Charging 24v battery bank with 12vg

[Chris1]

Doubled down on AGM. Typically AGM batteries require much higher charge rates which is still directly related to panel wattage. Use a good oure lead AGM like Concord or Odyssey require C/4 to C/2 charge rates You need that high rate to make them recombine O2 and H back to water.

So what's the benefit of a high quality battery like the Concorde AGM over the cheaper Brand X? Lower DOD without sulfation? More charge cycles?

[J.P.M.]

I think you got it wrong, There is no discrimination on a sub, we are equal opportunity offenders. Rank has no privileges on matters of passage, even the Skipper and XO walk the gauntlet. Look up a slang term used on U boats called "Boy Butter".

Well, and meant in a genuine and non humorous way, maybe I'm wrong, but it seems to me there is, at least in a positive sense/usage of the word. You get to choose and be discriminate to some degree to choose the e situation you serve in and in whose hands and actions you choose to trust with your life in ways most folks are clueless about.

Most Respectfully,

J.P.M.

[Sunking]

Don't know how you ever survived the political incorrectness. Oh, the humanity. !

I think you got it wrong, There is no discrimination on a sub, we are equal opportunity offenders. Rank has no privileges on matters of passage, even the Skipper and XO walk the gauntlet. Look up a slang term used on U boats called "Boy Butter".

[J.P.M.]

A fart smells better than amine. Truth be told a fart only last a few seconds, but constant with 130 men crammed in a small space. Air scrubbers and ventilation whisk away the methane, CO2, and hydrogen, but nothing takes away the Amine odor. Today I do not think Amine is used in many subs anymore to scrub away CO2.

Now the real question is what happens when you pass the equator or some bonehead does not have the latrine valves set properly and you change depth and what comes gushing out of the head. As a right of passage over the Equator, even officers, have to eat a M&M candy from a fat greased up cross-dressed sailors belly button. I will not tell you what we made SEALS do when they come on board to earn their Whack Shack.

Thank you. RUA.

I've heard stories from retired Dolphin friends including tales related to equator crossing virgins.

Don't know how you ever survived the political incorrectness. Oh, the humanity. !

[Sunking]

SK: Since you're the one who broached the flatulence barrier in this thread, and as a retired Dolphin, maybe you can enlighten me. What happens or how long does a fart stay in a submarine ? Length of the cruise ?.[/FONT]

A fart smells better than amine. Truth be told a fart only last a few seconds, but constant with 130 men crammed in a small space. Air scrubbers and ventilation whisk away the methane, CO2, and hydrogen, but nothing takes away the Amine odor. Today I do not think Amine is used in many subs anymore to scrub away CO2.

Now the real question is what happens when you pass the equator or some bonehead does not have the latrine valves set properly and you change depth and what comes gushing out of the head. As a right of passage over the Equator, even officers, have to eat a M&M candy from a fat greased up cross-dressed sailors belly button. I will not tell you what we made SEALS do when they come on board to earn their Whack Shack.

[Sunking]

Steve AGM does not sulfate like FLA. That is not to say they do no sulfate because they do. The main difference is FLA sulfate accelerates at 50% and lower DOD, AGM can go down to 80% DOD before sulfate accelerates.

Please no one take that as meaning you should or should not use AGM because it does have its application. For Solar the main advantage is you can charge and discharge AGM 2 to 5 times faster. So Steve for example your neighbors to the north in gloomy doomy Seattle and Portland receive less than 2 Sun Hours for several months out of the year. That means you must use much higher panel wattage and run Charge Rates up to 1C. Example you want 1 Kwh of of usable power in a day. You have 1 site in Seattle and 1 in Tuscon, Seattle needs a 1000 watt panel and into a 12 volt battery is 80 Amps. Tuscon only needs 400 watts of panels and 35 amps of current. Both need the exact same 12 volt 400 AH battery but not the same type. In Tuscon you can use a FLA battery that cost half as much as AGM and last twice as long. You cannot do that in Seattle with a C/5 charge current.

Most deep cycle AGM's need to be charged fast, that is what they are designed to do and are cousins of SLI batteries. They need to be pressurized to make them recombine O2 and H with the catalyst used. Bottom line is check what the battery requirements are before you make a selection. It all has to fit and be designed to work with everything.

FWIW Steve AGM batteries were developed specifically for military aircraft where inversion and G forces are encountered and no spills and excess weight can be tolerated. Concorde to this day made the first AGM's and today still make the best AGM's. They are one of the very few that use 100% virgin lead with no alloys like antimony, calcium, tin, or silver. The lead used is not from recycled material contaminated with impurities and alloys. I can only think of two other manufactures that do that, and they are not tailored to RE, rather motorsports made by Odyssey and Optima. You can tell a lot about a battery by looking at the Term Post. When you see Auto Term Post, you know it is made for motorsports. Cycle application batteries have Flags you can use 1 or more bolt through hardware. Now these are AGM batteries with dual Term Post.

[sdold]

Was it that AGM could be charged more slowly without risk of sulfation?

[Sunking]

Even AGM? I thought that only applied to FLA.

Doubled down on AGM. Typically AGM batteries require much higher charge rates which is still directly related to panel wattage. Use a good oure lead AGM like Concord or Odyssey require C/4 to C/2 charge rates You need that high rate to make them recombine O2 and H back to water.

[sdold]

Certainly. Batteries have minimum charge rate requirements which is directly related to panel wattage.

Even AGM? I thought that only applied to FLA.

[Sunking]

Now it's coming clearer to me. I could put all my solar resources into a shore based power station at the dock

Well have another cup of coffee and the rest should make sense. You are absolutely correct, if the boat is only out for a day, you have no need for solar on the boat. Solar Systems are designed to have 3 to 5 day battery capacity in the event you run into cloudy spells. Size the battery correctly, and you are good for 2 days with no charge. I am an honest injun, me no lie.

[Sunking]

If you are still willing, can you tell me why some battery mfgs. list a minimum solar panel size with which to charge their AGM batteries?

Certainly. Batteries have minimum charge rate requirements which is directly related to panel wattage.

[J.P.M.]

Well, now we're getting somewhere!

I'd add that the popcorn farts probably have a lower dew point so I'd use the higher heating value for the flaring process calcs.

SK: Since you're the one who broached the flatulence barrier in this thread, and as a retired Dolphin, maybe you can enlighten me. What happens or how long does a fart stay in a submarine ? Length of the cruise ? Just wonderin'.

[littleharbor]

One of my mentors who happened to be the dean of engineering at one of my Alma Maters once went through some quasi tongue in cheek calcs and came to the conclusion that a flea fart was ~ (within about an order of magnitude +/- a bit) equal to about 1 electron-volt or ~ 1.6 EE-19 Joules. So, maybe to a first approx., a beer fart ~= (1ev*(1 human mass/1 flea mass)).

Now, by googling "how much does a flea weigh", a decent approx. of a male flea's weight ( because, c'mon guys - who ever heard a female bust a fudgie - at least an unmarried female ?) after biting an animal is ~ 36 mg. Now, assuming 90 kg. human male.

--->>> (9 EE7 mg/36 mg)*1.6 EE-19 J = ~ 4*EE-13 J/beer fart.

To be clear, that's probably only lost Pv work associated with unrestrained expansion into a vacuum. Available PV work at sea level will be less because of the lost availability due to atmospheric back pressure.

Determination of any of that PV work as may be expressed as velocity head is left as an exercise in orifice flow characteristics for the student. That seems the type of usefulness most graduate work amounts to these days anyway.

Also, none of the above is to be confused with any energy resulting from thermochemical conversion processes should any of the beer fart be flared off. See the Koch brothers for further information on such matters.

As usual, take what you want of the above. Scrap the rest.

Well, now we're getting somewhere!

[J.P.M.]

How many watts does a typical beer fart contain? More than a popcorn fart, but less than a pickled egg fart is my guess.

One of my mentors who happened to be the dean of engineering at one of my Alma Maters once went through some quasi tongue in cheek calcs and came to the conclusion that a flea fart was ~ (within about an order of magnitude +/- a bit) equal to about 1 electron-volt or ~ 1.6 EE-19 Joules. So, maybe to a first approx., a beer fart ~= (1ev*(1 human mass/1 flea mass)).

Now, by googling "how much does a flea weigh", a decent approx. of a male flea's weight ( because, c'mon guys - who ever heard a female bust a fudgie - at least an unmarried female ?) after biting an animal is ~ 36 mg. Now, assuming 90 kg. human male.

--->>> (9 EE7 mg/36 mg)*1.6 EE-19 J = ~ 4*EE-13 J/beer fart.

To be clear, that's probably only lost Pv work associated with unrestrained expansion into a vacuum. Available PV work at sea level will be less because of the lost availability due to atmospheric back pressure.

Determination of any of that PV work as may be expressed as velocity head is left as an exercise in orifice flow characteristics for the student. That seems the type of usefulness most graduate work amounts to these days anyway.

Also, none of the above is to be confused with any energy resulting from thermochemical conversion processes should any of the beer fart be flared off. See the Koch brothers for further information on such matters.

As usual, take what you want of the above. Scrap the rest.

[Chris1]

Absolutely it can be done, but why would you? It can be done if you charge each 12-volt separately. Good luck with that.

But why if you do not have to. Wire you panels in series and set charger up for 24 volts. Personally I would not bother with putting up 2 small 50 watt panels on a boat. Shade will always be an issue, and with no fixed tilt or orientation to optimize solar harvest, you can fart more usable energy then the panels will produce in poor conditions. Wind Turds work better for boats.

If it were me I would buy a good High Voltage Grid Tied of 250 to 300 watts which cost less then your 2 x 12 volt battery panels, use the savings to buy a good MPPT charge controller configured for 24 volts, and forget about solar panel dead weight in the boat to slow you down with no meaningful power generated. At 250 to 300 watts into a 24 volt battery will require a small 15 amp controller. Morning Star makes a SunSaver MPPT 15 amp charge controller which should be perfect.

Here is some math to crunch. If you used PWM controller with your 2 x 50 wat panels on its best day with the panels facing directly into the sun at high noon on June 21 might briefly output 60 watts or roughly 2.4 amps of charge current or 60 watts. The farts from a can of beer will generate more energy and not near as big and heavy. Want to use those 2 x 100 watt panels for shore power. Well they will give you up to 4.8 amps of charge current or 12 watts.

Use a single GT panel of say 250 watts, a MPPT charge controller and you get 10.4 charge amps or roughly the full 250 watts. Who on earth would have thought you could get 250 watts from a 250 watt panel? You can if you toss those antiquated PWM Controllers over board and send them to Davy Jones Locker where they belong. Anyway you would have to be a serious alcoholic to generate more beer fart power than aa 250 watt panel with an MPPT controller. Not to mention less expensive than PWM. To get 250 watts from a PWM controller will require 375 watts. With your idea of using 100 watts from the boat, plus another 200 watts from shore only gives 8.3 amps of charge current or roughly 200 watts from 300 watts of panels.

Now it's coming clearer to me. I could put all my solar resources into a shore based power station at the dock. This boat will almost never be out for more than a daysail so it wold rarely need to produce it's own power. And if the batteries where dead and there was no wind there are still oars. I like that. And like you say, leave the dead weight of the solar panels off the boat. Genius!