wespelarno

This is the coolest homemade I have seen in a long time. Well done dude.

I assume you could alter the rate of fire by fiddling with the gear of the advancing arm?

Question: What about this: (Laptop Battery) Toshiba SATELLITE PRO A210-16V 9 Cell

- Type: Li ion
- Capacity: 7200mah
- Cell: 9

Is this possible?

or this?

Avoid those. They have high enough capacity and high enough voltage, but will seriously not appreciate being run around with nor the stop-start use that Nerf will put them through. I've seen a guy use a set of something similair in a RC car and it melted down. I doubt they would melt as you are using them at a fairly low amp draw, but you will get a really short lifespan out of them. In general avoid cheapo batteries, especially LiOn or lithium Ion as you really get what you pay for with batteries in terms of run-time, average voltage and recharge life.

Anybody chasing batteries, check out Towerhobbies.com for quality cells. Cells can be bought individually or pre wrapped and all are designed for rougher and higher amp use than we will put them through.

Pick a capacity and voltage you desire and make sure to use the same type of batteries if more than one is being used in a circuit.

Also, thanks for the new info regarding voltage. I wonder if it would work well to get a 9.6v pack connected in series with a 7.2v pack, for a total of 16.8v, which is right around your recommendation. I was considering getting another 9.6v pack in series, but that would be closer to 20v and probably too fast for the darts to load reliably.

Just a heads up to anyone considering this, mixing batteries is generally a BAD idea. Especially true for rechargeables. Try and keep them the same (Voltage, Amp-Hours etc.). When you are using mismatched batteries, they can drain at different rates and can "empty" at different times. This can confuse the sensors built into the batteries and cause all kinds of unpleasant surprises. They most likely aren't going to blow up, but it's better to be safe than sorry.

Go higher than what you want with your voltages, then bring it down to where you want in your circuit.

Can anyone with a Multimeter check the current draw on the stampede? I'm a bit curious.

The most likely event is that the battery that is emptying at the faster rate will discharge completely and enter a state of deep discharge. For NiCD batteries this is fine, but NiMH batteries will basically never work again properly, they will loose both peak voltage and capacity. LiPo/LiON/LiMn also won't appreciate this and are more likely to go up in a bang.

The mabuchi type silver can motors are usually fine up to 25V, although they prefer continous use as opposed to stop-start use which tends to lead to arc-ing on comm in the motor. If damage occurs, it wouldn't be too hard to find a replacement motor at an electrical store, and it shouldn't cost more than 7 or 8 bucks.

The use from nerf won't generate enough heat to damage the motor-I would be more concerned about some of the connections and circuitry giving up at 15-16V.

14.4V can be achieved nicely by running two RC car batteries in series, and cheapo (3000mAh) NiMh batteries should give literally hours of firing use without noticeable drop in voltage.

keeping this thing powered through a season of nerf is going to be a real pain.

RC car batteries-it will take about 9 seconds of sustained use for them to pay off.