artron9

How can I determine which battery to use. I am running a Hobbywing combo. 21.5 brushless motor with a Justock XR10 ESC. Currently, I am running with a Venom 30C 2S 5000mAh 7.4 Lipo. I am not racing this car. I have a Hoovo 80C 7.4 V 5000mAh battery. Will this battery be safe to use?

Roelof

I would like to know why you think it should not be safe to use.

As long the voltage is right and the capacity x C value can handle enough current, and that it can. Running 21.5T you can even use the most weakest battery available.

artron9

Roelof, thanks for your quick reply! That helped me alot! Ron

DirkW

iTrader: (1)

If C-ratings were reliable in any way, shape or form, a higher C-rating battery would actually be safer, as it is an indicator of what the battery can safely provide to the ESC/motor on demand. The battery is not forcing anything into the system.

billdelong

iTrader: (33)

So you multiply the C rating times the capacity to get the load that the battery can handle, so in this case it's 30C x 5Ah = 150A of constant current

Then you can cross reference the following chart to see that the 21.5T motor will pull a max of 32A which is no where near the limit for the battery:
https://www.hobbywingdirect.com/prod...30318655340659




What will be more important is to track the health of your batteries as they age, you do this by checking the IR (internal resistance), more info here:
Which charger is the best?

Roelof

Keep in mind that the high C values are only telling about short moment peak current, nothing about continious while the lower C rates can be a continious current rating. Again the modelcar industry did fuck up the standards.....

billdelong

iTrader: (33)

More info here where SMC has started providing "True Spec" ratings, hopefully more brands follow suit so that everyone follows the same standard:
https://www.smc-racing.com/index.php...egory&path=180

Another good article here on C Ratings:
http://rctruckstop.com/2019/09/25/ex...ipo-batteries/