Trying to get the most out of a charger.

Your talking chargers, an we have to assume things. I'm assuming anything, so I have no idea, depends. I blew out my Harbor Freight charger, don't know if it was something I did.

Start out slow charging the battery first before anything using one charger and see if it cranks.

I can't see the chargers or schematics. It could be regulated chargers with a 2 amp setting being lower voltage connected to ammeter. It's possible to connect two supplies in parallel under certain conditions and depends on circuit design.

Greg

I've used two battery chargers at the same time on cars many times. Never had a problem. Of course I'm talking about two small chargers. Like a 6 AMP and a 10 AMP. I would not connect two 30 or 50 Amp chargers together. I'm just charging at a rate of 16 AMPS, which charges the battery faster than the individual chargers. Since you can buy a 30 or

Just sharing my experience, not guaranteeing you can do it safely. But like i said, I've never had any problems doing it.

YIKES!

A few things about lead-acid batteries:

a) They do not like to be charged beyond about 10% of their AH rating. That is not to suggest that more amps will destroy them - but that some care is needed during the charging process.

b) Charging amps, AH ratings and the actual operation of the battery are, a t best, first cousins - related but not directly. For instance, even a high

-rated gel-type battery is generally not suitable for motorcycle operation as its chemistry is generally not suitable to provide the very fast dischar ge (very high amperage) needed to turn the starter motor at sufficient spee d to start the engine. Conversely, a much lower *rated* battery may be perf ectly fine for the purpose as its chemistry is designed for a very high amp erage discharge for the few seconds necessary.

c) That your charger jumped to 10A is not a surprise, most such chargers ar e 'smart' inasmuch as they recognize the draw of the battery and react acco rdingly. But 10A is not hardly enough to turn the average small starter mot or under load. For instance, a marine-grade Group 24 battery (most common g roup of that type) is rated at a mere 80 AH, but is capable of 800 CCA (col d-cranking amps) for a few seconds to start a big diesel boat engine, for e xample. Your little cycle-starter may need 50+CCA or more to operate proper ly.

d) A motor could care less how many amps are available to it, as long as th ey are in excess of its draw at a given load. If you want to test the start er, us a regular car battery. If you want to use an outboard device to tes t, get a Starter/Charger unit. These devices either have a rapid-discharge battery on board or a series of capacitors boosting the output the few seco nds needed to start.

e) Ganging up chargers is generally not a good idea unless they are identic al in behavior and type. It is generally not a good idea to use these thing s beyond their design parameters - at least, you would void any warranties. At worst, you would pick the only two chargers that if paralleled would go the way of Chernobyl.

Peter Wieck Melrose Park, PA

The open circuit voltage of a charger means next to nothing.

The only problem I can see is that most chargers today are automatic and need to sense battery voltage before they turn on.

If the battery voltage is too low, the charger will not even turn on so a non-automatic charger would need to be used to get the current flowing.

If the battery is /extremely/ low I've seen situations at work where we'd have to put the battery on a variable charger and crank the voltage quite high in order to get the charging process started...then after a very short time switch the battery over to a conventional charge.

(As you probably know by now I was in the industrial battery business)

At any rate I don't recommend putting two chargers in parallel but on the other hand I don't see that it would hurt anything just as long as you disconnected one once the battery got close to 80% charged.

NOTE: To avoid a spark and explosion do not disconnect while under power

Good enough. Thanks. (Though I've written down your email address and my estate will be suing you if this proves fatal.)

Not even an override switch? That seems like a bad idea.

For example, the battery I started with, which I have only for testing things, had a voltage of 0.1 or 0.2 volts, but I can usually charge it to 11 volts or more. Actually I'm not sure the battery will help here since it's sooo bad. But I'm stuck in the mold of my car, where the oldest crummiest battery I ever had would still, when jumped from another car, take a charge in about 5 minutes and spit it back to the starter motor when the jumper cables were too thin to directly start the car.

Somewhere I think I have an old motorcycle battery I also saved for testing, but I haven't found it.

Yes. I'm sure you know what you're talking about.

Okay. Once the scooter starts running, it has its own alternator/rectifier.

I'm told on a scooter forum that there are scooters that run on AC current mostly and that they will start without a battery, but that those that are DC won't. (or perhaps it's enough if they have a charger connected.)

For the AC current scooters, seems to me, they should make AC batteries. Isn't AC Delco a big maker of AC batteries?

If the battery was brought down to a very low voltage but charged within a few days, it should recover (if it was OK to begin with)

However if a battery is left to sit "dead" for a very long time...once stage 3 sulfation (permanent crystallization) has set in...there is zero chance of it being recovered.

Just amazing!!!!

Way back when some power stations in the UK produced DC mains - some people charged their car battery by putting it in series with an electric fire.

These days; you need a pretty hefty bridge rectifier.

One of the UK hobby magazines published a project for a super-duper battery charger involving 3x LV lighting transformers, all assembled in a cheap steel tool case.

Can't remember which one or how long ago.

It wont be fatal for you, it's only 12volts. But it could damage a charger or battery, although I have never had that happen. My chargers are old, so they dont have all the circuitry that some new ones have. It's just a transformer, some diodes, and a reset to shut it down in the event of a direct short. Very simple, and I have fixed several of them over the years. Usually it's a bad diode or two, or that reset device fails. I did have one burn the transformer out, after it got rained on. I learned that the hard way! I always cover them now if they are in use outdoors.

Somewhere I've got an ancient charger that the Halfords store used to sell - the metal case is the only original part.

The rectifier was replaced with one from a motorcycle and the transformer with one from a Philips black & white portable. The cheap & nasty plastic moving iron current meter was replaced by an Admiralty bulkhead mounting instrument.

A resistor was added before the rectifier to limit the current because a TV PSU transformer doesn't have a charger transformer impedance characteristic. A couple of big film capacitors were added to make the rectifier voltage doubling (for some strange reason it actually gets up to about 42V with no load!). Which works rather well for saving sulphated batteries. Later I added a big fat electrolytic for zapping whiskered nickel cells.

I had best luck with simple chargers. Most fail needing repair of clamp connection. I have a 4 amp one that's 30 years old, old trusty. I'll be looking for another.

Greg