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Old 09-06-2016, 09:07   #1
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I don't understand my batteries.

Hi there,

The past few weeks I have been mostly at anchor so I have taken a greater interest in my batteries. I have two 12v 140 amp Varta deep cycle house batteries.

The meter on my control panel is showing 12.0v. But that is while they are in active use but nothing drawing on them. When the fridge kicks in it goes to 11.9.

But what I am really confused about is if I take my battery meter it shows a reading of 14 and slowly increases to 16.

I really don't understand all this.

I do understand that if they are resting and showing less than 12.2 I risk damaging them.
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Old 09-06-2016, 09:34   #2
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Re: I don't understand my batteries.

Quote:
Originally Posted by AFKASAP View Post
Hi there,

The past few weeks I have been mostly at anchor so I have taken a greater interest in my batteries. I have two 12v 140 amp Varta deep cycle house batteries.

The meter on my control panel is showing 12.0v. But that is while they are in active use but nothing drawing on them. When the fridge kicks in it goes to 11.9.

But what I am really confused about is if I take my battery meter it shows a reading of 14 and slowly increases to 16.

I really don't understand all this.

I do understand that if they are resting and showing less than 12.2 I risk damaging them.

First if your batteries are "Varta" its more than time to replace them. Varta hasn't bee in business for decades!! Its amazing those batteries are still working!

What configuration are your batteries in? 2 x 12v in parallel

a fully charged 12v battery will show a resting voltage of about 12.7v at the battery terminals. if you're seeing 16v then this must be while you're charging but generally any charging voltage over 14.4 is bad unless you are equalizing them.

Step one I would say is to get new batteries
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Old 09-06-2016, 09:37   #3
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Re: I don't understand my batteries.

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First if your batteries are "Varta" its more than time to replace them. Varta hasn't bee in business for decades!! Its amazing those batteries are still working!

What configuration are your batteries in? 2 x 12v in parallel

a fully charged 12v battery will show a resting voltage of about 12.7v at the battery terminals. if you're seeing 16v then this must be while you're charging but generally any charging voltage over 14.4 is bad unless you are equalizing them.

Step one I would say is to get new batteries
What drivel. Varta are in business today.

Welcome | VARTA
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Old 09-06-2016, 11:05   #4
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Re: I don't understand my batteries.

"if I take my battery meter it shows a reading of 14 and slowly increases to 16."

What do you mean by taking your meter? Where do you take it to? Do you mean you put it across the battery terminals? What kind of meter is it?

Whatever it is, it sounds like it's broken to me.
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Old 09-06-2016, 11:12   #5
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Re: I don't understand my batteries.

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Originally Posted by MarkSF View Post
"if I take my battery meter it shows a reading of 14 and slowly increases to 16."

What do you mean by taking your meter? Where do you take it to? Do you mean you put it across the battery terminals? What kind of meter is it?

Whatever it is, it sounds like it's broken to me.
Yes we need more information. As Mark asked, where exactly are you connecting the meter? Have you tried connecting it at different spots in your system? What reading do you get if you connect it to the meter in your panel? Does the volt meter give the same reading?

Also, are any charging sources connected?

The voltage increasing on the meter after you connect it does sound odd. I would test the meter on some stable system that isn't in active use. Isolate a battery for a while and test that.
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Old 09-06-2016, 11:36   #6
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Re: I don't understand my batteries.

Forgive me if this is teaching granny to suck the proverbial, but are you sure you haven't got your voltmeter set on amps? That's the only way I can imagine the reading rising from 14 to 16 - presumably with the charging input from solar panels or your engine alternator.

If that's really the charging voltage e.g. while running your engine then you have a problem with your alternator regulator and it needs replacing before you wreck the batteries.

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Old 09-06-2016, 12:23   #7
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Re: I don't understand my batteries.

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Forgive me if this is teaching granny to suck the proverbial, but are you sure you haven't got your voltmeter set on amps? That's the only way I can imagine the reading rising from 14 to 16 - presumably with the charging input from solar panels or your engine alternator.

If that's really the charging voltage e.g. while running your engine then you have a problem with your alternator regulator and it needs replacing before you wreck the batteries.

GORDON KNIGHT
If the OP had the meter set on amps and touched the leads across the battery + and - terminals it would be a dead short and either pop the fuse or fry the meter.

You can probably guess how I learned this.
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Old 09-06-2016, 14:06   #8
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Re: I don't understand my batteries.

Another point, when it comes to measuring battery voltage, "at rest" does not mean that you just shut off everything and then check them. They need to be completely free of any charging or discharging for at least several hours before an "at rest" check is going to be meaningful.
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Old 09-06-2016, 15:00   #9
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Re: I don't understand my batteries.

If your meter on your panel is analog they are notoriously inaccurate.
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Old 10-06-2016, 09:01   #10
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Re: I don't understand my batteries.

You may also make sure the batteries on the volt meter are new.
I got crazy reading on mine when internal batteries are low.
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Old 10-06-2016, 09:06   #11
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Re: I don't understand my batteries.

Quote:
Originally Posted by AFKASAP View Post
Hi there,

The past few weeks I have been mostly at anchor so I have taken a greater interest in my batteries. I have two 12v 140 amp Varta deep cycle house batteries.

The meter on my control panel is showing 12.0v. But that is while they are in active use but nothing drawing on them. When the fridge kicks in it goes to 11.9.

But what I am really confused about is if I take my battery meter it shows a reading of 14 and slowly increases to 16.

I really don't understand all this.

I do understand that if they are resting and showing less than 12.2 I risk damaging them.
AFKASAP,

Assuming accurate voltage readings on you hard wired meter, either your batteries are under charged, or not holding a charge. You can troubleshoot/confirm both situations separately.

Regarding "...I take my battery meter it shows a reading of 14 and slowly increases to 16."

IF you are referring to a hand held volt-ohm meter [VOM] either it needs to be replaced or it needs the internal battery replaced.

The cheapo digital VOM that lives in my electrical tool bag [my good VOM lives elsewhere...] does exactly what you are describing when its internal 9 volt battery needs to be replaced. [i.e., Initial voltage read may be accurate, but after a second or so, the reading starts increasing incrementally, yielding bogus results.]

In case this is helpful.

Best wishes resolving these issues.

Cheers!

Bill
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Old 10-06-2016, 09:15   #12
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Re: I don't understand my batteries.

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Originally Posted by skipmac View Post
If the OP had the meter set on amps and touched the leads across the battery + and - terminals it would be a dead short and either pop the fuse or fry the meter.

You can probably guess how I learned this.
I can unfortunately concur this for the same reason
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Old 10-06-2016, 10:14   #13
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Re: I don't understand my batteries.

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Originally Posted by Emouchet View Post
You may also make sure the batteries on the volt meter are new.
I got crazy reading on mine when internal batteries are low.
Very true. My son got a new battery for his motorscooter last week, Our old analog VM was sitting around the house for years. It wouldn't read anything realistic. I brought my DVM home from the bota and the battery was just fine.
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Old 10-06-2016, 10:22   #14
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Re: I don't understand my batteries.

If the voltage is 12 at the panel and measuring with the meter at the batteries could be corrosion or undersize wire between the batteries and the panel cauisng a vootage drop.

Could also be as simple as a loose nut on one of the connections.
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Old 10-06-2016, 11:01   #15
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Re: I don't understand my batteries.

Moonrise you got it right I concur since I have seen the same on my boat turning off the fridge draw puts the current read at 12.6-12.8 the fridge drops it down to 11.9-12.0.
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