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Old 21-06-2006, 17:01   #1
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Solar expense

Okay so my electrical system is almost complete.

I have a nice old used Xantrex 1000W inverter/50A charger, an 80A alternator wired into a Quad cycle Regulator/monitor. Eveyrthing is working now. I am hoping to keep consumption down to <30 ah/day and having replaced all our lights with LEDs and having a very simple boat without referigeration or pressure water I dont foresee this being too difficult.

Assuming we use 40Ah/day we could keep the batteries topped up by running the engine for 30 minutes at the beginning and end of each day.

Even though we have a small 20hp yanmar that is pretty fuel efficient
I would prefer to have some solar to decrease the engine time.

I think 80W woud probably significantly reduce our overall power generation requirements. I am however quite offput by the rediculous prices out there today.

Cruisers I met who just returned from a 28000 mile pacific circle bought 80W panels in San Diego 2 years agoo for $250. The best price I can find those panels for today is in the neighborhood of $400. That is not a neighborhood I want to live in.

Can anybody suggest a more inexpensive source of solar panels?

I also have a question about topping up the batteries (while I am on the subject)

My smart regulator detects the overall charge state of the batteries. I have a 450Ah single bank and I consider 225Ah of this to be usable energy. Having a desire to get the most cycles out of my bank I want to charge frequently small amounts. Also I dont want to run the engine long. By my 50% standard if I charge every 40Ah I am replacing ~20% of my useful capacity every time I charge. From the regulator's perspective I am charging when down ~10% (from the 450Ah bank). The regulator detects a 90% charged bank and puts out only a trickle charge amount of amperage (maybe 10A) this means that I cannot get the 40A total potential idle output of my alternator into the batteries for that half hour I run the engine to top up.

Am I doomed to charge every few days instead of daily?

thanks in advance,
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Old 21-06-2006, 17:44   #2
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Gaining Amps

Adam,

I have the very same problem, as I suspect many do with high output alternator systems not kicking out enough amps to top of the batts quickly. Since you are not very discharged, the smart regulator will not push out lots of amps because it senses that the batts are reasonably full. Therefore you need long run times! ICK

In order to get you alternator to really kick out lots of amps you need to have a pretty discharged battery.

I am using 2 - 55watt solar panels. When everything is working (hahahaha) they provide a pretty constant "trickle charge" which can reliably add at least 10-15 AH a day depending on sun and shadows and so on.

If you live aboard and run the engine for things like making hot water or refrigeration... and charging your batts... or a run to the dock to top off water and or fuel... you might do fine. My panels are rated at 3 amps each, but that is in ideal conditions and I just never see that output. Lattitude counts too.

I can't comment from experience about whether it is better to run deep cycle discharge and recharge or lots of shallow ones on battery life.

I do know that with the systems that I set up on Shiva I have to run the engine for the frig, hot water and picked up charging each time. I do like the solar panels because they are quiet and maintence free, but who knows whether it would be cheaper to replace the batteries or have solar panels... The panels are quite expensive.

But if you are offshore and the engine fails... you still have a way to keep your batts up and use the radio! May Day May Day

Jef
sv Shiva
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Old 21-06-2006, 17:52   #3
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According to Calder the less you discharge the bank the more cycles you get. he suggests having one large bank because a bank that has 1000 50% discharge cycles in it will have 2000 25% discharge cycles in it.

I have simplified to the point of not needing to run the engine for anything but power, we have no water heater or water maker or refrigeration.

My thinking is with 450Ah if the engine dies offshore my VHF should transmit for a long time before it dies and my epirb is independant of the main battery system anyway

With the new LEDs I would draw about an amp with every light on.

I just want free energy! ;-)
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Old 21-06-2006, 18:34   #4
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AH

If my math is correct the examples you cite would represent the same amount of AH drawn from the batteries or charged back in.

The deal is that it is seemingly much harder to get the last AHs back into the bank when recharging. (my exprience)

If this IS in fact true, the engine running "cost" will be higher because you will be "refilling" at lower amps and at a slower rate meaning more engine hours per amp replaced.

Does this make sense?

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Old 22-06-2006, 10:09   #5
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Makes perfect sense but still makes me sad. Guess I have to drop some serious money on panels.
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Old 22-06-2006, 12:21   #6
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Fuel is expensive too. Let's say you have a 1 hour charge routine per day and you are a live aboard. and need to replenish 40 AH used on a typical day. I would guess that your alternator might supply 20-25 AH running for an hr..because you will be only 10% discharged and the voltage will be high enough to tell your smart charger not to kick out to many Amps.

If you pick up 15 AH from solar your fuel cost is now 1 hr engine time per charge cycle. I would guess that this is between .5 and . 75 gal x $3.50/ gal = $1.75- $2.50 / day with solar assist.

Without solar assist you might have to run for 1.5- 2 hrs so this could be 2 x the non solar solution or an additional $1.75 - $2.50 per day.

If a pair of panels cost you $700 they would be paid for in 1 yr of charging... from fuel savings. After that they are giving you free energy.

This is a crude calculation, but if you plan to live aboard for a few years you can see that the panels will pay for themselves in a year or two.

And if you have to buy fuel in Bermuda or the Caribean the cost of fuel is about $6.00/gal

Your call,

Jef
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Old 22-06-2006, 12:49   #7
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"The regulator detects a 90% charged bank and puts out only a trickle charge amount of amperage (maybe 10A) this means that I cannot get the 40A total potential idle output of my alternator into the batteries for that half hour I run the engine to top up. "

Sounds like you need a better regulator, or a manual charge controller. There's no reason that you can't charge at a higher rate, up to 20% of the battery nominal capacity (450A x 20% = 90AH rate) which would so if you are using 40AH per day, you SHOULD be able to run the alternator at full output for 1/2 hour (80A x 1/2 hour) and regain a full charge, or close to that.

If your regulator won't allow that, and you can't or don't want to add in something like a Balmar for "just use the damn engine and use it now" charging, you'll find plans for manual charge controllers at various sources and in some of the classic 12v boat power books.

You might consider a manual charge selection switch (or one that works from a photocell<G>) so that during the day, you're charging from the solar panels. After 4PM, you hit the switch and do your top-off charging from the engine, totally separate charging circuit to keep things simple.

That's assuming your alternator also can safely run at full rated power, if it is an automotive type, most of them will burn out very quickly at full power.
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Old 22-06-2006, 15:26   #8
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Originally Posted by defjef
If you pick up 15 AH from solar your fuel cost is now 1 hr engine time per charge cycle. I would guess that this is between .5 and . 75 gal x $3.50/ gal = $1.75- $2.50 / day with solar assist.

If a pair of panels cost you $700 they would be paid for in 1 yr of charging... from fuel savings. After that they are giving you free energy.

Your call,

Jef
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I wonder if I could hook the output of the solar into the Quad cycle to regulate the voltage. Im sure it isnt designed to do that but it seems like it might work for that. it should at least be able to tell me what is going in or coming out.

Looks like $559 for the 130W kyocera panel, still quite high but I dont see why I would want an 80W for 450 when I can get a 130W for $100 more.

Are there any other details Im missing? I assume I need a schottky diode to stop the batteries from bleeding overnight.
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Old 22-06-2006, 15:32   #9
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Adam,

If you buy a FlexCharge PV14 photovoltaic charge regulator and connect your solar panels to the battery bank your quad cycle will be able to monitor the charging. (no diode required) Make sure you connect the wires to the correct side of the shunts so that the current they add will be measured.

You might want to contact JR Energy for assistance. They sell all the electric gear you could need and offer lots of customer support.

Jef
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Old 22-06-2006, 19:47   #10
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"I would guess that this is between .5 and . 75 gal x $3.50/ gal = $1.75- $2.50 / day with solar assist." Versus a 15Ah from the solar??

I think the math is fuzzy without knowing the engine & optimizing the alternator used with it. I can run a 112hp gasoline engine, pushing maybe 10-12hp at cruising speed, for 30 minutes per gallon. Let's say, 10hp for 30 minutes, which translates to roughly 7500kw/30 minutes, is that about 260AH? Including the 60A alternator running in the car, let's say 20-30Ah comes out of that too.
Not to disagree, just a lot of variables. A 10-15hp diesel can cruise a boat for an hour on less than a gallon. So...Couldn't Adam be turning a pair of 150A alternators and getting 150AH in 30 minutes from that same gallon of fuel? If he's going to need engine time anyway, he might want to run the numbers on at least a single 150A alternator (which could be added to his existing rig if space allows, rather than replacing it) plus one large solar panel, rather than two solar and no alternator upgrade. No?

(Actually, since his battery bank can't take that fast a charge...he might not even need muich more alternator, just a proper marine alternator/regulator that allowed him to run at 80-100AH output not a reduced rate when it WAS charging.)

Then again, there's supposed to be some 2000 of those old Soviet strontium reactors floating around out there someplace...nice and small, long life, keeps the boat warm...<G>
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Old 22-06-2006, 20:10   #11
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Just got back into the states from the Bahamas and Turks and Caicos. Wonderful trip.

While I was there, diesel ran me from $3.75 to $4.65 per gallon. Gasoline was 4.10 to $5.00 per gallon, using a credit card cost 5% more (yes, I know they can't do that, but only two places did not!). (Here in Charleston, it was only $2.85!!! Only took me $100 worth of fuel from Grand Cay to Charleston)

Having said that, there is a lot of ROI for solar panels and wind generators and such. I will order two additional 24 volt 165 watt panels. I expect them to pay for themselves in less than 1 year on fuel savings alone. Let alone additional maintenance on the engines, replacing stuff that breaks cause you're running the engines, finding someplace to dispose of the old oil, time spent cleaning the boat after splashing the diesel while filling, time missed drinking and relaxing while I ferry over to where they sale the diesel, gassoline etc. ... Yada, Yada, Yada.

I have purchased a small gasoline portable 2kw generator for less than $900. It will let me run my microwave, and top up on those windless, sunless days. (In the 6 months I was down, I can only recall 3 such days, and I was watching for them.)

Shorter answer. If you're on your boat a LOT and away from shore power, the solar panels pay for themselves VERY quickly!!

Keith

Charleston and headed North.
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Old 22-06-2006, 21:07   #12
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If you have 450 Ah of and only use 40Ah a day why do you need to run the engine everyday. Why not wait say five days? You'll still have 250 Ah as cushion and most of the time spent charging will be at the quick rate.
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Old 22-06-2006, 21:28   #13
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Charlies suggestion sounds to be more economical. How many ah's do you draw everytime you start the motor??? By only starting the motor every few days you're saving those ah's and fuel.

And solor panels are like gasoline, the market will charge what the consumer will bare! Fine the best manufacture and surf the net until you find the best price..............._/)
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Old 22-06-2006, 23:11   #14
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Quote:
Originally Posted by AdamY
The regulator detects a 90% charged bank and puts out only a trickle charge amount of amperage (maybe 10A) this means that I cannot get the 40A total potential idle output of my alternator into the batteries for that half hour I run the engine to top up.
Unfortunately, there is no way around that. When the battery is that fully charged, you can't make the chemical reaction go any faster. If you try to force energy into the battery at a higher rate, it will just get hot.


Quote:
Looks like $559 for the 130W kyocera panel, still quite high but I dont see why I would want an 80W for 450 when I can get a 130W for $100 more.
It's a marketing thing -- that is exactly what you are supposed to think, and it works. People tend to be attracted to the brand that has the lowest cost product (consistent with what they are looking for), but once you have their attention, you can get them to buy the more expensive product by pricing it so that they ask the question you just asked. You might feel manipulated, but the right answer is still that $4.30/watt ($559/130W) is a better deal than $5.625/watt ($450/80W).

b.t.w. This is not just cynical speculation. At one job, I wanted to eliminate a proposed product from my development schedule on the grounds that almost nobody would buy it. The marketing group's response was an explanation of this strategy, and I had to design and implement a lame product that we didn't expect to sell.


Quote:
Originally Posted by delmarrey
How many ah's do you draw everytime you start the motor???
It depends how much current your starter needs. 600 amps for 5 seconds is 0.83 AH.

I found similar results for pressure water, shower drain pumps, and the LectraSan -- even with the high instantaneous current consumption, the run time is so small that the total energy consumption is pretty small.
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Old 23-06-2006, 10:34   #15
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Yeah im sure it is a marketing ploy but they all do it. Im thinking I might mount a couple 60W Momocrystallines ($270 ea.) to my windvane tower on swivel brackets.

The problem with running the batteries down by 200 Ah and then just living there is that the batteries will suffer a much shorter life.

In theory (and according to calder) a wet cell battery that will provide 100 cycles (number is arbitrary and for the sake of easy math) at a 25% discharge rate will only provide 50 cycles at a 50% discharge rate. Consequently the ideal solution is to have the largest single bank you can fit and then discharge/recharge it as often as possible keeping it at the top of it's capacity.

Since I plan on living off of these batteries for a couple years I intend to take good care of them. this is why I have build the electrical system I have.

When I got the boat she had 2 golf cart batteries and an elderly 35A Ferroresonant battery cooker. The batteries were dry to the plates and didnt care much for holding a charge.

Now there are 4 T-105s a Quad Cycle regulator/monitor (thanks DefJef I love that counter) new panel Heart 1000W inverter/charger etc etc etc.

I just want to keep my batteries at the top of their charge rate. It is looking like the only way to do this is with a constant trickle charge like that which solar would provide.

Cheers,
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