AC charger smarter than the 3 stage "smart" charger?

[CSY Man]

CSYman, did you ever stick a digital voltmeter on those batteries to see what voltage which charger was actually DELIVERING to them?

Well, the above battery monitor is hooked straight to the batteries and yes, I can read voltage directly on the screen.

No, I did not double check with a handheld digital multimeter, BUT I do have a back-up analog voltmeter in the panel, in addition to the Battery Monitor, upper left on the picture. Also a back-up analog ammeter to the right so I can see how much current is being pumped in from the analog gauge, as well as the digital Battery Monitor. (Hard to see it in the pic, lower right)

[hellosailor]

OK, that's good enough either way. (And a NICE little nav station!) Let me rephrase the question:
Using any kind of digital voltmeter, connected to the batteries directly, what have you confirmed is the charging voltage from each of the two charging systems? during "full" i.e. flat out charging? And tapering off to what?

Just to be sure the question of whether the two charging systems being adjusted or set up differently might not be the simple answer to the difference.

[CSY Man]

Just to be sure the question of whether the two charging systems being adjusted or set up differently might not be the simple answer to the difference.

Well, that is what I just did:

Adjusted the charging voltage on the AC charger:
Now it puts in about the same as the Alternator Charger.

The problem seems to be gone.

What I have not done is to read the book on the 3 stage charger that is hooked up to the Alternator, to see if it can be adjusted. Don't think so, but not sure.

At any rate, it puts out the juice for sure: During the bulk charge the voltage goes up high enough to shut the fridge compressor down and to block the SSB from starting up. (They both have an over-voltage protection at around 14.2 to 14.4)

As I said earlier in this thread: I have no reason to belive there is anything wrong with the ship's charging system: It has worked great for years. So has the solar panels with their intependent regulator.
The AC charger has also worked great since I installed it last year. The point of this thread was: Why does the AC charger / charge controller pump in more juice than the ship's system?
Answer: Because the AC charger had the wrong temp setting selected. (3 position switch: Cold, Warm, Hot)
I was in Warm with Hot batteries...Over 80 degrees F.

I am the culprit, did not set the switch right in June or so.

I am also getting the rum bottle 'cause I figured it out and flipped the switch to Hot.....

For the runners up, there is a bottle in yer future, but it can only be delivered and consumed locally in ZIP code FL 33315, with the donor helping out...

[Rick]

The problem is that if your shore charger with a warm battery setting caused more replenishment to your battery bank that did the alternator regulator setting then the problem is that your alternator regulator setting is too low. Here is how you can tell.

First of all forget any voltage readings that your analog meters might read...they just do not have sufficient resolution or accuracy period.

Next make your alternator, when in accept mode, WILL deliver the number of Amps (by number) that equals the number of Amp-hours missing from your battery for at least three readings between the beginning of the acceptance mode and the end (where the number of Amps equals 2% of the Amp-hour rating of your battery (multiplied by any degradation factor...more on that later). After the battery has been on float voltage for an hour or more restart the acceptance mode (either with the alternator or by turning on your shore charger) and note that the battery will or will not charge accept much current at the higher acceptance voltages. The phenomenon here that you are measuring is that when the battery is full and truly recovered lost capacity and has been cooled down it just will not charge accept much current at higher voltages...by applying a new acceptance cycle (merely for testing purposes) you can observe the phenomenon. You will be surprised that a fully charged and recovered battery just will only charge accept about 100mA per 100Amp-hour rating at 14.5V! If not, it is not full and not recovered and not sufficiently cool (80 deg.F is not hot).

Because your complaint was that the shore charger caused more charge to be accepted I concluded that your alternator regulator is set too low. Go back and set the shore charger to the previous warm setting or even the cold setting (I don't care that you are in an 80 deg. F environment the friggin' suggested settings are just too conservative except for fools who cannot watch what is going on...just think about it...it is easier to let the fools gradually loose capacity and replace their batteries than it is to perhaps cause too much gassing in unattended conditions with a shorted cell).

[hellosailor]

"consumed locally in ZIP code FL 33315, "
Hmmm....I'm over in 33319 coupla times a year. If I find a bus map, I might take you up on that, I give you fair warning to hide the boat and bottle.<G> I'd offer to bring down a multimeter, but of course, we're not allowed to fly with dangerous weapons like that any more, and I can't put it in the checked baggage because it is "electronics equipment" which is then uninsured and unprotected. I won't check bags until they can give me reason to expect them to be with me at the other end, complete and intact. (I keep telling them, I don't *want* a plane, I have no place to park one, I paid for them to do the flying and I won't do it for them, but no...they keep checking just in case I changed my mind.)

Rick-
Two small questions? WRT analog meters in boat panels being inaccurate, I tried to check one of those 9-16V type scale last year and found that if the meter was adjusted to read right at 11V, it was way off at 14.4, and vice versa. Off by more than a volt. (Voltages on the bench form the carefully checked supply.) So I could adjust it to show "running" system voltage correctly, or standing battery voltage correctly, but not both. Are "boat panel" analog meters typically THAT bad? Or was this just a clunker?

Second question "with a shorted cell". Just how common are shorted cells, or how often have you actually seen or heard of battery failures from shorted cells, as opposed to open ones?

[Rick]

Most analog panel meters are rated to give an overall accuracy of +/- 5% of the fullscale value. For the example of a 9-16V D'arsenval meter that translates to a +/- 0.35 V error at any reading. Any particular meter may or may not be better than that, you just must assume the worst case. On occasion you see a mirrored scale 1 or 2% rated meter which gives you a 70 mV error yet I'll bet yours is not one of those and, still, that is insufficient for the accuracy needed.

Battery charging accuracy is dependent upon current for charging modes other than float. Historically most vessels do not have the more expensive current shunts and digital displays AND the understanding of just what the readings mean. They use voltmeters to indirectly infer what the charging may be doing to their batteries. A 50mV change in charging voltage at the point where a high output alternator shifts from bulk to acceptance modes can make a 50 Amp difference in charging a 400 A-hr battery. The accuracy required for monitoring charging voltage needs to be +/- 20 mV in my opinion. This accuracy (not resolution) is easily obtained with a relatively low cost high quality DVM such as a Fluke and not even approached by even the highest quality panel meter found on our boats.

Analog panel meters are O.K. for monitoring ac input voltage and current yet the price of quality digital panel meters is sufficiently low so as to preferentially choose only digital based monitoring.

"Open" internal connections in batteries are relatively rare as compared to shorted cells. Opens usually occur to batteries not designed with internal current strapping sufficient to handle high charge/discharge currents and cyclic deep discharging, sometimes in conjunction with the use of a high specific gravity not appropriately commensurate with operating temperature. Such batteries are not applicable in our environment. Other "opens" are due to fracturing the internal connections from vibration and G-shock.

Shorted cells are much more common. Dendrite growth between cell plates may occur when excessive time is spent in a state of deep discharge. Sloughing off of the active plate material may occur from vibration and/or excessively high charge/discharge currents. Sloughing may occur from plates exposed to air (lack of electrolyte). Electrolyte contamination may ultimately cause shorted cells. One time I worked with an RV manufacturor who was experiencing excessive gassing whilst charging on many coaches rolling off of the production line. The problem was from the poor quality (cheap) batteries being provided by a questionable source.

[hellosailor]

Rick-
"On occasion you see a mirrored scale 1 or 2% rated meter" Still got my first multimeter, an EICO analog with a mirrored scale. No, the boat panel meters aren't that grade.<G> It's a bit like George Washington's Hatchet by now, a burnt resistor replaced with a home-made wirewound decades ago, some tape because the rear panel screws were lost, some hot wax or epoxy to repair the old slim style probe sockets....But it still works real good!<G>

[Rick]

Ahhh, a man from the Eico, Knight, and Heathkit days...probably even knows about Sam's Photofact publications!

[btrayfors]

Rick makes some excellent observations re: the accuracy of analog and digital meters, and the relevance of this accuracy to proper battery care.

A couple of months ago I started a thread on the SSCA discussion board re: the accuracy of multimeters. Readers may want to read the postings there: http://64.70.221.24/DiscBoard/viewto...ght=multimeter

Rick's observations paint a picture which, IMHO, is both too bleak and too optimistic. Consider the following.

1. While the limitations of analog panel meters are well known, and their accuracy is suspect unless calibrated, they still can serve a useful purpose. For over 30 years I've run all my ham radios on 12V, having been in the Foreign Service and serving in lots of places with -- shall we say -- challenging electrical environments. I have a setup at the home shack which is nearly identical to a boat: two T-105 golf-cart batteries, an old Marinetics analog meter, and a (very good) Iota 45A smart pulse charger. I only really care about voltages between 12.2 and 12.7. Voltages above and below that range are (almost) irrelevant...the charger is smart enough to take care of the charging, when switched on, and if the voltage falls below about 12.2 it's time to recharge. Using one of six multimeters I have on hand (a calibrated Fluke 189), I've adjusted the Marinetics meter to read accurately within the range of interest. With occasional checks using the very accurate digital multimeter, I've found the analog meter to be very close and more than adequate for my purpose.

2. Not all multimeters are created equal. Their published specs may have little to do with their current condition or accuracy. After much playing about, I decided to use the Fluke 189 as the "standard", and to tweak the pots in the "lesser" multimeters to equal the Fluke AT THE VOLTAGES OF INTEREST. Now, two months later, this has worked out very well. All my multimeters, except the clamp-on Fluke 335 which is not user adjustable, read almost exactly the same. Works for me!

3. I have a Professional Mariner digital voltmeter on my boat which I HATE. Mainly, I hate it because it's very noisy...it emits a great deal of RFI and interferes significantly with HF radio reception. I have to remember to turn it off. It also only reads to one decimal place. A good digital meter, to my mind, ought to read to at least two decimal places. One of these days I'll simply plug the hole in the bulkhead and refit an analog meter with an expanded scale, giving up the "accuracy" for a RFI-quiet voltage measurement tool which just gets the job done. If I want or need more accurate measurements, I'll just use a multimeter.

4. Unless you have a CALIBRATED digital multimeter or other voltage measuring device, you really haven't a clue as to what the voltages of your batteries REALLY are. And, it's important to note, a difference of only 0.4 volts is the difference between a fully charged (flooded) battery (12.6VDC) and a battery which is 50% depleted (12.2VDC).

Bill

[Alan Wheeler]

Bill, that last No.4 comment is why Rick has suggested what he did. Most all panel analogue meters available to most general ordinary joe blog boaters will not show you that 0.4V accuracy even when you study the meter real carefuly and then the remainder real good meters need to be studied carefuly to see a 0.4V difference. A digital read out is far far more accurate and especially if, as you say, it reads to two decimal places.

[btrayfors]

Wheels,

No question a digital meter readout CAN BE more accurate. Also, no question in my mind that you need a good, calibrated digital meter (either multimeter or panel meter).

However, as I said, a CALIBRATED analog meter with an expanded scale is just fine for day-to-day monitoring and will, indeed, discriminate well between a voltage of, e.g., 12.5 and 12.6! And, it doesn't put out RFI to spoil your HF radio reception. And, it can be read at a glance.

I used an analog meter, calibrated, for more than 15 years on my boat to read the voltage on my house and starting batteries. Occasionally, I'd check the accuracy of the reading with a multimeter to be sure it was reading correctly. Worked very well, til I got the silly notion to install a digital meter. Its lighted digits look good in the dark, but I still hate its noisy design :-))

Bill

[CSY Man]

Oh my, I have created a monster....

Guys, thanks for all the good and detailed info, but this is soaring into the expert level and most cruisers ain't there, or are trying to get away from it.

Now then: Yeah I am aware that an analog panel meter is not quite as accurate as a good digital gauge, or a good digital multi meter:
Have tried to "calibrate" my analog gauges using a digital multimeter: If I tweaked the screw to make it good on one setting, then it was way off on the next setting.
(Not linear as an engineer would probably say)
Therefore, the analog dispalys are only for general info, just like yer cars speedometer.

A friend handed me some Blue Panel or Blue something digital gauges to replace the analog ones, new in the box and all. Being a gadget guy, I put 'em in and hooked 'em up to get more accurate readings.

Guess what, they ate current just sitting there at idle.
Not good on a sailboat for anchor days at a time.
Any draw more than 0.0 at idle is too much for me.

Ripped out the Blue something and gave back to the donor. Told him to sell 'em on e-bay, he threw the things away instead. ($$ wasted money, the powerboat guys love those things with the gen-set running 24/7 anyway, plenty of power to supply the cute little pink and purple digits.)

I knew they ate current because the digital Battery Monitor said so.
After the analog (steam gauges) were back in, no more lost current.

So, uh the panel stays the same for the foreseable future.

(I don't care that you are in an 80 deg. F environment the friggin' suggested settings are just too conservative except for fools who cannot watch what is going on...just think about it...it is easier to let the fools gradually loose capacity and replace their batteries than it is to perhaps cause too much gassing in unattended conditions with a shorted cell).

Hmm, conservative is just fine with me.
On the other hand, I don't mind a bit of gassing and water-fills once a month or so. Wicth is what I have been doing the last few years with the solar regualtor set a bit high with the boat un-attended.

I don't leave the boat plugged in with the AC charger "On", excpect for unusual circumstances.
Kind of afraid of AC circuits going bad and sinking the boat. Bad stories from my live-aboard days 20 years ago. (Eat zinks, burn through-hulls, stray current in the water, all kinds of bad stuff.)

Have been working a bit lately and unable to try all the good ideas and testing stuff being mentioned here, but keep 'em coming, I am indeed listening and will do all of the above soon.

Uh, the bottle of rum is still there, come get it.....

[hellosailor]

Rick, don't tell me SAMS are dead?! I thought they were still online on the web, used one that way not...well...surely less than a decade ago.<G> But you know these days, if it isn't a cold solder joint, you can't SEE anything, much less order the part to FIX it anyway. My big/good TV is at that age where I have to tap the corner to make the green gun turn on....But I can't replace it until next year, when HDTV tuners might be included in the new ones. Hmmmm...Progress?
Don't forget to add "Lafayette" when you're doing the incantations.<G>

CSY-
"I don't leave the boat plugged in with the AC charger "On", excpect for unusual circumstances. Kind of afraid of AC circuits going bad and sinking the boat." Heck, I'd rather have a master kill switch at HOME too. If the public ever head how many homes (and that can mean entire apartment buildings) were total fire losses after a wall-wart of kitchen appliance caught fire, there'd be riots in the street. (Or, higher sales of the Enquirer and Globe that week anyway.<G>)
I think the analog meters have some purpose, in that they can tell you "The charging system is really fubar right now!" or "This battery ain't gonna start a can opener, much less your engine". I guess a couple of LEDs could do that much too...hmmm.
But I spoke to a vendor who makes, actually makes, high end LED and LCD displays that have voltmeters integrated into them. Asked them about marine use, and they said DO NOT USE THE LCD METERS, they will not withstand the moist environment. I don't know why, and I can't see any reason that "has to be", but apparently the power-hungry LED meters are the only ones inherently robust enough for marine use. (And these guys don't make cheap display/meters, either.)

[CSY Man]

Checked the battery (house bank) voltage at rest this evening:

After I diconnected the sol panels and turned the DC panel OFF, with the AC power also diconnected, the housebank resting voltage was 12, 84 after 2 hours: Measured on the digital Battery Monitor.

Looked a bit high so I put a digital multimeter on the batteries and got these readings: (4 X Six Volt Golf cart batteries): 6.43, 6.39, 6.41, 6.39.
Average 12.81 Volts.

Based on that, there should nothing wrong with the batteries or the measuring equipment. (?)

Will keep looking into this and again: I much appreciate the comments and suggestions, the rum bottles are waiting.

[CSY Man]

Now back fro the ship agin:

Ran the engine for 30 minuttes and measured charging voltage on the panel and on directly on the batteries:

Saw 14,15 Volts on the digital Battery Monitor, and 7.04, 7.05, 7.03 and 7.04 volts on the house bank measured by the same digital Multi Meter straight on the terminals, for an avearge of 14,08.

A very slight difference of 1/2 % or so.
So, uh again, batteries and on-board charging are good.?

(Did not get full out-put of the alternator as the battery banks were pretty much fully charged. Have seen 14.4 volts in the past with banks down 25%, that kind of voltage will also shut down the fridge compressor and prevent the SSB from cranking up due to over-voltage protection. Point is: Nothing wrong with the batteries or the charging system on the boat. Only the AC charger was pumping too much, but now better after temp. switch moved to HOT....The rum bottle is still mine )