Why do battery threads get so granular?

[tkeithlu]

Rule of thumb regarding any thread: After the first page, the replies are to other replies, not to the original question.

[hpeer]

Originally Posted by Bycrick

A64 is right when he states that after spending several thousands of dollars on batteries, one would like not to kill them too quickly.

But I’d suspect there are a couple of psychological factors here also.

I have to justify spending $x on batteries. After I have, I’m far less likely to believe that I was a dummy and made the wrong decision. So I have to believe that I was right.

There’s also a trend to think that increased display precision is the same thing as increased accuracy. Not true.
1. A $3 Chinese thermometer reads 79.2 degrees. Really?
2. A GPS displays latitude to 3 decimal digits of a minute. 1/1000 minute is about 6’. The specified GPS accuracy without augmentation is about 15 meters, or +-8 in the low order digit.
3. A digital volt meter displays 12.5 volts when the meter accuracy is +/- 1% +/- 2-5 counts. So it might really be anywhere from about 12.1 to 12.9 volts.
4. A battery monitor displays "state of charge" but only estimates things like Puekert's coefficient, temperature, actual battery capacity, etc. Then displays this to 1%.

But again, after I’ve spent a bunch of money on measuring equipment, I really, really want to believe that it’s right. If I believe it’s right, I really want to think that I understand what it really means.

Bycrik;

3. A digital volt meter displays 12.5 volts when the meter accuracy is +/- 1% +/- 2-5 counts. So it might really be anywhere from about 12.1 to 12.9 volts.

You tot me in that one buddy, i had to look that one up.

Thanks for tweaking me, i learned something.

Here is a good link.

https://www.fluke.com/en/learn/best-...gits-precision

Accuracy may also include a specified amount of digits (counts) added to the basic accuracy rating. For example, an accuracy of ±(2%+2) means that a reading of 100.0 V on the multimeter can be from 97.8 V to 102.2 V. Use of a DMM with higher accuracy allows a great number of applications.

[sailorboy1]

Originally Posted by Cthoops

I'm just wondering if the extra attention that is being paid by people on these battery threads is due to a larger boat? More electrical needs? A general interest in the subject? I truly would like to know because I find it rather perplexing.

Thanks.

It's because the details of the beer staying cold is a granular amalgamation of electrical and battery coalescence, which habitually occurs in boats that transcend 32' of protraction.

[hpeer]

Originally Posted by tkeithlu

Rule of thumb regarding any thread: After the first page, the replies are to other replies, not to the original question.

Yup, i routinely skip threads over a couple of pages long.

As our two posts demonstrate! LOL

[Bycrick]

“It ain’t what you don’t know that kills you, it’s what you’re sure you know that just ain’t so." — Mark Twain

[wingssail]

Originally Posted by Bycrick

A64 is right when he states that after spending several thousands of dollars on batteries, one would like not to kill them too quickly.

But I’d suspect there are a couple of psychological factors here also.

I have to justify spending $x on batteries. After I have, I’m far less likely to believe that I was a dummy and made the wrong decision. So I have to believe that I was right.

There’s also a trend to think that increased display precision is the same thing as increased accuracy. Not true.
1. A $3 Chinese thermometer reads 79.2 degrees. Really?
2. A GPS displays latitude to 3 decimal digits of a minute. 1/1000 minute is about 6’. The specified GPS accuracy without augmentation is about 15 meters, or +-8 in the low order digit.
3. A digital volt meter displays 12.5 volts when the meter accuracy is +/- 1% +/- 2-5 counts. So it might really be anywhere from about 12.1 to 12.9 volts.
4. A battery monitor displays "state of charge" but only estimates things like Puekert's coefficient, temperature, actual battery capacity, etc. Then displays this to 1%.

But again, after I’ve spent a bunch of money on measuring equipment, I really, really want to believe that it’s right. If I believe it’s right, I really want to think that I understand what it really means.

Yes, I've felt this way forever but you stated it most clearly.

[Hesti]

First, you want to get away from it all, want the simple life on a boat. Then, you want comfort on the boat and a lot of that comfort can apparently be provided electrically. Then, you realize that you have to have enough electricity to support all the gizmos you have fitted. Then, you realize that between providing and storing electricity for all your gizmos, things can become quite complicated, heavy, expensive and prone to failure.

[Stu Jackson]

Originally Posted by UFO

Any book(s) you can recommend for someone with a limited knowledge?

BOOKS

Every so often folks ask: "What book should I buy to learn electrical stuff about my boat?"

The appropriate answer is: "Depends on how you like to learn."

Go to a chandlery and read a few in person, and start by buying one that you think suits your "level" and is "readable" to you."

Here's a good start: https://www.bluesea.com/support/refe...trical_Systems

Jan. 2018 - West Marine revised their website, so the following link no longer works. Darn! But a Google or Amazon search for "boat electrical books" will do it for you. Charlie Wing's comes highly recommended by many.

A good starting list is provided by West Marine in the their online Advisors (and usually in their catalogs, one of which should be in your house and the other on your boat).

http://www.westmarine.com/webapp/wcs...trical-Systems

[Stu Jackson]

Originally Posted by UFO

Any book(s) you can recommend for someone with a limited knowledge?

In addition, two of us I know of have spent decades assembling boat electrical system information on the internet.


Maine Sail, a frequent contributor here, has his commercial marinehowto site.


I developed a series of links on our boat specific Association website, with many links to his writings not only on his site but others, as well as a series of our own. https://c34.org/bbs/index.php/topic,5977.0.html


Neither one of us "hides" what we do and I quote and link them often here and on other boating forums.


We have learned, however, that we can make the information available but we can't make folks read it.


If they don't understand it, we strive to help. That's a separate issue.

[tarian]

to some battery and figures are a religion abt like anchors ,and they will need to squeeze the last 1% out of their system to be able to boast about it , i do not know if there are star trek fanatics on here I am and it is when Jordi Laforge tells the Captain of the enterprise that he got .004 % more from the dilithium crystal at this point the Captn rolls his eyes and glazes over as he is fighting the romulans
The best I love is those with 1000 wattts of solar telling us they are full charged by 10 am which seems odd as they have to dump the other 8 hours of energy down the drain, while having their stability on their boat compromised
Oh did I start something

[Bycrick]

Post #15 is a good example of a case of thinking you know something that just isn’t (or at least might not) be true.

Let’s assume that I have an accurately calibrated 12 volt source. I attach my $4 eBay meter and it indicates 12.47 volts. What evidence do I have that the error is constant, ie that with a 13 volt source the meter will read 13.47 volts? None whatsoever. So even relative measurements are questionable.

Then add in, just say, environmental considerations. If I run the above tests at 40* in the winter, or after leaving the meter in the sun on deck in the summer, will I get the same results? Or when the internal batteries are low?

If the meter is inaccurate, one would have to calibrate it under all ranges and conditions in which one would use it. That’s why a cheap meter might not even tell you what they think the accuracy is, and Fluke will say something like "Accuracy is +/- 1% of full-scale, +/- 5 counts, with a temperature range of -X* to +Y* over the range being measured."

[bailsout]

I opened this thread thinking that their battery terminals were experiencing some electrolysis. Granular threads. Whatever.

[sailjumanji]

Originally Posted by sailorboy1

I gave away a pair of 46 month old cruised on T105 golf cart batteries yesterday. Their matching pair bit it 4 months ago. The guy who came and got them said his batteries last 10 years. So I can not comment anymore on batteries as i must not really know or understand batteries at all.

I had three Deka Group 31 AGMs that lasted 12 years on my previous Seawind cat. On our new cat, we managed to trash two 225 AGMs in first four months, and a second set in the last year. And not from undercharge or excessive withdrawal. See our separate thread please, if you have any suggestions. Thanks.

[Stu Jackson]

Originally Posted by sailjumanji

I had three Deka Group 31 AGMs that lasted 12 years on my previous Seawind cat. On our new cat, we managed to trash two 225 AGMs in first four months, and a second set in the last year. And not from undercharge or excessive withdrawal. See our separate thread please, if you have any suggestions. Thanks.

THREAD DRIFT ALERT



You will get a lot more feedback if you'd bothered to insert a link to your separate thread, so far unidentified.


Would it be this one?


https://www.cruisersforum.com/forums...rs-239438.html

[waterman46]

Not really sure what your question is. Electrical consumption and charging are major issues for most cruisers, that's why all the attention on this site. If your system is performing well, that's great.

What is your daily power consumption? Your electrical needs seem to be small compared to many cruising boats. Refrigeration, especially freezers, are huge power consumers when you cruise in the tropics. That Engel reefer only draws 2.8 amps if you have the one I checked on-line. Does it make ice?

Add a watermaker, large built-in fridge with freezer, microwave, TV, autopilot, radar, chartplotter, depthsounder, AIS, etc. it all adds up and has to be managed.