OT - Harbor Freight car battery testers

They will tell you the maximum output of the alternator/generator, as well as the load capacity of the battery.

Read the following about battery testing.

To expand: even a near-dead battery can look good with a voltmeter, but will fail under load. The same thing holds true for alternators- with a voltmeter, the alternator may seem to be charging, but in reality is only capable of a few amps of output.

For as often as they fail, it's cheaper to drag the suspect component to the local parts store and let them test it.

-Carl (who misses the Sun VAT-40, the best starting/charging system tester ever made)

They will detect high internal resistance, which means low cranking capacity. So will starting the engine with the headlights on and watching how much they dim.

jw

Right on, Jim. No one with a modicum of common sense ever needs a formal battery tester. HF sells them to the chumps, though.

Bob Swinney

They will detect high internal resistance, which means low cranking capacity. So will starting the engine with the headlights on and watching how much they dim.

jw

Tell me how to test a battery out of a vehicle, or a battery with no vehicle around! $10 or $25 does not seem like allot of cash to drop for one of these testers. I have considered picking up one myself. Also consider if you have a bunch of batteries around it may be worth having the tester to may your life easier. We had one where I worked a few years back, but then we were testing deep cycle batteries pretty often and it was near impossible to load test them as they were not used in a machine where we could put a high load on them. Between the load tester and a hydrometer we could get a pretty good idea if a battery was good or not. Greg

$10,

$25,

$50.http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=91129>

They give you a better idea of how the battery performs under load. The higher amperage ones just have a better load resistance. I've had one of the cheapies for years, works well for separating sheep from goats. I've had batteries that will take a charge, look good on a voltmeter statically and still won't spin the starter. Probably cracked links or something like that internally, too much internal resistance. You can also use them for determining if it's a bad battery you have or a bad charging system, or both. A voltmeter will just tell you if your voltage is below par, doesn't tell you if you've got a shorted battery, duff regulator or a failed alternator/ generator. Sometimes a bad charging system will take out the battery, replacing the battery just leads to another dead battery.

Stan

I repaired power wheelchairs for a while and used a hydrometer and load tester to estimate battery condition, but I knew what to look for. Cranking with the headlight on is a simple quick check of battery and *wiring* condition that even people who can't read a voltmeter can use. And I know a few mechanics who would try to measure Volts on an Amps range.

Old, cynical electronics joke: DANGER! 1 MILLION OHMS!

jw

Jim Wilkins wrote:And I know a few mechanics who would try to measure Volts on an

Boy is that hard on the movement.:-) ...lew...

DANGER! 1 MILLI OHM

Do not touch! Surface temperature 300°K!

(yes, I know you're supposed to use the ° with Kelvins anymore)

Best regards, Spehro Pefhany

McCain stopped by the VFW the other night and told some insider jokes that few people got.

Naval Aviation: "I tried to join the Marines first, but my parents were married."

A fellow POW: "He's so old he can hide his own Easter eggs."

jw, in NH

That joke is old enough to be senile:

Little Jim Dickens, on the 'Grand Ole Opry': "I'm so old that I can hide my own Easter eggs."

According to Jim Wilkins :

[ ... ]

Only once per multimeter. :-)

Or:

Caution! High Impedance

:-)

Enjoy, DoN.

According to lew hartswick :

And the internal shunt. :-)

I've seen a summer hire blow the shunt (epoxy housing, packed with sand) in the amps plugin in an old HP Digital voltmeter. The rest of it survived, and they were able to find a replacement precision shunt.

Enjoy, DoN.

On the later Simson 260s a factory fuse was added in the shunt circuit to save the rest of the meter from damage. I soldered in some of the older meters that our company used.

John

$10,

>

$25,

>

$50.http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=91129>>

I wouldn't waste my money on a load meter.. you have one built into the car, the headlights, heater fans and the starter itself. With the engine running and the accessories turned on you should be able to see

14 + volts at the battery terminals. If you don't you have a bad charging system. If your engine starter cranks slow, crank it for 10 seconds and feel the power cables to the starter.. If they are hot you have a bad starter or engine that is tight. If they are cool you either have a bad battery or a bad connection in the power wiring. If you have a bad connection you can feel the hot spot at the terminal but watch out you might get a burn. You could also put the volt meter on the battery and turn on the accessories with the engine off. The voltage should not go below 12 volts with a good charged battery.

John

DANGER!!! 1000 milivolts!!!

Checking electric is like checking how much water you get out of a water pipe... A little pipe with a lot of pressure will give the same amount of water as a big pipe with low pressure... So you need to check how big the pipe is (amps) and how much pressure you have (volts) to know how much water (electric) you will get... So you need to check both amp output and volts on your battery...