London Expo, antweights??

Marco Roberts · Post by **Marco Roberts** » Wed May 17, 2006 12:49 pm

well i probs will be going on both days
I have 2 packs of 4xaa batterys.
As for parts to build pay per drive ants, i really dont have anything spare.
All my decent servos are being used, and the rest are either missing gears or worse

olivers · Post by **olivers** » Fri May 19, 2006 11:12 am

Looks like I will be at the London Expo tomorrow. I won't have the ants or anything though as I am going with a friend and looking round so want to be sociable.

?15-20 per autograph, pah

Marco, not sure if you want to meet up.

Marco Roberts · Post by **Marco Roberts** » Fri May 19, 2006 11:29 am

.....tomorrow?

I just copied this from teh website

the next event on the 27th & 28th May 2006

olivers · Post by **olivers** » Fri May 19, 2006 4:58 pm

oops, mean next Sat.

Getting old and forgetfull. Being doing so much recently and lose track of time.

Simon Windisch · Post by **Simon Windisch** » Sun May 28, 2006 7:02 pm

Hi,

We spent the day at London expo (it was a lot of fun) and it really hit me that most of the time was spent recharging our batteries, rather than entertaining the masses. I've just experimented attaching a duracell 9v battery to Fast Dalek, and although it's probably a bit overweight, I imagine it'll run for a very long time now, and no need for a recharge, just change batteries... (although possibly a bit expensive it should work for "demo" competitions.
I'll test it at Ickenham.

Remote-Controlled Dave · Mon May 29, 2006 10:26 pm

I ran a standard 9v square NiMH rechargable (think it was duracel) in Apocalypse Then Redux at my first reading robot club. It worked fine and it's even possible to get them into weight limit.

peterwaller · Post by **peterwaller** » Tue May 30, 2006 4:16 pm

Simon I think you will find that the PP3 batteries are only about 150mA hour. The duracell ones are better but you would probably be better with a normal NiMh or Lithium Polymer. Especially as you are running at 9v which means you are increasing the current consumption.

Simon Windisch · Post by **Simon Windisch** » Tue May 30, 2006 6:21 pm

OK Peter,

So the problem is to have a robot that can run 100% of the time: on LiPos that would mean having four LiPos and three battery chargers? There must be another solution.

In the meantime, I am building a box which will be table mounted, and have a joystick and a flip switch on it to control a robot without the peril of giving a stranger your precious remote control. The box will be connected to a "real" skysport hidden under the table.

Post by **BeligerAnt** » Tue May 30, 2006 8:17 pm

Peter's right, the NiMH PP3s are low capacity and also low current. Alkaline PP3s would give plenty of capacity and current, but then there are the cost and environmental considerations.

NiMH calls can be recharged faster than Li-ion, some cells can be recharged at 4C rate giving a 15 minute charge time. For this to be successful, you really do need a good charger since overcharging at that rate can be catastrophic (the last thing you want at a public event!).
AFAIK there are no Li-ion cells that can be properly charged in less than 1 hour, the chemistry simply does not allow it. A real full charge takes about 4 hours, regardless of what any charger might say!

A pack of 4 AAAs or even AAs would provide plenty of capacity. As long as all robots in the fight carry the same excess weight, it really doesn't matter what the weight is. If you really want to stick to class rules, go for superants which can easily accomodate a pack of AAAs.

Simon Windisch · Post by **Simon Windisch** » Tue May 30, 2006 11:20 pm

OK, so 4 AAAs will give me 6V, for a cost of approx ?2, and one 9V battery also costs ?2, so why are AAAs more environmentally friendly than a 9V battery, or have I misunderstood?

Simon