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-   -   lipos In parallel, quick answer needed (https://www.rctech.net/forum/radio-electronics/804709-lipos-parallel-quick-answer-needed.html)

kitchen78 04-03-2014 11:24 AM

lipos In parallel, quick answer needed
 
I know if I wire to packs in parallel it will double the mah so no question there. Will it double the c rating also???

Thanks

Hoese37 04-03-2014 11:29 AM

No. I will lower the amp draw per battery tho.

kitchen78 04-03-2014 11:33 AM


Originally Posted by Hoese37 (Post 13155151)
No. I will lower the amp draw per battery tho.


If it increases the mah how does it lower amp draw??

Grasschopper 04-03-2014 11:35 AM


Originally Posted by kitchen78 (Post 13155160)
If it increases the mah how does it lower amp draw??

He said per battery so say your ESC is pulling 100A, that will now be 50A per pack rather than 100A from one pack.

kitchen78 04-03-2014 11:43 AM

OK got ya thanks, one more question is can a really high mah make up for low c rating. In other words if I am running 15000mah but the packs are 30c will it somehow make the discharge higher I quess I should say lol. Basically make up for a lower rating?

Hoese37 04-03-2014 12:19 PM

In theory yes. But there is no way to actually test the c rating of a battery.

kitchen78 04-03-2014 12:28 PM


Originally Posted by Hoese37 (Post 13155294)
In theory yes. But there is no way to actually test the c rating of a battery.

OK guys, thank you very much! !!. I have a xl2 esc I am putting in a rampage mt and the guy at castle says I need at least a 70c 7000mah and only recommends thunder power which to be honest I don't believe it needs all that and thunder power lipos like that cost 300 or over per pack so I will get 2 8s batteries and run them in parallel , I will go with a minimum of 30c and 5000mah a pack. Unless I get lucky and find some good 4s packs at a killer price

potatobed409 04-03-2014 12:46 PM

Talking C ratings in RC is like talking about Unicorns in fairyland. It's all just made up garbage.

kitchen78 04-03-2014 12:50 PM


Originally Posted by potatobed409 (Post 13155368)
Talking C ratings in RC is like talking about Unicorns in fairyland. It's all just made up garbage.

yea exactly, because there is no rating system or guidelines to follow right?? So someone can just use any label they like???

ta_man 04-04-2014 08:28 PM


Originally Posted by potatobed409 (Post 13155368)
Talking C ratings in RC is like talking about Unicorns in fairyland. It's all just made up garbage.


Originally Posted by kitchen78 (Post 13155373)
yea exactly, because there is no rating system or guidelines to follow right?? So someone can just use any label they like???

For most batteries it is made up garbage because no one will buy batteries with honest C ratings.

Danny Sullivan of SMC developed a specific and reproducible methodology for determining the C rating of a pack. What he found was that, based on the reproducible methodology, the best packs he could get were an actual 25C. So he sold them that way. I bought some of those 4S 25C packs and they are the best I've got. But most people looked at the 25C and saw MaxAmps offering 150C (which is total BS) and few people bought his packs. So he re-labeled them to 70C and they sell really well.

kitchen78 04-05-2014 12:33 AM


Originally Posted by ta_man (Post 13159107)
For most batteries it is made up garbage because no one will buy batteries with honest C ratings.

Danny Sullivan of SMC developed a specific and reproducible methodology for determining the C rating of a pack. What he found was that, based on the reproducible methodology, the best packs he could get were an actual 25C. So he sold them that way. I bought some of those 4S 25C packs and they are the best I've got. But most people looked at the 25C and saw MaxAmps offering 150C (which is total BS) and few people bought his packs. So he re-labeled them to 70C and they sell really well.

So if I went with the Smc 4s Lipos that would be the best choice?? I know they are good packs and they will be put to the test in my brushless rampage mt. Think that's a good choice?

thanks. It would be nice to have some to test out lol!

potatobed409 04-05-2014 05:58 AM

I like the SMC battery's the best and I understand the reason behind jacking up the C rating. If you figure the C rating of a 65C rating battery it should be capable of discharging all of its energy in 55 seconds. It will never happen.

Dave H 04-05-2014 08:41 AM

The lipo cells themselves are capable of very high discharge rates, although the attached wiring and connectors frequently aren't. Here is a set of discharge curves at up to 50C constant, 110 amps from a 2200mAh cell, from 4 years ago. Doesn't take very long at all.

Of course some ratings are silly, but not all are. There are real differences in cells, note differences in weight for example, but they have narrowed some as the technology has matured best I can tell.


http://www.rctech.net/forum/attachme...0-amps.cor.jpg


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