alternator output

[mopar440bbody]

hello

i have had a flat battery for last few fews so i pulled the alternator had it tested and found it to have a bad bearing and the output was about 11.58 on store tester. i have install a new liftime napa alternator and the output at battery is 12.26 and when testing just battery level is 12.56. so will this keep me charged . for some reason my ampmeter is not moving at all and yes is original ampmeter however i have a bypass to alternator and not relying on bulkhead connection.

 

[493 Mike]

You answered your own question in that last sentence. A fully charged 12 volt battery should read 13.2 volts in theory and voltages at the running alternator can go as high as 16 volts when a large demand arises. You should probably invest in a voltmeter if you have no ammeter.
Mike

 

[khryslerkid]

If your battery reading is the same with the engine running or not, you're still not charging.

 

[Glenwood]

The voltage regulator should probably be looked at as the alternator voltage will fluctuate. If the ammeter is not moving, the current, or load is likely not changing which is typical with a fully charged battery. It should show some movement with the headlights, blower, etc. on.

 

[Ranger16]

A fully charged 12 volt battery should read 13.2 volts

Wait, a fully charged battery is 12.6v (2.1v per cell).

 

[Mopars & Missiles]

Wait, a fully charged battery is 12.6v (2.1v per cell).

View attachment 516043

Well, that's a pretty little chart. But it ain't right. Modern batteries are well over +13 volts when NEW and FULLY charged. If you only have +12.6 volts and its FULLY charged, then that battery is OLD and about to FAIL on you.

I'm 100% in agreement with 493 Mike

 

[Nacho-RT74]

If "alternator is bypassed" straight to batt or starter relay stud, the ammeter won't move at all because the bypass will carry the load coming and going. The bypass offers a less resistence path than the ammeter and bulkhead terminals. Will need LOT of load to maybe be able to see a small ammeter flickering.

On an untouched charging system, if alt is powerfull enough to feed the car and batt is full on an extra load request the amm just will register the initial power bump coming from batt ( discharge ) until reg reacts to that to field the alt. Will be a small flick.

If alt is not enough, will show a discharge reading but will sway to charge getting feeded back the batt what lost on the previous discharge reading when revving up the engine.

 

[72RoadrunnerGTX]

Well, that's a pretty little chart. But it ain't right. Modern batteries are well over +13 volts when NEW and FULLY charged. If you only have +12.6 volts and its FULLY charged, then that battery is OLD and about to FAIL on you.

I'm 100% in agreement with 493 Mike

12.6v IS the correct number for fully charged standard lead acid automotive batteries. Some gel cell deep cycle battery manufactures list 13.0-13.2v as fully charged.

 

[Ranger16]

Per Wikipedia

Design
Batteries are typically made of six galvanic cells in a series circuit. Each cell provides 2.1 volts for a total of 12.6 volts at full charge.

 

[Mopars & Missiles]

Believe whatever you want to believe, fellas. You're quoting "theory" (which I'm well versed in) not reality which is what we live in. Oh, just found these in my garage a few minutes ago. What should I do, return them as defective?? Too much voltage?

Just an FYI, these 3 batteries are 4 yrs, 5 yrs, and 7 yrs old. Not a damn good one in the bunch, according to theory and Wiki (oh, and let's not forget Design) they should only be +12.6V MAXIMUM.

 

[72RoadrunnerGTX]

Believe whatever you want to believe, fellas. You're quoting "theory" (which I'm well versed in) not reality which is what we live in. Oh, just found these in my garage a few minutes ago. What should I do, return them as defective?? Too much voltage?

Just an FYI, these 3 batteries are 4 yrs, 5 yrs, and 7 yrs old. Not a damn good one in the bunch, according to theory and Wiki (oh, and let's not forget Design) they should only be +12.6V MAXIMUM.

Well damn, there goes 45+ years real world professional automotive experience and training down the drain. Those numbers sure look to include the slightly elevated voltage resulting from surface charge. How much time went by after disconnecting from a battery maintainer/charger, and what steps were taken to dissipate the surface charge prior to taking those readings curiously?

 

[mopar440bbody]

well i had battery test at napa and oriellys and they say its a good batty. 771 cca on load teat.............. alternator output up to 12.9 at high rpms.................took car out this morning for gas and drove about 25 mins and about 20 miles but on return to home no bleekers and so ni loaded the batty up by puting lights on and as i thougfht would not start after i killed it . i really think battery is bad . i can test voltage reg if someone tell me how and what the reading should be. voiltage reg has 2 connections plus 1 ground. thanks guys