L4Isoside Posted November 17, 2007 Report Share Posted November 17, 2007 After wating such videos as this: sometime ago i was wondering if you could do the same for a parallel circuit? (As in two 9 volt, 2000mAh battery packs, link them in parallel and get them working as one 9volt 4000mAh) Abit like this.... Yay, or nay? Another problem would be the connectors and space, i suppose lol. Thanks for any input, Chris Link to post Share on other sites
Foukus Posted November 17, 2007 Report Share Posted November 17, 2007 Yeah, it would work. Link to post Share on other sites
L4Isoside Posted November 17, 2007 Author Report Share Posted November 17, 2007 W00t! Thanks Chirs Link to post Share on other sites
yubbermax Posted November 17, 2007 Report Share Posted November 17, 2007 W00t! Thanks Chirs Yea you could do this in an MP-5 or something. Have one batty in the stock and the other in the foregrip. Link to post Share on other sites
maxxxmonster Posted November 17, 2007 Report Share Posted November 17, 2007 um correct me if i am wrong... but if you did two 9.6v 2000mah batterys in parallel wouldnt that equate to a 19.2v 4000mah battery? Link to post Share on other sites
nasty-nate Posted November 17, 2007 Report Share Posted November 17, 2007 ^^ that's what i was trying to figure out. and that would deffinitly KILL anything inside of your gun... hahaha Link to post Share on other sites
England Wonder Posted November 17, 2007 Report Share Posted November 17, 2007 two 9.6v in parrallel will still be 9.6v would in theory give you 4000mah instead of 2000mahat 9.6v it's not that simple the 2000mah is a typical capacity of the battery and they wont all be the same, even if they are slight differences in resistance between the two packs will cause problems in the long run when NiMH cells are charged in series they are all charged to the max capacity of the weakest cell, if you charge them in parrallel and discharge them in parrallel you can end up with some nasty reverse charging which is very bad for the cell, once it starts getting reverse charged it gets much weaker so it happens more often. It's safer just to get a 4000mah pack FWIW I do have a battery pack made up of a mix of parallel and series cells but I had to match all the cells first to make sure they all had the same capacity Link to post Share on other sites
England Wonder Posted November 17, 2007 Report Share Posted November 17, 2007 You may be able to use a PWM unit with two packs wired in series to get you an effective 4000mah at 9.6v (basically the PWM turns the circuit off and on a lot) but it would still mean charging the packs togeather in series to do it safely. You'd have to get a charger capable of charging 16NiMH cells (I think Pro Peak do one), most only do up to 14cells (though that may get you what you need) Link to post Share on other sites
L4Isoside Posted November 17, 2007 Author Report Share Posted November 17, 2007 I was considering just getting a 4000mAh pack, lol. How about if i connect them with deans connectors, allowing me to charge each pack sepratley? (Getting a charger that can do x2 packs or 2 chargers would be better i suppose) Anyway thanks for you help, guys Chris Link to post Share on other sites
L4Isoside Posted November 17, 2007 Author Report Share Posted November 17, 2007 Also, two battery packs bought together, at the same time, same make etc surley they must be the same resistance etc because they are new/not used? (Or maybe not in the case that i get a lemon lol) Chris Link to post Share on other sites
CobaltSky Posted November 17, 2007 Report Share Posted November 17, 2007 Most decent Li-Poly chargers have cell balancers because this is much bigger problem for lipos which are nearly always run in a combination of series and parallel. In that case its a lot more dangerous if you get any back current but with nimh you're only looking at damaging the cells rather than potentially blowing them up. You need specially wired batts if you want to use automatic balancers though so it isn't really an option for standard airsoft batteries. I don't even know if lipo balancers will work with nimh cells. Link to post Share on other sites
my_plague_666 Posted November 17, 2007 Report Share Posted November 17, 2007 two 9.6v in parrallel will still be 9.6v would in theory give you 4000mah instead of 2000mahat 9.6v it's not that simple the 2000mah is a typical capacity of the battery and they wont all be the same, even if they are slight differences in resistance between the two packs will cause problems in the long run when NiMH cells are charged in series they are all charged to the max capacity of the weakest cell, if you charge them in parrallel and discharge them in parrallel you can end up with some nasty reverse charging which is very bad for the cell, once it starts getting reverse charged it gets much weaker so it happens more often. It's safer just to get a 4000mah pack FWIW I do have a battery pack made up of a mix of parallel and series cells but I had to match all the cells first to make sure they all had the same capacity but surely rather than having 2 batteries linked in parallel you'd have 2 sets of connectors in parallel. and i dont see why it should be a problem at all, multiple car batteries are often fitted in parallel to increase capacity. just dont connect them in series, 19.2V wont do your gun a lot of good not sure about the theory of it (it was only briefly discussed in electrical principals on my course) but adding batteries/cells in series will add the voltage together, but adding in series will combine the ampere hours. Link to post Share on other sites
MDK_Marshal Posted November 17, 2007 Report Share Posted November 17, 2007 Also, two battery packs bought together, at the same time, same make etc surley they must be the same resistance etc because they are new/not used? (Or maybe not in the case that i get a lemon lol) Chris No. Each cell comes out of thr factory slightly different. One cell may have, say, a 2000mAh capacity and a 15 ohms resistance, and the one made right after it may have a 1900mAh and a 17 ohms resistance. The only way to have a definitely working parrallel pack is to get individual cells and match them in the packs. For this sort of thing you'd be best asking around RC forums - most airsofters really couldn't care less about their batteries - if they work, they work. Not many people care about individualy matching cells (which can take hours, and a fair whack of dosh) just to get a small, likely un-noticable preformance gain. In the RC world even a small gain is a lot mroe noticable and is desired by a lot, so there's more to be learnt from the RC gurus than Airsoft gurus. Link to post Share on other sites
L4Isoside Posted November 17, 2007 Author Report Share Posted November 17, 2007 Oh, okay thanks I'll stick to two of these then, lol. http://www.component-shop.co.uk/html/airsoft_etc_.html---9.6V 4400mAh SC NiMH Battery Pack. By the way, series adds volts, parallel adds mAh (basically) Chris Link to post Share on other sites
Woodco Posted November 17, 2007 Report Share Posted November 17, 2007 Not an electrician, but won't if you double two batterys that you double the voltage? Wouldn't that burn up the motor? Link to post Share on other sites
my_plague_666 Posted November 18, 2007 Report Share Posted November 18, 2007 like i said before, connect in SERIES and the voltage will be combined, and yes that wont do you a lot of good. but connect in parralel and the ampere hours will be combined. im doing an electrical course BTW. Link to post Share on other sites
L4Isoside Posted November 18, 2007 Author Report Share Posted November 18, 2007 I learn't that from my grandad, lol Series= - to + to - to + Parallel= + to + to +, - to - to - Im tired so its most likely wrong. Chris Link to post Share on other sites
Stealthbomber Posted November 18, 2007 Report Share Posted November 18, 2007 Batteries in parallel increase the current. batteries in series increase the voltage. If you have a 1000mah battery in parallel with a 3000mah battery then there's a chance you will overheat the small battery if used in a high current application. If you use batteries in parallel there's not much chance of differences in cell voltage or resistance causing problems. Problems start with BIG differences in current or voltage between cells. Even in a high current application this won't happen. Or, to put it another way, if your battery didn't explode during charging then there's very little chance it'll be cause a problem if you use two SIMILAR batteries in parallel. Course, if you decide to use batteries in SERIES then none of the above is true. In series you DO need matched batteries. Link to post Share on other sites
LondonPiggy Posted November 18, 2007 Report Share Posted November 18, 2007 Current draw would be the same. I wouldn't have worried about any scenrios in discharging but charging is best to use as few cells as possible in any situation wether series or parallel. Also when charging a battery pack the detection mechanism (delta -V) will not stop charging once the lowest cap cell has reached it's peak. It will stop charging once the battery pack as a whole reaches its peak, meaning 1 or 2 batts will be damaged in each battery cycle and in an ever increasing way. It's why when I first got my AEG I was looking for a battery holder that I could take the cells out individually... but I couldn't find battery holders for 2/3A batts. Link to post Share on other sites
ruzzz Posted November 18, 2007 Report Share Posted November 18, 2007 This is a bad idea for a lot of the reasons mentioned here. If you watched the youtube video mentioned in the first post, please use it as an example of what NOT to do ( Hint, cooling the soldered joint using water on the sponge just after you have made it, is not condusive to it working for a long time ). It will work as people have said if the cells are matched. Any slight amount of mismatch will lead to you getting a lot less capacity out of the batteries as one battery charges the other battery when there is a voltage difference between them. If there is a large voltage difference between them, it could mean the battery with the higher voltage tries to charge the battery with the lower voltage using a LOT of current. This will end up as heat, too much and thats where damage will occur. If you want 2 batteries, why not put the spare in your webbing/ assault vest/ pockets. It will mean your gun will weigh less and you end up with the same current capacity and less hassle Link to post Share on other sites
L4Isoside Posted November 18, 2007 Author Report Share Posted November 18, 2007 Exactly what im now planning to do! Thanks for your help guys I suppose this will help some other suspecting n00b in the near future Chris Link to post Share on other sites
Sale Posted November 18, 2007 Report Share Posted November 18, 2007 This is a bad idea for a lot of the reasons mentioned here. If you watched the youtube video mentioned in the first post, please use it as an example of what NOT to do ( Hint, cooling the soldered joint using water on the sponge just after you have made it, is not condusive to it working for a long time ). It will work as people have said if the cells are matched. Any slight amount of mismatch will lead to you getting a lot less capacity out of the batteries as one battery charges the other battery when there is a voltage difference between them. No, actually it's a good idea if the battery space of any given AEG is giving you headaches. A slight mismatch won't cause problems. Same type cells from the same manufacturer are close enough to avoid problems. You can match the cells individually if you want to optimize it, but people run unmatched battery packs all the time. Remember, the issue with having similar cells also applies to batteries in series. All airsoft battery packs have cells in series, and they are rarely individually matched. An AEG stops working long before the battery is completely depleted. This prevents individual cells from running dry. As long as you stop firing when the ROF becomes noticeably slow, you'll be fine. The battery packs actually have a lot of energy left at this point, just not enough to cycle the mechanism that merrily. If you want 2 batteries, why not put the spare in your webbing/ assault vest/ pockets. It will mean your gun will weigh less and you end up with the same current capacity and less hassle With two batteries in parallel, you get a faster response on semi and a slight improvement in ROF. And I think having one battery in the gun for one day without changing in between is the way of less hassle. Just remember to discharge and recharge the packs individually after use, and you're good to go again. And if you're not using the other pack, DON'T put a jumper in the free connector. -Sale Link to post Share on other sites
L4Isoside Posted November 18, 2007 Author Report Share Posted November 18, 2007 You always know what you are talking about Sale Would be a good idea, i dunno if they would fit into the stock now! lol Would have to wait and se i suppode Thanks again, Chris Link to post Share on other sites
England Wonder Posted November 18, 2007 Report Share Posted November 18, 2007 typicaly the internal resistance and voltage sag from a pair of 2000mah cells in parrllel will be greater then a single cell which is bigger though two lots of AA cells may give 5amp hours which you can get from a C cell, the cell may handle more then double the current though. It stands to reason as your waisting less space with the casing for the cell Link to post Share on other sites
Sale Posted November 18, 2007 Report Share Posted November 18, 2007 A good point from England Wonder. The main reason why you would ever run a parallel pack was if there's no space for a proper big battery. -Sale Link to post Share on other sites
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