battery failure

[jbob]

99 Leganza- Battery not charging.Battery tested...good. Replaced alternator,battery still going dead. What else could be the problem?

[daewoomofo]

wires or bad ground, check them both

[Spider]

wires or bad ground, check them both

Yes,
And let me expound a little on that ?

How was the battery tested ? And how old is it ?
Your battery needs to be "load tested"
I once had a battery tested at an auto-parts store and it tested ok.
Later was discovered that it would not hold a charge.
So, its best to absolutly sure your battery is good before you go any further.

You can check out a lot of stuff with a 'digital multi meter'.
This test will show you if the juice is getting to the battery.

Set the meter to 20 Vdc,

Red prob on the battery (+) post

Black probe on the battery (-) post

Find your helper, have him/her start the engine and rev it up to around 2500 rpm (no tach ? guess, its like a fast idle)
your looking for 13.5 volts on the meter (or a little higher even)
Now, have your helper run the rpms up more like 3000~3500 or a little more.
Don't over-rev it..increase rpm's slowly.
You are now looking for 14~14.5 volts..(this is a rough number and it will change as the rpm's go up and down) it shouldn't go over 14.8 though.
Now re-do the above test, only this time put your meter probes on the battery cables instead of the battery's lead posts.
This will tell you if the connections on the cables to posts are good.


If this checks out ? you can rest assured your charging system and cable connects at the battery are good.
So, if your still getting a dead battery after these tests ?
You have a short someplace beyond the battery that is pulling juice off the battery like if the headlights were left on overnight.
Shorts are harder to find but you can use your multimeter to find em.. Instructions will come with the meter.
If no shorts ? The battery needs to be replaced as it won't hold a charge anymore.



Oh yeah ? I just bought a small digital meter at Harbor Freight that was on sale for under five dollars.


And ?
welcome jbob to the forum