Scioly.org

Now that the rules are out, I'm trying to order classroom supplies that will likely be of particular use this year, and cost effectiveness is a priority. We have so many battery packs from experimenting with hovercrafts last year; I was disappointed to see the lithium ban (although it's certainly far safer this way) and the AA requirement.

https://www.amazon.com/AmazonBasics-Rec ... B00CWNMV4G This came up on a cursory google search - From the description, it seems as though this would be all you'd need for a year of testing and competing. Before I bought them though, I figured I'd ask if anyone has experience -

1. Any noticeable difference in performance between rechargeable and conventional AA batteries?
2. How quickly do typical hobby motors drain batteries? I recall rc cars from my youth die out very quickly, but that was a while ago...
3. For those who use rechargeables, are there any superior brands, or would they all tend to have similar output to the amazon batteries linked above?

Thanks for sharing any thoughts - good luck getting started!

SPP SciO wrote: 1. Any noticeable difference in performance between rechargeable and conventional AA batteries?
!

Wikipedia has a pretty nice page about AA batteries that explains the characteristics of the various cell types: https://en.wikipedia.org/wiki/AA_battery There is a significant difference between 'conventional' and rechargeable batteries.

SPP SciO wrote:Now that the rules are out, I'm trying to order classroom supplies that will likely be of particular use this year, and cost effectiveness is a priority. We have so many battery packs from experimenting with hovercrafts last year; I was disappointed to see the lithium ban (although it's certainly far safer this way) and the AA requirement.

https://www.amazon.com/AmazonBasics-Rec ... B00CWNMV4G This came up on a cursory google search - From the description, it seems as though this would be all you'd need for a year of testing and competing. Before I bought them though, I figured I'd ask if anyone has experience -

1. Any noticeable difference in performance between rechargeable and conventional AA batteries?
2. How quickly do typical hobby motors drain batteries? I recall rc cars from my youth die out very quickly, but that was a while ago...
3. For those who use rechargeables, are there any superior brands, or would they all tend to have similar output to the amazon batteries linked above?

Thanks for sharing any thoughts - good luck getting started!

Sorry for late notice, but I would recommend the EBL NIMH batteries. I use them for hovercraft. Though they are 1.2V and you can only have 8, you can overcharge them, or you can just have the 12v motor run on 9-10 volts. They are very good though for charging, and their voltage drop isn't very bad either.

Last year I found an article on line that rated several different alkaline batteries with voltage-time graphs for a given load. There was a major difference in their capabilities. Regular and HD carbon batteries are a waste of money if you want to be competitive.
If you are going to practice much, you will spend a lot on alkaline batteries. NiMH rechargeable is the way to go for that. There is a significant difference in the quality of NiMH batteries also. I have not found a site that does a similar rating, but with batteries from 3 different sources, there is a difference between batteries in each set. Some will not hold a charge ,some will not overcharge and a couple were just plain dead.
I have not noticed a big difference between the various lots.
NiCd batteries are not as capable as NiMH and have a safe disposal problem.
Saw NiZn batteries advertised yesterday. Initial reading is that they are not as good as NiMH, but I have not done enough homework to make a bold statement.
A good charger is a must have.

retired1 wrote:Last year I found an article on line that rated several different alkaline batteries with voltage-time graphs for a given load. There was a major difference in their capabilities. Regular and HD carbon batteries are a waste of money if you want to be competitive.
If you are going to practice much, you will spend a lot on alkaline batteries. NiMH rechargeable is the way to go for that. There is a significant difference in the quality of NiMH batteries also. I have not found a site that does a similar rating, but with batteries from 3 different sources, there is a difference between batteries in each set. Some will not hold a charge ,some will not overcharge and a couple were just plain dead.
I have not noticed a big difference between the various lots.
NiCd batteries are not as capable as NiMH and have a safe disposal problem.
Saw NiZn batteries advertised yesterday. Initial reading is that they are not as good as NiMH, but I have not done enough homework to make a bold statement.
A good charger is a must have.

Totally agree. My main problem is the 1.2v that they produce, if the trade off is worth it, to get faster times.

I agree that it is a problem. One way to overcome is to use a 3-6 V motor . One factor that affects speed is the battery's ability to allow a rapid use or discharge. It is an item in the choice of Li batteries , so it might apply to either or both alkaline and NiMH batteries.
Torque output of the motor and appropriate gearing will probably make a bigger difference for most at the state level.

Sorry for late notice, but I would recommend the EBL NIMH batteries. I use them for hovercraft. Though they are 1.2V and you can only have 8, you can overcharge them, or you can just have the 12v motor run on 9-10 volts. They are very good though for charging, and their voltage drop isn't very bad either.

[/quote]

So LiPO batteries are out too???

cheese wrote:

retired1 wrote:Last year I found an article on line that rated several different alkaline batteries with voltage-time graphs for a given load. There was a major difference in their capabilities. Regular and HD carbon batteries are a waste of money if you want to be competitive.
If you are going to practice much, you will spend a lot on alkaline batteries. NiMH rechargeable is the way to go for that. There is a significant difference in the quality of NiMH batteries also. I have not found a site that does a similar rating, but with batteries from 3 different sources, there is a difference between batteries in each set. Some will not hold a charge ,some will not overcharge and a couple were just plain dead.
I have not noticed a big difference between the various lots.
NiCd batteries are not as capable as NiMH and have a safe disposal problem.
Saw NiZn batteries advertised yesterday. Initial reading is that they are not as good as NiMH, but I have not done enough homework to make a bold statement.
A good charger is a must have.

Totally agree. My main problem is the 1.2v that they produce, if the trade off is worth it, to get faster times.

I don't see the downside with this plan. You can use 5 AA's to power a nice, high rpm 6V motor with great times, while also reducing the weight of the entire vehicle. What's the issue? It seems perfect to me. I did some calculations and its possible to get a very good time using a setup just like that.

sabacat wrote:

Sorry for late notice, but I would recommend the EBL NIMH batteries. I use them for hovercraft. Though they are 1.2V and you can only have 8, you can overcharge them, or you can just have the 12v motor run on 9-10 volts. They are very good though for charging, and their voltage drop isn't very bad either.

So LiPO batteries are out too???[/quote]

Yea.. lithium ban (as well as lead)

sabacat wrote:

Sorry for late notice, but I would recommend the EBL NIMH batteries. I use them for hovercraft. Though they are 1.2V and you can only have 8, you can overcharge them, or you can just have the 12v motor run on 9-10 volts. They are very good though for charging, and their voltage drop isn't very bad either.

So LiPO batteries are out too???[/quote]

Yes. You really should read the official SO Battery Policy: https://www.soinc.org/sites/default/fil ... _18_17.pdf