Good deal,Thanks for the heads up.

You are welcome, however, I expected some argument here.

"You are welcome, however, I expected some argument here".

One argument might be that one would be leaving an electrical device, that is easy to forget especially if your tractor is out in the shed, plugged in unattended.

Another argument might be that over time enough electrolyte could be evaporated to expose the cell plates and ruin the battery.

In the 70's Yuasa sold exactly what you describe with a quick disconnect harness so the connection could be left on a motorcycle. I'd rather plug that wall wart in for a couple days a month and then unplug it instead of leaving it plugged in.

Bill,
When you clip the coaxial plug off to install the clips, how do you know which is + and which is - ?

Hook up a volt meter to the leads. If it reads positive, the one connected to the red probe is + and the one attached to the black probe is negative.

If it reads negative, you've got them reversed.

Is there any other way to check the + from - if you don't happen to own a volt meter? I know that reversing the wires on a small DC motor will make it run backwards, but I don't know if I could tell from that alone which was which. Just curious.

You could hook them up to a speaker.

If you hook the positive lead to the positive speaker terminal and the negative lead to the negative speaker terminal, the speaker should pop out. If it goes in, you've got the + and - reversed.

I suggest using an old speaker for this and only touching the leads to the terminals very briefly.

With respect, if you don't own a voltmeter then you shouldn't be foolin' with battery chargers.

Everyone should own a DVM especially when Harbor Freight sells a very competent digital meter for $2.88

This will be the best $2.88 you'll ever spend

Buy a few and leave one in every toolbox and glove compartment... and don't forget your friends!

Respect acknowledged, justalurker. But I am almost 70 years old and you might be amazed with how many "need to have gadgets" I have managed to do without over the years, but a battery charger has not been one of them. Still, I admit that all of them were well marked Postive and negative and most had a volt meter built in. Thanks for the info on Harbor freight.

johntommybob,

When I was a kid a buddy's dad, who was an electrician, used to test for live circuits by licking his fingers and touching house wiring to see if they were live. After watching my buddy's dad a voltmeter seemed like a "must have"!

As soon as I was old enough to fiddle with electricity I ran down to Lafayette, or was it Allied, Electronics (I'm not that far behind you) and bought the cheapest "needle-swinger" volt meter they had.

Still have that meter in the toolbox.

Just a quick question for a voltmeter dummy. I bought one of those from HF, read the instructions (what there was of them), and still not sure how to test a battery/level. What section on the meter is used, what position is the dial set to, which holes are the testers plugged into, etc?

Plug the black (negative) lead in the bottom hole. And the red lead (positive) lead into the hole above that. Set the rotary switch to 30 on the VDC scale section. Measure across your battery first. It should read about +13 volts with the red lead on the + terminal and the black lead on the - battery terminal.

Measure the voltage on your cut off leads from your new battery charger. If it reads about +15 volts then the one you have the red test lead to is the positive lead and the other is the negative. If it reads about -15 volts then reverse your meter leads until it reads about +15. Again the red lead is on the positive wire.

To measure your house voltage, set the meter to VAC and the rotary switch to greater than 150.

Hope this helps.

Thanks bill...appreciate it.

Would those be the same settings to test for incomplete or faulty circuits from the batttery to ignition, solenoid, etc?

FYI, anytime a voltage is unknown you should set your meter to the highest range and work down until you can read it. No sense bending the needle on your first try.

Look closely at the wires coming from the power supply. On the ones I have tested for polarity, there is a white stripe on the negative wire and numbers and lettering on the positive wire. Whether or not this is a standard I don't know. If a battery is discharged the load would probably too great for the power supply unless the power supply had a voltage fold back circuit which I doubt. With that being said, they should work just fine to maintain a charged battery.

"If a battery is discharged the load would probably too great for the power supply unless the power supply had a voltage fold back circuit which I doubt."

I do not know what a "voltage fold back circuit" is. However, these little chargers are very safe, even when a short is applied. Otherwise one could have a fire in one's house and the maker of them would face multiple legal suits.

Bill in NC,

With respect, "these little chargers" were never intended by the manufacturers to be storage battery chargers so the product liability would be limited to their intended use.

Over the years I have seen wall warts overheat, melt down, and short a 110 outlet.

I'm reluctant to leave any electrical device plugged in, powered on, and unsupervised, especially 2 cent Chinese transformers.

It's obvious that you have sufficient knowledge to safely use those wall warts as chargers and understand their shortcomings but this thread has shown that some don't know how to tell the difference between + and -. Those people will be better off using actual battery chargers with charging indicators, fuses and/or circuit breakers.

When you scuffle across the carpet on a low humidity day your fingers build up a static charge. When you get zapped on the doorknob, is your finger positive, or negative ?

bill_in_nc - got home yesterday and tried to apply my new-found knowledge of multi-testers and came to the conclusion that I not only have a tester I can't read...no no else can either. I had the Sears tractor tech out and he couldn't read it either. LOL!! Guess I picked up some kind of tester that no one has a use for. I got it at HF couple years ago, but it's a yellow case instead of red. Either way, back to get another one...red this time.