

so that sounds not too bad for me..
iam not the strongest with my legs..
(ended some time ago at 330Wat on ergometer (every 3min watt were increased by 40watts)
for my power and weight (~71kg) the gears should hold

for the motor: if it are that kind of motors from power-tools (of the pre-liIon-area), than i know what power to expect from them.. not very much

so if i can fit it, i think it will become a lehner..
just a example:
http://www.lehner-motoren.com/diagramm/1940-20.18v_liste.txt

but when i replace the motors (i can not use the electronics than anyway, so i need a new controller as well)
i can even go up with voltage:
http://www.lehner-motoren.com/diagramm/1940-20.31v_liste.txt

the efficience was measured INCLUDING the controller efficience (controller with fixed timing to 15°, no hall-sensors
--> with automatic timing (controller varies timing of the motor depending on the load) the efficience can be even 1-2% higher)

well.. there are many other choices, will have to measure the speed of the brushed canned motors first to deside what is needed..
thx for your help..
will make some pictures and post them here when i open the unit

last one: just to compare the typical efficience-curve of canned cheap motors like you find in most power-tools
motor has a max. power of around 120Watt.. so it sounds similar from point of power to the sparc ones:
http://www.kraeuterbutter.at/Bilder2/sonstiges/Messwerte Mabuchi Lehner/Mabuchi RS-540SH-5045_Bild4.jpeg

not that nice when you compare it to the efficience-curve of the lehner !
http://www.lehner-motoren.com/diagramm/1940-20.31v_grafik.gif
(W stands for Wirkungsgrad and is the same like efficience, the red line)

 

[kraeuterbutter]

hmm...
when you look at this you can feel sorry..

a hub-motor weights something around 4kg, rated with 250Watt, 400Watt, 700Watt maybe even 1000Watt ??

this motor weights only 460g
44mm diameter
80mm long

http://www.lehner-motoren.com/diagramm/2240-17.33v_liste.txt

nevertheless it can put out 1850Watt
at 2000Watt input
efficience at that: ~ 92% including controller

and for short it can do even more (twice as much)...

of course its not that easy and only half the story (think alone about gearing)


this whole thing brings me to a question:
all the laws (200Watt, 250Watt, 400Watt) in the different countries..
are there input-powers meant (can be measured easily)
or are there output-powers meant (can not be measured that easily)

 

[coops]

Have I read that torque graph correctly kb? 95% efficiency @ 31V but 20A and 25708rpm!!!

 

[flecc]

for the motor: if it are that kind of motors from power-tools (of the pre-liIon-area), than i know what power to expect from them.. not very much

That's correct kraeuterbutter, I remember the reports that they were quite weak in power. The Lehner should be a very big improvement of it can be fitted.
.

 

[flecc]

this whole thing brings me to a question:
all the laws (200Watt, 250Watt, 400Watt) in the different countries..
are there input-powers meant (can be measured easily)
or are there output-powers meant (can not be measured that easily)

I think it's the mean (average) of the output power that is intended by the laws kraeuterbutter, as you say, not easy to measure or calculate. But that means it's not easy to measure for prosecution either!

The interpretations are very loose. For example, the Cycles Maximus goods and Taxi tricycles can have a Lynch motor legally rated at 200 watts, but it has a peak output of around 5kW. The power graph starts with this huge power peak which immediately drops almost to the baseline and continues, declining gradually to the end of the graph.
.

 

[kraeuterbutter]

@flecc: thx..
so: when iam not going 40km/h with an e-bike without pedaling i should not get problems with the police (even when i use a stronger motor, for faster hill-climbs)

@coops:
yes i think you read it right way..
are you wondering about some datas ?
the rpm ? the motors in that size are capable to handle 50.000rpm without any harm to the rotor
in competition this smaller motors (less than 160g weight) are used even up to 100.000 - 110.000rpm at glider models.. thats enough to shoot a 2kg heavy model with 4000Watt Power and over 200km/h vertically into the sky *lol*

for power:
Lehner offers now the new 30er-series, for the big rc-planes and boats:
a example here:
http://www.lehner-motoren.com/motordaten/Motordaten 3080/3080-7.70V.xls
this little motor weights 1.6kg (so halfe the weight of many hub-motors)
nevertheless you can see on the data:
its able to handle 600A at 70V which are 42.000Watt (42kw !) Inputpower..
revolutions: ~52.000rpm
nevertheless: the efficience at that power-level is at 94,6%, so its not the limit of the motor !!!

with 40V the same sized motor still can handle 24.000Watts Input at 93,7% efficience
http://www.lehner-motoren.com/motordaten/Motordaten 3080/3080-6.40V.xls

this motors are used for big rc-boats or planes where normaly a 200-250ccm nitro-engine is working

well that was now offtopic, just wanted to show what power-density is possible