Battery, need voltage

I have a rebuilt 87 22re. I would like to know what the highest voltage battery is that I can run. Thanks for y'all input.

 

Not aware of any vehicle running anything but a 12v. (except some classics like my dad's '50 Ford running a 6v)

Why do you think you need higher voltage?

 

My battery gauge goes down everytime I come to an idle... I checked the alternator a month ago, it was doing it then to.
New alternator maybe??

 

How far does it go down at idle? what's the voltage range?

You might have a bad alternator but could also be a bad battery. How old is your battery?

When you say your battery gauge, I assume you mean a gauge on your dash, right?
Check the voltage at the battery with a real volt meter with the engine off and with it idling. Should be low 12's maybe with the engine off, and 13 or 14 maybe with the engine running.

That's not really a fool proof test though... Many moons ago I had an '86 22RTE 4Runner, and my battery was going dead, I did some voltage testing under the hood and was getting like 14 volts while running. I ended up taking it into an Auto Zone type place for a bench test. They said it was fine - so time for new battery. A week later the battery was dead *again*. Turns out it WAS my alternator...

 

The battery is only about 4 months old, but I'll will do the testing and might just have to get a new alternator. Thanks for help, much appreciated.

 

No worries, I hope it works out for you.

hopefully you don't hunt me down in the middle of the night because I steered you wrong!

 

Haha even still thank you... I don't get to many legitimate answers to my questions, so again thank you, anything helps.

 

Alternators output does DROP at idle. So you probably go from a "charging" state, to a "reading" state. Most "old school " alternators charge around 2Krpm. Newer vehicles with the ECM tied into the Alternator, may behave WAAAYYYYY differently. ref. Jeep cherokee. et.al. (translation ANNOYING!!!) (theirs is done in order to achieve "advertised" HP) ,,l,, this is a chicken crap approach to meeting spec. Two things I recommend: 1: GOOD multimeter, 2: battery load tester. (available at Horror Fright) Then! load test the battery for two(2) cycles of 10seconds each, monitoring the minimum voltage at the end of both 10 second cycles. Make sure your battery meets spec at the end of the SECOND cycle test! Also, check your alternator with your voltmeter, and measure the voltage at different rpm, noting that it should "plateau" (almost) at a certain rpm and above. This is where the voltage regulator starts doing its job, and the battery starts taking a charge. An AGM battery DOES NEED a higher voltage to completely charge than a regular lead/ acid battery does. IF (and it would be nice ) we could adjust the Voltage regulator for a specific battery chemistry, we could set the float voltage to meet the specs of the AGM. What I do, is to try and keep the AGM on a HF float charger when not in use, and the results so far have been good. Hope this helps!