Portable Generator
- Thread starter Rays
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The Honda 12V DC output is a max of about 8A and the voltage is UNREGULATED. If you place a DVM on this output you will see upwards of 25V.... Not good for 12V batteries. If your batteries ever got to the point in the SOC curve where they require less than 8A then the voltage of the Honda's DC output would be come dangerous to the batteries.
The most efficient manner to use a generator for battery charging is to use it to power an AC shore power battery charger. Some battery chargers are as little as 50% efficient and some better quality models upwards of 90% efficient. A Honda EU2000 might run a 70-80A charger by one manufacturer and only a 45-50A charger from another manufacturer it just depends on the chargers efficiency...
For the direct dc charge function to work on the Honda, the Ecothrottle needs to be OFF. At full speed even the Honda is pretty loud. I don't think it's well regulated either. There will be some loss of efficiency going through the 120 V AC to the charger, but the generator will be quieter (depending on how many watts the charger draws) and the output would be regulated the same as on shore power. The Honda 1000 only puts out 8 amps direct DC and the 2000 puts out 16.
The EU1000i and EU2000i both have the identical specs for the DC output 12V and 8A. However the DC output is unregulated on both of these units and DC voltage can climb as high as 25V +/- ...
MaineSail... I have the manual here for my H2000 and it says the DC is rectified for charging 12V batteries, I do not believe the voltage would exceed 14-15 volts as exceeding this voltage would be a no-no for Honda to accept on it's generators. But I do see that it mentions the DC voltage is not regulated.
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Run the generator and stick your DVM into the 12V plug,. You will see upwards of 25V. If it was regulated you would see a max of about 14.4V regardless of EcoThrottle position...
The best way with modern batteries is a high quality marine charger with computer monitoring plugged into the generator. At first we tried using the 12volt plug, it took too long then when the battery was charged it kept on boiling the battery.
Modern 25 amp computer controlled marine chargers will top them off in a hurry and not damage the battery.
This is my humble opinion....Jeff
Modern 25 amp computer controlled marine chargers will top them off in a hurry and not damage the battery.
This is my humble opinion....Jeff
Ok.. MaineSail... You are right... I measured varying voltage from the 12V DC side... and since I've never used it for this purpose (charge batteries) I never had a need. I see why others are getting 'boiled', or failing batteries after using the DC voltage.
The fix I guess and I will do it is to purchase a 12V marine/auto voltage regulator that really is inexpensive anywhere from $13-75 for auto use and $60-200 for marine use... I will get the most robust sealed auto use regulator and install it in into the housing conveniently located so it could be replaced if need be. That then solves the issue with the generator... but we'll see as I never use it at all and is just a paperweight in the cockpit lazarette.
The fix I guess and I will do it is to purchase a 12V marine/auto voltage regulator that really is inexpensive anywhere from $13-75 for auto use and $60-200 for marine use... I will get the most robust sealed auto use regulator and install it in into the housing conveniently located so it could be replaced if need be. That then solves the issue with the generator... but we'll see as I never use it at all and is just a paperweight in the cockpit lazarette.
I don't know why you would go to all that trouble for 8A when a portable battery charger capable of supplying significantly more amperage can be plugged into the 120V outlet..
This has perplexed me, that a reputable company like Honda, would not put even a simple Zener Diode regulation.
I wonder if it is regulated when under a load? You might check it when charging a 12VDC Battery, to see if it is > ≈14.5 VDC.
I want to consider your power factor, but I am not sure if I understood right.
@druid , you consumed 11 amp of 120VDC to make 40 amps at 14VDC?
Jim...
The generator is sometimes used away from the boat and the 12V may be used for air pumps or other uses... I now it doesn't have to be regulated but using the generator with a 120V charger is carrying two pieces of equipment around. I never use the generator for charging batteries in the boat but it may be used in an emergency.
FYI I have the honda 2k generator but have found it to be pretty heavy and hard to find a good storage place for it on my 28 ft boat so I borrowed a friends 1k honda and found it to be so much lighter and fits nicely under the cut out in the stern under the helm seat and as a bonus it will run a portable ac with eco switch off , in the eco setting it runs but on start up of the compressor the voltage drop causes the compressor to kick back out, I aso have an ac unit that has manual controls as apposed to digital panel and it works well with the compressor in the eco mode
Most assuredly Option 2! First, the DC output from most Generators is very wimpy - MAYBE 10A on a good day, probably more like 5-6. And as you say, it's not "smart": it doesn't charge your battery in any type of smart curve. Option 2 would be faster AND better for your batteries.
druid
druid
Yup. That's because the voltage and current are out of phase. If you want an explanation, look up "power factor". It's an AC-thing...
As for "where did the power go?", it doesn't. It's still producing about 600 Watts, but it's also producing what's called Vars ("Volt-Amp-Reactive"). And unfortunately a "1000 Watt" generator is more correctly called a "1000 VA" generator: in other words, it only can produce 1000 Watts if the power factor is 1.0.druid
Might be something else going on (assuming everything was measured accuratly). Here is the spec for that charger http://www.xantrex.com/documents/Discontinued-Products/TC20_40(445-0050-01-01_Rev-A).pdf
The spec says the PF is .68 (from appendix A in the link above). Still not great but this is still WAY better than the .42 you measured.. Even taking into account the 83% efficiency still says you should have been able to get 745 watts out of the charger. Edit - the charger will only put out 40 amps so working backwards.. 40 amp @ 14V = 560 watts. With the 83% efficiency and .68 PF, this should require a VA of 1071 Watts from the Generator.
And.. checking the power factor of the charger is a good idea if you are using a generator - I had not thought of that.
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I had to read that Power Factor wiki article 3 times to begin to understand.If you want an explanation, look up "power factor". It's an AC-thing...
My brain hurts. Thanks for the tip and the 2 martini cure.
I agree with @walt.
I looked up my Freedom 20 I/C and it said "Power Factors" ..."ALL"???
That is the DC charger side
Full Load Efficiency =84% Peak=93%
Efficiency = Energy OUT / Energy IN
It doesn't matter how you call it... Watt hour, Calorie, BTU, Joules, etc.
But where did the other 16% of the Energy go?
Except for minor RF emissions.... HEAT!!!
(heaven forbid people are sending it to the ocean to my boat due to poor wiring practices)
The only time Ohms law works for Watts = Volt x Amps (VA) is in a DC circuit with a load.
Jim...
PS: Hoping everyones Efficiency it good. Trivia: Joule found that Ohms law relationship before Watt.
All the power factor stuff is ONLY on the AC side. DC does not have any "phase" so no power factor.
FYI, in AC, if all the numbers are in "RMS", then you can use the simple ohms and power equations. For example, for 120 VAC RMS and a 100 ohm load, the current is 120/100 = 1.2 amps RMS. The power delivered to the 100 ohm load would be 120*1.2 = 144 watts RMS. Any time you see a voltage, currrent or power for AC, the numbers are almost always RMS.
FYI, in AC, if all the numbers are in "RMS", then you can use the simple ohms and power equations. For example, for 120 VAC RMS and a 100 ohm load, the current is 120/100 = 1.2 amps RMS. The power delivered to the 100 ohm load would be 120*1.2 = 144 watts RMS. Any time you see a voltage, currrent or power for AC, the numbers are almost always RMS.
You pegged it. The shore power charger will treat your batteries much better and in some cases charge much faster. The DC outputs from most small generators is pretty small.
I should add to have a look at MainSail's recent post:
http://www.pbase.com/mainecruising/effect_of_charge_rate_on_agm_battery
He has tons of great stuff on his site.
Ken
and is unregulated on the Hondas. Don't do it.
Just like it says in replies #22 & 24 right on this thread.
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