Getting started, what do I need?

[grant_ploughbot]

Getting started, what do I need?

Yer they give out 5Ah more than standard sanyo Ni-Hm cells i beleive.

Oh hmm, okie wel thats kinda funny coz someone confused me there, so then the higher ampaere batts should be best to buy? am i correct in thinking and should weigh in at slightly more due to the extra stuff inside (im not an expert on what makes upo the weight lol)
Grant

[fwsorg]

Getting started, what do I need?

Its all to do with the chemistry inside- more electrolyte layers inside and so on. The weight fluctuates a bit but by very little. You can pretty comfortably say that Sub-C cells all weigh pretty much the same, or at least the variations arnt too big.

Its the chemistry that makes the difference. Traditionally Ni-mhs have a larger capacity that Ni-cds, and they dont suffer from memory effect so much. However Nicads can be discharged faster (i.e. you can pull higher currents from them) than Ni-mh. Thats quite a black and white way of looking at it, and thanks to advances in technology we have got to the point that some Nimhs cells are beginiing to outperform similar Nicd cells in terms of discharge rate, thus pushing Nimh into the lead so to speak :-) A case in point are the recently launched 2600SCU nimh cells, which are said to outperform the RC2400 cells (nicd), as well as having the obvious advantage of higher capacity.

As for the Nimh not getting warm, it depends on what youre doing with them. If you start pulling more than about 45A they start to get pretty warm. This is the point where having them spaced pays dividends. General word of mouth rates them at 45A continuous, 60A for a short time. The RC2600 cells, by the same token, are said to be good for 60A continous and 100A for a short time. Its all just a question of looking at whats best for your application.

[gizz]

Getting started, what do I need?

Have i got this right, do i only need about 2,6 Ah batteries in a FW?

[Guest]

Getting started, what do I need?

Yes, if theyre Ni-Cd or Ni-Mh cells.

[fwsorg]

Getting started, what do I need?

You can get away with even less. If its not a particularly current thirsty robot (which would suggest a simple drive and non-electric weapon, ed flipper) then small er batts will do. I know of Feather Flippers that have been running 1300 packs quite happily (although personally I wouldnt want to go beneath 1700)

[gizz]

Getting started, what do I need?

OK that sounds nice, what AH would i aprox need if i go for SLA batteries?

[stu]

Getting started, what do I need?

Depending on your drive and weapins.
I would suggest NOT to go below 2.8amp. You may get away with 2.1amp depending on your drive and setup etc, but 2.8amp is the average and safest.

Mr Stu

[geoff]

Getting started, what do I need?

How do you guys get away with using so little power in your machines? Scorpion Jr. with the new upgrades now needs at least 6Ah worth of NiMH just to see it through a 4 min. battle and even then its touch and go!:sad:

[Guest]

Getting started, what do I need?

Ahh but, Sir Chairman, Sir (Congrats btw), most people dont have a kin nasty great disc, spinning at n rpm on the back, do they?

Bob.

[maddox]

Getting started, what do I need?

Geof, TAN used 8Ah, and now 9Ah SLA, are you sure the electrics in Scorpion Jr are ok? No short cirquits anywere?

[galexa9308]

Getting started, what do I need?

Thanks for all the replies, sorry Ive not acknowledged the responders before now, but were just in the proccess of selling our house, and its gone a bit mental, so Ive not been online for a bit. In reference to Geoffs comments re safety, how do you guys go about testing out your bots? Obviously drive testing isnt too major an issue with feathers, but what about weapons testing? I dont think Ill be going for a spinner myself (at least not yet), but your comments and advice are certainly encouraging, so once the move is out of the way, Ill be putting some effort into putting a chassis together. Thanks again for taking the time to reply

regards

Graham

[fwsorg]

Getting started, what do I need?

Ill be perfectly honest, I go out from the garage and hide behind a sheet of poly and start smashing things up. We dont live on a built up street tho, so I have quite large area of drive that i can play on. The more standard solution is to boldly drive out and find a good flat, quiet parking lot or someother good flat space. As long as there arnt any people around, youre onto a winner.

[gizz]

Getting started, what do I need?

Ok, I have been thinking of using 2 fanmotors from personal cars as drives and those Electrolise speedcontrollers and I am wondering on how much Ah you think a good SLA batteri that will need? Im not planning on using any weapons yet as it will be my second robot, I´ll build an Ant first when i get the R/C

[fwsorg]

Getting started, what do I need?

The fan motors use a lot of juice and are quite heavy, plus i think theyre times slightly, which means theyre designed to spin faster in one direction that the other. This is less than ideal as im sure you can appreciate. I would be tempted to go for something like 4 drill motors 9one on each wheel) for a decent pushy rambot. SLAs? as large as you can fit in the design and weight. Bigger batts mean not only longer run times but faster acceleration and faster turns. So go for ones as large as you can get.

[grant_ploughbot]

Getting started, what do I need?

the only problem i found with SLAs, is that if you go very large, you may end up having to build your robot around your batteries! And then if you do ever upgrade you have this HUGE space of nothing, and i personaly hate thatm, i live likkle sweet compactor bots, lol.

Oh and by the way, how can you find out from any normal shop what discharge rate batteries have, because the shops by me know f**k all, they cant tell the difference between NiCads and Ni-Mhs lol

Grant