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Discussion Starter #82
If you were convinced that was true, why ask more textbook questions? Do you see three stages of charging in your tables? I’m just trying to tell you I don’t. I’ve also said I’m not so sure about your measurement system, so feel free to take it all with a grain of salt.

You may get your desired 7 years, which is also a factor of your discharge usage . No way to know.
I see what you mean, but I wasn’t sure how to interpret it. FYI, the clamp on charger I was using I borrowed from a friend and it’s readings tended to fluctuate a little, sometimes up to .2.


So, tell me if I’m reading this incorrectly but…from 10:00 am until about noon, it’s in Bulk Charge as the Volts are steadily climbing up to 14 (Current in this period is between 16 and 8 when I suppose it should be steady at a high rate, right? Why isn’t it 30 for a 30 Amp charger? This part puzzles me. That the starter was received only 11.69 when it began compared to the 25.87 amps going into the House bank is strange too… I wonder why the same voltage isn’t getting to that battery. Perhaps those wires are too small).

Anyway, then from 12:00 - 2:00, the house battery’s voltage reading was between 14.05 and 14.15. Is it possible, due to the measurement unit it was actually closer to 14.4 at twelve o’clock, and so for a couple hours (until 2:00) there was in fact steady voltage, and this was the battery in Absorb - max voltage while the amps drop? During that time, amperage is steadily decreasing from 6 down to around 2 amps by 5:30pm (which I believe is normal based on the graphs I’m seeing online of the three stages).

136907

So, by 6:00pm, the voltage has dropped in to the 13’s like it does in this graph here, while the amps have begun to level out at around 2 (is that still too high? #’s for the starter battery are a little different, but same trends). To my untrained eye, this is looking like Float now, which I assume would have continued into the night had I not gone home.

To recap: I gather from your posts, and john’s posts, that perhaps it should have spent more time in Absorb (if it was ever that at all)? Is it possible that it was in Absorb from 12-2:00 but didn’t spend more time there because it’s a brand new battery and I’d hardly run any loads on in?
 

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Discussion Starter #83
Below is a more legible chart. I turned the charger on again the following the morning thinking I could pick up where I left off, but that's not what the numbers showed. Now it was clearly at 14.4.

For what it's worth, today I dropped by curious what the voltage would read since the charger has been left on the last two days and both batteries read 13.67 V.

136910
 

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You're all over the place, and I'm tired.

Before you run another test cycle, let's get the protocol and parameters nailed down.

Go back and read my posts, see if you can summarize how to construct a valid test, ask questions to clarify anything you you aren't certain you understand.

Focus on things you now know you should differently.
 

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I think you are starting to understand the concepts. I can’t answer why it appears, in bulk stage, that voltage is rising (as it should) but amps are declining (which they should not). That and the appearance of no sustained Absorb stage were my original reaction. Absorb usually takes quite a while, because the battery chemistry won’t accept charge at the same rate as in Bulk. The more charged the bank becomes, the less it accepts. If you flip to Float prematurely, you often see charge amperage stay steady, while if done properly, amp acceptance will approach zero. In your case, it continues to decline, which is a good sign, but still makes no senses, with near zero Absorb time.

Is there a load on these batteries, while you are charging? If so, your readings may be the sum of charge and load and, therefore, meaningless. The only way to run your test, with a clamp meter, is to full disconnect the house and anything else drawing on the bank (ie bilge pump). I’d monitor closely, if I had no operating bilge pump, or hook the bilge to something else.

In normal operations, a charger provides power to both the bank and appliances, therefore, rarely sees the entire rated charge going into the bank. There can also be settings that throttle back max charge, as some batteries require less bulk amperage than the charger could send.
 
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Amps can often begin trailing down, long before the CC-CV transition, that is normal and depends on the inherent physics / chemistry, current rate etc, nothing to do with the charger regulation circuitry.

Of course the steep decline (down to 0.01C or lower) does not happen until after Absorb stage is nearly finished (by definition :cool:
 

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The source does not "send" a current rate.

It just makes a certain maximum available.

The loads are in control of the actually current drawn.

Including a battery being charged, which in this type of test should be the only load connected to the charger.

So long as the bank is properly depleted before the test starts, say 40-60% SoC, then the charge cycle should usually take at least 6 hours, 7+ is normal, to get back to 100% Full.

The charger going to Float prematurely is the most common fault needing adjustment or some workaround.
 

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This seems to be a lot of worrying about nothing. we charge the batteries so we can go sailing not go sailing so we can charge the batteries. In the end what is all this voltage worrying about? charge the batteries with a good charger and they last 5 to 7 years worry about the voltages for the next 5 to 7 years and the batteries last 5 to 7 years plus one week.
 

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This seems to be a lot of worrying about nothing. we charge the batteries so we can go sailing not go sailing so we can charge the batteries. In the end what is all this voltage worrying about? charge the batteries with a good charger and they last 5 to 7 years worry about the voltages for the next 5 to 7 years and the batteries last 5 to 7 years plus one week.
Yes, it does seem to be a lot of extra worry, however, it is a good way to build knowledge and understanding of how the system is working.

My wife was making fun of me because while we were on holidays I was regularly checking the battery system to see what was happening with solar, alternator and shore power charging sources. She can laugh, but I learned a lot about the power systems on the boat by doing so, and she will appreciate the end result.

Looking at the OPs data it seems like his charger is doing an OK job. I suspect that his charger is similar to my Cristec charger in that it drops out of the bulk phase based on elapsed time, rather than state of charge. My charger drops out of Bulk after 4hrs regardless of how charged the batteries are.

My obsessive battery monitor monitoring also taught be that charger output current is entirely dependent on the acceptance rate of the batteries. With my FLA bank I never saw my charger output it's full 40a rated output, nor did I ever see my alternator put out it's full 80a rated output. At best I saw just over 30a out of the charger, and around 40a out of the alternator. With my new bank I get 40a out of the charger, and over 60a out of my alternator.



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charge the batteries with a good charger and they last 5 to 7 years
Have a look at the title.

Most of the time even with "the best" charger, it is not "a good charger" until it has been adjusted to work properly within the given context.

A good bank can last well over ten years, or reach EoL in two years, depending on the various care factors.

If the topic does not interest you, move on and ignore it.
 

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Discussion Starter #91
I think you are starting to understand the concepts. I can’t answer why it appears, in bulk stage, that voltage is rising (as it should) but amps are declining (which they should not). That and the appearance of no sustained Absorb stage were my original reaction. Absorb usually takes quite a while, because the battery chemistry won’t accept charge at the same rate as in Bulk. The more charged the bank becomes, the less it accepts. If you flip to Float prematurely, you often see charge amperage stay steady, while if done properly, amp acceptance will approach zero. In your case, it continues to decline, which is a good sign, but still makes no senses, with near zero Absorb time.

Is there a load on these batteries, while you are charging? If so, your readings may be the sum of charge and load and, therefore, meaningless. The only way to run your test, with a clamp meter, is to full disconnect the house and anything else drawing on the bank (ie bilge pump). I’d monitor closely, if I had no operating bilge pump, or hook the bilge to something else.

In normal operations, a charger provides power to both the bank and appliances, therefore, rarely sees the entire rated charge going into the bank. There can also be settings that throttle back max charge, as some batteries require less bulk amperage than the charger could send.

to answer your question, no loads were drawing on the battery. Only thing going on was the charging itself when I ran this experiment. I think I understand most of what you're saying... for whatever reasons (though I'm not sure if it's a big deal or not), my charger's outgoing amps are dropping during Bulk when it should remain steady. I'm not really sure what to make of that. They charged fully, but I guess they're not as full as they could be perhaps. All I know is that when I looked at the battery the next day, it was 12.8V, so fully charged.

Re: going to Float prematurely, assuming the charger is set to charge FLA batteries (the old batteries were the same as my new ones), the Float charging more than likely dropped off due to an internal timer... but all in all, since my battery had been discharged to 60% SoC before I began the experiment, it looks like it charged it rather effectively over the course of 8+ hours (even though the amp readings were declining at one point).

Much of this is making alot more sense to me now...the rest will crystallize as I continue working with these systems. When I rewire all battery-related wiring in the spring, I'll be on the look out for other problems.
 
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