After some details of SLA weights and stuff

[terry]

no you wont need more capacity, if you upgrade to mags then you will need batteries that will be able to charge faster and deliver a higher current when required, a123's or lipo would be best, nicd still available and cheaper but most are moving away from that chemistry now. i run 2 mags and have 30v with 9.2 amps and have between 40 - 60% remaining after fights.

[daveimi]

Ok that's great. Going through the specs of motors and pilfering details of people's heavy specs, I'd wondered if I'd get away with it with just a lowly pair of 10A wheelchair motors lol. The theory says that with my 9.something AHR batteries I'd be able to run for an hour or so. I know that's never gonna happen in reality but the numbers feel like they give me breathing room.

[craig_colliass]

You will find with the SLA type of batteries the amp/hour number doesn't strictly apply, I ran SLA 16Ah with Bosch 750w motors and found the batteries were going flat in the last minute of a fight. if the batteries were left to "rest" they would recover and when charging the charger would only put in about 6 Amp/hour. It's to do with this type of battery chemistry.

In your case I doubt the motors are more than 250w so the batteries you have ordered should be fine. my advice is to make sure the gear ratio is quite low. so you have the chance of pushing other robots about the arena (just not that fast) I think it's good to try to make a budget heavy at the beginning that is what Saint was!

My advice if it is not going to have an active weapon, go for something the crowed would love, give it a face, a character or some other facet that would connect with the audience Like Kettlebot!

Looking forward to see what you come up with.

[daveimi]

Thank you for the words of encouragement. The robot is just a basic cheap heavy just for some fun.

The robot is like a thwack bot but not to just sit and spin, to sort of drive all over and bounce about a bit like Stinger used to. We've gone with this as we know we don't really need any shove for it and are likely to get thrown all over. I got a bit bored with the feathers so thought I'd have a go at a heavy.

The wheel chair motors are about 21:1. I know this as I spun the motor and counted the times till the wheel did one full revolution haha I'm not very scientific! Before I dismantled the wheel chair I gave it some stick up and down the drive way and was really quite impressed at the torque they had flinging me about lol. I've taken the brakes out, regreased everything and got new inner tubes and tyres from the mobility shop so they've had an informal refurb

This is a rough sketch I did to show John n Dad the basics in my head lol.