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Battery Load Tester- Question

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Maddawg46

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I bought this battery load tester. The green area scale is stepped 200,400,600,800. What do those numbers correspond to? The directions don't mention it. My battery is in the green, but close to the yellow step depending on what step I look at.
 
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The tester has 2 scales: Battery voltage and load current. The way it works is that the load tester is a very high current, variable resistance short circuit. You use the load knob rotating ccw to reduce amperage and cw to increase it. Always leave the instrument fully ccw......open circuit essentially.

Assume your service manual says that your engine requires 200 amperes to start; a 200 hp may be in that range. My little 90 could need as much as 150 amps. You want to know if your battery is capable of putting out that much current and holding it's voltage. In short, are all the cells performing as expected? If not the voltage that is not across the battery terminals for you to send to your starter is being dissipated inside the battery across the bad cell.

In making the measurement, move quickly so as to not discharge your battery or overheat the tester or wiring. Move the load (amperage) knob cw rapidly until you get to 200 amps on the amperage meter and quickly take a reading on the battery voltage meter. Turn the load knob right back to zero as fast as is convenient.
The reading you got was the terminal voltage of the battery supplying that amount of current. To get a bendix on your starter to operate correctly it needs about 10v min. If your battery reading was 11v or higher you are in good shape as long as your interconnect resistance isn't high meaning the wiring and terminals are clean, bright, and tight.

A better way to make the measurement is to put one of the voltage clips (black) on the starter black lead, or - or engine block at a good solid tie point as close to the starter - as you can get. Put the red lead from the tester on the 3/8" input stud to the starter solenoid; not the lead from it to the starter but to the input.....you don't want the starter to turn over.

Run the test again and this time when you make it you have all the circuit, except the internal resistance of the starting solenoid in the current loop.

Now run your amperage up to 200 amps and check the voltage. If 10v or better you are good to go. If less, somewhere between the battery and these two points mentioned, could be in the red wiring circuit or the black, you have a bad connection. I'll tell you this, it won't take it long to get hot so it's pretty easily detected.

HTH,
Mark
 
Mine has no adjustment know. Just a spring loaded switch to put a load on it. It's not a multi meter. It's just for checking batteries and alternators. Looks like the snap-On one. Paid $50 at Oriley auto parts.
 
The load is nothing more than a string of carbon plates sitting side by side. The looser the interconnect between them the lower the current. The knob on mine or possibly the spring on yours puts pressure on these separate plates forcing them together with more and more pressure. The more pressure applied, the better the contact and the lower the resistance of the pile. Obviously the lower the resistance the higher the current.

I just googled O'Reilly auto parts and in the battery accessories and all, that section it was down for maintenance. So I'm pretty much at a dead end but one more guess.

Yours may be just a single test point. The switch and spring are probably to allow you to connect it to your battery and then flip the switch which allows the spring to put pressure on the carbon pile and pull the plates together thus allowing high current. Somewhere on it there should should be an amperage number. Probably around 150-200. That's plenty for your test.

So, if it's that simple one would then expect that you were to use your personal multimeter on the battery's terminals (or circuit connection points if testing the circuit) to read the terminal voltage when you flip the switch. Essentially you have the same mechanism as I have just simpler. You can still hook it up like I said, across the battery or across the circuit, flip your switch and get your reading. Just put your meter leads across where your tester's leads are connected.

Mark
 
The meter puts a 135 amp load. It's called a Super Start. The needle measures volts like you said. You hold the button down for ten seconds to put the load on. Battery only goes up to 11 volts while applying this load. My question was what ate the graduated green scale numbers 300, 400,500. Have not a clue. Can't be volts, or amps.

But only getting 11 volts seems to be not good, unless that is normal when applying a 135 amp load. Maybe the scale is amp/hours? The scale has green for good, yellow weak, red poor.
 
Don't know about your scale numbers. The colors could be indicating battery condition under load for a fast check; like a go-no-go test. The fact that it's in the green but close to the yellow at 11v makes sense. 11v under that load isn't all that bad if your interconnects are good. As long as you don't loose 1v on the way to the starter and 135 will start your engine you are good to go.

I just took another look at my service manual and the spec for my starting current, under load...aka turning my 90 hp 3 cyl engine, is 120 amps. For the 4 cyl 125 hp engine, current is listed at 150 amps.

I think you are alright on your battery. So backing the truck up to the starting gate, what was the purpose of your question in the first place? Just trying to understand your meter or were you trying to solve a problem?

Mark
 
I agree -11V with 135A load is a "like new" battery if we're talking typical size Group 24 or similar marine batt.. wouldn't worry about the other numbers.
Had a look at that load tester on the O'Reilly site - what a dumb tool with only 1 load. I guess it's sort of idiot proof so someone doesn't wind it right down, walk away and blow the battery to smithereens.
 
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hystat said:
I agree -11V with 135A load is a "like new" battery if we're talking typical size Group 24 or similar marine batt.. wouldn't worry about the other numbers.
Had a look at that load tester on the O'Reilly site - what a dumb tool with only 1 load. I guess it's sort of idiot proof so someone doesn't wind it right down, walk away and blow the battery to smithereens.
Click to expand...

Might be to get the lowest price and serve the majority of customers requirements, with the simplest operation for the reason you mentioned.

I got mine from Harbor Freight. Happy with it and it does the job. Forget what I paid for it.

Mark
 
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