About batteries

[Lozart]

Motors don't work in C, it's dimensionless, they work in Amps and that would be a much better way.

Like quoting TPA for example instead of RPM. And quote motor torque not high low etc. All this sort of thing muddies the water if you want to compare things.

Most of Titans blurb is meaningless, some is just wrong. Even the bits that are in fact true are also true comparing lipos. 

Unfortunately most airsofters wouldn't know a Newton-metre if it stole all their apples.

While motors don't work in C they do respond differently when the supply current is governing their performance; if a battery can't supply enough current quickly enough then performance will suffer in an AEG because that initial spin up is where the motor will spend a lot of its time. It's less relevant in things like drones or RC planes because once you get the rotor spinning and you've overcome that moment of inertia then the motor can settle into a fairly consistent running current. Once you reach that "steady" state then the capacity calculations etc make more sense because your load behaves more like the graphs that battery manufacturers like to throw around. Even when you run an AEG in constant full auto, the load is never stable. Every cycle the gears have to compress the spring and then it releases so the load comes off the motor. The current draw is never smooth and the battery's ability to deliver a lot of current quickly becomes more important than the mAh rating as long as it is sufficiently high. 

 

[Sewdhull]

Drone currents vary by a magnitude compared to airsoft.

We either have semi or auto. Semi draws more power for a shot, requiring more current as the motor starts from 0 RPM.

Auto is a varying load for sure but cells don't mind that if it falls within their specs.

For sure mAh rating is less useful than the current the battery can supply, and you'd need to do power calculations to estimate battery life. Way easier to get a pack and see how long it lives ( For me it only needs to last half a day, I can change it at lunch.

For me, I use the largest batteries (physically) that will fit in my gun, current being more important than capacity. I have a couple of watt meters so i can see what my  load is and therefore what type of cells I can get away with.

My preference is Lithium iron Phosphate (Life), then Cylindrical cells, then Lipos. When I flew drones weight was an issue so they are all Lipo. I have some enormous packs, now in ammo boxes.

I'm leaning towards 12.8v Life packs if they will fit, because they are so forgiving in use, last a really long time and supply good current, the voltage not being as high as the 12.8v 4 cells would give you because as we have seen in tis thread, voltage drops quickly and stays at a level for a good while before the battery is exhausted. However, often there isn't enough room for such luxuries.

 

[Lozart]

I'm leaning towards 12.8v Life packs if they will fit, because they are so forgiving in use, last a really long time and supply good current, the voltage not being as high as the 12.8v 4 cells would give you because as we have seen in tis thread, voltage drops quickly and stays at a level for a good while before the battery is exhausted. However, often there isn't enough room for such luxuries.

Where are you finding decent LiFe stick packs? They were all the rage for airsoft a few years back but most places only seem to have one or two choices these days (or are you repurposing RC packs?)

 

[Dan Robinson]

. Every cycle the gears have to compress the spring and then it releases so the load comes off the motor

Would be fun to see that on a sillyscope

RE - Moment of inertia and steady state - one of my drones has nearly 12" blades and the thing weighs a few KGs.  I'd guess there is a fair impact with a rapid speed and direction change.  You should see the pitch change when it tries an emergency stop from 40ish miles an hour.  I had a very squeeky bum when it was avoiding a massive oak tree once after chasing a dirt bike across a field LOL.

 

[Sewdhull]

Even those little drones draw some mighty amps at fully throttle as they whizz about.

You'll see 70C or even 100C packs being used. There's some tests online you can Google.

Where are you finding decent LiFe stick packs? They were all the rage for airsoft a few years back but most places only seem to have one or two choices these days (or are you repurposing RC packs?)

I use xt connectors, because they are better so I don't need to repurpose anything, Nuprol do some life packs, I have one and it's fine.

https://www.tactical-clothing.co.uk/product/nuprol-np-power-1100mah-99v-20c-li-fe-slim-stick-type-battery-216629?gclid=CjwKCAiAjfyqBhAsEiwA-UdzJDECrsOk5S3L-TZEarDw3YC1QjQkIYJuQ9zcAi3Kpuk0A0wBlpJ8LBoCUkEQAvD_BwE

 

[Sewdhull]

Vapex and Nuprol packs look the same, because the voltage is lower motors won't pull as much current from a 3S life Vs a 3s lipo or lion.

However I haven't used the life's much, as I just have the one for testing.

I'll measure some of my batteries and let you all know what they are like.

 

[Sewdhull]

Would be fun to see that on a sillyscope

RE - Moment of inertia and steady state - one of my drones has nearly 12" blades and the thing weighs a few KGs.  I'd guess there is a fair impact with a rapid speed and direction change.  You should see the pitch change when it tries an emergency stop from 40ish miles an hour.  I had a very squeeky bum when it was avoiding a massive oak tree once after chasing a dirt bike across a field LOL.

Your wish etc

http://www.airsoftlab.eu/docs/experiments/motor_current/

 

[Lozart]

Even those little drones draw some mighty amps at fully throttle as they whizz about.

You'll see 70C or even 100C packs being used. There's some tests online you can Google.

I use xt connectors, because they are better so I don't need to repurpose anything, Nuprol do some life packs, I have one and it's fine.

https://www.tactical-clothing.co.uk/product/nuprol-np-power-1100mah-99v-20c-li-fe-slim-stick-type-battery-216629?gclid=CjwKCAiAjfyqBhAsEiwA-UdzJDECrsOk5S3L-TZEarDw3YC1QjQkIYJuQ9zcAi3Kpuk0A0wBlpJ8LBoCUkEQAvD_BwE

I have no doubt that they draw high currents, I was more suggesting that the load is less peaky.

 

[Sewdhull]

Yeah I understand, I wasn't clear.

It's not as frequent as auto fire for example, but the loads will go from zero to 100% as the drone races around. Batteries only last 3 or 4 minutes.

Our Airsoft batteries are pretty poor by comparison.

 

[Sewdhull]

Here have a look at this battery.

https://www.quadcopters.co.uk/lipo-batterys/3s-lipo-batteries-111v/tattu-1550mah-111v-3s-75c-lipo-battery-2114

I'm unsure why our Airsoft batteries are so poor.

I realise it's out of stock.

 

[Dan Robinson]

I'm unsure why our Airsoft batteries are so poor.

3kG airsoft gun gets dropped worst case scenario is a black toe and possible broken pewpew.

3kG of quadcopter dropping 300m out of the sky with 4 12" spinning blades = dead squishy human.

Just checked - my Inspire 1 does 50mph...

 

[Sewdhull]

That battery is 15 GBP from techshop.

I don't think it's about reliability. 

Airsoft doesn't need the great performance drones do, but there's no excuse for the offerings in Airsoft at the price they are offered at.

I suppose it's because people buy them.

 

[Lozart]

I suppose it's because people buy them.

Hit the nail on the head there.

Let's face it, that's how Nuprol/Vorsk/Raven et al have been in business for as long as they have.

 

[Sewdhull]

View attachment 119607

Here's a selection of my batteries, Airsoft at the bottom. They have all been bought for different applications, the 2 big green ones are spares for large drones I've built in the past, some for electric planes. The big ones were used in pairs and didn't need a high C in the large drone they were used for. The 2 batteries supplied 200A.

When I came back Airsoft, Hobbyking had stopped trading so I got some of what was on offer, it wasn't good .

The green 2.2s are 30C and 40C 11.1s, they might fit in a stock.

The .95 nanotech is for an aep, I have one with the pack split to fit. It's a 25C battery.

Just incase anyone's interested.

 

[Rogerborg]

Let's face it, that's how Nuprol/Vorsk/Raven et al have been in business for as long as they have.

But they're reputable brands!