Mondraker Thundra losing power

_Nutty_

Member
Feb 27, 2022
7
4
Azores
Hello!

First post. I actually joined the forums just to post this question. So far, no one helped me, not even the reseller.

After a few (less than 10) miles, if help is turned on always, even in ECO, bike reduces assistance to a minimum! If I change to BOOST, the level of help feels like ECO! If I continue to push on, it cuts off!

I once started a ride on a hill of over 10% for one mile. By the time I got to the top, help was next to zero and even cut-off twice. For a few moments all I had was leg power!

It's a nuissance since it happens when the legs start losing power (I don't ride that much) and when help is needed the most!

Any ideas?
 

Mikerb

E*POWAH Elite World Champion
May 16, 2019
6,531
5,008
Weymouth
sounds like thermal cut off. It may be a faulty motor or it could just be you using a low power mode/low cadence/ too high a gear.
 

Mabman

E*POWAH Elite World Champion
Feb 28, 2018
1,122
1,851
Oregon USA
Check you battery voltage at full charge. Sounds to me more like a low voltage situation.
 

lightning

Well-known member
Apr 5, 2021
715
410
UK
ls this a new bike? How many miles has it done?
It could be a faulty battery. Ebikes like you to spin the pedals, say around 80-90 rpm

lf you grind up a hill in a high gear, with a slow cadence, as suggested above the motor could overheat.

Not saying that's what you are doing, just throwing it in as a possibly
 

_Nutty_

Member
Feb 27, 2022
7
4
Azores
Replying to all...
I bought it new. It has around 800km. I doubt it's battery related. It happens regardless of battery charge and after it happens, if I let it cool down, power is back to normal. I read about thermal cut-off and it's true I'm not able to sustain medium/high cadences. I usually ride at 60 or 70 rpm. In climbs, maybe even 50. I just want to be sure that this behaviour is something I should expect and not some sort of malfunction since warranty ends in less than a year.
Is there a way to be sure it's thermal cut-off?
Thanks.
 

lightning

Well-known member
Apr 5, 2021
715
410
UK
l'll try riding mine like that later and see if any issues come up.
But it does sound like you have a fault somewhere with the bike.
 

Mikerb

E*POWAH Elite World Champion
May 16, 2019
6,531
5,008
Weymouth
l'll try riding mine like that later and see if any issues come up.
But it does sound like you have a fault somewhere with the bike.
your trial in 8/9 degrees C is not going to be the same as the OP in the Azores.....17/18 degrees.!
 

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