Alternator too hot?

[galynd]

My alternator is charging at 14.65 volts most of the time. I've had it about 6 months, when I put a newer yanmar into my boat. I bought it rebuilt from an alternator/starter local rebuilder who tested it at 94 amp capacity. It is on a Yanmar 3gm 30f. My current battery setup includes two 6 volt 210 aH house batteries, a combinor, then a 12 volt starter battery. I previously replace 2 12 volt house batteries and replaced them with the 6 volt batt's. Is 14.65 v too high? thanks.

 

[Don S/V ILLusion]

No, unless the batteries are fully charged. A voltage of 14+ is fine for bulk charge. Does it step down as the batteries reach full?

 

[galynd]

batteries monitor showed 100% charge, still charging about +8 amps, with 14.65 v.

 

[JoeWhite]

I would say that it is normal - check the water of the batteries . If they are bubbling while charging - then the voltage is too high. You can make adjustment on the charger settings.

 

[Benny]

Are batteries boiling over? Are you running a high amp load like refrigeration? Confirm your battery monitor reading with a quality voltage meter. If no load and confirmed 14.65V output reading you may have a voltage regulator issue.

 

[Bill Roosa]

Need to understand the system

You have a battery combiner. That means your alternator output voltage could actually be higher by about a volt than the voltage that reaches the batteries.
Where are you measuring the voltage?
Where does the alternator measure "battery" voltage? Before or after the combiner? It should be after so it provides the higher voltage to account for the diodes in the combiner.

14.65 is not outlandish, 8 amps is not either, full charge as indicated by a battery monitor is not always "full charge" on the batteries as combiners have a bad rap at monitoring float charging. This is due to the very low efficiency during float charge. 1 AH @ bulk = .95* 1 AH, 1AH @ float = .25*1AH. Most monitors don't/can't account for the loss in charging efficiency during float charging.

 

[Maine Sail]

Before or after the combiner? It should be after so it provides the higher voltage to account for the diodes in the combiner.

If he has a "combiner" no voltage drop and no diodes just a large relay, usully activated by rises and drops in voltage. Isolators have diodes and voltage drop but ACR type combiners don't. I am still not convinced he has a "combiner" as the terms are often misused as interchangeable. Perhaps we could get some more clarification?

14.6 is not an overly high voltage for wet cells but will be one that likely burns off more battery fluid than a setting of 14.2-14.4v so he'll just need to check and fill more often.

 

[zeehag]

it has been my experience, that, when batteries are low, my alternator charges at 14.something amps. i wouldnt worry about th amperage output until i knew my batts werent accepting the charge. monitor the output via your gauges and see if it doesnt lower as you watch--after a couple of hours at 14.somethong , mine always reduces its output as the batts charged. maybe this is your case also. research batteries and charging--you will find that batts and charging are not always exactly 12 v all the time. when batts dont hold or have charge, the alternator works overtime to make up that difference,if batts do hold charge but arent charged fully, the alternator will put out until the batts are ready for the alternator to reduce output. you will see that on your gauges also.

 

[galynd]

Thanks to all. I had 2 12 v batt's that were only a couple years old. I took a trip 2 weekends ago where I ran the motor continuously for 11 hours. I hadn't returned to the boat until this weekend to find the 12 v batt's showing 10.5 volts per Victron BMV-600 batt monitor. after checking each battery, this weekend, I determined I had a dead cell on each battery and also one showing "poor," but not dead, thus the 10.5 volts. I purchased 2 6 volt, 208 aH batt's from sam's ($66 ea by the way) and ran it for several hours to fully charge them. the monitor never read below 14.65 volts. I also checked the batt's with a voltmeter to determine the accurate reading. The series of charge is alt to bank batt's, then combiner, then start batt.

My concern is that perhaps after running such high volts, 2 weekends ago, that perhaps that was the cause of 2 batteries having dead cells.

 

[galynd]

By the way, I checked the water level on the 12 v's and it was fine.

 

[Don S/V ILLusion]

By the way, I checked the water level on the 12 v's and it was fine.

The most prevalent cause of battery failure is external; in your case, it may be the regulator as a constant 14+volts is a problem. This scenario gets more interesting as you mention the water level was okay as over-charging typically cooks the batteries and that apparently didn't happen here. Regardless, with 2 new batteries, you want to get better voltage regulation before this gets to be a recurring trip to Sams Club.

 

[zeehag]

what did the batteries' voltage read before the initial charging attempt?

i have found most batteries fail because folks do not know how to charge them properly.
if the voltage reads too low, it is going to take more than mere charging to bring them back correctly. i use a rubber mallet gently , yet firmly enough to desulfate mine and then charge more ..LOL..... hasnt failed me yet. been doing this since 1990-my batts last me 8yrs each. the places that charge to do this same thing charge too much for the simple service...
i went away for a year-i came back and , despite having solar panels charging my batts constantly
I didnt know for how long. i gave each one a whack after i found i was wasting gasoline and generator hour trying to charge them. th3ey would not accept charge. after whacking them each one time, they charged well--i m still using these 5 yr old batts with no further problems. try it.

 

[galynd]

zeehag. it's funny you do that but I guy I know takes his batt's out everyonce in a while and drops them. I've not seen him do it but he discribes it as dropping them onto a wood surface from about a foot I believe. He claims he's had the batt's for over 10 yrs.

 

[Rich Stidger]

zeehag,

Interesting maintenance trick- "giving each one a whack".

Do you find that many things work better after a whack or two?

 

[Stu Jackson]

Try the Ample Power Primer at www.amplepower.com, tech tab.

Your 14.65V sounds way too high. You should break in your new batteries.

Read the primer.

 

[Don S/V ILLusion]

zeehag,

Interesting maintenance trick- "giving each one a whack".

Do you find that many things work better after a whack or two?

didn't work very well for Ralph Kramden on Alice

 

[zeehag]

LOL i learned the whack the battery with a mallet trick from a man. lol-- was a repair man who actually knew what he was doing. not everything fixes with a hit from a mallet--most things fix with a gentle hand--is why most men have difficulty with many things when trying to fix 'em. too heavy handed.

 

[JVB]

zeehag,

Interesting maintenance trick- "giving each one a whack".

Do you find that many things work better after a whack or two?

Whack it with your hand was actually in the Apollo Moon landing procedures for how to deal with recalcitrant electronics.