Ideal battery and motor temperature?

Cyklefanatic

Well-Known Member
I just downloaded Blevo for my Vado 4 and now after two rides I am inundated with new information.
The first ride the outdoor temp. was 2-3C. Battery was in the garage and started at 11C but warmed up to 14C during the ride.
The temperature today was 6C and my average battery temp was 22C. Is that good?
What is too high or damaging? What is too low?
I had charged my battery indoors so it was 20C at the start of my ride. Then as I ride it got a little hotter. Does that mean that I do not have to worry about loss of range at low temperatures as long as I store the battery indoors between rides? I ride throughout the winter as long as the temperature is above -5C so I am thinking range loss due to cold temps is not a problem.
The Vado has the Brose mid drive motor. The first ride it hit a max of 27C on the second ride I left the bike on turbo at the end to see how hot I could get the motor and it hit 34C. So the question is how hot can these motors get with out damaging them? Peak temp for a few seconds and also long term average temperature?
Would be nice to know before the warm weather hits?
 

theemartymac

Well-Known Member
You're not even warmed up yet.

A rule of thumb for motor temp is not to exceed 100C for long, if at all, and some manufacturers have electronic derating (or complete cutout) around 90-100 degrees C. Many if not most folks who monitor their temps talk about seeing mid-high 60's commonly on climbs and hard rides. Batteries shouldn't get that hot, and 40C is getting into the harmful range. You could also see a power reduction or complete cutout if your battery gets to that point, but it should return once it has cooled. I have recently seen that on my mid drive after a hot commute on a 10C day with a thick battery cover on. Lost a bit of power at the 18km (of 20km) point on my max assist and heavy throttle ride home, and when I pulled in to the garage and removed the cover, the battery was obviously way too warm. Not too hot to handle, but noticeable warm. The motor was still fine and cool to the touch, but of course the case is not a great indicator of the winding temp. I won't use the thick battery cover until next winter now, and will be more careful as the spring temps climb.

My bikes tend to perform best in all around battery range/motor performance when it's low-mid-20's C outside. The range drops due to cold battery around 10C (cover helps there), but 15-25 I can't notice a difference in general performance. I notice the hub bike really likes 10-15 degrees as it keeps the hub cool, but it begins to drop off quite quickly when outside temps are above 25C and I push it hard for 5 minutes or more, meaning there is little room left in the total system 'heat sink'. The mid-drive motor has yet to show any signs of thermal strain or power loss, but I didn't have it last August, so we'll see this summer if I can find the limit naturally. So far, the battery has been the only thing to show a bit of weakness on that one.
 

Cyklefanatic

Well-Known Member
You're not even warmed up yet.

A rule of thumb for motor temp is not to exceed 100C for long, if at all, and some manufacturers have electronic derating (or complete cutout) around 90-100 degrees C. Many if not most folks who monitor their temps talk about seeing mid-high 60's commonly on climbs and hard rides. Batteries shouldn't get that hot, and 40C is getting into the harmful range. You could also see a power reduction or complete cutout if your battery gets to that point, but it should return once it has cooled. I have recently seen that on my mid drive after a hot commute on a 10C day with a thick battery cover on. Lost a bit of power at the 18km (of 20km) point on my max assist and heavy throttle ride home, and when I pulled in to the garage and removed the cover, the battery was obviously way too warm. Not too hot to handle, but noticeable warm. The motor was still fine and cool to the touch, but of course the case is not a great indicator of the winding temp. I won't use the thick battery cover until next winter now, and will be more careful as the spring temps climb.

My bikes tend to perform best in all around battery range/motor performance when it's low-mid-20's C outside. The range drops due to cold battery around 10C (cover helps there), but 15-25 I can't notice a difference in general performance. I notice the hub bike really likes 10-15 degrees as it keeps the hub cool, but it begins to drop off quite quickly when outside temps are above 25C and I push it hard for 5 minutes or more, meaning there is little room left in the total system 'heat sink'. The mid-drive motor has yet to show any signs of thermal strain or power loss, but I didn't have it last August, so we'll see this summer if I can find the limit naturally. So far, the battery has been the only thing to show a bit of weakness on that one.
Thanks for the information. So I guess using a warm battery stored inside on a cold day is no problem at all because it will only get hotter as you start to ride.
 

Cyklefanatic

Well-Known Member
Forgive my ignorance but how are you measuring the motor temp
?
BLevo is an app that gives you access to everything and also allows you to customize what you can see as you you ride. It also has a good mapping setup. I think it only works on Specialized but there may be other apps for other brands that do the same thing.
 

theemartymac

Well-Known Member
Thanks for the information. So I guess using a warm battery stored inside on a cold day is no problem at all because it will only get hotter as you start to ride.
That's what I do. I store everything in the garage (never gets below 0C here on Vancouver island), and the night before my ride I bring the battery in the house to warm up. If it's well below 10C outside, I'll throw either my thick (12mm yoga mat) or thin (4mm neoprene) battery cover on depending on whether it's going to get colder or warmer on my return commute. Most rides, the initial thermal mass of the battery seems to do the trick nicely while it warms up under load. With the covers on, I seem to keep at least 70% of my normal range and the battery stays lukewarm to cool to the touch after. Without, I lose easily 50% or more of my range and the battery is obviously frosty to the touch.

A couple of weeks ago was the first time I saw too much battery heat retained, but it was firmly 10C or so on my ride home and I rode max assist for 40 minutes. Lesson learned...