Battery Bank Assessment

[djousset]

My 12V lead acid house batteries are 5+ years old and I think their power may be fading. Is it age, amount of use, charging habits or a combo of all that predict the life span? Simplest way to assess the health of a battery bank?

[s/v Jedi]

Originally Posted by djousset

My 12V lead acid house batteries are 5+ years old and I think their power may be fading. Is it age, amount of use, charging habits or a combo of all that predict the life span? Simplest way to assess the health of a battery bank?

Yes, all those reasons. Look into possibilities for a LFP battery. Even the “cheap” drop-in types will be a huge improvement over LA, but you need to be able to change charge sources for the correct chemistry.

[Mike OReilly]

Originally Posted by djousset

My 12V lead acid house batteries are 5+ years old and I think their power may be fading. Is it age, amount of use, charging habits or a combo of all that predict the life span? Simplest way to assess the health of a battery bank?

I'm no expert, but two simple ways to test your batteries are:

#1. Use a load-tester. This is a device which puts a significant load on the battery, and then measures the response.

#2. Charge the batteries fully, then let them rest for at least 12 hours. There needs to be zero charge or discharge going on. At the end, take a voltage measure. This measure gives you a rough idea of the health of the batteries:

https://www.batteryskills.com/batter...-voltage-test/
12.6v = 100%
12.4v = 75%
12.2v = 50%
12.0v = 25%
11.9v = 0%

[Stu Jackson]

Diane,



One or more of our "regulars" on this forum has often mentioned that batteries are consumables. Too often they are not thought of that way. Like fuel filters, they get used up and have to be replaced.


One way to check, in addition to Mike's ideas, is this one:


20 Hour Capacity Test by Maine Sail

http://forums.sailboatowners.com/ind.../#post-1295253

[ItDepends]

Originally Posted by Mike OReilly

I'm no expert, but two simple ways to test your batteries are:


#2. Charge the batteries fully, then let them rest for at least 12 hours. There needs to be zero charge or discharge going on. At the end, take a voltage measure. This measure gives you a rough idea of the health of the batteries:

https://www.batteryskills.com/batter...-voltage-test/
12.6v = 100%
12.4v = 75%
12.2v = 50%
12.0v = 25%
11.9v = 0%

This method tells you (almost) nothing about the health of the batteries, only their state of charge. You could have batteries that when new were 500 Amp-hour batteries, and have lost most of their capacity and are just 100 Amp-hour batteries. If you fully charge them, and let them sit for 12 hours, guess what? they are fully charged and the voltage reading will reflect that.

If you had a shorted cell this test would flag it, but batteries that are simply old and tired will show as fully charged--because that is exactly what they are!

[S/V Illusion]

Originally Posted by djousset

My 12V lead acid house batteries are 5+ years old and I think their power may be fading. ?

If you think that, you presumably have a reason.

[smac999]

Originally Posted by Stu Jackson

One way to check, in addition to Mike's ideas, is this one:


20 Hour Capacity Test by Maine Sail

http://forums.sailboatowners.com/ind.../#post-1295253

this is the only vaild way to test them

[PaulCrawhorn]

If gross fade symptoms are showung then do not bother testing, they are past EoL for sure