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Why are battery capacities so large these days?

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Why are battery capacities so large these days?

Old 03-04-2020, 07:13 AM
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Default Why are battery capacities so large these days?

Hi folks. Old school racer here so I'm well used to NiCd and NiMh battery use over the years and struggling to get a complete run out of 2000maH cells! I have recently gotten back into RC and see really big capacities, 8000+ maH for example. Personally, I'm using 3200 shorties in my car as that's all I can actually fit (2004 Losi JRXS). They work fine, I notice maybe a very slight voltage drop towards the end of a run.

But really, why are modern batteries so large? Is it really worth carrying around a lot of extra weight for the 'benefit' of an extra 3000 odd maH that you're never, ever going to use? Is it purely about 0 voltage drop? I've wondered this since I started back a few months back, just wondering if I'm missing something, and I'm all about learning and understanding things so any input is appreciated!
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Old 03-04-2020, 07:30 AM
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See the thread next to this one, "Running shorties in a TC"... it covers the pros/cons of big vs small lipos.
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Old 03-04-2020, 08:00 AM
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Originally Posted by Andy_F View Post
Hi folks. Old school racer here so I'm well used to NiCd and NiMh battery use over the years and struggling to get a complete run out of 2000maH cells! I have recently gotten back into RC and see really big capacities, 8000+ maH for example. Personally, I'm using 3200 shorties in my car as that's all I can actually fit (2004 Losi JRXS). They work fine, I notice maybe a very slight voltage drop towards the end of a run.

But really, why are modern batteries so large? Is it really worth carrying around a lot of extra weight for the 'benefit' of an extra 3000 odd maH that you're never, ever going to use? Is it purely about 0 voltage drop? I've wondered this since I started back a few months back, just wondering if I'm missing something, and I'm all about learning and understanding things so any input is appreciated!
Ahhh, the Sony SCR days, I remember them well. Trying to make 4 mins before they dumped hard on the last couple of laps. Good times.

Anyway, its mostly about voltage drop during a run. Larger battery capacity means a nice flat voltage level during a run from the 1st to the last lap. The real question is why do we only run for 5, 6 or 7 minute mains. We could easily go for at least 10. I'm an old 1/8 nitro guy and mains were always at least 15 mins, enough time to make up for a mistake which I was usually good for. Electric you make a mistake and your done.
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Old 03-04-2020, 08:16 AM
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Originally Posted by Andy_F View Post
Hi folks. Old school racer here so I'm well used to NiCd and NiMh battery use over the years and struggling to get a complete run out of 2000maH cells! I have recently gotten back into RC and see really big capacities, 8000+ maH for example. Personally, I'm using 3200 shorties in my car as that's all I can actually fit (2004 Losi JRXS). They work fine, I notice maybe a very slight voltage drop towards the end of a run.

But really, why are modern batteries so large? Is it really worth carrying around a lot of extra weight for the 'benefit' of an extra 3000 odd maH that you're never, ever going to use? Is it purely about 0 voltage drop? I've wondered this since I started back a few months back, just wondering if I'm missing something, and I'm all about learning and understanding things so any input is appreciated!
Technology, baby! Today's Lipo's make our old nickel based batteries look silly. And lipo's are way lighter than your average 6 cell pack.
Originally Posted by sugs View Post
Ahhh, the Sony SCR days, I remember them well. Trying to make 4 mins before they dumped hard on the last couple of laps. Good times.

Anyway, its mostly about voltage drop during a run. Larger battery capacity means a nice flat voltage level during a run from the 1st to the last lap. The real question is why do we only run for 5, 6 or 7 minute mains. We could easily go for at least 10. I'm an old 1/8 nitro guy and mains were always at least 15 mins, enough time to make up for a mistake which I was usually good for. Electric you make a mistake and your done.
Batteries that didn't last kept motor technology in check. Once the capacity went high enough, motors went nuts.

Every time I bring up running longer races, I get my butt handed to me


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Old 03-04-2020, 08:16 AM
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Originally Posted by Andy_F View Post
Hi folks. Old school racer here so I'm well used to NiCd and NiMh battery use over the years and struggling to get a complete run out of 2000maH cells! I have recently gotten back into RC and see really big capacities, 8000+ maH for example. Personally, I'm using 3200 shorties in my car as that's all I can actually fit (2004 Losi JRXS). They work fine, I notice maybe a very slight voltage drop towards the end of a run.

But really, why are modern batteries so large? Is it really worth carrying around a lot of extra weight for the 'benefit' of an extra 3000 odd maH that you're never, ever going to use? Is it purely about 0 voltage drop? I've wondered this since I started back a few months back, just wondering if I'm missing something, and I'm all about learning and understanding things so any input is appreciated!
Hi Andy,

Welcome back to the hobby. Battery tech has evolved quite a lot over the past few years and with it the hobby.

For us here in Brunei, we use the 8,000 and 10,000mah batteries for endurance races. It allows us to run EP races for hours on end and extends racing possibilities.

No longer will a crash or spin put you out of your final, you have a whole hour to make up positions and fight your way back to the top. We also have to deal with mechanical issues, poor battery management issues, as well as tyre and driver changes. We run 13.5 turn stock for these races and alternate between 1/10 TC cars or M-chassis. An 8,000mah pack allows you to drive over an hour with our current set up.

The last race we had was just last weekend. It was using the M-chassis and the race ran for two hours. We had two drivers for each team and at least one mandatory pitstop. Motor temps were easy to control as it was a night race and the winner clocked 300+ laps in the race. A lap was approximately 23 seconds. The nitro guys can no longer boast that nitro provides more run time.



This is my setup running 8000mah GNB batteries. We pitted on the hour mark for our first stop and made a second pitstop after 40 minutes of running. Our seccond battery is a 6,400 Sunpadow. When we made our second pit stop, it still had not reach our ESC cutoff of 3.4volts.




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Old 03-04-2020, 08:26 AM
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Part of it come out to weight, too. Once battery capacity AND chemistry has gotten to the point that you're getting little or no voltage drop through the run, you STILL need enough weight make legal weight AND to balance the chassis. A 300ish gram battery seems to be just about the sweet spot in TC chassis right now.
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Old 03-04-2020, 08:58 AM
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This is a short clip of our endurance race.


It is quite fast as we are not undergearing the cars. 13.5 turn motor with 3.8fdr. Granted this was M-chassis at the time so it was 2 wheel drive but still a testament to modern battery, motor and esc tech.

We have been running races like this since last year and the batteries are still in great shape. Mine hasn't swelled and stilk has punch and holds charge well.


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Old 03-04-2020, 11:09 AM
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Originally Posted by tak4 View Post
Hi Andy,

Welcome back to the hobby. Battery tech has evolved quite a lot over the past few years and with it the hobby.

For us here in Brunei, we use the 8,000 and 10,000mah batteries for endurance races. It allows us to run EP races for hours on end and extends racing possibilities.

No longer will a crash or spin put you out of your final, you have a whole hour to make up positions and fight your way back to the top. We also have to deal with mechanical issues, poor battery management issues, as well as tyre and driver changes. We run 13.5 turn stock for these races and alternate between 1/10 TC cars or M-chassis. An 8,000mah pack allows you to drive over an hour with our current set up.

The last race we had was just last weekend. It was using the M-chassis and the race ran for two hours. We had two drivers for each team and at least one mandatory pitstop. Motor temps were easy to control as it was a night race and the winner clocked 300+ laps in the race. A lap was approximately 23 seconds. The nitro guys can no longer boast that nitro provides more run time.



This is my setup running 8000mah GNB batteries. We pitted on the hour mark for our first stop and made a second pitstop after 40 minutes of running. Our seccond battery is a 6,400 Sunpadow. When we made our second pit stop, it still had not reach our ESC cutoff of 3.4volts.
How about tire change, how often? I wonder if the tire duration can coincide with the lipo, that would be perfect.
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Old 03-04-2020, 11:57 AM
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Originally Posted by sugs View Post
Ahhh, the Sony SCR days, I remember them well. Trying to make 4 mins before they dumped hard on the last couple of laps. Good times.

Anyway, its mostly about voltage drop during a run. Larger battery capacity means a nice flat voltage level during a run from the 1st to the last lap. The real question is why do we only run for 5, 6 or 7 minute mains. We could easily go for at least 10. I'm an old 1/8 nitro guy and mains were always at least 15 mins, enough time to make up for a mistake which I was usually good for. Electric you make a mistake and your done.
Regarding run times, we just had a 'Championship' race day at NORA this past weekend and ran 10 minute quals with 15 minute mains (F1, 21.5 2S World GTR, Euro Trucks, and USGT) , and the only people that had problems with run time were the folks running very old 3000mah batteries, or under 3000mah batteries. I think the primary reason we are still running short heats is because of overall time. A normal raceday will see us getting out of the track at 6PM or later. bumping each heat to, say, 10 minutes, would add an hour to the race day at minimum but more likely upwards of 3 hours. we only ran 4 classes on Sunday, and those long heats resulted in a race day that was as long as a typical race day with 8 classes represented.

Personally, I'd like to see fewer classes that are running longer heats. I find that as I settle into a long run I get better and I like the challenge of being on the stand longer. I don't leave many club days with TQ and 1st, but I left Sunday with both in 2 of the 3 classes I ran.
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Old 03-04-2020, 05:50 PM
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Originally Posted by b20btec View Post
How about tire change, how often? I wonder if the tire duration can coincide with the lipo, that would be perfect.
For my team, we decided not to go with a proper tyre change during the race. What we did was cross the tyres at the one hour mark, along with our first battery change, as the front was wearing out quicker than the rear. I don't think the tyre crossing helped much in terms of grip but we wanted to even out tyre wear and prevent any ring of death situations.

Some other teams also changed tyres at the one hour mark. I know the eventual winners planned to change tyres at the one hour and thirty minute mark but i can't confirm this as I was racing at the time.
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Old 03-05-2020, 12:08 AM
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Thanks for the input everyone. Interesting reading your experiences! I should have probably mentioned that I run 5 minute races, so it seems for races of this length it's fairly pointless going for a huge capacity. I'm currently using 3200 shortys with 12-14 turn brushed motors at the moment (also working on a full brushless version of my second JRXS chassis so I can race in some proper events but still use the cool old chassis) which uses around 2500maH in a 5 minute race.

I hadn't even thought that electric endurance races were a thing, that sounds fun. I had read the post about running shortys, which inspired me to make this post to see if i could understand why more people don't seem to do it. I just kinda thought (unless you're running really long races obviously) that a lighter battery which gives you the flexibility to put the rest of the ballast exactly where you want it would have been more favourable.
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Old 03-05-2020, 04:49 AM
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Originally Posted by tak4 View Post
This is a short clip of our endurance race.

https://youtu.be/am9_vV1v6bk

It is quite fast as we are not undergearing the cars. 13.5 turn motor with 3.8fdr. Granted this was M-chassis at the time so it was 2 wheel drive but still a testament to modern battery, motor and esc tech.

We have been running races like this since last year and the batteries are still in great shape. Mine hasn't swelled and stilk has punch and holds charge well.
How did you gear the m-chassis at 3.8? The Tamiya minis are around 5.8.
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Old 03-05-2020, 04:57 AM
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Originally Posted by Andy_F View Post
Thanks for the input everyone. Interesting reading your experiences! I should have probably mentioned that I run 5 minute races, so it seems for races of this length it's fairly pointless going for a huge capacity. I'm currently using 3200 shortys with 12-14 turn brushed motors at the moment (also working on a full brushless version of my second JRXS chassis so I can race in some proper events but still use the cool old chassis) which uses around 2500maH in a 5 minute race.

I hadn't even thought that electric endurance races were a thing, that sounds fun. I had read the post about running shortys, which inspired me to make this post to see if i could understand why more people don't seem to do it. I just kinda thought (unless you're running really long races obviously) that a lighter battery which gives you the flexibility to put the rest of the ballast exactly where you want it would have been more favourable.
The downside to running a light battery and adding weight where you want it, is that weight is dead weight. Using a heavier battery gives you a higher average voltage towards the end of the run. It's a trade-off.
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Old 03-05-2020, 10:23 AM
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Originally Posted by gigaplex View Post
How did you gear the m-chassis at 3.8? The Tamiya minis are around 5.8.
Most of us run the ABC Gambados/Grid here and it allows for some pretty aggressive gearing. We also have a few Sakuras and they are just as fast which suggest similar fdrs.

Here is the gearing chart for the Gambado.


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Old 03-07-2020, 04:53 PM
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We have run a class which is called GT500. We use a USGT body, a 21.5 motor and regular touring car tires. It is a team event. We have battery changes and we switch drivers. One teammate always has to turn marshall. The race lasts over 2 hours. We have won the event twice. It is by far, my most favorite event of all time. It has a much different feel as it is a team event. We have even run this type of event as a 150 lap event on 2 man teams. We have also run this endurance type of event as a single driver event for a 50 lapper. So much Fun! The 21.5 motors do not deplete the batteries as much as lower turn motors. It brings a new dynamic to an event aka strategy.... I wish this would take off...………….
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