Edd,

Amp-Hour capacity is a moving target.  For lead acid batteries, it depends on 
the amp draw.  This is because the battery internal Resistant consumes power at 
a rate squared to the current draw (I^2 R power lost).    It is common to rate 
deep cycle batteries at a 5 amp draw.   

You could run your own 5 amp test with simple volt and amp meters and get a 
reasonable idea of the battery capacity.   Start off with a full charged 
battery and turn on loads until you get about 5 amps.  Measure how long it 
takes until the battery voltage gets to 12.0V (which is the 50% capacity 
voltage).   Take your time in hours multiply by your current draw  and then 
multiply by 2.   Do not run a lead acid battery below 12V.    Of course, there 
are much better ways to measure capacity.  

A simple $15 watt meter works well too. I have one of these from Amazon 
https://www.amazon.com/gp/product/B01GZXWH7E/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
 
<https://www.amazon.com/gp/product/B01GZXWH7E/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1>.
    I use Anderson power pole connectors which allows me to insert this meter 
virtually anywhere.  For example, I have used it measure the amp-hrs used by my 
refrigerator (25 amp-hrs/day in July) and more recently to measure the amp-hrs 
used by my SSB.  Power pole connectors are great. Look them up if you are not 
familiar with them.  

I have also heard great reviews on this $40 battery meter.   It does not have 
Bluetooth and a phone app that the $200+ meters have, but the DIY off grid 
solar folks love it and swear by its accuracy.   This meter is a true charge 
discharge meter whereas other cheap meters I seen go only one way.  

https://www.amazon.com/dp/B07CTKYFTG/?coliid=I28MK0USN5TE67&colid=4DEXPPL436LK&psc=1&ref_=lv_ov_lig_dp_it#customerReviews
 
<https://www.amazon.com/dp/B07CTKYFTG/?coliid=I28MK0USN5TE67&colid=4DEXPPL436LK&psc=1&ref_=lv_ov_lig_dp_it#customerReviews>

I’m a big fan of quality item like Victron products but I don’t shy away form 
affordable solutions too.



-
Paul E.
1981 C&C Landfall 38 
S/V Johanna Rose
Fort Walton Beach, FL

http://svjohannarose.blogspot.com/

> On Jan 27, 2020, at 6:36 PM, cnc-list-requ...@cnc-list.com wrote:
> 
> Listers,
> 
> Hope everyone had a great New Years. 
> 
> So when you buy a battery, it?s pretty clear from the label what it?s Amp 
> Hour rating is ? so how does one actually verify that information? Is there 
> any way to test your battery?s actual Amp Hours when they are either new or 
> used for some time (but fully charged)??
> 
> All the best,
> 
> Edd

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