I am looking for info on how to recharge batteries using a generator.I dont know how fast a battery "accepts" a charge,how long it takes,how to size the generator etc. A generator with a larger gas tank for a longer run time might be more desirable than a generator with a smaller tank but more kw output. Any info would be very helpful, LLOYD
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Are you suggesting DC?
Most generators are AC and will charge through your regular battery charger with its built-in regulator. This is just like shorepower and protects your batteries. If you are suggesting a DC generator then you would need an external regulator. Just like on my '57 Plymouth(before alternators for you young 'uns).
Most generators are AC and will charge through your regular battery charger with its built-in regulator. This is just like shorepower and protects your batteries. If you are suggesting a DC generator then you would need an external regulator. Just like on my '57 Plymouth(before alternators for you young 'uns).
batts and gens
Lloyd; I use a Honda EU2000i. Buy another shorepower cord to take with you. Place the gen. on the bow, lead the cord back and plug it into the shorepower connection. I run mine about an hour to charge up my house bank of 420 A/Hs, and another 30 mins. to use the electric water heater. I can barely hear it run. It beats running the diesel, with all its stink and noise.
Lloyd; I use a Honda EU2000i. Buy another shorepower cord to take with you. Place the gen. on the bow, lead the cord back and plug it into the shorepower connection. I run mine about an hour to charge up my house bank of 420 A/Hs, and another 30 mins. to use the electric water heater. I can barely hear it run. It beats running the diesel, with all its stink and noise.
Generator to power DC charger
Hi lloyd - As Ed indicated, you'll want to use the AC genset to power your onboard DC charger if you have one. Most portable gas generators run between 600W and 2500W. Any of them should be able to easily power your charger, which is likely between 10amp and 40amp. Best of luck, Trevor
Hi lloyd - As Ed indicated, you'll want to use the AC genset to power your onboard DC charger if you have one. Most portable gas generators run between 600W and 2500W. Any of them should be able to easily power your charger, which is likely between 10amp and 40amp. Best of luck, Trevor
Seems like a waste
to convert the generator AC output to DC. Wouldn't it be more efficient to charge batteries off the DC output of the generator? You question was posted just while I was in the midst of shopping for a generator...now I'll have to keep checking back to see if a better informed poster can tell me if I'm missing something there! Jack
to convert the generator AC output to DC. Wouldn't it be more efficient to charge batteries off the DC output of the generator? You question was posted just while I was in the midst of shopping for a generator...now I'll have to keep checking back to see if a better informed poster can tell me if I'm missing something there! Jack
it really makes sense
The generators usually put out a lot of ac and a little d.c. so if you charge with a generator and you have a battery charger of any size you can charge more batteries faster with a generator powering the a.c. charger that you can by hooking up the generators d.c. side to the battery bank. My big charger is 5o amps. and will charge 3 banks at once. the generator can,t do that on its d.c. output.
The generators usually put out a lot of ac and a little d.c. so if you charge with a generator and you have a battery charger of any size you can charge more batteries faster with a generator powering the a.c. charger that you can by hooking up the generators d.c. side to the battery bank. My big charger is 5o amps. and will charge 3 banks at once. the generator can,t do that on its d.c. output.
For Island Jack.
You should post the make and model of the "DC" generator that you are considering. Then if some "better informed" contributors read this they will be better able to reply to your question.
You should post the make and model of the "DC" generator that you are considering. Then if some "better informed" contributors read this they will be better able to reply to your question.
Don't use gen. DC
A friend of mine used a 1000w Honda to charge his batteries on an extended trip and had to replace 3 batteries in 2 months. It appears that the generator DC output is not as well regulated as typical boat chargers. You might get away with using the generator to charge the batteries occasionally, but the daily re-charge just cooks the batteries. As others in this thread have said; hook the generator AC output to the shore power and let the boat charger do what it was designed to do.
A friend of mine used a 1000w Honda to charge his batteries on an extended trip and had to replace 3 batteries in 2 months. It appears that the generator DC output is not as well regulated as typical boat chargers. You might get away with using the generator to charge the batteries occasionally, but the daily re-charge just cooks the batteries. As others in this thread have said; hook the generator AC output to the shore power and let the boat charger do what it was designed to do.
We use our genset to charge batteries all the time
We are on a mooring all summer. We live by our generator. It provides 120v power for the water heater, A/C units, and battery charger. We have the original 30A Guest charger (junk, IMO) and a 70A regulated charger. Our house bank is 450AH and we use both chargers together to put back the bulk of the charge. We run the genset about 1 hour every morning and evening. That amount supplies all our needs. It is important to note that the batteries do not charge at 100A constantly, but accept charge according to their state of charge. If the bank is down by about 100AH, the initial charge rate is about 100A but that drops to 70A within a minute or two. After 30 minutes, the rate is down to about 40-50A. These two chargers, the Guest and my 70A unit draw about 12-14A of 120V AC power at max output.
We are on a mooring all summer. We live by our generator. It provides 120v power for the water heater, A/C units, and battery charger. We have the original 30A Guest charger (junk, IMO) and a 70A regulated charger. Our house bank is 450AH and we use both chargers together to put back the bulk of the charge. We run the genset about 1 hour every morning and evening. That amount supplies all our needs. It is important to note that the batteries do not charge at 100A constantly, but accept charge according to their state of charge. If the bank is down by about 100AH, the initial charge rate is about 100A but that drops to 70A within a minute or two. After 30 minutes, the rate is down to about 40-50A. These two chargers, the Guest and my 70A unit draw about 12-14A of 120V AC power at max output.
Island Jact Part II
With regard to a Honda EU1000i: 1. 12V Charging (from the manual) DC RECEPTACLE The DC receptacle should ONLY be used for charging 12-volt automotive type batteries. Rated DC output of the 1000i is 8amps (216W). 2. Rated AC output of the 1000i is 900W, 1,800W for the 2000i; maximum output is 1000W and 2000W respectively (but this depends on the power factor). In reality, it takes a bit for the gen set to warm up. If a full load is applied to a cold generator it will kill it. 3. Old fuel will also decrease the output - use fuel stabilizer. The manual says "Most motorized appliances require more than their rated wattage for startup." As has been mentioned, charging through the boats inverter is far and away the most effective way to go. However, if the battery banks are really large and the batteries are low they could potentially kill (i.e., overload) the generator. In this case see if the inverter output can be manually decreased to a level so as not to overtax the generator. Hope this helps a bit.
With regard to a Honda EU1000i: 1. 12V Charging (from the manual) DC RECEPTACLE The DC receptacle should ONLY be used for charging 12-volt automotive type batteries. Rated DC output of the 1000i is 8amps (216W). 2. Rated AC output of the 1000i is 900W, 1,800W for the 2000i; maximum output is 1000W and 2000W respectively (but this depends on the power factor). In reality, it takes a bit for the gen set to warm up. If a full load is applied to a cold generator it will kill it. 3. Old fuel will also decrease the output - use fuel stabilizer. The manual says "Most motorized appliances require more than their rated wattage for startup." As has been mentioned, charging through the boats inverter is far and away the most effective way to go. However, if the battery banks are really large and the batteries are low they could potentially kill (i.e., overload) the generator. In this case see if the inverter output can be manually decreased to a level so as not to overtax the generator. Hope this helps a bit.
My coleman
My little 23 pound generator from coleman has a switch for ac or dc. It will not do both at the same time, however, It does put out 90 amps at 12 volts which is 10 times more than most generators supply as dc. It will chage a flat 100 amp hour battery to full in about an hour. For the first several minutes the battery will take all 90 amps and then it starts to taper off the amount it will take.
My little 23 pound generator from coleman has a switch for ac or dc. It will not do both at the same time, however, It does put out 90 amps at 12 volts which is 10 times more than most generators supply as dc. It will chage a flat 100 amp hour battery to full in about an hour. For the first several minutes the battery will take all 90 amps and then it starts to taper off the amount it will take.
I haven't come across any DC only's
I've just been looking at the DC side of the regular generators.....to give me an extra day of lights and radio if I'm out more than 2. They seem to all put out more amps DC than AC (usually at least twice as many amps)....and I know from my old a/c electrician days there is a big energy loss from converting ac to dc and vice versa. I wonder if some of these generators are really alternators with a diode tree in them.....and maybe the first output of the 'generator' is really ac. The excess current isn't going to hurt the battery...otherwise you would never jumpstart a car... IJ
I've just been looking at the DC side of the regular generators.....to give me an extra day of lights and radio if I'm out more than 2. They seem to all put out more amps DC than AC (usually at least twice as many amps)....and I know from my old a/c electrician days there is a big energy loss from converting ac to dc and vice versa. I wonder if some of these generators are really alternators with a diode tree in them.....and maybe the first output of the 'generator' is really ac. The excess current isn't going to hurt the battery...otherwise you would never jumpstart a car... IJ
Generators...
From all the responses I have seen so far, everyone seems to have a little piece of the puzzle. Portable generators can be bought to provide whatever power you need. With the less expensive generators, AC power tends to be very noisy. By that I mean that the voltge is not a true sine wave. This may damage certain electronic equipment and some other equipment may not work at all. So if you plan on running AC to power your regular charging system be careful about what you are supplying it with. Now for the DC chargers. It is true that they are not regulated in the sense that when the battery bank is fully charged it wont go into float or turn off to prevent "boiling" of the sulfuric acid. This also causes heating of the battery plates which shortens the life of the battery. If you use the DC generator, were talking portable units now, do as the one respondent said. Charge it for an hour and then shut the unit off and just run your loads on the battery bank. Don't run on the DC side of the generator expecting it to regulate while you have loads drawing from it. The charger will more than likely put out more than you can consume and as mentioned before cause damage to the batterys if left on for an extended peroid of time. I use a Coleman portable 1000W (this is a peak rating) generator. This has a DC output of 70 amps. I only run it for an hour when the bank gets low and it charges everything just fine with no damage to the batterys themselves. The DC side also has noise on it due to the fact that the generator uses an alternator to generate AC and then rectifies it to DC. The good news is that the batteries act as a capacitor and smothes out the noise.
From all the responses I have seen so far, everyone seems to have a little piece of the puzzle. Portable generators can be bought to provide whatever power you need. With the less expensive generators, AC power tends to be very noisy. By that I mean that the voltge is not a true sine wave. This may damage certain electronic equipment and some other equipment may not work at all. So if you plan on running AC to power your regular charging system be careful about what you are supplying it with. Now for the DC chargers. It is true that they are not regulated in the sense that when the battery bank is fully charged it wont go into float or turn off to prevent "boiling" of the sulfuric acid. This also causes heating of the battery plates which shortens the life of the battery. If you use the DC generator, were talking portable units now, do as the one respondent said. Charge it for an hour and then shut the unit off and just run your loads on the battery bank. Don't run on the DC side of the generator expecting it to regulate while you have loads drawing from it. The charger will more than likely put out more than you can consume and as mentioned before cause damage to the batterys if left on for an extended peroid of time. I use a Coleman portable 1000W (this is a peak rating) generator. This has a DC output of 70 amps. I only run it for an hour when the bank gets low and it charges everything just fine with no damage to the batterys themselves. The DC side also has noise on it due to the fact that the generator uses an alternator to generate AC and then rectifies it to DC. The good news is that the batteries act as a capacitor and smothes out the noise.
D.C. Generators
Just wondering if the posters who mentioned having a 70-90 amp dc generator are talking about a Coleman unit that I believe was called the 'Dyna-Mite'? I checked-out one of those on a web site and it sounded like a good thing. One question though, how noisy is it? If I remember right, it's sound rating was quite high. Afew years back, as an experiment, I built a little homemade DC generator using a Honda 5 hp vertical shaft lawn mower engine hooked to a Chevy 60 amp internal regulated alternator. I use it to charge the batteries in my home back-up power system. (I live up in the Sierras and power up here can be kind of spotty in the winter, especially when it's snowing hard. I use my 5kw generator for a few hours to run the big stuff and charge the batteries. I can then kill the generator and the invertor runs the fridge, lights, stereo, TV, etc. Basically just like a boat system only it's in my basement.) I built the Honda thing to increase the charge rate and as a back-up to the main generator. It works fine and I'm thinking of building another for my boat. If I build one for the boat, I'll use an external regulated alternator so I can get a 3 stage regulator and be a bit nicer to the batteries and give them a full charge without cooking them. If anyone is interested, I'd be happy to provide details.
Just wondering if the posters who mentioned having a 70-90 amp dc generator are talking about a Coleman unit that I believe was called the 'Dyna-Mite'? I checked-out one of those on a web site and it sounded like a good thing. One question though, how noisy is it? If I remember right, it's sound rating was quite high. Afew years back, as an experiment, I built a little homemade DC generator using a Honda 5 hp vertical shaft lawn mower engine hooked to a Chevy 60 amp internal regulated alternator. I use it to charge the batteries in my home back-up power system. (I live up in the Sierras and power up here can be kind of spotty in the winter, especially when it's snowing hard. I use my 5kw generator for a few hours to run the big stuff and charge the batteries. I can then kill the generator and the invertor runs the fridge, lights, stereo, TV, etc. Basically just like a boat system only it's in my basement.) I built the Honda thing to increase the charge rate and as a back-up to the main generator. It works fine and I'm thinking of building another for my boat. If I build one for the boat, I'll use an external regulated alternator so I can get a 3 stage regulator and be a bit nicer to the batteries and give them a full charge without cooking them. If anyone is interested, I'd be happy to provide details.
Hey Gerry, Thanks!
Thanks for the info....I was hoping somebody with the big picture would weigh in on some of the tech side. Question for you if you ck back on this topic. If the battery has 100 amps and is fully charged, won't it quit accepting charge from the chrging source? or is it the higher voltage at source that keeps this from happening? Jack
Thanks for the info....I was hoping somebody with the big picture would weigh in on some of the tech side. Question for you if you ck back on this topic. If the battery has 100 amps and is fully charged, won't it quit accepting charge from the chrging source? or is it the higher voltage at source that keeps this from happening? Jack
What about the carbon monoxide exhaust?!!
It's deadly; especially with the generator mounted on the bow when at anchor.
It's deadly; especially with the generator mounted on the bow when at anchor.
Gerry...
A "dumb" charger will continue to push current thru a charged battery and damage it. That's why some have suggested using the DC side of their generator for only a limited time period to get a depleted battery charged back up most of the way, then switching to a more intelligent charger to finish the job w/o boiling the battery. Ron Mehringer h26 Hydro-Therapy
A "dumb" charger will continue to push current thru a charged battery and damage it. That's why some have suggested using the DC side of their generator for only a limited time period to get a depleted battery charged back up most of the way, then switching to a more intelligent charger to finish the job w/o boiling the battery. Ron Mehringer h26 Hydro-Therapy
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