Alternator and Battery test with multimeter

#21

On Sun, 18 Feb 2007 17:51:17 -0000, "tishtash" <none (AT) host (DOT) com> wrote:

Quote:

"Soggy matches" <wont (AT) light (DOT) com> wrote in message
news:era300$5l7$1 (AT) aioe (DOT) org...

The red goes to the thinner lead which should be disconnected from the
battery + and the black to the battery + although if it's a digital meter
it won't matter much which way around the meter is connected as you'll
just get a '-' sign on the meter (set it to DC). Indeed the '-' sign will
come and go as you go from charge to discharge. If it's an
analogue meter the needle will swing hard left on discharge and right on
charge.

IMPORTANT NOTE!:- DO NOT PUT THE METER IN SERIES WITH THE THICK BATTERY
LEAD to the + terminal, just the thinner lead. (The meter won't pass the
current and will burn out in a dazzling display of smoke and flames!!!)

Sorry to be thick here I really don't understand what you mean.... What does
putting the meter in series with the thick batter lead mean ?

It's just as easy to put the meter across the battery with the engine off,
(Set it for 20+ VDC usually 25V) note the reading (probably 11-12V) then
start her up and so long as the Volts go up a bit (anything up to 15V) the
charging system is probably fine. Alternators usually work or don't so I
wouldn't get bogged down with precise charging currents if your electronic
skills are limited. I'd do it this way.

If the ignition warning light goes out when the engine runs, the system is
probably charging.

Hope that helps.

Thanks all for the help and info, I think I have a grasp of what to do. That
last bit is basically all I need to do. So to recap just set meter to 20/25
volts dc engine off red probe on postive battery terminal and black on
negative (does it matter which probe goes on first?) and take reading
? )while here I was just wondering does it matter if I touch the battery
terminal or the clamp>)

alternater test with engine on and lights on, demiter etc do the same thing
and not reading ?

Is that it basically in morons terms ?

I can be a bit thick as you can
see with such things!

The multimeter should be enough to tell you if the alternator is
working properly.

Bear in mind, though, that a multimeter won't necessarily tell you if
the battery is shagged. Shops that sell batteries have a special
instument which measures fast discharge.

#22

Harry Bloomfield (harry.m1bytNOSPAM (AT) tiscali (DOT) co.uk) gurgled happily,
sounding much like they were saying :

Quote:

Battery test: Engine off, disconnect positive clamp on battery (does
the neg one need disconnecting?)

No, better/safer to disconnect the negative terminal first and always
reconnect this last.

Agreed. It saves all those embarrasing sparks as you hit the spanner onto
something whilst loosening the +ve clamp's retaining bolt.

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Alternator and Battery test with multimeter

Cars Maintenance General car maintenance (uk.rec.cars.maintenance)

Re: Alternator and Battery test with multimeter - 02-19-2007 , 05:45 AM

Re: Alternator and Battery test with multimeter - 02-19-2007 , 04:31 PM