London Expo, antweights??

Simon Windisch · Post by **Simon Windisch** » Wed May 31, 2006 11:14 pm

OK, thanks Gary, I understand now. I don't know about you, but my batteries don't last the "thousands" of recharges that they're meant to. Leaving a robot switched on overnight, with no circuitry to protect the battery will kill the battery in most cases, there's also the occasional short-circuit, and plugging the battery in the wrong way round doesn't do it any good either.

I don't know if everyone has these experiences, but I'd say my batteries last a year or so if they're lucky.

Simon

josh · Post by **josh** » Thu Jun 01, 2006 2:55 pm

its a bit off topic but all my lipos seem to be dyin after events the lipos were fine at rrc but wen i got them home they wouldnt work but they were left turned off and plugged into the robot so didnt short out but this also happened at aws19 i got home and a brand new lipo that worked fine was completely dead, any ideas?

Simon Windisch · Post by **Simon Windisch** » Thu Jun 01, 2006 7:54 pm

Josh,

Completely discharging a LiPo will kill it. They're used in phones etc, but these devices have circuitry in them that turn them off after the voltage drops below a certain level.

You say that they were turned off but still plugged in. Are you sure that your turning off procedure stops any current drain from the batteries? I remember putting my switch in the wrong place in Electra once, and although the robot stopped moving, the battery was still being drained.

You may be able to revive them by charging and discharging them a few times. If the LiPos go "puffy" then they're completely dead.

All the best

Simon

Rhys · Post by **Rhys** » Thu Jun 01, 2006 11:51 pm

I've found the larger capacity li-pos seem to last me a lot longer. the 145mah ones seem to stop holding charge, or swell up more often. The 360mah ones are more dureable and can take a lot more punishment. Mind you, i'm sure if I took care of my Li-Pos properly, I wouldn't have had any dead ones.

I've had 4 x 145mah ones in my time. One just stoped holding charge after about 3 months and not very many charges and I don't know why. The charger said it was full but it only lasted about a minute before it seemed dead again. Another was destroyed (ballooned!) by leaving it plugged in TNT for about a week. The very day I put the replacement in, I did the same mistake! I found a discharged Li-po, but after a charge it now seems fine. The other is new and has had no problems yet.

I've had 4 x 360mah ones (3 x 7.4v, 1 x 11.1v), and they've been used, abused, bent, crashed, short circuited and run dry many times. Remarkably though, they all still hold full current (or what seems to be) and are all working fine. I bought the oldest ones about 18 months ago (right after AWS 15, thats right isn't it?), and the newest ones about a year ago. They might weigh a bit more, but they last longer and give more current.

As for getting back on topic (sort of), it seems the best ting you could do for a demo would be just to use some standard commercial AA cells. The Ni-MH AAs now go up to 2500mah (maybe more, thats the most I've seen). This should easily run an ant for a couple of hours. And while these are being run in the demo bot, you could have another set on charge. There's quick chargers now for standard AA cells that'll have them full charged within an hour. The antweight fun would never stop!!!

josh · Post by **josh** » Fri Jun 02, 2006 7:59 am

well there was a switch plugged accross the possitive side and was switched off and i had a charge plug wire and plug comin off the batt from the otherside that wasnt plugged in. like that>>>

charge--------batt-------switch---------bot