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Nerf Stampede - Voltage Increase / Rof & Firing Tests

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#26 wespelarno

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Posted 05 September 2010 - 10:33 AM

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.
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#27 MavericK96

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Posted 05 September 2010 - 04:14 PM

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.


Yeah, I'm thinking now I might pick up a couple of 7.2v batteries and run them in series to achieve 14.4v easily. Will let you guys know when I get it done, possibly post a write-up (shouldn't be difficult).
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#28 RanulfC

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Posted 06 September 2010 - 03:00 PM

Not too bad... looks like a set of those rechargable Li-Ion batteries could easily last most Nerf games. Imho, 40 x 18-dart clips = 700+ darts. Thats alot of darts to fire, pick up and reload in a single Nerf game! :lol:

Scary thought of having to have a couple of those "paintball-sucking-vacuum" robots running around during a game to pick up the "used" darts ain't it? :o

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#29 Chadpuff

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Posted 06 September 2010 - 03:57 PM

How much of a weight difference are we looking at with this mod? Is it less or more than stock with batteries?
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#30 MavericK96

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Posted 07 September 2010 - 08:22 PM

I've got a general question to ask regarding battery packs:

Can someone with two standard 7.2v battery packs (like this for example) see if they will both fit in the Stampede without having to modify the blaster shell too much? Based on the measurements given it looks like they MIGHT fit, but they also might not by a small amount (kind of depends on how rounded they are on the height and depth side of things). I was just wondering if anyone had tried it, because it looks like almost the right size, but if they won't fit I don't want to buy the packs and attempt it if it's not going to work.

Thanks in advance. B)
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#31 Longbow

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Posted 08 September 2010 - 03:48 PM

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.
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#32 MavericK96

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Posted 08 September 2010 - 05:22 PM

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.


Yeah, I wondered about this as well, actually. I went ahead and purchased two 7.2v battery packs of identical capacity and build to test with the Stampede, should get them on Friday. I will post my results when I test with them.

I will try to get some current draw readings as well, if I can.

EDIT: Just did some current tests. In my test, using 6 well-charged alkaline D batteries in the battery sled, the current draw was anywhere from 1.0A to 1.6A. It was not very consistent, though in fully-auto the first shot seemed to be closer to 1.6 Amps, while the subsequent shots were closer to 1.1 - 1.3 Amps. Sometimes there would be a random spike of 1.5 - 1.6 Amps after a few full auto shots were fired.

So for example, a readout while firing fully auto would be (each readout is about a 0.5 second time interval):

1.6
1.4
1.1
1.1
1.3
1.2
1.4
1.1
1.5
1.6
1.2

Something of that nature.

Edited by MavericK96, 08 September 2010 - 05:37 PM.

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#33 Longbow

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Posted 08 September 2010 - 06:30 PM

I will try to get some current draw readings as well, if I can.

EDIT: Just did some current tests. In my test, using 6 well-charged alkaline D batteries in the battery sled, the current draw was anywhere from 1.0A to 1.6A. It was not very consistent, though in fully-auto the first shot seemed to be closer to 1.6 Amps, while the subsequent shots were closer to 1.1 - 1.3 Amps. Sometimes there would be a random spike of 1.5 - 1.6 Amps after a few full auto shots were fired.

So for example, a readout while firing fully auto would be (each readout is about a 0.5 second time interval):

1.6
1.4
1.1
1.1
1.3
1.2
1.4
1.1
1.5
1.6
1.2

Something of that nature.

The variation makes sense, the motor isn't going to be doing the same amount of work at all times. Drawing the bolt back will take more power than in between for instance. That is still a surprising amount of current draw though. Thanks for doing the tests. I need to crack one of these open, but our walmart still has them flagged as not for sale.
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#34 wespelarno

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Posted 09 September 2010 - 02:35 AM

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.
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#35 MavericK96

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Posted 09 September 2010 - 01:25 PM

The variation makes sense, the motor isn't going to be doing the same amount of work at all times. Drawing the bolt back will take more power than in between for instance. That is still a surprising amount of current draw though. Thanks for doing the tests. I need to crack one of these open, but our walmart still has them flagged as not for sale.


I didn't think about it that way, but you're right. The high readings must have been taken when the motor was doing the most work (pulling back the plunger) and the lows must have been during the lower-torque part of the cycle. So for a maximum current draw you're probably looking at 1.6 to 1.7 Amps.
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#36 SpectreX

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Posted 09 September 2010 - 11:23 PM

Hey, I don't really have any electrical engineering experience, but I've been keeping up with this thread and looking around online for an ideal battery replacement that will be; lighter than 6 D-cells, run at ~15-16v like SG says has been working well, and have a high capacity.

This is what I've found. I wouldn't necessarily be buying this specific one, but would something like this do the trick? I was figuring I'd hook the leads up to a tamiya connector for putting it in the Stampede. Is this feasible, or is it a serious fire hazard?
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#37 MavericK96

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Posted 10 September 2010 - 01:02 AM

I think that should work fine, since the current draw is only like 1.7A max. Pretty expensive, though. You might be better off trying to buy 4 of those 18650 batteries and put them in a holder. Probably would be a lot cheaper.
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#38 SpectreX

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Posted 10 September 2010 - 12:08 PM

I think that should work fine, since the current draw is only like 1.7A max. Pretty expensive, though. You might be better off trying to buy 4 of those 18650 batteries and put them in a holder. Probably would be a lot cheaper.


Yeah, if I go with this kind of setup that's exactly what I was thinking of doing. A four pack of Tenergy 18650s from Amazon is about half the price of that pre-built pack. It was just easier to link to something that had all of the numbers summed up already. Glad to know this setup should work.
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#39 MavericK96

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Posted 10 September 2010 - 04:48 PM

Just FYI for anyone interested:

I just recieved my 3000 mAh 7.2v battery packs and charger from Amazon. To my delight, I found that they both will fit easily in the Stampede battery compartment. Not sure about the battery sled itself, but it might be able to to be modded to hold them. In any case, I am charging the batteries now and will let you guys know when I get results, probably with a write-up and pictures.

Here's what I bought (for reference):

Two of these: http://www.amazon.co...&sr=1-1-catcorr

One of these: http://www.amazon.co.../ref=pd_sim_t_1

Also, it looks like the charger came with two female adapters which I can modify to use with the Stampede, without having to buy extra connectors (they come with the charger as adapters, but since I will only be using the one type of plug, I can just use the adapters for what I want)

--EDIT--

So, these two battery packs won't fit in the Stampede battery sled, even modded. But that's okay! Because all you have to do is take the battery sled apart, which allows you to basically disconnect the back screw cap of the sled from the rest of the sled. All you have to do then is jam the battery packs into the back (with padding so they don't roll around too much if you want, though they fit pretty nicely in there) and then screw the back cap back on. Works perfectly.

Edited by MavericK96, 10 September 2010 - 05:09 PM.

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#40 MavericK96

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Posted 11 September 2010 - 06:32 PM

So actually, in response to my previous post, the battery charger did NOT come with the correct adapters I needed. It had two female connectors instead of the two male ones I needed to connect the female ends which are on the batteries. So it looks like I'll be getting two male connectors soon and trying again, lol.
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#41 Cannonball

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Posted 11 September 2010 - 08:26 PM

I don't know much about all of this battery stuff, but I dug out some old batteries from an airsoft aeg and compared them to the tray. this is what I came up with: Posted Image

I took the picture inside with my Iphone. The light isn't too favorable in this picture, but I basically just sat the battery ontop of the dividers to check and see if it could even fit in there. I haven't modified the tray yet at all. it seems like it will slip right in on either side. You just have to remove a set of dividers on each side. I don't know if two of those would work right for the stampede though. I might just take a shot in the dark and try it out.
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#42 MavericK96

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Posted 12 September 2010 - 02:30 AM

Looks like it should work fine, I'd give it a shot.
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#43 MavericK96

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Posted 12 September 2010 - 06:47 PM

UPDATE: I've installed the two 7.2v battery packs in series, and I'm having a problem where the blaster will fire quickly but then when I let go of the trigger it will continue to fire until I switch it off manually. Not sure what is causing this.
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#44 Cannonball

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Posted 13 September 2010 - 03:22 PM

Do you think you could take pictures of how you are hooking the batteries up? I'd like to see so I know where to start with mine.
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#45 MavericK96

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Posted 13 September 2010 - 05:45 PM

I don't have a picture but it's simple enough. It's like:

red alligator clip (hot) <-----> red wire of Tamiya 1 connector, black wire of Tamiya 1 <-----> red wire of Tamiya 2 connector, black wire of Tamiya 2 <-----> black alligator clip (ground)

The alligator clips are hooked to the inner leads of the Stampede battery compartment.

However, at this time I can't recommend doing what I did, as the two fully charged 7.2v battery packs in series appear to be too much voltage for my Stampede at least. It will continue to fire by itself after the trigger is pulled and it jams up extremely easily. I will do some more tests but at this point I may just have to re-wire it to accept one 7.2v battery pack, as I tried this and it seems to have the same ROF as 9V and actually works properly.

Not sure why 15-16V works great for SGNerf and not for my Stampede, but it's just too fast and doesn't work properly.

Edited by MavericK96, 13 September 2010 - 05:46 PM.

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#46 ZimZam93

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Posted 13 September 2010 - 07:49 PM

So I just got my Stampede for my birthday and nothing in my hands last longer then 24 hours stock, so i was wondering if anyone has had their motor completely melt of stop working on any voltage?
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#47 Cannonball

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Posted 13 September 2010 - 08:12 PM

I don't have a picture but it's simple enough. It's like:

red alligator clip (hot) <-----> red wire of Tamiya 1 connector, black wire of Tamiya 1 <-----> red wire of Tamiya 2 connector, black wire of Tamiya 2 <-----> black alligator clip (ground)

The alligator clips are hooked to the inner leads of the Stampede battery compartment.


Is this all within the tray, or did you hook it up within the gun itself? That would mean you would have to have taken the back end of the tray to seal up that compartment of the gun with. Did you have to unscrew those triangle screws? I have a 12v rechargeable battery that could fit into that space, but I didn't want to tear up that battery tray just to figure out how to close the gun up.
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#48 MavericK96

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Posted 13 September 2010 - 09:22 PM

I don't have a picture but it's simple enough. It's like:

red alligator clip (hot) <-----> red wire of Tamiya 1 connector, black wire of Tamiya 1 <-----> red wire of Tamiya 2 connector, black wire of Tamiya 2 <-----> black alligator clip (ground)

The alligator clips are hooked to the inner leads of the Stampede battery compartment.


Is this all within the tray, or did you hook it up within the gun itself? That would mean you would have to have taken the back end of the tray to seal up that compartment of the gun with. Did you have to unscrew those triangle screws? I have a 12v rechargeable battery that could fit into that space, but I didn't want to tear up that battery tray just to figure out how to close the gun up.


I just hooked it all up within the gun, and then detached the rear piece of the battery sled from the rest of the sled and used it as an endcap. And yes, to do that you will need to remove the triangle screws because those hold the end cap on the rest of the battery sled.
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#49 MavericK96

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Posted 14 September 2010 - 03:18 PM

So here's what my setup looks like currently.

The batteries:

Posted Image

The connectors:

Posted Image

The batteries inside the case with the end cap off:

Posted Image

But...Here's what I end up with (video):

Stampede Battery Mod @ 16 Volts

The batteries are currently running at about 16v, and apparently this is way too much for my particular blaster. I'm not sure what the difference between this Stampede and SGNerf's numerous Stampedes that work fine with 16v are, but it's definitely not doable currently with mine.
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#50 TantumBull

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Posted 14 September 2010 - 08:18 PM

He has a much stronger spring that slows down the bolt. No idea about the continuous firing, though.
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