Charging Batteries--Serial or Parallel?

[Elnath]

I'm looking to expand the number of batteries that I can charge at once. Usually I'm talking AA NiMH, but for the purpose of this question, it probably doesn't matter.

If I'm using one of the high tech controlled chargers like a Triton, is it best to configure a battery holder that will present a parallel configuration or a serial configuration? I understand that the serial would require more voltage, and the parallel more current, but since the charger is selectable for either, I wasn't sure what to do. Serial is probably easier since most of the battery packs are set up that way off-the-shelf....but parallel seems intuitively better for the batteries....

Hopefully the experts here can clear this up for me.

thanks!

 

[js]

Elnath,

NEVER parallel, always serial, as far as I know. The Triton delivers a set CURRENT to NiCd and NiMH batteries, and varies the voltage accordingly. It does have a gentler trickle charge current towards the peak, but still it is controlling CURRENT, not voltage. Li-ion and Li-poly are charged constand current up to a point, and then constant voltage after that.

The Triton can charge up to 24 NiCd and NiMH cells. Atsa lota batteries in serial. And the batteries you put in serial should all have the same state of charge so that they peak at nearly the same time. If this is not the case you'll need to trickle charge them with no peak detect for a long enough time that they all equalize. Or charge them separately.

The Triton is not designed for consumer charging of AA's and AAA's and wouldn't be a great choice for such an application. Well, not if convenience is important, although I suppose once you get your battery holders buit it might be easy. Eh. I don't know. Perhaps Ginseng will chime in on this one.

 

[Doug S]

[ QUOTE ]
Elnath said:
I'm looking to expand the number of batteries that I can charge at once. Usually I'm talking AA NiMH, but for the purpose of this question, it probably doesn't matter.



[/ QUOTE ]

Actually, battery type matters alot. Generally bad practice to parallel charge NiCd or NiMh. Parallel is preferred for Pb-acid or Li-ion assuming *roughly* similar initial state of discharge.

 

[Mr Ted Bear]

I had a chance to discuss this very issure with the PK, as it related to the Kenrad HID, the Beast and the M6.

Intially when Kenrad offered their PS35 HID, they had as a optional 123 pack, with batteries in a series/parallel configuration. Similiar configs are used in the Beast, and on a smaller scale the M6.


The answer to your question is a question of ratios. I understood the parallel config to be the more stable of the two. In the first case, you have more current potential, and in the casee of serial, greater voltage potential, and of the two, voltage can more easlily do damage

 

[Ginseng]

Something like a Triton is not the best bet for charging handlfulls of loose AAs. I have to ask, what's the point? If you're using loose AAs in a bunch of toys and electrical appliances, then you'll have many different sized groups of cells at various states of charge. Trying to bulk charge a ton of them all together would be a nightmare whether you run in parallel or serial. As js stated, to insure your cluster charges safely, you'd have to do a long, low rate trickle to help equalize the cells. This would probably take longer than just putting them in groups of 4 through a dedicated AA smart charger lke the MAHA 401.

Ok, so perhaps we're in agreement that for general purpose use and charging of AAs, specifically, the Triton would be a poor choice. Let's assume then that you have an application which requires the use of a set of 12 cells. Enough info? Not really. Are they 2000mAh AAs? 4000mAh 1/2Ds? 11,000mAh full Ds? Keep in mind that the Triton has a limit on current delivered as a function of voltage. String together 12 cells serially and your max current will be limited to 5A. String 24 together and it drops to 3A. And this is assuming your DC power supply has the juice to give the Triton what it needs.

If you try to run two sets in parallel, cut your current delivery in half.

So what's the bottom line? For me, I have charged as many as 15 3.5Ah nimh 1/2D in series with no problems. However, this consisted of three 5-cell soldered sticks and heavy gauge connectors between eack pack. The implication is that whether parallel or serial, the quality of the connections between each cell is paramount. Just stacking them end-to-end will result in connections which may be iffy and if they get moved around, the voltage sensing will be screwed up potentially screwing up the peak sensing ability of your charger. You might be able to mitigate this risk by building a dedicated charging rack.

The other bottom line is that it's beneficial, almost critical to keep your cells in natural groups that fit your device needs. Using loose cells in a MagCharger? Keep a five pack in the light and another five pack in reserve.

Wilkey

 

[illumiGeek]

For charging lots of AA or AAA batteries there are several 8/10 cell capacity chargers available from the likes of Vanson, Lenmar, etc. These have individual charging circuits for each cell and would be much more practical for your needs.

I personally use a V6988 10 cell charger and have been quite happy with it. It is a very slow charger though, but with 10 cell capacity it has lots of room, so I usually have some batteries on there that are ready to go. I also have a 4-Hour "Fast" charger, and more recently have gotten 2 of the Rayovac PS6 "15-minute" I-C3 systems, and I'm loving those (8 batteries in 15 minutes!).

Aloha, iG