Charging Batteries

No....I just wanted to present the other side of the argument, but this is all I can manage just now....

I reiterate, it makes no difference....

http://batteryuniversity.com/learn/article/serial_and_parallel_battery_configurations

Yep, Yep, Yep, Yep, Yep.

The second and further agreement means, that I agree, you and most others are clueless. It is not personal, Ronsetto, as you toss in intriguing questions.

The basic problem is manufacturing process control. Mostly the lack of it. Results in too much variation in capacity, mainly.

When you charge them serially, the low capacity will overcharge time and again.

When you charge them parallel, the slightly lover voltage one will overcharge.

A very complicated and sophisticated set of electronics is still being developed for battery powered vehicles. For a good reason.

Battery powered powered hand tools will benefit from that.

So, NO, we ain't there yet, for a long time.

Well what type of cells? Ni-CD, NiMH, lead acid, LiFeP04? All require a different algorithm. Some 2 step, some must have 3 step charging. Some Alkaline are now able to be charged, they require a different charge algorithm and charger. You need to get the most out of your battery cycles as possible to be cost effective.

If this is a hypothetical question, I will think it will charge quicker in parallel because of the less resistance.

IF... The cells are virtually the same, in manufacturer, year, are new, etc. and used in series together for whatever application, then yes, you can charge them in series with the appropriate type and voltage charger. This works as they all are close enough in parameters and all subjected to the same use so as to be handled as one multicell battery. Most all batteries of over 1.5 volts are in fact multi-cell. If your individual batteries are being used in separate applications, then they are subjected to different conditions and will become the weaker or the stronger link in a series charging system causing premature death to the whole chain. The answer is, it depends.

Hey Ron,

I can't speak to the "proper" way my friend. What I can do is share several years of experience racing radio controlled 10th scale cars. These were powered by six 1.5 to 1.7v sub C size niCads wired in series. We would charge and discharge these battery packs quite agressively. Basically pumping in almost 12 volts into the pack, which would be quite hot. We would hold them on the charger until just before the race, then with the car geared just right, manage a full discharge in 5 minutes. The car would fly for 5 minutes 10 sec.then die. These battery packs were amazingly resilient and would last several months or about one hundred charge cycles before showing signs of wear. The most important thing was making sure the batteries in given pack were as close to matched as possible. One out of spec cell would cripple the entire pack.

In any case Ron these packs would fully charge in 10 minutes or less using a computer controlled speed charger or even an old silicone plate rectifier pumping out 16v at 10amp with Fluke 87 monitoring. The folks at Gates would often tell us this was not a good idea even as they sold us the matched cells. In the 5 years I did this, I never saw an explosive failure although I was told they could occur. I did see a pack rupture on the track at Whipoorwill raceway in Florida. (BTW this was a 10th scale replica of Daytona that close in 93) FYI these 10th scale cars would routinely exceed 50 mph.

Don't know if that helps, but there it is.

Yes, it was for FACTORY MATCHED cells. With close monitoring during charging.

Wallwart type AA and AAA chargers (the ones I checked) have a specialized chip in it for monitoring and controlling the charging process either for each cell singly, or for pairs. To know which is which, insert a single fully discharged defective cell with others properly partially discharged ones. If the charger kicks off one cell, it is the first one. If it kicks off 2, it is the second one. If it is the second one, you have to mix and match even good looking cells until they are accepted for charging.

So, normally manufactured cells have loose parameters, which are changing due aging on the top of it.

A typical chip I run now across:

.Smart charger chip

It is regulating and monitoring all parameters including temperature.

Simple it ain't.

Its always best, when possible, to charge each cell individually, which is what all GOOD chargers do.

As you neglected to mention either the battery type or the charger, it is difficult to answer any more than Del already did.....

Chargers must be designed to charge the chemistry of the battery concerned, which is why for example a 12v car battery charger cannot be used to charge anything other than a lead acid battery......as a general rule anyway.

Some chargers are voltage orientated (car battery for example) and some are current orientated (nimh/NICAD for example).

Some need special monitoring to preclude over charging, over heating and possible water/chemicals loss.....

In your case, I suspect that you may be looking at a car charger, that should not be used on 1.5 volt cells, only 2.2 volt LA cells, 6 at a time.

Althought this question was intended to be qeneral, I do have a specific situation at present. I have a golf cart, 36V (6-6V batteries in series). They were all installed new at the same time. One battery has failed. Corrosion build-up on the posts and finally breaking off. I will have to replace this one battery and now they will not be "matched" (as if they ever were). I use a 36V battery charger designed for this cart, but wonder if I will see other battery problems down the line, like over or undercharging of any of the batterise that could lead to overall failure and shortened life. These batteries are 2 years old with a 3 year warranty. It is my understanding I can return the one bad battery at no cost to me. (Bought at Sams Club)

Ah!

In that case your problem is manageable. As your replacement is new, its capacity is expected to be higher, than the others. Monitor their voltages during the first 2-3 charging cycle. Stop charging before any one is overcharged. After that - in all likelihood - you will be able to charge and use normally.

In any Battery (which is simply a name for more than one cell connected in series), there are weak and strong cells.

When charging, one cell is always finished charging first, further charging just damages it. The other cells will not be fully charged at this point.

This is why all good chargers charge one cell at a time.

Due to the fact that this is difficult in a battery (of cells) to charge each one individually, that is simply why a cell always fails first before the others.

(This a further reason to only charge to 70% of capacity for LA and SLA batteries, they simply live a lot longer.....)

Remember, a battery with one bad cell, is now a bad battery.....

The above is basically the same for all chemistry types....

What type of 1,5 Volts rechargeable cell? I don't know any of this value, but would like to know where to find these.

Most I know are 1,2 Volts or in that range.

Thanks

Various Lithium chemistries produce about 1,5-3,7V. See Wikipedia.

The lower value usually NiCad.

Then there are specialty batteries.

Gates, Sanyo, just off the top of my head both produce 1.2v Sub C batteries in 1.1 to 1.7 ma and beyond. I would imagine a little catalog surfing would produce an even more comprehensive list of manufacturers and voltage/amp combos. Been 20 years since I was active in this area I am sure much has changed since then too.

Charging in parallel would be best in my opinion.

Generally a bad idea as every cell is ALWAYS an individual and needs a charging cycle for it and it alone.

No single charger (except for a charger composed of several separate chargers internally, each with its own control electronics and connections) can handle each battery (or cell) individually.

Its already a problem when two or more cells are combined to form a battery as usually the inter cell connection is not accessible and charging on a single cell basis is not possible, always one is from new, weaker than the other(s)......

So I disagree entirely with your comment.

My comment (opinion) was rather uncalled for when you consider that the OP originally just wanted to know the difference between they two methods.

However I was basically pointing out the same thing that you did in post #17. And that was the view that if there one bad cell encountered in the series, that you would lose the charging capabilities.

OK, I thought you were recommending that as a good way to go.....

Have a great day/night.

I get a newspaper from LT (Linear Technology). It's very well done and I read it every time it arrives, well worth having. See:- LT

The April edition has some interesting new chips and the cover information details some very pertinent infos for us here, I cut a picture up to stop having to type it all in again:-

I hope its all readable.....