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Understanding batteries?


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#1 Codeman

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Posted 02 January 2019 - 10:54 AM

Ok so I need some help on batteries?

 

I have watched a ton of videos on modding nerf blasters and done a few up.  I have yet to take the plunge into a battery pack, but I have rewired a bunch with heavier wire and removed the PTCs, the unecessary safeties and the junk off the motors.  This made a bit of a difference on performance.  Now I noticed my rapid strike fires way better after bypassing the limited revup that was limited to get full rev now on the rev trigger.

 

So I am trying to work on figuring out some battery options.  I don't need or want to go lipo.  I thought a nimh pack but still 7.2v is going to bump up performance some and I play with my kids inside and don't want them to not want to play any more.  I am basically sick of buying batteries.  So then I thought rechargeable batteries but I tried a few and it worked ok, there was a slight performance drop with the lower voltage vs alkalines.  I did just get some D cell adapters that allow you to use two AA in parallel for more capacity.  I might try this.  Then I got to looking at packs.  I found some 6v packs but most are rated at 2000mAH and are simply 5 AA cells fused together.  I could easily adapt something similar in the larger battery trays but am wondering will a simple pack offer more true amps of discharge than running 5 AA rechargables which is in sense the same as the pack except the added resistance of the springs in the holders.  Or am I missing something and a 2000mAH 5 cell AA pack will  offer more true amps than regular good quality 2000+mAH rechargeable AAs.  I don't want to buy a pack and have it be the same as I have now.  

 

I did try a 9.4 or 9.6v pack I had and that ramped up the guns but again I don't want to use that because I don't want to make my kids not want to play and I figured by the time I used rectifying diodes to drop my voltage down I could just as well get a different pack or use other batteries.

 

 


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#2 noahback

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Posted 02 January 2019 - 11:47 AM

A 3s 1000 mAh lipo is like 15$ 4 imrs can be bought for like 10$ and have 14.8 volts but must draw more than rated current to run stock motors.  If you plan on upgrading motors go lipo if you are just going to use stock motors use imrs for cheaper and better gains.  If you use imrs in upgraded motors you will destroy them.


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#3 shandsgator8

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Posted 02 January 2019 - 12:06 PM

Forget the IMRs and other commonly used lithium ion batteries in the Nerf realm. If you don't want mess with lithium based batteries like lithium polymers, you also don't want to mess with lithium ion cells.

 

As for NiMH cells, that's what I used. I've use both a re-purposed R/C 6 cell Sub-C battery pack (7.2v nominal) for use in some flywheel blasters, but I currently use Eneloop AA cells (I use 6 of them to get 7.2 v) in my flywheelers (Stryfe with MTB Rhino motors and Rapidstrike with stock motors).

 

As a general rule (and all else being equal), the larger the cell is in size, the better it will be able to deliver more current. So a AA cell won't be able to delivery the same current load as efficiently as a C or D cell. However, for a stock flywheeler as in your case, using a AA cell will be just fine, as long as it's a high quality cell, such as an Eneloop. With 6 AA Eneloops, you will notice a slight bump in ROF and can avoid having to buy alkaline cells. But keep in mind that you'll need a charger (an R/C type) to charge your battery pack.

 

Here's a link to my Rapidstrike: http://nerfhaven.com...ke-battery-mod/

 

And Stryfe: http://nerfhaven.com...odified-stryfe/

 

EDIT: You might find this thread useful: http://nerfhaven.com...rent-discharge/


Edited by shandsgator8, 02 January 2019 - 12:11 PM.

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#4 Codeman

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Posted 02 January 2019 - 02:50 PM

Yeah I don't want to mess with lithium batteries due to my children using the blasters.  I will maybe mess around with adding aa (cell) rechargeable NIMH batteries if 4 is not enough.  I was just curious because I see some NiMH say sub c so that just means more available current due to the larger cells.  I know Lipos use the c rating which is nice but NiMH don't use any rating like that that I have seen.  

 

And yes all of my blasters are stock motors, stocks switches, not wanting to burn too much up.  I just removed some of the resistance by using larger wire, removing some safeties, and removing as many circuit boards as possible and more direct wire the blasters.  And I did notice some slight improvements in the blasters.  

 

Thanks for the help, I will maybe just do something similar and make a RC style pack just using my rechargeable AA batteries.  I am running energizer ones that are rated at I think 2100mAH and have high reviews and they seem to be pretty decent.  


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#5 shandsgator8

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Posted 02 January 2019 - 03:39 PM

Yeah I don't want to mess with lithium batteries due to my children using the blasters.  I will maybe mess around with adding aa (cell) rechargeable NIMH batteries if 4 is not enough.  I was just curious because I see some NiMH say sub c so that just means more available current due to the larger cells.  I know Lipos use the c rating which is nice but NiMH don't use any rating like that that I have seen.  

 

And yes all of my blasters are stock motors, stocks switches, not wanting to burn too much up.  I just removed some of the resistance by using larger wire, removing some safeties, and removing as many circuit boards as possible and more direct wire the blasters.  And I did notice some slight improvements in the blasters.  

 

Thanks for the help, I will maybe just do something similar and make a RC style pack just using my rechargeable AA batteries.  I am running energizer ones that are rated at I think 2100mAH and have high reviews and they seem to be pretty decent.  

 

A few years ago, Energizer NiMH AA were notoriously awful in capacity and internal resistance (i.e. can't hand high current draw). Maybe they've gotten better recently, but if not, you could definitely do better.


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#6 Codeman

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Posted 02 January 2019 - 05:35 PM

What about something like this Tenergy NiMH Receiver RX Battery with Hitec Connectors 6V 2000mAh High Capacity Rechargeable Battery Pack for RC Airplanes/RC Aircrafts and More https://www.amazon.c...i_GXtlCbA1SHYHE
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#7 shandsgator8

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Posted 02 January 2019 - 07:34 PM

What about something like this Tenergy NiMH Receiver RX Battery with Hitec Connectors 6V 2000mAh High Capacity Rechargeable Battery Pack for RC Airplanes/RC Aircrafts and More https://www.amazon.c...i_GXtlCbA1SHYHE

 

No, a "hitec" connector is not suited for high current applications. That's basically a receiver pack that powers solid state electronics, not multiple motors lauching foam darts.

 

As for the cells themselves, I have no idea if they're any good. They're probably not Eneloop quality, and because they're intended for use in slow drain applications, I doubt they would be that much better than alkalines.

 

If you want a ready made pack that uses NiMH cells, you'll need to find something other than AA. In the R/C hobby, AA cells aren't used much beyond powering radio systems, so they'll be hard to find. SC (Sub-C) will be much easier to find.


Edited by shandsgator8, 02 January 2019 - 07:35 PM.

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#8 Codeman

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Posted 03 January 2019 - 01:06 PM

Ok.

 

So many decisions.  So my AA batteries didn't pan out tried them in my demolisher and ECS12 and decreased performance noticeably from even regular alkalines.  So fortunately I now have some AA rechargeables to use around the house.

 

I contemplated taking the camera tray wiring in series and add a 5th battery rechargeable to get me to the stock 6v and use 3 dummies which would not be a problem but that would not be possible on the demolisher without adding an external battery tray.

 

So now I am back to a pack.

 

After seeing your guys thoughts I am kind of thinking a 7.2v sub c pack around 3000mah which should suffice.  The only thing I worry is that this pack will obviously supply me with more than enough current for stock motors but with the increased current due to my rewires and the better battery I worry the blasters will shoot too hard for kids and indoors.  I like the NIMH pack because I was just going to make a box that I can velcro or zip tie to the blasters since they are relatively safe batteries.  How much of an increase in FPS would I see on the demolisher, rapidstrike, and ecs 12 with a 7.2v sub c pack?  I have upgraded all the wiring to 16 or 18awg in the semi's and left stock switch for rev and stock motors but removed clip switches and jam door switches and all the stuff from the motors and any PTCs.  

 

Also I have an infinius that I bought would the 7.2v destroy the loader mechanism stuff?  I don't want to mess with the internals on that blaster because after looking online it looks super super complicated and I may just remove the stuff off the motor but I don't want to burn out the internals using a better battery.

 

Thanks


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#9 Meaker VI

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Posted 03 January 2019 - 03:16 PM

Just swapping to a pack on stock motors/wheels/cage will max out at 130 FPS, and IIRC it wont hit much harder than 100-110 without new wheels and new motors.

Current is demanded by the motors, you cant supply more than theyll ask for. Meanwhile, supplying *less* than they want is bad for your batteries, and doing bad things to some kinds of batteries is what leads to fire and explosion.

You might consider swapping for a dartzone or adventure force fly wheeler, those hit 80-100 OOTB with AAs. The AF double trouble is $20 and theres a file on thingiverse to make it side-mag fed.

Ed: RE Voltage: if the setup is designed for 7.4ish, supplying 7.4ish shouldnt hurt things. Voltage *is* pushed from the pack to the motors, and upping it can burn stuff out. That said, I use a 20v pack on my nominally-3s motor builds and it hasnt caused immediate problems.

Edited by Meaker VI, 03 January 2019 - 03:18 PM.

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#10 shandsgator8

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Posted 03 January 2019 - 03:45 PM

Just swapping to a pack on stock motors/wheels/cage will max out at 130 FPS, and IIRC it wont hit much harder than 100-110 without new wheels and new motors.

Current is demanded by the motors, you cant supply more than theyll ask for. Meanwhile, supplying *less* than they want is bad for your batteries, and doing bad things to some kinds of batteries is what leads to fire and explosion.

You might consider swapping for a dartzone or adventure force fly wheeler, those hit 80-100 OOTB with AAs. The AF double trouble is $20 and theres a file on thingiverse to make it side-mag fed.

Ed: RE Voltage: if the setup is designed for 7.4ish, supplying 7.4ish shouldnt hurt things. Voltage *is* pushed from the pack to the motors, and upping it can burn stuff out. That said, I use a 20v pack on my nominally-3s motor builds and it hasnt caused immediate problems.

 

This. So no worries about using that Sub-C 6 cell R/C style battery pack.


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#11 Codeman

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Posted 07 January 2019 - 07:03 AM

Thanks for all the help guys.

 

I ended up remembering I had an old drill laying around with the old NICD battery packs.  So I opened it up and it had some 1300 mAH sub c nicd cells.  So i decided to take it apart and solder together 5 cells to stick with stock voltage.  On my rapid strike I wired in a connector and man that thing rips.  Off the charger the battery is 6.6v or so and it doesn't slow down at all even when emptying a 30rd drum.  Sometimes it jams and just will pull through which is not so good but doesn't slow flywheels at all really.  I am really happy.  It works well.  I also tried it in my stock infinius by removing the batteries and putting some adapters from D to AA in there that I soldered on some leads on the internal posts so the battery converters went in place of batteries and had leads so I could hook the pack up.  This was all stock and it made a decent improvement.  This is what I was looking for it doesn't have the shoot down that normally happens on full auto.  Thanks for all the help.  These are not as crazy as the other builds but for my situation it works awesome.  And the battery pack seems to have fair life.  I have fired 4 30rd drums, 10-18 round mags and still going strong.  Now to find a good 6v charger which I talked with a local hobby RC store and they said they have one that works with lipo, nimh, nicd and multiple voltages so would allow me to buy one charger and if I upgrade down the road it will work for that and anything else I get.

 

Thanks

 

EDIT: Last night I still thought the gun fired a bit hard for inside after some more testing and decided to try dropping a cell to 4 cells.  Put me a little over 5v fresh off charer.  Tried that and blasters fire good, fire a small amount harder than stock.  Does bog some on the infinus that is all stock inside in long full auto bursts but doesn't shoot down near as bad.  Found a sweet charger that charges to my voltage and any kind of battery and will cycle discharge.  So thinking I am going to go with this route.  Plus the 4 cell packs fit in stock battery slots and I am going to make some simple connections so I can swap between regular alkalines or these rechargeable packs that are homemade.  I think better/larger and newer cells might reduce shoot down and also removing maybe the PTC on the infinus might help but that beast don't want to tear into since it is so complicated.  My rapidstrike doesn't fire down just fires a little harder than stock, which no chrono but just from shooting it is a small improvement but not too much.  I may post some pics if I ever get the cool battery trays done.


Edited by Codeman, 08 January 2019 - 09:15 AM.

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