Adding a 6v boost to a 12v battery charger

That's a kilowatt problem, of course... If the charger has inductive filtering on the outputs (this is likely, because it allows better rectifier conduction duty cycle, keeps things cheaper), then you might be able to lower the RMS input voltage from 120VAC to something lower, and get proportional output. Some kinds of light dimmer (the ones for inductive loads, like dimmed halogen-lights-on-a-transformer) can safely handle it.

I think that's not a good assumption. You need about a 6 volt tap on the transformer. I had an old battery charger/car starter that put out 300 amps at 10.5 volts. Somebody stole it, %$&^%! Mike

Thanks for the responses so far...anyone else?

And any suggestions to other sites where I can post this question? Links please.

Thanks

No more suggestions?

Any suggestions where I could post this question where designers hang out?

Thanks

TMT

Let's try casting the net a bit further...anyone else have a suggestion as to how to do a conversion? Thanks

TMT

Why don't you open it up and see if its got any taps on the output of the transformer. Or if you are lucky a 220/230 volt centre tapped primary winding.

See if you can get a tap on the transformer?

It should be obvious by now, that to many want to step up to the plate.

There are ways, but if you can't comprehend the basics of how, would it make any difference?

And I thought this was answered once before ? Or are you just spamming?

For starters, assuming that this unit has no voltage reliant devices in it. install a step down 2kw transformer to drop the incoming by half.

The price of this xformer will most doubtably change your mind on the project.

th

I am not trying to be a smartass.

My apologies to anyone who thought I was.

When a question is out there for days with minimal responses, you prompt the group for any other comments before moving on..which I did.

TMT TMT

OK, I kinda hate to suggest this as a solution... I'm afraid too-many- tools will become too-few....

But, if you had a second UNCHARGED battery to put in series it could act as the dropping resistor.

Please note the emphasis on uncharged. I'm afraid you will blow something up!

George H.

snip

I presume this is one of those wheel around big guys seen at repair shops and service stations.

I take it that the 200 amp is a feature you can select to start vehicles if you are in a big hurry and can't wait for the original battery to accept an adequate charge.

The 6 volt battery will, for a time, swamp the 14-16 volt charging voltage output down to the 7 or 8 volts if you hook it up as is. Better if you have a trickle charge or lower charging current feature selection to buy yourself more time with the 12 volt charging hook up.

You could then actuate the 200 amp feature to see if you can start the problematic vehicle. But I wouldn't leave it on for long.

Older chargers used selenium rectifier stacks and they have a built in current limiting (intrinsic resistance) and are very conservatively built.

Charging batteries is hazardous even with the right equipment, but unless this is a very tiny ampere hour battery, you should be able to do it for a minute or two before you start heating up the plates and permanently destroying the battery and possibly the rest of the automotive electrical system.

The suggestion about adding another 6 volt battery in series would work as well, you would have to position it between the vehicle being charged and hook up the positive of the vehicle battery to the negative pole of this added battery. The positive of the added battery going to the potitive lead of the charger.

Joe Rooney

Okay...I found a schematic of a similar charger that Sears sells....

Does this help?

TMT

Difficult to see but it looks to have a multiple tapped primary. It also looks to have dual parallelled secondaries going into the rectifier.

th

The schematic is a valid one...who do you think makes the Sears charger?

TMT

--- What difference does it make?

Even if it's Schumacher there's no guarantee that the one you have is the one the schematic is for.

Again, why don't you contact Schumacher and ask _them_ for help?

JF

I did. ;