Only two parameters rule a Pack choice for optimum Powerplant performance :

- Specific Power (Power / weight)

- Specific Energy (Power x Time / weight) mainly required for racing reasons

Its cells-count makes the equation more complex considering the wide diversity of cells available. Note also that the Batt is only one part of the complete Power Chain !

 

Most people use to compare Capacity for a given number of cells or Capacity will not give you the power available and even if it gives it to you, the fixed number of cells does not allow you to reach the optimal performance of your motor !

Higher capacity cells is mainly a commercial approach of performance that was comforted by fixed cells-count on most competitions. ESC car market is logically ruled by this fact as a mature market. To simplify, this allow the most simple market control you can imagine : Only one parameter that rules the game. How many dollar do you want to go fast ? Just pay for Amp ! Quite scrimpy in fact ...

Keep also in mind that a low weight/power ratio is critical to get the best of your powerplant !

Running a car that is 20% less heavy let the motor sucking at least 20% less power (with no rotating mass !) so for a given number of cells, less Amp. This less Amp let you use a lower Total Energy battery so a lighter one (lighter tank) ... so your car is even more performant. it's all about comparing a motorcycle with a truck! You'll know why I consider some entry-level motorgliders as a small engine car tracting a mobil home !

Keep also Power available as high as possible if you want excellent acceleration of the car. More HP doesn't mean higher consumption on all conditions but simply the capability to accelerate quickly, as do a 30HP/160Kg Racing motorbike

Some simulation will give you that higher available Amp / Lower cells count Ni-Cd are best (with very few Ni-Mh that really hold the Amp) ... But the motor itself possible efficiency breakdown at Hi-Amp is also to consider ! Ferro motors actually ruin such an approach.

The Hi-Amp / Low cells Count (Low Voltage) combo is best when using motors that supply excellent efficiency at Hi-Amp ... Only Samarium-Cobalt and Neodym designs offer such a performance level. Keep in mind that Ferro B/Ls are far from this.

Ferro motors actually can't reach a decent efficiency at Hi-Amp even if their price tag is huge ! Prefer for them a lower Amp / Higher Voltage combo for max performance. At this game, Ni-Mh packs can be good if the extra Total energy is useful to you (longer runtime) ...

This is the reason why I used various Capacity and cells count batteries on my projects depending on the motor choice, the anticipated runtime and the targeted whole vehicle performance !

 

Car Examples

Considering a 1:10 vehicle, most people follow commercial tips, to say very short winding motors (10T-12T) and Huge capacity cells. Some of them understood that only first-quality cells offer the extra Amp required, whatever their given capacity. Note racing class only allow 6 cells packs and Ferro motors

Actually, some longer winding motors overperform this combo, even if considering similar Ferro magnets. The fact is these motors waste most of their energy under heavy Amp, so a higher Voltage / Lower Amp is noticeably better

Prefer 8x 1300CP or 1600CP cells along with a 15T-19T motor ... Those cells deliver slightly less Amp and less capacity ... Their weight will be as low or even lower than a 6 cells pack that stands nasty winding motors

 

For extreme sport, first choose a good performer motor and then adapt the pack in order to deliver enough power than required by the motor but no more : This let your ride very light and still easy to drive

The left example shows you a Plettenber Neodym motor that offers 80% efficiency under 8-cells and 50A ... So about under 400W input and more than 300W output ... Some 2400MAh cells were be heavier but not that more powerful ...

Remember that best racing Ferro 05-can motors only offer 200-240W output under 300W input ... The left example is far from what can be seen during 1:10 racing events ...

Is there's a similar combo on a heavier car

10x1250SCRL cells and the same Plettenberg powerhouse

The Hirobo Alien Mid4 gear drive hold the extra power ... This superior power offered to the old Buggy a very decent power/weight ratio even if running it compared to a nowadays 4WD could be described as running a Racing truck compared to a dune buggy !

 

A supert sport combo can be achieved on a budget with just a larger can motor ...

There, a Mabuchi 700 motor was used along with a light 12-cells pack in order to deliver drag-like performance. Neodym magnets can be a right option if you like extra acceleration and runtime

2/3 cells can do the job as for higher juice 1250SCRL or 1600CP cells

Note that only a good quality BEC device can be used along with 12cells. If not available, please prefer an OPTO isolated ESC with no BEC and add an RX battery

500AR for up to 20A

140g for up to 140W

80g for Fast charge RX supply

For some light airplanes or separate Rx units, I also use a tiny 4x 110AA cells pack that weights only 30g

Such a pack actually require many more care in order to not damage it with an over-rated charge or discharge.

My 500AR based Rx packs proved to be far more convenient than their slow charge conuterparts

Ni-Mh cells are another solution to consider but with a dedicated charger that you can let overnight, not charging your cells 1 hour before the run !

800AR for up to 30A

240g for up to 200W

The Amp you read there in what can be measured at max throttle continuously. It doesn't mean the peak Amp the motor sucked during a transition !

Car ESCs actually communicate Peak Amp and now won't go back and reset their "marvelous numbers" to more practical ones such as these. Please don't be fooled by any Car ESC data !

The left example was a classical Battery choice for 7-cells Ferro powered racing motor-gliders. This unit can empower a 900-1000g FE boat as well with say a 20T to 17T motor depending on the prop and boat setup

Who said that Cell packs are only a Fuel tank ?

1300CP - 2/3 for up to 35A

285g for up to 280W

8x 1300CP batts : Those provide extra-Rpm for 1/10 cars along with a medium winding ... Example : Along with a 17T motor on a Tamiya TB-01 ...

Note the pack weight is actually less than a classical 6-cells pack ...

This one was soldered in line with a T-type iron and equipped with 4mm female plugs. A gold-plated bridge joins the 2 rear cells as well

800AR costed 19FF each June 2000 at Euromodel French Shop. Their price tag dramatically increased once they were repackaged by Sanyo ... Did you say business ?

430g for up to 420W

12x 2/3 cells can be seen as the same cells after Sanyo repackaging

Their internal resistance made them ok if used with 05-cans but not a good choice for higher power motors

The compact arrangement of the left actually makes heat dissipation more difficult (cells radiate themselves) so prefer a lower internal resistance if big power is required !

1250SCRL - 1600CP for up to 45A

370g for up to 360W

8x 1600CP batts can be seen as a 1250SCRL improvement. Similar internal resistance and 300 extra MAh capacity are the key data to keep in mind

Logically they're longer than their 1300CP counterparts

The following pictures present my favourite packs. The 1250SCRL cells proved to be very competitive and easy to arrange.

They typically allow Speed700 use if correctly bridged and offer enough runtime for me : As mentionned above, an optimized vehicle actually can run the same time with a lower capacity pack

Once said, I understand easily why people prefer classical 2000RC sized cells

345g for up to 360W

430g for up to 450W

520g for up to 540W

1700SCR - 1700RC for up to 60A

extra 285g for up to extra 300W

Here's the Neodym battery place !

I actually kept 1700mAh as a limit due to my 3A charger but 2000RC are now similarly priced and generally offer a slightly improved internal resistance

Large bridges, wires and connectors are a must have there if you REALLY use them for what they are supposed to be

The rcsaga.com Connector page gets it resumed for you

As previously explained, these batteries offer best power/weight ratio than their lower capacity counterpart. With the E-powerplant as a complete chain, keep in mind that only good motors can actually let you exploit this advantage

 

455g for up to 480W

450g for up to 480W

690g for up to 720W

Final thoughts

WHO said that a Battery pack was only a Fuel tank affair ??

E-power is a chain so its optimization or reliability actually relies on each element : The cells, their bridges, the wiring, the connectors, the ESC, the motor have all to be correctly scaled together in order to not ruin any performance or even operation !

Can an engine ruin a Fuel tank, fuel tubing or a carb ? Surely not !

Misunderstanding of E-power chain actually deserved its use and keep many people in some Nitro addiction ... Knowledgeable Vendors still are not that common and crap stuff is still selled as basic

Please, get rid off your Tam plugs, sticker-powerful ESCs and lazy sport packs and have a second look to your stuff. Your R/C motorsport fulfillment first relies on it !