Sorry to hear about the battery but at least it means you have to upgrade, just stick a lipo in there, much lighter, extremely high power density and very affordable nowadays.
Get one from some kind of clearance-sale. I got a pair in a clearance-sale from Sussex Model Centre really inexpensively.
12V 7Ah SLA can be replaced with 2 3S 2200mAh for a lower weight and pricetag.
I've used LIPOs in antweights before, and even in them they're vicious little things.. Would just be concerned about making that much power available to a home made speed controller, which are prone to shorting tracks. I'm gonna try it anyway, but still would make me a little nervous. My ESC has survived 12 fights fine so far now though, so i'm a little more confident in it than I was at least. Under voltage cut out for LIPOs is only an advisory rule; I'd like to have it, but depends how hard it is to add, and on what capacity lipo I get; as long as I charge it every fight it should be fine.
Also decided to fit external bearings to my drill motor shafts to take the weight of the robot; the gearboxes on them aren't really designed to take the sideways force of a feather dropping on them.. I almost lost both my motors today in that flip from the floor flipper!
EDIT: Those Lipos are cheaper than i'd expected! I might get away with just one of those; The drive doesn't take a whole lot of power to run the two drill motors, and the lifter isn't running half the time. Obviously would have to try and see how fast it got through one, and fit undervoltage protection in that case, but worth a shot; The moto of this build is the less money spent the better :L
Last edited by Rapidrory; 27th April 2014 at 22:25.
If you're worried about the speedo's blowing, add a fast fuse.
It's actualy mandated when using LiPo, and nobody says you need to put in a fuse that can get the limit from the battery.
The external bearing on the axle, not a bad plan, but avoid putting that in the outside armor without any shock mounting
Mario's got a point, a 7ah sla has got to weight 1.5 possibly getting on for 2kg? a 2200mah 3s lipo would be more than enough for a 3 minute fight on two drills and a lifter, would weigh next to nothing and provide much more power than the sla could ever hope to. It would also take less space and like Mario said you could get two for the price of 1 sla.
Originally Posted by mrsam
I ran Loki for three fights at Yeovil on 4 drills and a lifter on a 2200 mAh 5s lipo without charging it and it was fine(admittedly I didn't last very long in those fights, what with magic smoke and being oota'd and having the link knocked out but still...)
My wheels are inside my armour, and the bearings would probably be in a HDPE (or maybe even hardwood) mounting, so would have a little bit of shock absorbance. Bearings of that size are pretty cheap, so if they did go then it'd be much cheaper than replacing a motor.
My SLA's actually weigh about 2.5Kg! The plan always was to swap them for a Lipo at some point. The only reason i used SLAs is because i had them lying around at home from an old mobility scooter, and i didn't have time to add the safety features and order lipos... (SLAs like mine are actually only about £6-£12, so not a huge saving, but I'd much rather a lipo for the weight)
Last edited by Rapidrory; 27th April 2014 at 22:35.
It says the UK warehouse is out of stock on those ones.. Did you get them from the international warehouses or have they been in stock in the past? (with Hobbyking you can never tell..)
Hobbyking backorder stock if you buy it, usually takes up to 7 days for them to backorder it. So you could buy it now and have it within the next week and a bit
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