This is exactly the same conclusion I came to as well. I also looked at Polar, Panda and Z something as well. I have probably seem the same web sites as you about Fischer Panda. Another consideration is redundancy in case of inverter failure or generator failure. With an AC generator you still use your AC stuff in case the inverter fails. In case of generator failure you can charge the batteries from the main engine and use the inverters. Altogether a conventional DC generator seems to be a much more robust solution at the current state of the art of DC generators. On 05/01/2015 20:21, Steven Dubnoff via Trawlers-and-Trawlering wrote: > > I was looking for a DC generator as well. After much searching I > concluded they were relatively expensive and, in general, came from > companies that were run out of a garage (those strapping alternators > to Kabuta engines) or which would not likely be around to support > their more sophisticated technology (Polar Power). And Fisher Panda > has some very bad things said about it on the web! Arild agreed with > me that a better solution might be to get a new AC generator (mass > produced and relatively cheap) coupled to powerful inverters to do the > charging. Inverters, it is clear, provide the least expensive way of > buying high output chargers. > > I have 800 Amps of L-16's at 24 volts, so I can use a lot of power. I > installed a new Phasor 8KW generator and two Magnum inverters that are > each capable of 100 Amps charging. I can pump over 160 (24volt) amps > into the batteries and keep the generator well loaded. As things > taper off, I add in the watermaker and still keep the generator > loaded. I paid less for this whole setup than I would have for a > Polar Power DC generator and I have maintainable gear and redundancy. > It may, in theory, be less efficient, but it gets the job done at a > reasonable price. > > Best, > > Steve > > > _______________________________________________ > http://lists.trawlering.com/mailman/listinfo/trawlers_lists.trawlering.com > > > To unsubscribe or modify your subscription options (get password, > change email address, etc) go to: > http://lists.trawlering.com/mailman/listinfo/trawlers_lists.trawlering.com > Trawlers & Trawlering and T&T are trademarks of Water World > Productions. Unauthorized use is prohibited. > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2015.0.5577 / Virus Database: 4257/8874 - Release Date: 01/05/15 > >

I agree with the concept that a conventional AC generator is the way to go on a boat. Here is my logic: PREAMBLE -- First, a few facts. 1. Every time you convert power, there is some degree of inefficiency. 2. Shore power is almost always the least expensive source of 120 VAC power. 3. In the calculation of cost of watt-hours of power, all components must be included, including the cost of deep cycle batteries. LOGIC -- There is no free lunch. 1. Assume you start off with fully charged inverter bank of 10 each 220 amp/hour (A/H) 6 volt batteries and want to end up that way as well. This gives you a nice healthy (and necessary) 10 div/by 2 (for 12vdc) x 220 A/H = 1100 A/H inverter bank. 2. Assume that you are simply going to calculate the power useage for one overnight and the following morning, and that you would like to keep a small air conditioning unit (AC) going overnight, plus the refrigerator, and nothing else. 3. On my boat, the small AC unit (5000 BTU) and associated sea-water pump consumes about 6 amps @ 120 vac or in other words over the 10:00 PM to 08:00 AM uses 6 amps x 120 vac x 10 hours = 7200 watt/hours of energy and the fridge cycles so it uses about 1 amp x 120 vac x 10 hours x 50% duty cycle = 600 watt/hours for a total of 7800 watt/hours from the inverter bank. 4. You get this from your battery bank, so that is 7800 watt/hrs div. by 12 VDC = 650 amp hours (A/H) and this then represents 650 AH/1100 A/H or 59% of your inverter bank capacity, thus leaving the recommended depth of discharge 40% (nearly) remaining in the bank. 5. You get up in the AM, your batteries are discharged down to about the lowest level of discharge that is healthy and now you have to begin to (a) replace these A/H's in the battery bank, and (b) heat hot water tank back up to make up for overnight heat loss, run a hair dryer for the Admiral, run the toaster, run the coffee maker, run the microwave, and perhaps run the AC and keep the refrigerator going. 6. The typical 400 amp DC generator will only provide 4800 watts of steady state power (400 amps x 12 volts) so this might be just be enough to run the toaster, the coffee pot, the refrigerator and hair dryer. The microwave, hot water tank, AC and inverter bank will have to wait, as there is no capacity left in the DC generator while it runs these loads, and this presume that the battery bank is not sucking a bunch of the DC trying to recharge at the same time. 7. After the hair is dry, the toast, cereal and coffee are made and the 'fridge is running, then you can start heating hot water, and running the AC and other loads. Also, you can begin pumping SOME amperes back into the inverter bank. However, remember that any ongoing AC loads (like the refrigerator, and AC and water heater element, television, etc) are tapping off some (say 2000 watts or half the DC gen capacity) of that power. 8. Now the task is to pump the 650 A/H back into the inverter bank while still supporting these other AC needs. Even if you have the whole 4000 watts of DC available, the DC generators do not seem to have any 3 stage charge control, so the acceptance rate of the battery bank comes into play. At first, being down to 40% of charge, the batteries will likely happily take most of the theoretical 400 amps, but fairly quickly their acceptance rate will drop the charge rate down. Hard to estimate, but likely the average will be on the order of 50% of max rate over the full charge to 100% state-of-charge. So this will take 650 A/H / 200 amps = 3.25 hours, and it will be longer if there are any AC loads on the inverter running tapping off some of the DC current. Air and refrigerator would need about 1200 watts or 100 amps DC so you get the idea. There may also be a problem if the battery bank is right on the generator output, since the battery bank may demand so much current initially that without a way to cut the bank off they may not leave nearly enough for the inverter to handle the morning loads. TBD. 9- This has been a discussion of being at anchor. If you get back to a marina, then shore power is available, but if you are going to use it, then in any case you need a good battery charger to use the cheap source of power, so even with the DC generator you will still need to have a good charger since you don't want to be using the DC generator burning diesel to do the recharge job. Net of this all is that you would be rather busy allocating power (and perhaps debating priorities) and running quite a long time to keep the inverter bank charged. Also, since you would be entirely relying on the inverter bank plus inverter for your 120 VAC, you will likely be going through your 500 charge/discharge cycles (approx at discharge to 40%) on the inverter bank rather rapidly. I would be surprised if you would get more than a couple of years out of the inverter bank, while putting up with slowly diminishing capacity. I think the fuel that you might save would never recompense the hassle of power management, and the cost of the batteries. My MDKD 8.0 kW Onan uses 0.65 gallons per hour with one AC unit and the fridge, and is hassle free. Just my 2-cents worth for consideration. Ken Bloomfield m/v Tellico Lady. --- This email has been checked for viruses by Avast antivirus software. http://www.avast.com