What are the differences between these HF test lights?

[qqzj]

1 This is the cheapest one

6/12V Circuit Tester

Amazing deals on this 6/12V Circuit Tester at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

2 2nd cheapest one

6/12V Circuit Tester with 5 ft. Lead

Amazing deals on this 6/12V Circuit Tester With 5Ft Lead at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Seems it is better than (1) because it has longer cord?

3 a pack of three

Circuit Tester Set, 3-Piece

Amazing deals on this 3Pc Circuit Tester at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

It is only $7 but it has three test lights. Are they the same as (1)?

4 The most expensive one

Computer Safe Automotive Logic Probe

Amazing deals on this Computer Safe Automotive Logic Probe at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

What does this mean? Does it use an incandescent bulb to load the circuit a bit or it is a tiny LED bulb?

Finally, why is the Lisle test light so expensive at $45? Seems it has a digital display to show voltage, but isn't a test light is mostly used for current? A multi-meter is much easier to use for voltage, right?

https://www.amazon.com/gp/product/B01GOJC77E/?tag=atomicindus08-20

 

[Reese]

The second light in my opinion is the best of the three incandescent options you show. it has the longest cord and a decent sized alligator clip. The logic probe has higher impedance, draws less current, and probably uses an led or lcd display. It would be used when testing computer controlled circuits. Since it doesn't load the circuit as much as the incandescant testers it is less useful in testing non computer controlled circuits. In a circuit with a large voltage drop from a poor connection or wire damage, the logic probe won't load the circuit enough to show the circuit fault.

I've owned testers comparable to the HF tools and a Lisle, the difference is the better build quality with the Lisle. The HF tools use shorter leads, smaller alligator clips, and have less robust insulation. On my Lisle testers, I installed small battery charger clamps in place of the clip provided and installed 6-8' long cords made from test lead wire. These changes make it easier to get a good connection and reach anywhere under the hood.

 

[qqzj]

I see. Thanks! I think I am going to get both (2) and (4). Lots of stuff from HF on my list now. Next time when there is a 30% off coupon, I shall finally make the trip. Does HF also sell test light bulbs?

Also some more expensive test light has digital display of current and voltage. I am debating whether that is a feature worth getting. It is desirable of course. But for Astro Pneumatic and OTC test lights with such features, a lot of people comment that the test light tend to fail prematurely. So I am not sure. Don't want to end up with a dead tool.

 

[qqzj]

Found a video about (4). It is actually fancier than I thought. Works like a safe and cheaper powerprobe.

 

[MadeFromMetal]

Found a video about (4). It is actually fancier than I thought. Works like a safe and cheaper powerprobe.

I generally find LED based test lights useless for 90% of diag on automotive electrical diagnostics.
They usually use between 5-35mA of current draw which is nowhere near enough to stress a circuit to see numerous types of issues that normally occurs in a circuit.

A conventional test light circuit tester with filament bulbs or incandescent bulb generally draw 100-250mA the OTC I have does 200mA and that's not a current I'm worried about frying computers with. Obviously there's a very quick peak amperage jump of around 900mA right when touching but quickly goes to 100-300mA and is generally safe in 95% of situations.
Besides there's ways to test computer signals without the test light after you quickly eliminated all other possibilities on the problem circuit.
And you shouldn't have a problem with any computers if you know what you're doing.

TLDR;
LED circuit testers(without voltmeters) are useless in 99% of automotive electrical diag.
Incandescent bulb circuit testers are the best option because they draw a load that stresses the circuit showing you the problem. If you're only pulling 30mA it will show absolutely nothing and can't go dim.

I do use LED circuit testers with Voltmeter and polarity identification for testing the voltage potential in the circuit and not having to pull out a multimeter and unwrap the leads and setup the meter. Much faster to use Voltmeter circuit tester. So they aren't useless for identifying voltage potential or voltage drop but incandescent bulb testers are much faster and have a wider capabilities for diagnostics.