Batteries I'm lost

9

97warrior_rider

Member
So this falls under misc I guess I'm still in a learning curve on lipo battery's from nimh battery's. That being said I have been searching for two days for a conversion equation for lithium ion battery's to lipo battery's and trying to figure out what the max battery size is I can run via lipo. I currently have a nightmare rc that was made over seas and uses a couple of standard 18350 lith. Ion battery's tied in on a weird plug I've never seen, the battery's are 3.7v x 2 600mah Udi type battery's the problem is I want a lipo set up instead I got the charger and all to run lipo and even ordered 20 sets of deans plugs to convert all my rcs over what's a safe guess as to the conversion to lipo if I don't know my c rating


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9

97warrior_rider

Member
4122b2bb92c1a744ac4d99a4765edc2f.jpg

If this helps with my issues resolution maybe it will help with someone else's as well.


Coty c
 
murankar

murankar

Staff member
Your capacity is going to be limited to weight. As for volts that's the key. Lipos are 4.2 volts fully charged and 3.7 volts nominal. So what ever your max lithium voltage is that's what you want to get close to. Now there are life-po (life4) packs that are 3.3 volts nominal and I think 4 volts fully charged per cell. These packs might be the closest to what your looking for. I found 2 sights that sell those.

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9

97warrior_rider

Member
Which means lol I'm so new I understand a lot of the batteries terms but I think that's about the only part I don't really understand sorry man for being a pain


Coty c
 
murankar

murankar

Staff member
Nominal is the lowest voltage that the cell is rated for. Anything lower could result in cell damage.

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9

97warrior_rider

Member
Gotcha so a 3.7 isn't really a 3.7 it's 4.2 now would a 7.4 20c 2000mah battery work as a replacement if I don't know my discharge rate


Coty c
 
murankar

murankar

Staff member
4.2 is a fully charged cell. So when looking at how much power something can handle you will need to know the max voltage of your packs. If a servo can handle 8.## v then a fully charged 2 cell lipo should work.

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murankar

murankar

Staff member
All of the electronics will tell you what input voltage they can handle. Most servos listed as HV can handle 8.4v max. Most fbl units can handle 8.4v and most RXs can also handle 8.4v.

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9

97warrior_rider

Member
Thanks Murankar for all the information I'll do some research and worst case senario I melt the esc down on the 7.4 20c in which case I'll just switch out esc and other base line electronics in order to run it


Coty c
 
murankar

murankar

Staff member
What esc do you have (brand and model)? The input for an esc is expressed in 1s, 2s, 3s, ect, ect ect.... The s number is the cell count and is based on nominal voltage. Like my esc; Castle Phoenix edge 50 amp, is rated for 3s to 6s. So it can handle up to 22.2 volts input.

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murankar

murankar

Staff member
Just to add more info for you. The C rating is how many Amos a pack can out put at one time. Your electronics will take only what they need in the way of amps. My 2250 3s 35c packs can put out 77 amps, my esc is rated for 50 Amps and my motor pulls 45 amps.

If your NiMH batteries are 3.7v then they should be compatible to a 1s lipo. Your mah is going to relate to operation time. If your NiMH batteries are 600mah then you should aim towards 550 to 700 mah. Now the weight of the packs should be close to your NiMH packs.

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murankar

murankar

Staff member
Chemistry not all that important, its the voltage you need to be concerned with. Just make sure the peak voltages are the same.

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9

97warrior_rider

Member
Hmmm interesting still not sure how I would figure this out its not necessarily capable of being used with a lipo charger that will read off voltage as it finishes out the charge cycle and even more so its not a typical brand battery that gives you some idea as to specs this thing has absolutely nothing on it other then the very basic 3.7v 600mah x2


Coty c
 
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