scsmith

scsmith

Well Known Member
I did a forum search and didn't find much.

My new Plane Power alternator is charging at 14.6 - 14.7 volts. This seems just a bit high to me, was expecting more like 14.2. Nothing in the instruction sheet seems to indicate this can be adjusted. Just wondering what others see.

Possibly related: My Concorde battery only holds 12.2 volts. It is two years old, spent the first year of its life connected to a 'battery minder' type charger. I'm wondering if the electrolite is weak? And if so, could the charge resistance be low, so that the alternator is floating to the higher voltage?
 
Steve, that is actually fine. It is even needed for the Odyssey batteries, or they won't charge properly. Do check the voltage under a normal flight load, including lights if you have them, and if your Concorde battery is a wet cell type, then pay attention and make certain it is not boiling away the electrolyte. Chances are you will be fine. Almost all current day electronics are designed to operate from 10-30 volts. Most are spec'd at 14-28 volts, since those are the numbers we are used to seeing when referring to aircraft electrical systems.

Vic
 
scsmith said:
I did a forum search and didn't find much.

My new Plane Power alternator is charging at 14.6 - 14.7 volts. This seems just a bit high to me, was expecting more like 14.2. Nothing in the instruction sheet seems to indicate this can be adjusted. Just wondering what others see.

Possibly related: My Concorde battery only holds 12.2 volts. It is two years old, spent the first year of its life connected to a 'battery minder' type charger. I'm wondering if the electrolyte is weak? And if so, could the charge resistance be low, so that the alternator is floating to the higher voltage?
Click to expand...

Steve,
Your voltage is on the high side of normal for a "wet" battery. For an AGM [sealed] battery, that is right in the middle of normal. Your battery should be at 13.2 volts when fully charged. Each of the 6 cells should generate 2.2 volts. Often, a float type charger will slightly under charge the battery, as this is better than to over charge it.
A battery which will not accept and/or hold a full charge is sulfated. When the battery discharges, the sulfur in the sulfuric acid, migrates onto the lead plates. This creates lead sulfate. When you charge the battery, the sulfur is driven off of the lead plates and back into the electrolyte. If the battery is old or left discharged for a long time, the sulfer can not be driven back into the electrolyte. The sulfur has become permanantly bonded to the lead plates. This will often happen in only one or two cells. This means that the battery is sulfated. In most cases, the battery is ruined.
Charlie Kuss
 
I'm afraid you are right

I think Charlie is right, reinforces what I feared. My cheapo battery minder only charged the Concorde RG-25XC to about 12.0 - 12.2 for about a year and a half, so the battery suflfated and now won't take more. I know sometimes 'equalizing charge' of higher voltage can restore a sulfated battery, and I was kind of hoping that 14.6 might be enough to do that. But 25 hrs of flying, its not getting any better, if anything, slightly worse.

I'm thinking of a PC-680 clone,
 
When I installed a new Plane Power a week ago, it seems like it started out at 14.6 also. I noticed that because my Van's alternator would run around 14.2. But when flying with the plane & everything on line, it settles in around 14.2 volts. I have the 680 battery, so I'm fine either way.

L.Adamson -- RV6A
 
Surface charge

scsmith said:
I think Charlie is right, reinforces what I feared. My cheapo battery minder only charged the Concorde RG-25XC to about 12.0 - 12.2 for about a year and a half, so the battery suflfated and now won't take more. I know sometimes 'equalizing charge' of higher voltage can restore a sulfated battery, and I was kind of hoping that 14.6 might be enough to do that. But 25 hrs of flying, its not getting any better, if anything, slightly worse.

I'm thinking of a PC-680 clone,
Click to expand...

Steve,
Often, owners will check a battery's state of charge using only a voltmeter. Often, one or more cells will become sulfated, yet still show 12 to 13 volts with no load on them. Yet, when even a slight load is applied, the battery's voltage will drop significantly. This is referred to as a "surface" charge.
The best way to check a "wet" battery is to use a hydrometer, to measure the specific gravity of the electrolyte.
For a sealed battery, the only way to do a proper check is to use a carbon pile load meter. First, determine the "cold cranking amp" [aka CCA] rating of the battery. Divide this rating by 4. Using the carbon pile load meter, apply a load of 1/4 of the CCA to the battery for 15 seconds. At the 15 second mark note the battery's voltage. A good battery will read 9.6 volts or higher [at room temperature].
Prestolite has a good web page on battery care and testing, below:

http://www.prestolite.com/pgs_training/training_2.php

A carbon pile load tester is an essential tool for testing batteries. Harbor Freight sells a very nice, basic tester. See

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=91129

These often go on sale for $50 or $60. I've seen and owned other "electronic" testers which don't actually put a heavy load on the battery to test it. Basically, they are all a waste of money. A carbon pile load tester is the way to go. This Harbor Freight tool is affordable for the average plane owner or for a group to share.
I will say that my HF carbon pile's volt meter was off by about 0.5 volts [read low]. I found this out by comparing it to my digital multimeter. Not a problem, as both meters have a simple adjustment screw, to correct issues like that.
Before giving up on your current battery, try this. Partially discharge it [to about 50%], then charge it up completely. Repeat this several times. If this does not help, it's time for a new battery.
Charlie Kuss
PS The worst thing you can do to a battery is to completely [or nearly completely] discharge a battery. Then let it sit discharged. The longer it sits in the discharged state, the harder it is to drive the sulfate back into the electrolyte. Repeated deep discharges also shorten a battery's life, unless it is rated as a "deep discharge" battery. Deep discharge batteries are commonly sold for marine applications.
 
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