Power Management Ideas (12 V)?
- Thread starter Kings Gambit
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I have three roll up panels that are 22 watts each. They are no longer manufactured however. Had them for ten years. In my experience, they will handle the frig & freezer on my boat during good daylight. Figure five hours, maybe six in long summer days. However, the other 18 or 19 hours are pure draw. So, i run my Honda 2000 for an hour a day. I think for your set up, you would have some small surplus of power since you have one rather than two compressors.
I think the key is a Honda generator and a charger to match. You need a battery monitoring system such as a Link to figure out what's going on. On a personal note, I think you would be happier with a Honda 2000 and a 20 amp AC charger to give you back about 80 amps in an hour of running. Or, you could get a 1000 Honda and run it twice as long. I agree run time is important, and I'd go with the bigger one.
As far as solar, you just have to figure out how much you want to mess with them. I may go with two 90 watt panels mounted on the aft lifelines which will be replaced with S/S tubing. That's about $600 plus $300 for a MPPT solar charge regular plus the S/S construction. Even with the 66 watt flex panels added in, I expect I will still need to run the generator a half hour a day or an hour every other day. But that set up could cover you. But, you have to factor in the hassle of rigging and unrigging them and storing them. And, you wouldn't want them during races. So, I think, in your case, a Honda 2000 and appropriately sized charger is the way to go. BTW, I rarely get much more than three years out of a set of batteries, but I do work them pretty hard.
I think the key is a Honda generator and a charger to match. You need a battery monitoring system such as a Link to figure out what's going on. On a personal note, I think you would be happier with a Honda 2000 and a 20 amp AC charger to give you back about 80 amps in an hour of running. Or, you could get a 1000 Honda and run it twice as long. I agree run time is important, and I'd go with the bigger one.
As far as solar, you just have to figure out how much you want to mess with them. I may go with two 90 watt panels mounted on the aft lifelines which will be replaced with S/S tubing. That's about $600 plus $300 for a MPPT solar charge regular plus the S/S construction. Even with the 66 watt flex panels added in, I expect I will still need to run the generator a half hour a day or an hour every other day. But that set up could cover you. But, you have to factor in the hassle of rigging and unrigging them and storing them. And, you wouldn't want them during races. So, I think, in your case, a Honda 2000 and appropriately sized charger is the way to go. BTW, I rarely get much more than three years out of a set of batteries, but I do work them pretty hard.
To really get it right, ya going to need a battery monitor like MaineSail talks .. Search on his posts to find it.. In really rough round numbers, though, the duty cycle of the fridge and how fast ya want to charge will determine the size of the solar package. September issue of SAIL magazine (page 78) has a basic article on solar powering a fridge.
Example.. if your fridge draws 5 amperes at 12.5 volts and it runs (the compressor and fan or pump) 10 total hours to keep the box cool, then that is 50 ampere hours per day to do that. (about 3 days to half discharge both your batts) A solar panel will be rated at a max amperage in bright sun with the panel oriented directly at the sun.. so a 15 ampere panel (at 13.5Volts) would be rated at 200 watts or so.. ya have to discount that by about 60% for the real world , and the sun shines about half the day, so you can depend on about 100 ampere hours per clear day from a 200 watt rated unit.. That would really extend the time between running the gen set.. Canadian Solar looks to have some well priced units .. It will take about 60" by 40" size panel to do that.. Of course if your fridge is better than my guess, it will take less panel, but that is in the ballpark..
Good post, Rick.. ya beat me to it..
Example.. if your fridge draws 5 amperes at 12.5 volts and it runs (the compressor and fan or pump) 10 total hours to keep the box cool, then that is 50 ampere hours per day to do that. (about 3 days to half discharge both your batts) A solar panel will be rated at a max amperage in bright sun with the panel oriented directly at the sun.. so a 15 ampere panel (at 13.5Volts) would be rated at 200 watts or so.. ya have to discount that by about 60% for the real world , and the sun shines about half the day, so you can depend on about 100 ampere hours per clear day from a 200 watt rated unit.. That would really extend the time between running the gen set.. Canadian Solar looks to have some well priced units .. It will take about 60" by 40" size panel to do that.. Of course if your fridge is better than my guess, it will take less panel, but that is in the ballpark..
Good post, Rick.. ya beat me to it..
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Some missing information from you KG: how large is your charger, what kind?
Running a fridge is 60 ah per day, so with nothing else on you get three 24 hour days without recharging. We are miserly with our lighting and other electrical things, and also use a trawler lamp, but if you anchor out expect to use between that 60 ah and 100 ah per day. With only 180 ah useable in your house bank, that tells you how long you can be out.
Alternator charging (and running a generator) is useful only between 50% and 85% SOC. The rest has to be done by shorepower. That cuts into that 180 ah storage capacity big time.
I agree with Rick, those are your options. Other good monitors are made by Victron, since the Link monitors are no longer being made. We have a Link 2000.
Here's an example: http://c34.org/bbs/index.php/topic,6353.msg41471.html#msg41471
Running a fridge is 60 ah per day, so with nothing else on you get three 24 hour days without recharging. We are miserly with our lighting and other electrical things, and also use a trawler lamp, but if you anchor out expect to use between that 60 ah and 100 ah per day. With only 180 ah useable in your house bank, that tells you how long you can be out.
Alternator charging (and running a generator) is useful only between 50% and 85% SOC. The rest has to be done by shorepower. That cuts into that 180 ah storage capacity big time.
I agree with Rick, those are your options. Other good monitors are made by Victron, since the Link monitors are no longer being made. We have a Link 2000.
Here's an example: http://c34.org/bbs/index.php/topic,6353.msg41471.html#msg41471
OK, thanks for (all of) your input. However, it's 2 x 180 = 360 ah capacity in the house bank--there's also a separate cranking battery. The AC charger is a Xantrex 40-amp smart charger. With the generator running, the greatest draw I saw from the charger toward the end of our stay was 20 amp; however, it's marked 10, 20, 40 on the scale. It usually dropped to 10 after about 40-45 min of charging with the generator. I guess I need to do some figuring with those numbers you all have given me.
1. You can only use 50% of your battery capacity, since you don't want to draw down more than half - you start killing the batteries that way.
2. What you're describing is called battery acceptance. As they get fuller, batteries accept less current. That's why the 50-85 rule I mentioned before comes into play.
You may be interested in many of the links included in my "Electrical 101" thread, as well as reading "Musings with Maine Sail" under the Forums tab, "Featured Contributors" on the top of each page right here on this site.
http://c34.org/bbs/index.php/topic,5977.15.html
I think what Stu was getting at is that since you dont want to draw your bank down below 50%, you really only have 360/2 = 180 amp hours to work with. AND since you are charging via alternator, you are going to have a tough time getting the last 15% or so back in. Most people just manage their banks between 50% and 85% when away from the dock.
I suppose that's what I'm doing. I can monitor the house bank voltage from the panel (factory installed) monitor. Toward the last few days it was dipping to 10.9 V. The cranking battery was always in good shape.
I think you're "over doing it." 10.9V is a dead battery. If you peruse the Electrical 101 topic I linked before, you should read the Ample Power Primer about batteries and their care.
And contrary to what many folks say, voltage is a horrible way to measure your battery SOC. You need to let them rest for 24 hours, not 30 minutes, to even begin to think of using that method. Battery monitors are the right solution for you. Victron, $158. Read Maine Sail's posts, also linked in my 101 topic.
Happy reading.
And contrary to what many folks say, voltage is a horrible way to measure your battery SOC. You need to let them rest for 24 hours, not 30 minutes, to even begin to think of using that method. Battery monitors are the right solution for you. Victron, $158. Read Maine Sail's posts, also linked in my 101 topic.
Happy reading.
Yeah, I was pretty much coming to that conclusion myself. That's why we came in with supplies enough for another few days. The good news is, they charged back up after about 24-hr on shore power. Next time out, I'd rather something else be the limiting factor. Thanks again for your suggestions! Will do the recommended reading.
KG
KG
A voltmeter is not a good indicator of battery state of charge. A battery monitor like the Victron will give you a much better indication of battery SOC.
Between 50% and 80% you have about 110 AH to work with. Not a whole lot when refrigeration is cycling constantly.
A 3 stage regulator will not charge the batteries any faster. Battery acceptance is the determining factor. Between 50% and 80% the batteries will accept up to 90 amps in your case or the max alternator output whichever is lower. Where a 3 stage will help is if you are motoring for a long time as it gives you a float stage you currently don't have if using the standard internal reg.
Here are the state of charge voltages. There may be a slight variation between brands but it's pretty close.
Between 50% and 80% you have about 110 AH to work with. Not a whole lot when refrigeration is cycling constantly.
A 3 stage regulator will not charge the batteries any faster. Battery acceptance is the determining factor. Between 50% and 80% the batteries will accept up to 90 amps in your case or the max alternator output whichever is lower. Where a 3 stage will help is if you are motoring for a long time as it gives you a float stage you currently don't have if using the standard internal reg.
Here are the state of charge voltages. There may be a slight variation between brands but it's pretty close.
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I'd be interested in knowing more about your batteries. I've come to the conclusion that they do not make 4D deep-cycle wet cell batteries anymore and that any wet cell 4D battery you buy will be about 100 amp-hrs. If I am correct that would imply your 4Ds are either AGMs or Gels if they are actually rated at 180 amp-hrs. If that is the case then you would probably have some worthless batteries if you ran them down to 10.9 Volts. Can anyone see a flaw in my reasoning?
Well, I'm sure they are 4D's b/c I got out my purchase receipt from 2008 this morning to check, and I'm sure they are wet cells b/c I put water in them from time to time. The AH is essentially an "educated guess" (at least I hope so) based on Interstate's battery chart for the 4D's it either sells or used to sell. I can tell you that a recent hydrometer check before leaving on the trip put them in a fairly poor state--if you can trust that. So, yeah, it's quite possible that they are worn out or are heading that way real soon.
I suppose my wish is to upgrade the entire 12 V power system (and its management) soon with new batteries, battery monitor as suggested, and maybe a solar panel or two (roll up), etc., and/or portable generator of the correct wattage. The goal is to get as much staying power as possible from the least amount of weight, special rigging, and other paraphernalia--no surprise there. Of course, cost is an important factor, but I also desire efficiency and flexibility.
I suppose my wish is to upgrade the entire 12 V power system (and its management) soon with new batteries, battery monitor as suggested, and maybe a solar panel or two (roll up), etc., and/or portable generator of the correct wattage. The goal is to get as much staying power as possible from the least amount of weight, special rigging, and other paraphernalia--no surprise there. Of course, cost is an important factor, but I also desire efficiency and flexibility.
I had a couple of friends getting their boat ready to go around the world. When it came to their power needs, two, 135 watt Kyocera panels and an MPPT controller really did the trick on their 45' sailboat. They found that they didn't need to run the generator much after that to keep up the battery to full charge. Thier biggest drain was the fridge and freezer. Most of the lighting was replaced with LED's.
Interstate 4D's
2 4D's interstate came with my 2007 H-36 and had to replace one in 2008 under warranty and the battery wharehouse had a ton of them hard to believe stop making.
I had to replace them again this year with 4-6 volt T-105's and love them and so much easy to put in boat and they are great.
I have Gen and inverter but would like to add solar panels over my bimini some day,usually run ref and portable ref/freez 24/7 and computers and cell phones ,interent on droid when cruising.
Do yourself favor go with 4-T-105's
Nick
2 4D's interstate came with my 2007 H-36 and had to replace one in 2008 under warranty and the battery wharehouse had a ton of them hard to believe stop making.
I had to replace them again this year with 4-6 volt T-105's and love them and so much easy to put in boat and they are great.
I have Gen and inverter but would like to add solar panels over my bimini some day,usually run ref and portable ref/freez 24/7 and computers and cell phones ,interent on droid when cruising.
Do yourself favor go with 4-T-105's
Nick
Nothing came up when I googled 4D wet cell. I wound up replacing my original 4Ds in 2007 with plane-jane 4Ds from batteries plus--only 115 amp-hrs each. I just replaced the last of my 4Ds with deep-cycle group 31s from wally world. My question above stemmed from my inability to find any wet-cell, deep-cycle 4Ds over 115 amp-hrs. However, I, too, am glad to be rid of the dam 4Ds; they are just too heavy for me.
4D's are way too hard to handle and even fit in some cases. The best bang for the buck is definitely flooded 6 volt golf cart batteries. Trojan T-105 are the industry standard but there are many comparable batteries from Exide and others. 225 AH each a bank of 2 is 225 AH @ 12 volt or if you have room for more a bank of 4 is 450 AH. By far the most durable affordable battery available. Trojan T-105 will handle more cycling than any other 12 volt or 6 volt Trojan battery.
Check out Dyno batteries here in Seattle - They make a Deep Cycle 4D that is rated for 180 amp hours - Dyno seems to make good batteries.
I have two 130W Solar Panels with an MPPT charge controller and two 8D AGM Batteries (510AH total). Also have a 100Amp Balmar Alternator. Run both refrigerator and freezer. May/June/July that puts in an excess of about 60AH during sunlight into my batteries, which doesn't quite make up for night usage when we are on the boat (lights, DVD, etc.). In August we were still getting a surplus of 40AH during the day. Went a week at the Channel Islands (Santa Cruz/with one day at San Miguel) last week without having to worry about battery usage -- normal motoring handled that. But I motored more than you did (6 coves). At the end of the week we were down 180AH according to the Link 10 monitor.
When I sit I generally find that after two or three days I need to start running the engine an hour a day to make up for the negative usage. Before I had the solar panels and had Gel 4Ds (400AH total) I had to run the engine an hour in the morning and an hour in the evening to keep the batteries charged -- that was a pain.
Those of you who think 4Ds are heavy should try 8Ds.
When I sit I generally find that after two or three days I need to start running the engine an hour a day to make up for the negative usage. Before I had the solar panels and had Gel 4Ds (400AH total) I had to run the engine an hour in the morning and an hour in the evening to keep the batteries charged -- that was a pain.
Those of you who think 4Ds are heavy should try 8Ds
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