State-of-charge automatic "full" synchronisation

[ayates]

billknny and smac999 - Many thanks, and I completely agree with you, and have that exact same recommendation on the table (with a 16 page report to back it up ).

With reference to the comments on voltage dropping to 12V and current draw, attached are graphs with the whole 78 days season. The average discharge rate was 12.97A or 311 A-H/day.

One question I had though... For a stock 90A alternator, is there value in upgrading to an external regulator? My thoughts are that while the charge rate will still be low, it may get the voltage higher and help prevent sulphation. But I am not sure... One engine alternator charge graph attached.


Allan.

[billknny]

Sulphating a battery happens by keeping it undercharged for extended periods of time, which you are doing with your current system--big time.

An internally regulated alternator will never bring a battery bank like yours up to full charge--ever. For that you NEED a smart regulator. BUT...charging at the normal absorption voltage will NOT have a significant effect on fixing a sulfated battery. For that you need an equalization charge.


You have more data about your batteries than anybody I have ever seen. But what you really need is understanding. It is really hard to get good understanding a bit at a time asking internet questions of people who don't know what your whole system looks like, and because of that might be giving you incomplete advice. Besides, you might be shocked to hear, there are some people offering advice on the internet that don't really know what they are talking about. Shocking.

If you don't have a copy of Nigel Calder's "The Boatowner's Mechanical and Electrical Manual" go buy one. If you have one, read it! If you have read it before, read it again.

Your system has a common problem. People who have large electric power needs install bigger batteries thinking that solves the problem. It does not. If you use 1000 watts of power in a day, you need to be able to generate 1500 watts (or more) to replace it. That's true no matter how big the batteries are.

[CharlieJ]

Post #12

The PE of 1.79 and the CE of 85% are way out of line for quality deep cycle batteries. I suggest you call the Trojan factory directly or you can calculate the PE for your bank using the procedure in the BMV manual. I would expect a PE in the 1.3 range.

Here is the link to more than you ever wanted to know about Peukert's Exponent. The sidebar has five articles: SmartGauge Electronics - Brief detals about Peukert's Equation

[billknny]

Originally Posted by CharlieJ

Post #12

The PE of 1.79 and the CE of 85% are way out of line for quality deep cycle batteries. I suggest you call the Trojan factory directly or you can calculate the PE for your bank using the procedure in the BMV manual. I would expect a PE in the 1.3 range.

Here is the link to more than you ever wanted to know about Peukert's Exponent. The sidebar has five articles: SmartGauge Electronics - Brief detals about Peukert's Equation

Actually, the charge efficiency reported is not "out of line."

There are two different ways of reporting "charge efficiency." One is the Amp-hour efficiency. This is typically something like 95% to 99%. It is the number you enter into your amp-integrating battery monitor. It is not a measure of the real energy efficiency of the battery, but it is likely the one you are thinking of.

The REAL measure of the overall energy efficiency of a battery is the Watt-hour charge efficiency, and 85% would be a typical number for this from a lead acid battery. This is the number that Trojan is specifying.

Why are they different? When you charge a battery you charge it at an average voltage of 14 volts or so. Therefore one amp-hour contains 168 Watt-hrs (more or less) of real energy. When you pull out of the battery you discharge at about 12.5 volts, so one Amp-hour contains only 150 Watt-hrs (more or less) of real energy.

I have never understood why "amp-hrs" became the sailor's standard measure of battery charge and usage. Watts are just as easy to measure and report, and are more meaningful. But Amp-hrs are what our meters report, so we are mostly stuck with it.

[rom]

Originally Posted by billknny

Actually, the charge efficiency reported is not "out of line."

There are two different ways of reporting "charge efficiency." One is the Amp-hour efficiency. This is typically something like 95% to 99%. It is the number you enter into your amp-integrating battery monitor. It is not a measure of the real energy efficiency of the battery, but it is likely the one you are thinking of.

The REAL measure of the overall energy efficiency of a battery is the Watt-hour charge efficiency, and 85% would be a typical number for this from a lead acid battery. This is the number that Trojan is specifying.

Why are they different? When you charge a battery you charge it at an average voltage of 14 volts or so. Therefore one amp-hour contains 168 Watt-hrs (more or less) of real energy. When you pull out of the battery you discharge at about 12.5 volts, so one Amp-hour contains only 150 Watt-hrs (more or less) of real energy.

I have never understood why "amp-hrs" became the sailor's standard measure of battery charge and usage. Watts are just as easy to measure and report, and are more meaningful. But Amp-hrs are what our meters report, so we are mostly stuck with it.

Things would be easier indeed if everyone talked W instead of A. I am here making a mistake on purpose as I should have stated "instead of A@xV". Anyway, I suspect things will change when everyone uses Tesla batteries.

Unless I misread, I have to disagree however with your explanation. Efficiency is efficiency. But most importantly efficiency is already calculated by the battery monitoring system thanks to the PE parameter you set. So whether you read it Ah (@xV) or Wh, it has to be the same. And if correctly configured (which we already admitted is not really possible) the battery will reach 100% SOC when amp counter reaches 0.

[ayates]

For those following this thread...

I have just completed installation of 2 x Victron Skylla 12.60 chargers. They are running in synchronisation, with a combined charging capacity of 120A. the previous 40A Xantrex charger has recently bit the dust, so the house bank was a little low when the new chargers came on line. This was actually a great test, and they put out a solid 120A, with 111A making it into the batteries (the remaining few amps was the ship's load). These units are a lot bigger than they look; they dwarf the previous Xantrex unit.


Allan.