Climbing and overheating

[stevenatleven]

I wanted some sensible advice about overheating the motor when my speed drops on long climbs.
Where i live is quite hilly and to get out of town i have to tackle moderate hills with average gradients of 5% to 10%. they are mostly 1 to 2 miles in length and my speed is about 9/10 mph.
the motor is a 36v Dapu M155 which i believe is a geared motor. I wondered if you could give me some guidelines of minimum speeds and duration to avoid

 

[Emo Rider]

This reply may be a bit smplistic but if your motor is laboring under the strain of a hill climb, you need to put more rider input (drop into lower gears and pedal harder/faster) into it. Continuously putting strain on your motor, that it can not handle, could damage your system. Not knowing your situation heath wise or if this is an option, it is what I do.

 

[stevenatleven]

thats the thing at 9/10 mph i don,t know if the motor is laboring but i am in the lowest gear and my cadence is about 80 rpm.

 

[Emo Rider]

thats the thing at 9/10 mph i don,t know if the motor is laboring but i am in the lowest gear and my cadence is about 80 rpm.

At high assist your motor is tying to spin at a rate equivalent to 15mph. If you are in low gear, pedaling at 80rpm and maintaining 9 to 10mph I do not believe you are doing any harm to your motor or system. Most modern ebikes are built for this kind of use.

 

[VictoryV]

thats the thing at 9/10 mph i don,t know if the motor is laboring but i am in the lowest gear and my cadence is about 80 rpm.

stop and feel the motor at the top of the hill, if it is labouring then it will be considerably heated and uncomfortable to touch

 

[Deleted member 4366]

9 to 10 mph will be OK, 8 mph probably OK, and 6 mph not OK on a long hill, but OK for short ones.

 

[stevenatleven]

Emo Rider thats what i was thought but wondered what others felt
VictoryV nice tip about feeling the motor, thanks
d8veh thats the kind of guidelines i want

 

[trex]

he is right to ask this question, he's got a hub motor, his good cadence does not help the motor spinning any faster. Presumably, he'll run the Dapu at maximum assist on the climb. Using the motor simulator at ebikes.ca, I think the OP can approximate the Dapu as equivalent to the XFC07.
The XFC07 can manage 9.5mph on 9% gradient assuming 100kgs load.
The motor's yield is 33%, 67% are turned into heat and the motor will overheat in 57 seconds.

 

[stevenatleven]

you have got me worried now trex, the motor will overheat in 57 seconds
can you expand on "overheat" like just get a bit hot and nothing to worry about
or this motor will self destruct in 57 seconds !

incidentally i use level 3 on these climbs from levels 1 to 5

 

[1boris]

he is right to ask this question, he's got a hub motor, his good cadence does not help the motor spinning any faster. Presumably, he'll run the Dapu at maximum assist on the climb. Using the motor simulator at ebikes.ca, I think the OP can approximate the Dapu as equivalent to the XFC07.
The XFC07 can manage 9.5mph on 9% gradient assuming 100kgs load.
The motor's yield is 33%, 67% are turned into heat and the motor will overheat in 57 seconds.

Why do you think the Dapu motor is the same as XFC07? The dapu M155 motor is the same as the Motor in the newer Bh emotion neo cross:It is buildt like a mac motor and takes a LOT to get hot.I am 100kg and have been up some very long and steep off road hills.The motor never gets hot,But I belive the Neo cross torque sensor and the controller setup is very effective for reducing overheating problems.But in imo,this is the absolute best hub motor on the market,incredible torque for its size

 

[trex]

that 57 seconds number is from ebikes.ca - to be taken for comparision between motors. Just listen out for your motor and reduce the throttle if it whines badly.

 

[trex]

Why do you think the Dapu motor is the same as XFC07? The dapu M155 motor is the same as the Motor in the newer Bh emotion neo cross:It is buildt like a mac motor and takes a LOT to get hot.I am 100kg and have been up some very long and steep off road hills.The motor never gets hot,But I belive the Neo cross torque sensor and the controller setup is very effective for reducing overheating problems.But in imo the absolute best hub motor on the market,incredible torque for its size

From the OP's quoted figure of 9-10mph for gradients between 5% to 10%.
if you take the XFC07, 9% and 9.5mph, it's ballpark comparison.
If you replace the Dapu with the BPM, you get 10.6mph, 35% yield, 65% turned into heat.

 

[1boris]

From the OP's quoted figure of 9-10mph for gradients between 5% to 10%.
if you take the XFC07, 9% and 9.5mph, it's ballpark comparison.
If you replace the Dapu with the BPM, you get 10.6mph, 35% yield, 65% turned into heat.

I talk from practical experience ,my neo cross have never been to hot.In Norway on the west coast there is a lot of mountains.So my rides are VERY steep and long.I have compared the Dapu motor with a 500w bafang cst a 250w cst and a BPM 500w motor code 13. I used the same controller s09p on every motor and the same 36v battery.I tested all motors on the same hill with throttle ony.The Dapu was clearly the strongest and did produce a lot less heat than the other motors

 

[trex]

my mistake, the M155 is a 350W - same power as the 8-Fun BPM, the XFC07 is a 250W.
http://www.dapumotors.com/portfolio/m155cd/

 

[Deleted member 4366]

You've got all your units mixed up, Trex. That motor has an efficiency of 63% at 9.5 mph. It won't overheat at that speed and efficiency regardless of what the simulator says.

 

[stevenatleven]

trex i found the dapu site confusing. all the M155 motors have the wording available in rated power 250w to 500w and then when you look at the motor specs it says 350/500w. Now the bike is i understand a 250w motor.

one thing i will say is on the level using the throttle it is still accelerating at 20 mph !

d8veh thats put my mind at rest

 

[trex]

d8veh figure of 65% is correct, I did have my units mixed up.
Your motor won't overheat, nothing to worry about.

 

[stevenatleven]

That is a really handy graph,many thanks

 

[tongxinpete]

I have never bunt a motor but had a controller overheat & fail on me at the crest of a long hill, this was some years ago & they have much improved. But I would put a hand on both motor & controller after your long hill climb.
(motor was a 408 clone in a 20'' wheel, then powered by SLA batts, just junking these batts dropped 8 Kg from the bike!)

I have a Q100 laced into a 24 in wheel, it takes some tough hills round here but never gets hotter than the temp of my hand. My controller is in open air & never really gets warm to the touch.
For those in areas with tough hills I would recommend the 24'' rim - BMS say a 201 rpm is for 700, 26 & 24 wheels. My guess is they are saying 24'' rim for hilly areas. I have a 26'' frame so my seat is only an inch nearer the ground than it would have been originally

 

[stevenatleven]

Thanks for the advice Pete, i do intend to give the hub a feel when at the top of the hill and i will add the controller to that list as well