Max Amp Draw Battery Math


#1

So I’ve been looking into batteries and which is best blah blah. I thought that I’d made a pretty good choice with the Turnigy nano-tech and maybe for now they’re ok. I found it very interesting to compare the power to weight ratio with fluctuating C ratings and weight changes. So much so that I’ve made a simple spread sheet that i enter details into to help me understand what Im buying. Here’s my results for the nano-techs if anyone wants to check my math:

Full motor potential = 3480g pull @ 25Ax4 = 100A draw
My 20A ESCs = 2784g pull @ 20Ax4 = 80A draw ( i.e. 3480 x 0.8 )

Brand Capacity Ah Constant C Burst C Batt. Weight Con. P:W Bur. P:W
Turnigy nano-tech 1.0 45 90 124 3.46 6.15
Turnigy nano-tech 1.3 45 90 155 4.21 5.75
Turnigy nano-tech 1.6 25 50 172 2.78 5.56
Turnigy nano-tech 1.8 35 70 207 4.09 5.19

#2

This is probably not even remotely interesting to anyone other than myself, but here is some interesting comparisons… assuming my maths is correct.

Brand Capacity Ah Constant C Burst C Batt. Weight Con. P:W Bur. P:W
Turnigy nano-tech 1.0 45 90 124 3.46 6.15
Turnigy nano-tech 1.3 45 90 155 4.21 5.75
Turnigy nano-tech 1.6 25 50 172 2.78 5.56
Turnigy nano-tech 1.8 35 70 207 4.09 5.19
Tattu 45 1.3 45 58.5 163 4.14 5.38
Tattu 75 1.3 75 150 156.4 5.74 5.74
Tattu R-Line 1.3 95 190 164 5.65 5.65
Tattu 45 1.55 45 90 174 4.83 5.53
Tattu 75 1.55 75 150 180 5.47 5.47
Tattu R-Line 1.55 95 190 192.6 5.34 5.34
Tattu 45 1.8 45 90 199.5 5.27 5.27
Gens Ace 3.3 25 50 366 4.00 4.00

#3

These numbers are assuming that you have strapped you battery to a quad that weighs 325g (coz that’s what mine weighs in at without power)


#4

So looking at the numbers …

Brand Capacity Ah Price Constant C Burst C Batt. Weight Max Con. Max Bur. Pull Con. Pull Bur. Con. P:W Bur. P:W
Gens Ace 3.3 £44.79 25 50 366 82.5 165 2761.90 2761.90 4.00 4.00
Tattu 45 1.8 £20.75 45 90 199.5 81 162 2761.90 2761.90 5.27 5.27
Tattu 75 1.8 £22.17 75 150 198 135 270 2761.90 2761.90 5.28 5.28
Tattu R-Line 1.8 £32.93 95 190 196 171 342 2761.90 2761.90 5.30 5.30
Tattu R-Line 1.55 £30.44 95 190 192.6 147.25 294.5 2761.90 2761.90 5.34 5.34
Tattu 45 1.3 £13.12 45 58.5 163 58.5 76.05 2019.64 2625.54 4.14 5.38
Tattu R-Line V2 1.55 £32.89 100 200 187 155 310 2761.90 2761.90 5.39 5.39
Tattu 75 1.55 £21.89 75 150 180 116.25 232.5 2761.90 2761.90 5.47 5.47
Tattu 45 1.55 £17.49 45 90 174 69.75 139.5 2408.04 2761.90 4.83 5.53
Tattu R-Line 1.3 £25.93 95 190 164 123.5 247 2761.90 2761.90 5.65 5.65
Tattu R-Line V2 1.3 £27.94 100 200 163 130 260 2761.90 2761.90 5.66 5.66
Tattu 75 1.3 £17.94 75 150 156.4 97.5 195 2761.90 2761.90 5.74 5.74

I think the Tattu 75 1300 at £17.94 is the best value.
I draw that conclusion from the fact that it has the highest performance output for ‘Power:Weight’ and the cheapest price in that category.
Interesting to note that even if I upped my ESCs to support the full potential of my motors (ChaosFPVs), this battery would still be the best value. Even with the added power draw I still wouldn’t exceed the maximum draw from the battery’s continuous C rating.
Sooooo I guess it’s time to but a new set of ESCs too :slight_smile:


#5

Thanks for sharing the info, and I personally like tattu batteries, they are not the cheapest, but they do offer great performance, but more importantly they do last a long time (have a long cycle life)

You can get into alot of details when comparing batteries as other things to look for are voltage sag, as some of the cheaper battery bands have big voltage drops when you pull close to the maximum C rating… just as one example. But in general I have found gensace batteries have always been solid and are the brand we all trust (which is why we mainly only sell gensace batteries at our shop)