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Old 26-07-2017, 08:57   #16
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Re: Are My Batteries Toast?

Ken, this may be helpful for you:

The Ample Power Primer http://www.amplepower.com/primer/primer.pdf

Just double the 12V #s for your system.
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Old 26-07-2017, 09:02   #17
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Re: Are My Batteries Toast?

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Originally Posted by Kenomac View Post
Will it eventually display an average voltage after settling down, or will it continue to be kind of all over the place?
It should show actual voltage at the terminals just like a multimeter. The SOC will settle after three or four charge cycles.
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Old 26-07-2017, 09:39   #18
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Re: Are My Batteries Toast?

Since you are new to solar the voltages will jump around a lot more than you would be used to using your genset. I am guessing it is partly cloudy today where you are? [emoji6]
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Old 26-07-2017, 09:55   #19
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Re: Are My Batteries Toast?

Yes, partly cloudy all day. Kotor, Montenegro.
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Old 26-07-2017, 09:58   #20
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Re: Are My Batteries Toast?

Ken, it will help a lot to get an open circuit voltage vs. state of charge chart for your batteries, and study it. Something like this:

Attachment 152714

As you will see, 28 volts in the absence of a charging source does not correspond to any normal open circuit voltage, so this is a surface charge which doesn't mean anything. Put a heavy load on and the surface charge will disappear, and the change of voltage doesn't correspond to change of state of charge. Also, at any state of charge, voltage will sag to some extent under load.

Trust your Smart Gauge -- as long as you haven't been charging recently, it will give you an extremely accurate picture of the state of charge. You can also do it yourself with the chart -- just read it when you're sure there's no surface charge on.

To know how much capacity you have left, you could do an internal resistance test (I have such a tester), but best of all do a load test like surveyors do. You take some kind of electrical resistance load (a heater or special load device) which corresponds to whatever discharge rate you want to test (usually 20 hours). Charge your batteries to 100%, take off all other loads, and put on the test load. Time the discharge. With the SmartGauge, I guess you don't have to continue the test past 50% since you will know pretty exactly when you get there.

This test will tell you what % of nominal capacity is left, or in general how many real amp/hours of capacity you have altogether.

I never do this as I don't really care -- I know my batts are shot when the first dead cell appears. But I think it would be nice to know for anyone who's at all interested.


EDIT: I just saw you're using solar. That will push voltage up when it's working and make it very hard to understanding SOC or anythign else. Disconnect the solar for a few days if you want to evaluate your batteries.
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Old 26-07-2017, 10:03   #21
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Re: Are My Batteries Toast?

Re the windlass.

I too would plump for it being a singular issue to do with the wiring or contacts or motor of the WINDLASS and not of your battery bank.

I dont know how old your batteries are, but from my limited experience with similar setups on motor boats... everything appears to be working correctly. This of course has nothing to do with the longevity of your batteries and I suppose it would be nice to know....

it is a good battery system. I favour Dockheads infallible system of waiting till one cell blurps and then changing...
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Old 26-07-2017, 13:05   #22
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Re: Are My Batteries Toast?

Do not bother with any "load tester" gadget, not capacitance, internal resistance, pulsed load nor carbon pile testers.

The ones that actually show remaining AH capacity with any accuracy cost thousands.

The only accurate method using affordable gear is to physically test the batteries at the 20 hour rate, AKA BCI test standards.

You may be able to locate a professional to do this for you if you prefer, but it won't be cheap.

Note if your bank tests out anywhere below 75-80% of its rated AH capacity - e.g. if a bank 600AH when new is now tested at 480AH - they are considered scrap lead, will deteriorate from that point much faster and should be replaced.

Procedure:

Charge battery to 100% Full, at the mfg spec'd Absorb voltage, current dropping to say <.01C, e.g 6A for that 600AH bank

Then if appropriate (not done in the last week or two, should be doing monthly as regular maintenance) equalize ("condition") charge the bank as per mfg specifications.

allow the bank to rest at least 24 hours.

Try to get ambient temp during that time around 75°, pro's use a water bath to maintain that for the whole test.

Record the time, and turn on lamps, heater whatever to draw a constant Load at 1/20 of the AH rating, so e.g. 30A for the 600AH bank.



When voltage drops to 10.5V record the time and end the test. If the bank is at full capacity this would take 20 hours.

Calculate actual AH capacity out based on actual hours, pro-rata compared to 20.

Credit to Maine Sail, more details here

http://www.pbase.com/mainecruising/p...attery_monitor
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Old 26-07-2017, 14:51   #23
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Re: Are My Batteries Toast?

If your batteries are good for 300 cycles in their lifetime, Equalizing them will account for one complete cycle. It would be good to do that once every month or two. It helps dissolve the sulphate off the plates that builds up when you deficit charge them over some time. You have a Hydrometer ? If you don't know how to use it then at least you can check all your cells and if you got one cell way out of whack ,then you'll know that , that battery is pooched.
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Old 26-07-2017, 15:36   #24
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Re: Are My Batteries Toast?

I like to test with a hydrometer. It measures the weight of the water and the sulfuric acid in the water (the electrolyte) in the batteries. When batteries are fully charged, there will be more sulfuric acid which will vary depending on the state of charge. If the batteries are charged, there will be more acid in the electrolyte so it will be heavier. Sulfuric acid weights 1.85 more than water and a fully charged battery will have electrolyte that has about 32% sulfuric acid so the hydrometer will have specific gravity readings measuring how much more the electrolyte weights than pure water. A charge level of 100% has a specific gravity of 1.255, at 50% the specific gravity is 1.190 and at 1.120 the battery is completely discharged. State of charge and specific gravity are built into hydrometer on the float in it. What I like about a hydrometer is there is no guessing about the state of charge and you do not have to worry about discharging the battery a certain amount to get a reading. Also, if you are getting a cell that is weak, the hydrometer will tell you. A hydrometer is cheap, about $15. The liquid in the battery will eat holes in cotton cloth and will sting a little on skin so use a little care. I like to have a plastic container to put the tip of the hydrometer into so I will not leave drops here and there.
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Old 26-07-2017, 15:46   #25
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Re: Are My Batteries Toast?

If a battery sits for months while discharged, sulfation occurs which means it becomes impossible to charge the battery. When a battery is discharged, the sulfuric acid in the electrolyte is transferred to the lead plates in the battery and the electrolyte does not weight as much. At first the battery plates form fine lead sulfate crystals, allowing a lot of surface area for charging to take place. With months time, the crystals become large and charging is impossible. At this point the batteries are toast.
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Old 26-07-2017, 16:06   #26
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Re: Are My Batteries Toast?

I answered this in the other thread where you asked the same question:
http://www.cruisersforum.com/forums/...ml#post2442308

Voltage variation. An overly simplistic explanation, but it will give you the idea: when you operate a device with a high Amp draw, you pull down the "surface voltage" on the plates in your batteries since that is where the chemical reaction is taking place. It takes a while for the voltage to even out again through the plates and electrolytes (i.e. "equalize" - but not in the high voltage charging sense of that word).

The microwave will do that all the time it is running. The fridge compressor will do that at startup when it has a large "inrush current". Once it is running, the demand is not so high and the "equalization" will take place.

Water Use:
Water is lost when charging and discharging, but primarily when charging because of the generally higher Amps involved. . The faster the charge, the higher the water loss. You are now charging the batteries more slowly over a longer period so less water is lost.
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Old 26-07-2017, 20:46   #27
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Re: Are My Batteries Toast?

If you read (and comprehend) the almost universally recommended https://www.amazon.com/Boatowners-Me.../dp/0071432388 you will find the answers to 99% of your electrical questions.
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Old 27-07-2017, 00:43   #28
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Re: Are My Batteries Toast?

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If you read (and comprehend) the almost universally recommended https://www.amazon.com/Boatowners-Me.../dp/0071432388 you will find the answers to 99% of your electrical questions.
Thanks, but I already have the book and did read the section on battery equalization. The book explains what equalization does, but not how to perform the task, and doesn't contain any charts on 24v specifications, only 12v.
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Old 27-07-2017, 02:27   #29
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Re: Are My Batteries Toast?

Instructions for your batteries (including how to equalize) are found here:

http://www.trojanbattery.com/pdf/Tro...UsersGuide.pdf

Your voltage variations are normal. Your batteries are not toast.

When you equalize you have to disconnect almost all loads else things can be damaged. The Smart gauge should be ok to leave it connected. But everything else except the battery charger should be disconnected.
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Old 27-07-2017, 18:36   #30
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Re: Are My Batteries Toast?

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Originally Posted by Captsteve53 View Post
... ... 4) To test your batteries you need a "load tester"...
Can someone comment on this alternative approach?

A short brought my batteries (of unknown age) down to 7 volts before I noticed; so I got myself a decent battery monitor with shunt; factory setting on the monitor is 100Ah, my batteries are nominally 210Ah; early morning (before solar charge kicks in) showed 'resting' voltage of 12.4 (= 60% charge according to Excide) while monitor showed 90% charge according to current drawn; so current draw equivalent to 10% of the 100Ah factory setting has drawn down 40% of battery bank capacity: does this indicate actual battery bank capacity is around one quarter of 100Ah? As a first approximation anyway?

Readings on other mornings show a similar relationship so I'm guessing my batteries are now down to around 25Ah total capacity, from the original 210Ah? Is this a reasonable assumption?
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