I have been in this hobby for about 4 years now and I just want to say, "Thank You", for all your vidoes has helpe me better understand and enjoy this hobby.
Batteries are funny things. Batteries create heat internally as they push current due to their "internal resistance". The internal resistance of most Lithium batteries actually falls as their internal temps rise, so your batteries may be seeing less voltage sag as they heat up. This means that you are probably getting more power out of your warm batteries under load, even though you are starting off at a lower voltage. Racers have long known about this so there are actually ROAR rules in place to bar folks from heating their LiPo batteries before races. JM Speck also did a video a while back where he observed a similar thing in some of his Rustler speed runs. The problem is that if the internal temperature your batteries get too hot , they can go into "thermal run-away" which is essentially an internal short circuit that can cause a battery to catch fire or even explode. Most quality batteries are fine after a few runs, but you should always check your cells before a run to make sure that they are not puffed excessively or too warm. On a related not, the purpose of C-Ratings is to find a way to combine a rating of the internal resistance of a battery with its ability to dissipate internal heat to give consumers an idea of the current levels that the batteries could push SAFELY.
im running a stock velineon system with a 3s 150c 6500mah maxamps on a tc4 & the battery barely gets warm. it did the same thing with my 9000mah 60c smc battery too. i seen your 70mph video & you didnt get 70+ til like your 4th or 5th run so i figure you was the right person to ask. so basically you saying as the battery warms up it can produce more power or run more efficiently.?
LiPo batteries are made up of stacks of very thin material that store energy. As these sheets release energy, they also release heat. High C-rated batteries should 1) not produce as much heat as "normal" LiPos because of their low internal resistance and 2) conduct heat out of the battery's core pretty well, so they should not get very warm to the touch. As a result, it makes sense that it could take a few runs to get the batteries "warm" and many guys say that their cars are usually slowest on their first passes. The danger comes in the fact that batteries can go from "warm" to "hot" to "on fire" fairly quickly under really abusive conditions. I've witnessed a lot of LiPo fires at the RUN DMV events and they are usually not on the first couple of runs. During the 70+ mph run you mentioned, I'm pretty sure that each run was getting the batteries a little warmer, so I was probably getting a little more power out with each pass. However, I think some of my extra speed was actually coming from improved technique. I was getting a little more comfortable with each pass, but I was also getting more aggressive to better use the road, accelerating a little harder and braking a little later. Now that I am running data logging ESC in most of my cars, I will be able to track how the batteries' performance changes with each pass. This will let us know what is really going on so we won't have to guess. I plan to run this weekend, so I should babe able to get some good data then.
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I have been in this hobby for about 4 years now and I just want to say, "Thank You", for all your vidoes has helpe me better understand and enjoy this hobby.
Thank you! That's exactly why I do this. 😆
i have a ? & i think your the right person to ask. why do i get higher speeds on my third or forth run when my battery voltage has drop?
Batteries are funny things. Batteries create heat internally as they push current due to their "internal resistance". The internal resistance of most Lithium batteries actually falls as their internal temps rise, so your batteries may be seeing less voltage sag as they heat up. This means that you are probably getting more power out of your warm batteries under load, even though you are starting off at a lower voltage. Racers have long known about this so there are actually ROAR rules in place to bar folks from heating their LiPo batteries before races. JM Speck also did a video a while back where he observed a similar thing in some of his Rustler speed runs.
The problem is that if the internal temperature your batteries get too hot , they can go into "thermal run-away" which is essentially an internal short circuit that can cause a battery to catch fire or even explode. Most quality batteries are fine after a few runs, but you should always check your cells before a run to make sure that they are not puffed excessively or too warm.
On a related not, the purpose of C-Ratings is to find a way to combine a rating of the internal resistance of a battery with its ability to dissipate internal heat to give consumers an idea of the current levels that the batteries could push SAFELY.
im running a stock velineon system with a 3s 150c 6500mah maxamps on a tc4 & the battery barely gets warm. it did the same thing with my 9000mah 60c smc battery too. i seen your 70mph video & you didnt get 70+ til like your 4th or 5th run so i figure you was the right person to ask. so basically you saying as the battery warms up it can produce more power or run more efficiently.?
LiPo batteries are made up of stacks of very thin material that store energy. As these sheets release energy, they also release heat. High C-rated batteries should 1) not produce as much heat as "normal" LiPos because of their low internal resistance and 2) conduct heat out of the battery's core pretty well, so they should not get very warm to the touch. As a result, it makes sense that it could take a few runs to get the batteries "warm" and many guys say that their cars are usually slowest on their first passes. The danger comes in the fact that batteries can go from "warm" to "hot" to "on fire" fairly quickly under really abusive conditions. I've witnessed a lot of LiPo fires at the RUN DMV events and they are usually not on the first couple of runs. During the 70+ mph run you mentioned, I'm pretty sure that each run was getting the batteries a little warmer, so I was probably getting a little more power out with each pass. However, I think some of my extra speed was actually coming from improved technique. I was getting a little more comfortable with each pass, but I was also getting more aggressive to better use the road, accelerating a little harder and braking a little later. Now that I am running data logging ESC in most of my cars, I will be able to track how the batteries' performance changes with each pass. This will let us know what is really going on so we won't have to guess. I plan to run this weekend, so I should babe able to get some good data then.
Coo Cause this is like the only video explaining the data log & i been really wanting to understand what im looking at. So thanks for this video
TABOO
I didn't realize there were no other Castle Link videos out there. I'll add a detailed tutorial to my todo list.
good video