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Old 01-03-2011, 06:23 AM   #1
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Default Lipo C or mAH, which more important

ok i know there are plenty of other guys opening up such new threads about lipos these past few weeks, but i beleive my question is different.
For the past 3 years i have been using a SP GT1.1 Brushless ESC and a SP11.5R motor. this ESC does not have any turbo. With 20C up to 35C batteries, from 3200mah to 4200 mah, i dont have problems of making runtime of more than 20 minutes before the cut off on the ESC of 3.4V per cell.
i Just changed to a new Hobby Wing 120A V2.1 with turbo and a team powers 10.5R motor. with the boost timing set at a lowly 3 and the turbo set at 1,i am getting wayyy more speed than i ever did with my turboless ESC, but also much much shorter runtimes.
Now i am only getting runtimes like back when we were running brushed motors, like about 8 - 10 mins with my so called 35C 4200mah cells. So i know i need new batteries, but i am on a budget. There are so many choices, some batteries with higher mAH (5200-6000) and higher C (45-60).
some with higher mAH (5200-6000) but lower C (30-35).
of course the lower Cs are cheaper, but will i get longer run times from them? but even if i had longer runtime from a 5200mah 35C , will the battery spoil from the heat generated? keep in mind i live in a hot tropical country near the equator.
or is it a good thing be running shorter since the batteries and the motor will get hotter the longer i run? will the 50C cells tolerate more heat? take note i do not need the punch.
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Old 01-03-2011, 10:34 AM   #2
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C rating and capacity go hand in hand. The ''punch'' of the pack is determined by amp rating, and you work that out by:

capacity divided by 1000, mulitplied by C rating equal amp rating.

so,

5000mah 20C pack
5.0 x 20 = 100A

3800mah 30C pack
3.8 x 30 = 114A

5400mah 40C pack
5.4 x 30 = 216A

etc.

But all timing advance ESCs are pretty power-hungry. If you're struggling to get good runtime with the new ESC, maybe sell it and pick up a cheap non-timing adavnce ESC? Match that with a 6000mah pack and you should be fine.
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Old 01-03-2011, 11:23 AM   #3
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If you are finding you have less run time, and want more, then reduce the timing on the speedo, or your endbell, and that will help. If you want to eliminate the timing advance then install the 508 software on your ESC.

This will make your car slower, but longer runtime.

Shawn.
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Old 01-03-2011, 10:04 PM   #4
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Quote:
Originally Posted by academygaz View Post
C rating and capacity go hand in hand. The ''punch'' of the pack is determined by amp rating, and you work that out by:

capacity divided by 1000, mulitplied by C rating equal amp rating.

so,

5000mah 20C pack
5.0 x 20 = 100A

3800mah 30C pack
3.8 x 30 = 114A

5400mah 40C pack
5.4 x 30 = 216A

etc.

But all timing advance ESCs are pretty power-hungry. If you're struggling to get good runtime with the new ESC, maybe sell it and pick up a cheap non-timing adavnce ESC? Match that with a 6000mah pack and you should be fine.
thanks for your reply, but once i go turbo, i dont want to look back ! maybe i would just turn off the turbo sometimes. looks like there is no free lunch !
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Old 01-03-2011, 10:05 PM   #5
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Quote:
Originally Posted by Shawn68z View Post
If you are finding you have less run time, and want more, then reduce the timing on the speedo, or your endbell, and that will help. If you want to eliminate the timing advance then install the 508 software on your ESC.

This will make your car slower, but longer runtime.

Shawn.
yes, looks like there is no choice is there ? well again, no free lunch i guess.
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Old 01-04-2011, 05:28 AM   #6
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Your Hobbywing might not go into turbo if you have weak batteries. Get at least 50c to be safe.
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