Barry Rietz
New member
Has anyone tried this product?
http://www.greatlakesscuttlebutt.com/ne ... ard-boats/
http://www.greatlakesscuttlebutt.com/ne ... ard-boats/
12 Volt Water Heater
- Thread starter Barry Rietz
- Start date
Of course one could look it up, but it's sort of funny that the article goes on (and on) for around ten paragraphs, and includes the sentence "The 12V Water Heater has a rapid heat up time producing hot water in less than an hour, and is highly efficient," and yet doesn't bother to mention how much it draws. Which is a pretty important piece of data.
That said, Whale tend to make quality products.
Edited to add: Of course I had to go look. And download the product datasheet to get past the "fluff" info. It draws 30 amps, and takes 40 minutes to heat to 104ºF and 80 minutes to heat to 140ºF (I didn't see mention of what temperature they presume your "plain" water is - perhaps there is a standard).
That said, Whale tend to make quality products.
Edited to add: Of course I had to go look. And download the product datasheet to get past the "fluff" info. It draws 30 amps, and takes 40 minutes to heat to 104ºF and 80 minutes to heat to 140ºF (I didn't see mention of what temperature they presume your "plain" water is - perhaps there is a standard).
30 amps and I wish it was around when we had the 25. About time somebody did this right. Most consumers don't care how it works so long as it works. Skipping amp draw in a marketing/press release is not too surprising. I can see many more sport boats featuring a hot/cold shower on the swimstep soon.
Greg
Greg
Aurelia":q68dzg3n said:
Oh fair enough. However then it was not on their many-tabbed web page for the product either. I had to download the data sheet. Not a problem, and I'm not in the market anyway, but I just found it curious, as it would seem to be a salient point (among others). Too, I have high expectations of Whale because they make great products. I've used their pumps for years and am a fan in general.
The base temp was 60 degrees for the heat time. The 30 amps and 80 minutes means than the average group 24 battery would be depleted--and potentially damaged. With the Honda 90, the 16 amps alternator would take at least 2 1/2 to 3 hours to replace that amount of power---or running my Honda EU 1000 generator with 30 amp battery charger at fill tilt for 80 minutes. The box is 13" x 13" x 10" ; although smaller than the 6 gallon Atwood, the heater is still fairly good size.
Not going to buy one, but it is an interesting concept.
Not going to buy one, but it is an interesting concept.
journey on
New member
That's an interesting hot water heater. Let's look at what it does. And I'll summarize upfront: It's not for anybody with an outboard who doesn't want to run that motor for about 1 1/2 hr, just to supply the current needed. The best alternative is to use your portable generator if you're not plugged into the grid at the dock. 23 to 30 amps for over an hour is not going to come from any battery the C-Brats carry.
First there is a specific definition between heating water and energy used. For heating a liter of water 1 deg C, the energy required is 1000 calories, by definition. This is equal to ~1.2 kW_hr. Yes, definitions are in metric for even our world. The picture indicates the heater uses 300 watts, which at a nominal battery voltage of 13 vDC is 23 amps. Or 24 amp @ 12.5 VDC.
So, 3 gal is 11.3 liters and we can heat it 2 ways. First lets try using 300 watts to heat the water to 140 deg F (60 deg C) in 80 min, as the (blurry) picture indicates. Working through the arithmetic means that we start with 400 W_hr (300 W X 80/60 hr). Given that energy and an end point of 140 deg F, we have to start with water at 86 deg F. So, where do you get fresh water at that temperature? Probably at the equator, since we saw a max of 70 deg F while cruising in Washington this summer.
So, lets try starting with 70 deg F water and arriving at 140 deg F. If we want to do it in 80 min, that takes ~30 amps. Or if you want to hold the wattage to 300 watts (23 amps), it'll take over 100 min.
The ad is optimistic as any ad should be. Whale is a reputable company, but either there's something I missed or they dropped the ball on this one.
Boris
First there is a specific definition between heating water and energy used. For heating a liter of water 1 deg C, the energy required is 1000 calories, by definition. This is equal to ~1.2 kW_hr. Yes, definitions are in metric for even our world. The picture indicates the heater uses 300 watts, which at a nominal battery voltage of 13 vDC is 23 amps. Or 24 amp @ 12.5 VDC.
So, 3 gal is 11.3 liters and we can heat it 2 ways. First lets try using 300 watts to heat the water to 140 deg F (60 deg C) in 80 min, as the (blurry) picture indicates. Working through the arithmetic means that we start with 400 W_hr (300 W X 80/60 hr). Given that energy and an end point of 140 deg F, we have to start with water at 86 deg F. So, where do you get fresh water at that temperature? Probably at the equator, since we saw a max of 70 deg F while cruising in Washington this summer.
So, lets try starting with 70 deg F water and arriving at 140 deg F. If we want to do it in 80 min, that takes ~30 amps. Or if you want to hold the wattage to 300 watts (23 amps), it'll take over 100 min.
The ad is optimistic as any ad should be. Whale is a reputable company, but either there's something I missed or they dropped the ball on this one.
Boris
There's that pesky "physics" thing rearing its head again. Dangit! It just isn't going to happen.
Heating a water tank at 12V is just not practical no matter how many different ways you carve up the thermodynamics problem.
If you don't have a diesel with a heat exchanger, then the next best 'anchored' solution is an EU2000 plugged into your shore power outlet for 20min.
Well, except for the sunshower or garden sprayer, of course......
Heating a water tank at 12V is just not practical no matter how many different ways you carve up the thermodynamics problem.
If you don't have a diesel with a heat exchanger, then the next best 'anchored' solution is an EU2000 plugged into your shore power outlet for 20min.
Well, except for the sunshower or garden sprayer, of course......
Lost Petrel
New member
Yep, the only energy this took was hoisting it up on the roof
Although I don't need a water heater, I clearly *could* use one of those arches. They look handy for all manner of things :thup Plus I could get the anchor light out of my eyes (shines through hatch in the V-berth) (I did order a little black shield for it, but how much nicer to have it completely away/aft and get my reasonably dark sky back).
Seems like the folks from many other places have made heating water in modest quantities with DC power work well for years. This is the type of sink I am considering for Ari and I think would be suitable for the way lots of C-dorys are used. They normally are designed/installed to only run when the engine is running.
http://www.tealwash.com/product-tag/motor-vehicles/
http://www.eberspacher.com/products/handwash.html
file:///C:/Users/Greg/Downloads/handwash_brochure_ebuk_22385.pdf
Unfortunately, there is not a single source of them in this country because everyone is brainwashed by our complicate-the-heck-out-of-it approach to appliances.
Some C-dorys do carry enough power on board to take a 30AH+ draw. I do it every time I charge our Torqeedo battery from below about 30% using 12v and it works quite well. Instead of adding a brick of a generator, a person could add another battery and possibly not need the generator at all.
Seems to work for many in other places where physics follows the same rules. Couldn't resist the counterpoint. Sometimes good enough gets overlooked in a sea of bigger/better.
Greg
http://www.tealwash.com/product-tag/motor-vehicles/
http://www.eberspacher.com/products/handwash.html
file:///C:/Users/Greg/Downloads/handwash_brochure_ebuk_22385.pdf
Unfortunately, there is not a single source of them in this country because everyone is brainwashed by our complicate-the-heck-out-of-it approach to appliances.
Some C-dorys do carry enough power on board to take a 30AH+ draw. I do it every time I charge our Torqeedo battery from below about 30% using 12v and it works quite well. Instead of adding a brick of a generator, a person could add another battery and possibly not need the generator at all.
Seems to work for many in other places where physics follows the same rules. Couldn't resist the counterpoint. Sometimes good enough gets overlooked in a sea of bigger/better.
Greg
cmetzenberg
New member
I haven't done any research on this at all but, has anyone looked into gas/diesel water heaters and the viability of their application aboard a small boat?
cmetzenberg
New member
I've always thought it would be cool to be able to have a way of pouring hot water into the water heater's tank on Kanaloa. Then i could fab up something like this but a bit less redneck.
journey on
New member
Greg/Aurelia,
I'm interested in recharging your Torqueedo battery. You mentioned that it takes 30 A from a 12 V battery. How long does it take? ! hr? More, less?
Looking at those heating units, they're intended for hand washing. They use 10 amps at 13.5 VDC (135 W) to raise the water temp to ~110 deg F, and it's certainly smaller than 3 gal. So, yes it's just the temperature difference and how much water against the available power. And the Teal unit only runs when the engine/generator does.
And, yes a Group 27 battery has a 90 A-H capacity. So you could run a fully charged battery down to 50% and then recharge it. I'm just not sure that I'd want to do that on a regular basis. Journey On's Honda 150 has a 40 amp generator and it cost $12,000. A Honda 2000 costs $1000, so I'd rather use that.
Boris
One makes their own choices and they'll all work out.
Boris
I'm interested in recharging your Torqueedo battery. You mentioned that it takes 30 A from a 12 V battery. How long does it take? ! hr? More, less?
Looking at those heating units, they're intended for hand washing. They use 10 amps at 13.5 VDC (135 W) to raise the water temp to ~110 deg F, and it's certainly smaller than 3 gal. So, yes it's just the temperature difference and how much water against the available power. And the Teal unit only runs when the engine/generator does.
And, yes a Group 27 battery has a 90 A-H capacity. So you could run a fully charged battery down to 50% and then recharge it. I'm just not sure that I'd want to do that on a regular basis. Journey On's Honda 150 has a 40 amp generator and it cost $12,000. A Honda 2000 costs $1000, so I'd rather use that.
Boris
One makes their own choices and they'll all work out.
Boris
The Victron says it takes 16-34 amp hours to charge so far (depending on how much we discharged it) and we usually do it overnight while anchored so far. It is not a fast charger and runs at a few amps for many hours. We have a 220AH house bank and so far we have not really needed even 50% of that. We like having the extra margin. I also would not run an outboard for charging instead of a generator, We tend to motor somewhere even if we come back to the same spot for the night so we get pretty reliable charging from that outboard while running around for sightseeing for fishing. Even at low speeds it charges at over 10amps (older Honda). I am sure we are not the only ones that move around regularly. A sport boat that is always running would be in good shape.
The Tealwash unit has a 20amp draw. And they do offer a non-sensed unit for heating when the engine is not running. That was the model I was looking at for us but in the Handiwash size.
Greg
The Tealwash unit has a 20amp draw. And they do offer a non-sensed unit for heating when the engine is not running. That was the model I was looking at for us but in the Handiwash size.
Greg
The Honda EU 1000 weight is 26 lbs, and will recharge batteries at over 50 amps (30 amp dedicated to freezer battery and 30 amp built in battery charger) many times, vs the weight of an additional battery at about 68 lbs for a 110 amp hour battery.
Depends on what you call a "small boat". We had a 45,000 BTU hydronic diesel fired heater on our Cal 46, which would also heat water via a heat exchanger, as well as heating all 3 cabins of the boat. It worked very well, but it much larger than would be practical in a C Dory. The water in a tea kettle works very well, and you can add it to a Personal sun shower--for hot water in a squeeze bag! The smallest hydronic heater for boats I can find is an EbersPäCHer at about 2 to 4 KW. Although it is not huge, it is still fairly large in size, one could remove the water heater in a C Dory 25 or Tomcat 255, and substitute their own hydronic water heater, plus a insulated storage tank in that same volume. These tend to be fairly easy on both fuel use, and power consumption, but are a bit on the noisy side. They are really intended for multiple cabin boat, and the air heater is far better for the C Dory sized boat.
The extra battery takes up less space, you don't have to lift it regularly, carry any fuel for it, build a platform on the transom for it, keep it out of the weather, protect it from theft, it doesn't put out exhaust (AGM), and it makes zero noise.... Bring on the 40lbs.
Don't forget the other likely parts of the generator:
custom transom or other mount
storage box
security cable
padlock
canvas cover
gas can/funnel
user manual
portable 30amp charger
dc charging cables
That all adds some weight and not a small amount of additional stuff in a small boat to live with.
Now we just need to get more creative with solar panels. How about a roll out panel to cover the bow area at rest. Could be tied to the bow rail and shade/cover the berth hatch and front windows. Maybe even travel with it rolled up on the front of the roof?
Greg
Don't forget the other likely parts of the generator:
custom transom or other mount
storage box
security cable
padlock
canvas cover
gas can/funnel
user manual
portable 30amp charger
dc charging cables
That all adds some weight and not a small amount of additional stuff in a small boat to live with.
Now we just need to get more creative with solar panels. How about a roll out panel to cover the bow area at rest. Could be tied to the bow rail and shade/cover the berth hatch and front windows. Maybe even travel with it rolled up on the front of the roof?
Greg
Aurelia":3ez6ika1 said:
The above is true, but it is only good for one charge--unless you move regularly, and have more than the 16 amp alternator which is the standard on the carved 90 Hondas. As for Solar--good discussion area--Pat Anderson, ands C Puffin had solar panels--100 watts and 60 watts--the concesis was that at least 200 watts of solar panels was necessary, or better tracking--the 60 watt panels were on a pole with 2 axis adjustment, but did not supply enough for a refrigerator. Pat's were flat mounted, slightly downward slope--and did not put out enough at Powell (probably because of high ambient heat, requiring more run time), thus did require periodic topping off with the generator. 200 watts of solar panels are gong to run an additional $350 to $700, plus mounts.
For us the generator allows many more options, and we already have 330 amp hours of battery power… (The freezer was running all of the time-where in the past it ran about 50% of the time. Little Bit had the identical freezer, and his was running less than 50% as ours had the first year. There is an issue with the freezer (gas leak?). The generator sits on the fish cleaning board most of the time. No CO issues, rare to have to be lifted.
Here the generator is charging at 30 amps for the external charger, plus a second built in charger @ less than its rated 30 amps, plus the fan battery. Generator also will run the convection cooker, a cube heater or an air conditioner…none of which the battery will do. Plus some of us have learned to sit and enjoy a place for extended times--with the only distraction being a short run for ice every 4 days (that can be eliminated with a second chest refrigerator). Different strokes for different folks--different life styles. Much of our long distance cruising was a passage for a day or so, and then several weeks in the same place. Many different styles of cruising, and ways that we outfit our boats.
Nominal capacity is measured at a 20-hr discharge rate - that's only about 5A for a 100Ah battery. If you take 30-40A out of this battery, it will not supply it for 100/40 hours, it will probably be less than 50% of that. Not to mention the damage if done often to such a small capacity battery.
There is lots of info on the 'interwebs' about Peukerts constant, for example, http://all-about-lead-acid-batteries.ca ... explained/
To take Ray's comment to another level--the battery capacity; is also measured as "Reserve capacity"--that is how long a battery lasts until the voltage drops to 10.5 volts, with a load of 25 amps. This is a bit closer to what the water heater draws. HOWEVER when a battery is dropped to a voltage of 10.5 volts, for any period of time--or even less than 11.8 volts for any period of time, it will damage that battery. Peukerts law also holds for residual capacity, as well as amp hours.
Peukerts constant, is "k", in the formula to derive the capacity of a battery, and theoretically is 1. The AGM battery comes closes to this, at 1.05. Lead acid batteries are closer to 1.15.
I prefer to measure amp hours, since it is closer to the way that we us a battery on the C Dory. The battery I use on the C Dory has an amp hour rating of 110, and reserve capacity of 200 minutes.
Amp hours are measured as to the number of amps it takes to fully discharge the battery (that old 10.5 volt number) over 20 hours.
Peukerts constant, is "k", in the formula to derive the capacity of a battery, and theoretically is 1. The AGM battery comes closes to this, at 1.05. Lead acid batteries are closer to 1.15.
I prefer to measure amp hours, since it is closer to the way that we us a battery on the C Dory. The battery I use on the C Dory has an amp hour rating of 110, and reserve capacity of 200 minutes.
Amp hours are measured as to the number of amps it takes to fully discharge the battery (that old 10.5 volt number) over 20 hours.