Battery testing

Yesterday I bought the HF 500A carbon pile battery tester 91129. The instructions are aimed at a one time Go/NoGo garage test of customer batteries, for 15 seconds at 1/2 of the CCA rating.

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The adjustment is unstable below 30A and drifts upward as the carbon heats up. It isn't the good 5A or 10A discharge test load I had hoped for, but it does what it's supposed to well enough.

It seems to me that the current draw at the pass/fail voltage step for the ambient temperature would be a more sensitive indication of battery condition -if- you record it to compare to later. There is a large change in current for a small change in voltage, and the pass/fail voltage point should be the same for any starting battery size or condition.

Has anyone else used a variable load tester this way, or have a better idea?

--jsw

Reply to
Jim Wilkins
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I've thought about getting one of those. I was thinking of using it as a test load for my arc welder. The latter is infinitely adjustable but the adjuster is pretty crude. I wanted to try measuring the open circuit voltage and then try correlating that to a more accurate welding output current. The reviews on that HF load were quite the mixed bag and it cost just enough that I haven't done it...

For a smaller load that may be more repeatable you might try some glow plugs. The usually draw around 5 to 10 amps. Some of the generics aren't all that expensive.

Reply to
Leon Fisk

These cheap testers are sold under many brand names.

I looked into them on amazon and the more knowledgeable reviews all say that they are crap, made as cheaply as possible just to sell them.

i
Reply to
Ignoramus12566

A bank of old sealed beam headlights works great. And you can use them to draw a battery right down to dead if you want - unlike a glow plug which you will most likely burn out.

Reply to
clare

I didn't mention my other hamfest acquisitions because they are expensive new and hard to find used, for example:

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I can set up a 12V resistor test load for up to about 50A, with some gaps in the range of currents and a lot of exposed terminals and stiff, springy wires. Someone could buy the HF carbon pile load new for a lot less than that rheostat.

5 Ohms 150W is a useful size IF you get a good one.
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"I would give a zero star rating if possible."

A tubular variable power resistor very quickly becomes too hot to adjust.

--jsw

Reply to
Jim Wilkins

"Ignoramus12566" wrote in message news: snipped-for-privacy@giganews.com...

The construction of this blue HF one isn't that bad inside, nothing cried out for repair or improvement. It has a (skywired) multiturn pot in series to adjust the gain of the voltmeter plus the front zero adjustment. The ammeter agrees with my analog 50A Weston ammeter and my DC clamp-on as well as you might expect for an analog meter. Unlike some similar ones they ran the separate voltage measuring wires inside the heavy current cables, not tie-wrapped onto the outside.

--jsw

Reply to
Jim Wilkins

I certainly -don't- want to drain them dead, so I use my 20 Amp solar panel controller to cut off the load when the battery drops to 10.7V.

If you don't have solar a 12VDC to 120VAC inverter with a lamp or heater load will work, but may cycle on and off. The solar controller's cutoff and reconnect voltages are programmable.

I just measured a 4001 round high beam as 3.0A at 12.8V.

--jsw

Reply to
Jim Wilkins

The voltmeter on the HF 91129 tops out at 16V. It has a 15 second timer circuit inside that may not take much more than that. I didn't find another inexpensive carbon pile load, which is what I was searching for, not specifically a 12V battery tester.

If the welder varies the primary - secondary coupling, series inductance or shunt leakage you may not see a good correlation, since a fairly high open-circuit voltage aids striking the arc and the adjustment is to the source impedance.

At school I used a Lincoln Square Wave newer than mine, with a digital current display. You can't read it while welding and you adjust current by the puddle anyway, so the readout was no more helpful than a knob pointer on a scale.

--jsw

Reply to
Jim Wilkins

That could be problem without some modifications. Probably looking at ~60 vac. Of course I also have the AC to deal with too. Could be completely unworkable. I know I talked myself out of getting one because I didn't feel like it would work out well.

Looks like just using an amp meter and having a video camera on both meters while putzing around would be the simplest way to go. If I ever get around to it...

I suspect that could be the way it goes too. The welder uses a movable shunt I believe. Rather than over think the test set up I figured to just hook up some meters and see how it acted.

From what I've seen they let you pre-program the output current on a digital display but that doesn't mean it is calibrated very well. And that doesn't take into account your cable length and poor connections along the way.

A lot of my welding is for little stuff here and there. Never get enough run time to establish good settings. It would be nice to be able to preset the machine to what worked good before or to say the low, mid, or high end of what is recommended. Usually by the time I've gotten a feel for how it is running, re-adjusted the output a tad, I'm already done. On thick stuff it doesn't matter much but thinner items...

Reply to
Leon Fisk

I've used carbon piles to test very high current power supplies. One needs to verify software. Set 800 amps at 5v and see what is flowing. Set 1000 amps and see if the pile is smoking.

We actually smoked our pile once - man that was a fast race to disconnect and start to float some co2 around it to cut off the air and turn off the fire if any.

It was a bit more crunchy the next time we used it, inside it was toast.

We had 2000 Watts across it and it was rated at 1500. Was to be used at max of 1000 by ourselves.

We never used them to ramp up/down since ours was a mechanical 'resistor'.

We had static voltages in hundreds of amps at fixed voltages variable I fixed E.

We had IEEE 488 voltage programming with high current ability. The boxes protected themselves by trimming the voltage back to limit the current.

I would think you could use that but not by turning knobs in real time. Set and switch & see. Set and switch & see. You might be watching results of the 'machine' and not of the battery. Once you find something specific, try to re-create or verify with another load. Which then takes out the servo effect of the pile electronics and heating... of electronics and pile. Hot pile, wrong results.

Mart> Yesterday I bought the HF 500A carbon pile battery tester 91129. The

Reply to
Martin Eastburn

Right - and you can see when the light blows out.

My father, years and years ago at White Sands, needed a load resistor for a new design Radar system before dumping it out on the range.

He used 1000W bulbs - 1000 of them. Big radar. He had a special room with lots of coolant and racks of bulbs. The Radar was certified and went on line. Dad then had the bulbs salvaged by a local city who used them in large storage areas. The purchasing man ordered another set for the next month. They returned those and canceled further orders.

The Radar Design then went to the Pacific Missile Range for use.

I also use the car head light as a low voltage bulb over the ways are of my metal lathe and wood lathe. They are bright and worked.

Martin

Reply to
Martin Eastburn

I haven't seen a really big carbon pile load since the 70's, at a GM plant. When I tested electric vehicle batteries we used an electronic load that dumped its heat into a barrel of water. I'm very happy that the testing program was quiet and uneventful and didn't produce any hair-raising tales to pass on here.

--jsw

Reply to
Jim Wilkins

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look at the article 'The Smoke Tester' (on page 159) for an adjustable solid state load.

Here is a link to just that one page article, on my Google Drive. It is only 118 KB, VS 71 MB for the entire magazine.

Reply to
Michael A. Terrell

Some of the other distributors for that model say "50-500A", but HF doesn't. Any reason you didn't go with the 100A model, if you wanted to test smaller currents, Jim?

That was a fun romp in the Seventies. Ampl'Anny, eh?

I just brought home some Kenwood TK715 VHF FM radios from my sister's. She wants me to sell them for her. Any idea what they're worth? They're NOS NIB (1 cardboard box missing, but still in styrofoam box) Straight 715, not N or other suffix. Vehicle mount 25W HAM.

Reply to
Larry Jaques

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