Battery > alternator check out - Toyota 4Runner Forum

Traveler74 · 08-07-2020, 08:48 AM

My replacement alternator has finally arrived and I will be putting it in this week-end.
However, I only know what Haynes Repair Manual says. So, I would appreciate it if guys will confirm the following.

A fully charged new battery, with engine OFF, should read aprox 12.4- 12.6 volts. With the engine ON, the voltage at the battery should read 13. - 14.6

Additionally, the headlights should get BRIGHTER when the engine is rev'ed up ?

If all of the above check out, can I assume that the alternator is correctly charging the battery ???

Any other thoughts you may have would be greatly appreciated.

jgue467 · 08-07-2020, 09:21 AM

A good, well charged battery, sitting overnight, should be At Least 12.7 in the morning.

A new, well charged battery overnight is typically more like 13.3-13.5.

Charging can vary, at least on mine (original alt at 326k), using Torque I can watch it waver anywhere from 12.9 to 13.8, but hey its nearly 20 yrs old and never rebuilt/replaced.

Mind gets No brighter when revved, and no dimmer when engine is shut down.

I just use cheap ol' $49 walmart 2 yr batts btw....last 3 yrs in texas heat....

19963.4lsr5 · 08-07-2020, 11:38 AM

Engine running and nothing else on you should read anywhere from 13.5 to 14v at the battery posts.

Get a cig lighter volt meter.

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LittleCaesar · 08-07-2020, 12:59 PM

If your battery is in good order then you should be seeing 14.2 to 14.4 volts at start up. Anything less than 13.4 volts under load at idle(AC, Defrost), fully warmed up, is a problem.

Traveler74 · 08-07-2020, 01:13 PM

Quote:

Originally Posted by 19963.4lsr5

Engine running and nothing else on you should read anywhere from 13.5 to 14v at the battery posts.

Get a cig lighter volt meter.

Sent from my iPhone using Tapatalk

I never heard of a cigarette lighter volt meter. How does it work ?

calimobber · 08-07-2020, 01:27 PM

Battery volts can vary depending on the brands. When the cars on the volts will always be 13v+ but when its off it depends on the battery. My autozone agm is 12.6 when fully topped off while an optima will be over 13v when full.

The cig plug volt meter is just a small device you can plug into the cig plug and it shows your voltage. To get exact voltage read from the battery. The tiny wires going to the cig plug will drop the voltage down slightly

19963.4lsr5 · 08-07-2020, 01:29 PM

Quote:

Originally Posted by Traveler74

I never heard of a cigarette lighter volt meter. How does it work ?

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