The only thing I would add about running the generator close to the edge of it's current capacity is be aware of what happens when it trips. I found this out on a cruise recently:
It was puzzling at first until I realized what had occurred. When the Honda 2000 generator trips it does not shutdown. Unless you are paying real close attention you might not even know that the breaker has tripped. The Honda will keep running but, won't be providing power. So it could lull you into a sense that you think you are motor sailing with it. When in fact you are actually just draining down your battery bank. I'm not sure if other generators operate the same way. Just be aware when you are operating close to the limits of your generator how it behaves when it trips. Check the breaker for a trip or a fault light.
Capt. Mike
From: Eric <ewdysar@yahoo.com>
To: electricboats@yahoogroups.com
Sent: Monday, February 27, 2012 8:58 PM
Subject: [Electric Boats] Re: motoring with ,quickcharge 48/V 25 amp,6V agms,and a honda 2000
To: electricboats@yahoogroups.com
Sent: Monday, February 27, 2012 8:58 PM
Subject: [Electric Boats] Re: motoring with ,quickcharge 48/V 25 amp,6V agms,and a honda 2000
I'll assume that you're talking about a Quickcharge SCO4825 Select a charge on-board charger. On their website they provide the following specs, 48V, 25A, 12A@117VAC. If all this is true, then I don't see a problem. But I don't believe these numbers.
Lets look at the energy input, 12A x 117V = 1404W. That's easy enough.
You know that your 6V batteries don't charge at 6V, the peak charge voltage for your AGM batteries is 7.2-7.3V. So your peak pack charging voltage for 8 batteries in series is 57.6V. Let's call it 54V for the bulk of your charging. 25A @ 54V = 1350W. The Quickcharge website doesn't mention the technology that they use, but at the bottom of their promotional PDF, they mention "100% copper transformer heavy duty rectifiers..." These types of chargers have traditionally operated at 80-85% efficiency. So being generous, 1350W output will take only 1600W input (assuming 85% efficiency). 1600W/117V = 13.7A. Not a big deal you say, it's only a difference of 1.7A, but let's read on.
Now let's look at your generator. A Honda eu2000i is rated for 1600W continuous output, so now you're right on the line. If your charger only pulls 13.7A while charging, you're good. But it might pull more. If it does, your Honda will shut itself down when the load getts too high. My Yamaha 2000 will do the same.
Maybe the SCO4825 only puts out 1200W (48Vx25A), if so, then the output at 54V will be around 22A. If that is the case, then the Honda should handle it fairly well, but you won't be getting 25A.
If you have access to one of these chargers, then the simple way to check it's power requiremetns is to run it through a Kill-A-Watt meter while charging your batteries. I have a P3 model, they are available at Radio Shack for less than $30. If you don't have access to the charger, you have to take the manufacturer's word, but their published specs are suspicious to me. At almost $500, that could be an expensive experiment. Of course, if you buy it somewhere with a good return policy, your risk is lower.
I went through the same debate and I chose an Elcon PFC2000+ charger for around $600. The manufacturer specs were more believable and they were able to load a charging profile that was perfect for my LiFePO4 battery pack, AGMs are even simpler. My measured thoughput effieincy is close to 93% with the fully electronic (no transformer) PFC charger. Elcon's spec of 14A@115V nominal input turned out to be right on (as measured with a Kill-A-Watt monitor)during the bulk charge phase for my batteries. This 14A exceeds my Yamaha generator's continuous rating of 13.7A, but I've run the charger for an hour from the generator and it hasn't missed a beat, I would expect the same from a Honda. I've also verified that I'm getting a consistant 27-28A at 55V from the charger/generator combo. This powers my 30' 10,200 lb boat at 4.2-4.3kts without using any battery at all.
Most of the other peoplpe in this group that have electro-motored on their portable generator (Myles, Mike, etc.) are running chargers with lower input/output so their generators are not as close to the limits. So your proposed setup might work, and it might not.
After all of this work, I've never had to use my generator to get home. I motored the boat for an hour on the generator as a proof of concept, and it worked fine, but I've never needed it in real life.
Perhaps someone else in the group has more hands on experience with the specific charger that you're looking for. If so, hopefully, they'll jump in.
Fair winds,
Eric
1964 Bermuda 30 ketch, 5.5kW Propulsion Marine drive, 8kWh Lithium batteries
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "Bill Falk" <fsailing35@...> wrote:
>
> anyone using this set up? if so how is it working for you and what charge settings are you using? any info thanks
>
Lets look at the energy input, 12A x 117V = 1404W. That's easy enough.
You know that your 6V batteries don't charge at 6V, the peak charge voltage for your AGM batteries is 7.2-7.3V. So your peak pack charging voltage for 8 batteries in series is 57.6V. Let's call it 54V for the bulk of your charging. 25A @ 54V = 1350W. The Quickcharge website doesn't mention the technology that they use, but at the bottom of their promotional PDF, they mention "100% copper transformer heavy duty rectifiers..." These types of chargers have traditionally operated at 80-85% efficiency. So being generous, 1350W output will take only 1600W input (assuming 85% efficiency). 1600W/117V = 13.7A. Not a big deal you say, it's only a difference of 1.7A, but let's read on.
Now let's look at your generator. A Honda eu2000i is rated for 1600W continuous output, so now you're right on the line. If your charger only pulls 13.7A while charging, you're good. But it might pull more. If it does, your Honda will shut itself down when the load getts too high. My Yamaha 2000 will do the same.
Maybe the SCO4825 only puts out 1200W (48Vx25A), if so, then the output at 54V will be around 22A. If that is the case, then the Honda should handle it fairly well, but you won't be getting 25A.
If you have access to one of these chargers, then the simple way to check it's power requiremetns is to run it through a Kill-A-Watt meter while charging your batteries. I have a P3 model, they are available at Radio Shack for less than $30. If you don't have access to the charger, you have to take the manufacturer's word, but their published specs are suspicious to me. At almost $500, that could be an expensive experiment. Of course, if you buy it somewhere with a good return policy, your risk is lower.
I went through the same debate and I chose an Elcon PFC2000+ charger for around $600. The manufacturer specs were more believable and they were able to load a charging profile that was perfect for my LiFePO4 battery pack, AGMs are even simpler. My measured thoughput effieincy is close to 93% with the fully electronic (no transformer) PFC charger. Elcon's spec of 14A@115V nominal input turned out to be right on (as measured with a Kill-A-Watt monitor)during the bulk charge phase for my batteries. This 14A exceeds my Yamaha generator's continuous rating of 13.7A, but I've run the charger for an hour from the generator and it hasn't missed a beat, I would expect the same from a Honda. I've also verified that I'm getting a consistant 27-28A at 55V from the charger/generator combo. This powers my 30' 10,200 lb boat at 4.2-4.3kts without using any battery at all.
Most of the other peoplpe in this group that have electro-motored on their portable generator (Myles, Mike, etc.) are running chargers with lower input/output so their generators are not as close to the limits. So your proposed setup might work, and it might not.
After all of this work, I've never had to use my generator to get home. I motored the boat for an hour on the generator as a proof of concept, and it worked fine, but I've never needed it in real life.
Perhaps someone else in the group has more hands on experience with the specific charger that you're looking for. If so, hopefully, they'll jump in.
Fair winds,
Eric
1964 Bermuda 30 ketch, 5.5kW Propulsion Marine drive, 8kWh Lithium batteries
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "Bill Falk" <fsailing35@...> wrote:
>
> anyone using this set up? if so how is it working for you and what charge settings are you using? any info thanks
>
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