Team MedBots

**maddox10** · 26th July 2013, 16:19

Originally Posted by razerdave

Why can't you charge them during an event?

No money for chargers I guess. Or to difficult to remove the batteries.

**Max** · 26th July 2013, 16:46

The problem is as Mario says I can't afford loads of chargers to charge them all and they will take ages to charge I imagine, easier I imagine to do what the saint team does and just have a battery pack per fight. I am still considering hobbyking lipos, there a good price as long as I can charge the packs between fights as I can't afford more than one set of packs.

**Max** · 26th July 2013, 16:59

Here are some pictures of the layout I'm planning:

I think it is very large but I'm not used to heavyweights! Also as it is pneumatic but not a flipper it has to be quite flat to make it invertible so it has become very large.

**maddox10** · 26th July 2013, 17:05

You're planning to run the Bosch 400's @12V. That gives you 2 realistic options for LiPo. 3S or 4S. (5S is 18.5V, right in the ballpark for "overvolting", but then the gearratio is a tad low). A 8000mah pack will probably see you trough a fight.

This means you need 1 Imax B6 AC , cost, less than £50 delivered at your door. And that one can charge the 4S 8000mah pack from "safely flat to full" in less than 2 hours.

Pricetag together, a tad more than 1 45Ah gelcel or AGM SLA without charger.
Difference in weight..... huge. 1 kg compared to 12 kg.

**maddox10** · 26th July 2013, 17:11

4 kg of CO2. That's 2000 liters of gas @1 bar @ roomtemperature. Your ram uses per stroke 27 liters. That means 60 strokes at least(not counting losses due liquid CO2 venting). In a 3 minute fight it's an action every 3 seconds (or 6 if it's double acting)

I would say, use only 1 main storage bottle if size is bothering you.

**Max** · 26th July 2013, 17:35

It's 800mm long, about 900mm wide- not sure how that compares. The good thing is only the front needs heavy armouring as all the expensive parts are there, just need to protect those bottles from axes.
Losing the buffer could save some space but not very much, and by having the ram, buffer and valve inline I should get a nice flow, even with just one Burkert.
If I went for SLA I'd buy a number of 6v 10ah batteries then change them each fight, that gives me flexibility to upgrade to 18v and means I don't have a ton of weight! I feel I'd need 2 of those 8Ah lipos to stay safe with discharging, then I'd need 2 chargers as I can't charge them in parallel. I may see if a mate has one I could borrow for events, he does rc planes so should have one.

**maddox10** · 26th July 2013, 17:44

I would retain the buffer, such a 1.1 kg CO2 bottle is exact the size you want for that ram.

You can do the setup with 1 Burkert, use the same setup as most feathers use. The flow is enough to satisfy your ram.

**Max** · 26th July 2013, 17:48

Should have thought of that about an hour ago before I ordered 2! I meant just one burkert as an inlet, second for an outlet.
The advantage of going lipo is I won't need a voltage boaster to operate my 12v burkert, does it need overvolting?

**maddox10** · 26th July 2013, 17:54

A 12V burkert? You sure that's a 5404?
But even if it's a 5404 with 12V solenoid, you want 15V+ going to that. There is a small difference between every burkert, what makes that one will work reliably @ nominal voltage, and another will want overvolting, especialy when it is warm.