jond36 Posted June 18, 2009 Report Share Posted June 18, 2009 Which one is better? Simple question, but I am about to buy alot of the same batteries in my wholesale order. I wanna get it right. Roughly 8.4v or 9.6v / 2500-3500 mAH. Which has a high ROF with the same mAH? Which battery gives about 15 RPS? Link to post Share on other sites
gzus11 Posted June 18, 2009 Report Share Posted June 18, 2009 nimh are better. get the biggest capacity mAh that will fit in thre battery compartment and 9.6v will have higher rof voltage relates to rof, and capacity relates to duration. 15 rps i have no idea. Link to post Share on other sites
MDK_Marshal Posted June 18, 2009 Report Share Posted June 18, 2009 gzus is mostly right, but there's hidden nuances to it. NiMh is generally the best, yes. There were a couple of reasons to use NiCd back in the day, but to be honest, they're all moot now. Go NiMh. The main factor from the battery that determines ROF is the discharge rate, THEN the voltage. Yeah, if you slap a huge 12v pack in a gun, it'll run faster than an 8.4v pack, but it's not just because the voltage is higher. The higher voltage should, on a given unloaded motor, make it run faster. However, when put under load (IE, when used to cycle a gearbox), The motor will require a non-trivial amount of current to run at peak efficiency. How much is determined by (amongst other things) the load and the motor. If the battery can't supply enough juice, then it'll run slowly, and not very efficiently. It is entirely possible to have a high-voltage pack that turns a motor over slower than a low voltage one because of this. Generaly, buy a decent pack with the highest discharge cells you can for max rps. As for which pack will get 15rps - how the hell should we know? What gun are you using, what internal components are in it, how well shimmed is it, how well is the motor height set, what sort of wiring is used, how good is the soldering, do you use a MOSFET, have you short stroked anything, what ambient temperature is the gun used in, what phase of the moon is it, how many licks to get to the center of a tootsie pop... It all depends on the gun you use, and even then it's not guaranteed. I mean, I could recommend you a half-charged 4.2v mini NiCd pack if you really want, as at one point I had my M4 running at about 15rps on that. Doubt it'd do the same on your gun though. Link to post Share on other sites
jond36 Posted June 18, 2009 Author Report Share Posted June 18, 2009 Alright sounds good. I bought several stock CYMAs for about 20 friends. AK,MP5 a5, and SD6 models. So they will all be stock models. However my weapon will have a mosfet and will probably a different brand. Gearbox will be stock though. We are trying to keep a 15-18 RPS limit. Link to post Share on other sites
MDK_Marshal Posted June 22, 2009 Report Share Posted June 22, 2009 ...why exactly are you having an RPS limit? Just run them on 8.4v packs and be done with it. Besides, if you run them too fast stock, then they'll just break down. Push much above 20-25rps in a stock gun and it'll start shredding itself quickly. You'll also use ammo faster. Link to post Share on other sites
LordElpus Posted June 22, 2009 Report Share Posted June 22, 2009 15rps is only 900rpm. Most stock guns manage 800rpm Link to post Share on other sites
jond36 Posted June 22, 2009 Author Report Share Posted June 22, 2009 Yeah I found out it really depends on the brand too. One guy had a stock 8.4V 1100 mAH battery that ran 11.2 RPS. Another guy took his Intellect 8.4V 1200 mAH battery and it ran 15.6 RPS in the same gun. So you never know. edit: Both were Ni-Mh. Link to post Share on other sites
Azulsky Posted June 23, 2009 Report Share Posted June 23, 2009 Stick to 8.4V packs with the 2/3A cells and it should stay lower SC cells have monster discharge if you get high quality cells(Elite, Intellect) Link to post Share on other sites
greg Posted June 23, 2009 Report Share Posted June 23, 2009 When I first saw the title on this one, I thought it was some necro dug up from way back when nimh's first became available. The main advantage of the nimh is the fact that they need less cycling & can be topped up rather than fully discharged & recharged. But to be honest, this is 2009 & you should be thinking about a lipo . Compact lipos such as Flight Power's 7.4v 30C 2200mah are about the same size as an 8.4mini but give better performance than a 9.6v 4300mah nimh. Higher rof, & approx 3-4 x the bb's per mah. As per rof, this will depend on the gun, spring, gears, motor etc. Greg. Link to post Share on other sites
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