First to point out the truck was for sale at a delaer for 6 months before I bought it, wasnt sure if they bothered to take care of the battery but I doubt it. It has been hovering around 12.0-12.3 volts. My commute to work is about 20 mins long. Have been worried about my battery not charging up because the alternator only puts out 15 volts for a minute and then drops to 13. Looked online and it said this is a smart alternator and to unplug a grey connector on the negative battery terminal. This puts the alternator into normal mode putting out 14.2 volts constantly.
What should I see on my battery as far as full charged voltage? This is a flooded battery, the original nissan/renault rebrand. I drove around awhile and noticed it charge up to about 12.8 but always looses about .3 volts overnight. Battery tests say its health is 100% but is that reliable? Should it be draining that much overnight? Driving around it shows alternator output about 14.16 with a scan tool, 13.9 with a multimeter on the battery. Voltage gauge in the truck is sitting at 13.3 volts and not moving anywhere (who knows where that sensor is or how it measures). Am I overthinking this? No starting problems yet, ignore until that happens?
Anyone know about the nissan smart alternators? Friend of mine says plug that connector back in. If its not charging the battery it feels it doesnt need it. Battery lasts longer?
Also I did plug it back in to see how it fairs driving aorund a while but its still putting out the same 14.2 volts, it wont come back down at all, so the smart alternator wont turn back on?
My commute to work is about 20 mins long. Have been worried about my battery not charging up because the alternator only puts out 15 volts for a minute and then drops to 13.
Even if the truck's gauge is 'off', if it cranks and runs fine then don't worry. Since there's no issues with it starting or otherwise, you might be overthinking it.
Ok so I got a battery charger from harbor freight and it said the battery at 12.8v was at 60% capacity.
I have one like that and it works OK (at least after returning the first one which was DOA ). However I would not necessarily trust its evaluation of the battery state of charge.
Use a voltmeter connected directly to the battery terminals and check it against this chart:
The battery shouldn't be charging at 14.2 volts all the time, It should float some between about 13 to 14.5 or so, depending on the pull from the alternator.
First off, what are you testing the battery with? When you said it was around 12-12.3, 12 is basically dead, 12.3 is fairly low.
When you said it will be 12.8 when driving around, when did you test it, right after driving? If so, the voltage will slowly settle a bit lower then when you first turn the car off. If it settled to 12.5 that is pretty well charged.
I read it several times after work and it was 12.3. The next morning before work it was 12.0.
This Sunday I drove around a few hours and it read 12.8v over the course of most of the day sitting at home. It read 12.8 at 8pm. And at 6:30 am monday before work it was 12.7, Tuesday morning it was 12.5 and this morning it was 12.38 before starting.
Ok so I got a battery charger from harbor freight and it said the battery at 12.8v was at 60% capacity. I did recharge it and it holds at 13.0v and says 100%. But the voltage gauge on my truck still reads 13.3v with the battery fully charged and the alternator is putting put 14.2 volts.
@squeaky2073 what battery charger specifically?
The viking 2/8/15 amp from harbor freight.
@squeaky2073 That's the one I have as well. Harbor Freight electronics have the reputation of being pretty sketchy, though quality has gotten better in recent years. In fact a few years before buying this one I bought one of their old-school chargers and never could get one that worked even after several exchanges so I gave up on it.
I took a chance on the 2/8/15 "smart" charger because there was a very good coupon price on it. The first one was completely dead. After exchanging it the second one has been fine but as I said in my other post in this thread I would not trust it for battery analysis. Also unless they have since added the feature it will not charge a completely dead battery so I have an ancient 4 Amp "dumb" charger for that purpose.