I think Whitey's Battery is going...

[MPGranger]

So when I got my new ultragauge EM, I think there was some power draining. I altered the UGs power up and power down settings and it still started at a high idle. It's ran a few days without a SG2 or UG, with my wife driving, and it is still idling high at start up.

So I think the battery was drained too low and now is damaged. I don't really know much about electrical systems.
How do I check?
And if it's going, what are some FE solutions? I'm thinking deep cycle and an alternator delete.

[Daox]

High idle at startup isn't an odd occurance at all. What is the batteries resting voltage?

[nemo]

Originally Posted by MPGranger

So I think the battery was drained too low and now is damaged.

Why do you think that? Did you need to jump start it or charge the battery to get it to start? There can be several reason for a fast idle at start up.

[MPGranger]

it used to start up and idle at 750 rpm. And by used too I mean since November '09 when I bought it.
now it starts up and idles at 1250 rpm. And eventually it settles back down to 750 during my glides.
I'll put the battery voltage on the SG2, the UG is taking up space in the altima. Then I'll start posting some info. But it isn't idling like it used to so my question is why and what can I do to fix it?

[ecomodded]

From personal experience what you should do is buy a terminal cleaner and clean up the battery and the leads. You may have to clean the terminals 2 or 3 times in the batteries life.
I replaced a battery not to long ago to find out later it was do to tarnished connections.
Start there, then trickle charge the battery and see if she has any life left in it.
A few hours after a full charge has been completed and the battery has rested it should read 12.6 -13.8 if its still in good health. 12.5 puts it at about 80% health, so on and so forth. 12.2 volt after a few hours of rest would indicate a near dead battery and in need of replacement.
Check its fluids, add distilled water after it has been charged for a while, do not dilute it too much thinking it will help matters, keep the fluid 2 inches above the plates not near the top of the vents, you do not want to dilute it and attempt to charge it normally. Its pretty straight forward really.

[euromodder]

Originally Posted by ecomodded

A few hours after a full charge has been completed and the battery has rested it should read 12.6 -13.8 if its still in good health. 12.5 puts it at about 80% health, so on and so forth. 12.2 volt after a few hours of rest would indicate a near dead battery and in need of replacement.

Looks like I'be looking for a new battery then ...

It's down to around 12.4 V, and under 14V (13.5 - 13.8) while charging (used to be around 14.5 V)

[euromodder]

Originally Posted by ecomodded

A few hours after a full charge has been completed and the battery has rested it should read 12.6 -13.8 if its still in good health. 12.5 puts it at about 80% health, so on and so forth. 12.2 volt after a few hours of rest would indicate a near dead battery and in need of replacement.

Looks like I'be looking for a new battery then ...

It's down to around 12.4 V at rest (used to be 13 - 13.2 V),
and under 14V (13.5 - 13.8) while charging (used to be around 14.2 - 14.5 V)

[ecomodded]

I would switch it out also, all that charging will hurt your mpg and your alternators life span.
While charging the battery should read the same voltage as the chargers output so i am unsure why it read 14.5 volts earlier in its life if on the same charger, could be a indication of a dying cell.

[Daox]

High idle at startup has nothing to do with the battery going bad. If you think your battery is bad, you need to read the battery voltage after its been at rest for say an hour, not right after you've turned the car off.

If you're simply trying to diagnose the high idle startup I'd start looking elsewhere.

[christofoo]

Originally Posted by ecomodded

I would switch it out also, all that charging will hurt your mpg and your alternators life span.
While charging the battery should read the same voltage as the chargers output so i am unsure why it read 14.5 volts earlier in its life if on the same charger, could be a indication of a dying cell.

I just started using a desulfating charger. (BatteryMINDer, bought it on Amazon.)

My results might not be definitive, but I believe my 2 batteries hold a charge better, and the charging asymptote has gone down. I.e. it was 2 A previously, now it is ~0.5 A.

FWIW, I don't change a battery until the starting gets weak. One of my two batteries was beginning to get weak before the desulfating charger. It "seems" a lot stronger now. This is cheaper than 1 battery, probably more environmentally friendly, and will ultimately save the cost of many batteries (assuming it works, which I probably can't say definitively for a few more years).

I wasn't clear on the testing method here, but the asymptotic charging current is a better test than the asymptotic charging voltage. I.e. run an outboard charger overnight and check the current in the morning. If the asymptote is high it will place a waste load on the alternator which will have a very small effect on MPG. I.e. ~30W for 2A, or probably 0.3-0.5%.

(Also as was pointed out, the battery is not likely the culprit on idle speed.)