25C or 35C

[mcmxii]

Hi guys, what lipo discharge do you recommend for a average edf jet of say <64mm? Not very sure if the average plane needs a high performance of a 35C lipo

The price different for a 2100 25c vs 2200 35c is about $15

[brownie]

Hi guys, what lipo discharge do you recommend for a average edf jet of say <64mm? Not very sure if the average plane needs a high performance of a 35C lipo

The price different for a 2100 25c vs 2200 35c is about $15

price differs only $15? i would buy the 35C.
however, the general guideline is 2.1x25c =52.5amp and 2.2x35c = 77amps.
does ue edf draw more than 50 amps? if yes the latter one should fit ur operating requirements.

[blueangel]

price differs only $15? i would buy the 35C.
however, the general guideline is 2.1x25c =52.5amp and 2.2x35c = 77amps.
does ue edf draw more than 50 amps? if yes the latter one should fit ur operating requirements.

Try to factor in another 20% of amperage drawn for EDF.
So at 80% maximum to protect the lipo, useable amp should be around :

2100 / 25C = 42 Amp max
2200 / 35C = 62 Amp max

Trying to get a Lipo to perform close to its specification will probably make it bloat.

A 1800 / 30C will also be comparable to the 2100 / 25C
1800 / 30S = 43 Amp max.

[edmond22]

Try to factor in another 20% of amperage drawn for EDF.
So at 80% maximum to protect the lipo, useable amp should be around :

2100 / 25C = 42 Amp max
2200 / 35C = 62 Amp max

Trying to get a Lipo to perform close to its specification will probably make it bloat.

A 1800 / 30C will also be comparable to the 2100 / 25C
1800 / 30S = 43 Amp max.

Dude. I dun calculate this way.

Generally people use 80% of the capacity, not the max discharge capability. I use max discharge and even burst very very regularly for a few years now and reputable brands batts do not bloat on me yet. Even the HC ones like flightmax will give you pretty good performance.

I would say keep the max draw to 80% of capacity and monitor the heat. The remaining 20% has the most resistance build up which causes heat and that is what kills the batts. Feel free to do burst draw so long as you do it earlier in the flight and keep it within reasonable timing and specs. Otherwise if you keep to 80% draw, it would be quite boring to fly.

I would say go for 35c. EDF has less cooling on batts generally, you want batteries that doesn't break sweat too easily.

[Sunstorm]

Dude. I dun calculate this way.

Generally people use 80% of the capacity, not the max discharge capability.

Wish to clarify. Let's say we have a 3 cell 2200 aH batt rated at 20c. So what you're saying is that in our flight runs, I'll just use up about 1600 - 1800 mah in order to keep the batts nice and cool, yeah? So occasional bursts of high speed drawing about 50 amps should be ok provided we keep within the discharge ratings and capacity usage recommendations?

[edmond22]

Wish to clarify. Let's say we have a 3 cell 2200 aH batt rated at 20c. So what you're saying is that in our flight runs, I'll just use up about 1600 - 1800 mah in order to keep the batts nice and cool, yeah? So occasional bursts of high speed drawing about 50 amps should be ok provided we keep within the discharge ratings and capacity usage recommendations?

Yes, use up to 80% of the capacity which is about 1760 of 2200. For planes, I do that, for heli I use only 75% because of the governor function, I keep some buffer as the draw is not as consistent as planes.

For bursting, that is fine, just dun burst beyond spec. For the hotliner people, they are drawing something like 250 amps using neumotor and CC180 esc. The TP batts they are using are capable of 60c burst of about 270amp max. The hotliner will draw 250 amp for 3-4 seconds, stop motor, fly, burst 3-4 seconds again as a cycle. They can do this on and on for near 80% of the batt capacity and then land. Just search for any F5B competition video and see. Mostly, they will kill the esc first than batteries, the cooling holes made are usually for esc too than batteries.

It is the same for Heli. When you are on governor mode, you are essentially giving your esc the mean to govern the hs for you. As long as the esc does not go into overamp or heat protection, it will throttle up as much as it needs to keep HS you want. So when you load it doing tic toc for 10 seconds, you may be already taxing your batts bursting it unknowingly already. So people often complain that doing 6s for 50 size heli is kinda hard on the batts, and some will go higher S route to get the same or more power in watts and less amp.

[Lplate]

Very educational. Thanks Edmund22