Portable DC Generator

Do you mean a 2kW generator like a Honda EU2000 sort of thing?

Yes I should have specified a inverter type generator with a 120 VAC charger attached.

There are a few alternator voltage regulators that can be installed pretty easily with some light soldering. These can offer everything from full smart charger ability, to a simple voltage control knob. The advantage I see with this type of setup, is that is allows folks with medium-large lithium banks to rapidly charge at a lower cost. Also at higher rates than most chargers. A good 60A+120V power factor corrected charger is $$$. non PFC chargers are much less efficient.

Gasoline has about 32.78 kWh per gallon. So assuming 35% efficiency in the engine, and 50% efficiency in the alt/belt drive, you are looking at 5.8kWh per gallon. At 1.7kw output, I would estimate fuel consumption at 1/3 gallon per hour

Forsake of organization let's consider the two most common types first the Flooded Cell and AGM. We can discuss Li later.
The portable alternator as it stands would make a great bulk charger for these two battery types. To carry charging further is going to take like you said a smart regulator or additional hardware. For those of us that might be interested this portable alternator and making full use of it, could some links to the recommended additional hardware be added to the discussion? There are some highly intelligent people in the group that have more knowledge of batteries and charging systems than most of us.

I can see this setup being left unattended and when a complete charge cycle is finished shutting itself off. No need to sit around the camper just to wait to shut the alternator down. A simple isolated relay shorting the spark plug to ground will shut down the motor.
 

DaveInDenver

Middle Income Semi-Redneck
I can see this setup being left unattended and when a complete charge cycle is finished shutting itself off. No need to sit around the camper just to wait to shut the alternator down. A simple isolated relay shorting the spark plug to ground will shut down the motor.
Honda appears to provide that so you don't have to hack the ignition system. What you use to control is the question, current sense in a simple circuit or a charge complete from an intelligent controller.

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While that is great that Honda does that for us, I still think an isolation relay controlled by charging hardware would be best suited to isolate sensitive electronics from the ignition system.
 

luthj

Engineer In Residence
@luthj, is the engine's lb/HPh fuel consumption linear? Honda specs it at 0.51 but doesn't say if that's at maximum HP.

Its probably roughly linear with engine output, at least withing 50-90% of rated. My estimate it pretty rough, as the actual efficiency of these engines varies quite a bit. I would say 1/3gal is likely optimistic based on some quick searching I just did.

Yes I should have specified a inverter type generator with a 120 VAC charger attached.


Forsake of organization let's consider the two most common types first the Flooded Cell and AGM. We can discuss Li later.
The portable alternator as it stands would make a great bulk charger for these two battery types. To carry charging further is going to take like you said a smart regulator or additional hardware. For those of us that might be interested this portable alternator and making full use of it, could some links to the recommended additional hardware be added to the discussion? There are some highly intelligent people in the group that have more knowledge of batteries and charging systems than most of us.

I can see this setup being left unattended and when a complete charge cycle is finished shutting itself off. No need to sit around the camper just to wait to shut the alternator down. A simple isolated relay shorting the spark plug to ground will shut down the motor.

Here is one regulator example.
https://www.amazon.com/STERLING-Pro...ocphy=9009976&hvtargid=pla-570016601165&psc=1

Balmar makes a couple good ones as well.

Honestly if you are just bulk charging, you can just adjust the regulator to about 14.4-14.7V. Assuming the battery bank in question is not terribly small, it should have no problem with 80-100A charge rates initially.

Depending on the alternator being used, you may need to just run the 2 field wires outside the case, and the external regulator does all the work.

As far as auto shutdown, you could easily rig a voltage sensing relay. They are commonly available for industrial applications. Adjust it to kick out the ignition at a certain voltage. If desired, an timer module can be wired together with the VSR, to add a lag to allow proper equalization. Honda uses a transistor controlled ignition, so there is not much risk for a normal relay being driven from the VSR. You could make a simple circuit with a grounding FET and a opto-isolator.

The smart regulators like the sterling drop to float after a charge is complete, you could set the VSR to a low voltage cutout that way.

Alternatively, a simple mechanical timer could be set to ~2 hours to do a bulk charge.


Personally I would make sure the setup in question can output enough voltage for a equalize cycle (assuming flooded lead). As getting a good equalize cycle can be very tough on solar alone, especially in winter.
 
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DaveInDenver

Middle Income Semi-Redneck
While that is great that Honda does that for us, I still think an isolation relay controlled by charging hardware would be best suited to isolate sensitive electronics from the ignition system.
Certainly a possibility but isolation or not would depend on the controller. I'd expect all you're be looking at is the base of a transistor, so not a difficult load and if it was me I'd isolate every external signal on a battery charger as matter of course. God only knows what sorts of things an end user might try to do.
 

DaveInDenver

Middle Income Semi-Redneck
Fwiw, Its not really a ’tap’ but a separate (1Ø) stator coil. Its output obviously rectified, but dunno how its regulated.
I expect other manufacturers use a similar scheme for 12Vdc.
Got it, was just an assumption really and prompted further research. It never sat well that they would generate ~12V nominally for the main output anyway since there's no benefit to stepping up if you're really after 120VAC and not 12VDC.

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Skinny

Active member
Hey guys

Great conversation going on here! I'll throw into the mix, hopefully don't miss anything.

1) Built to a price point, that is why it is one type of alternator and engine. 10si and 12si can be found in all forms, voltages, and regulation. New, reman, aftermarket marine versions, etc in voltages from 6 to 24 and even a permanent magnet 48v version. Single wire, 3 wire, and externally regulated. It is THE most amount of options depending on your needs. So all of the talk between what to use is great because my kit gives you those options. I can build my kit with an $80 alternator which is great for what I need it to do. If you needed something for a non-traditional battery bank, you can do it with one of those Balmar units.

2) Honda GC160 is a perfect fit. They are used everywhere, cheap, good quality, and it goes well with my bracketry. The unit when you pick it up is well balanced. It had a fuel pump which means you could tee it into an external tank easily for extended run time.

3) I was looking at Leece Neville J180 alternators but you do need some more power, and it becomes heavier, and the pricing starts to go up. A good option but it all starts to get bigger and bigger which you lose portability.

4) I think the perfect combo is to use this to bulk charge which it will do, 14.5v and outputs roughly 110a with an off the shelf one wire alternator for $80. Then use solar to finish the rest of your float charge if you want to get fancy. I think running this to go up to 100% SOC as with any generator becomes less effective where a small panel and controller would suffice. Again, at $600 fully assembled, you have a lot of budget left over to supplement and have the most efficient system. My competition doesn't have any fancy regulation either, less output capability, and they range from $1000-2500.

5) You could easily run a remote throttle control on this with a service or cable along with a remote shut down. All you need to do is ground the magneto wire which is what the factory throttle does if you close it all the way. Easily accomplished with a relay or remote switch. Again, at $600 you have a lot of budget for extras you want to do. You could even pad mount it on something if you wanted it to be a more permanent fixture.

I believe my kit is a great starting point whether you want a simple bulk charge or 110a power supply as primary or backup function for less then $600. If you want more control over charging it have AGM or lithium, you can step up to a special regulator with a different setpoint or use a Balmar. You still would be way under what my competition charges which still has none of that capability.

Sent from my Moto G (5) Plus using Tapatalk
 

john61ct

Adventurer
The EU2000 gives you a 12V tap I think, which is just the output of the alternator and is essential all this is.
No, the 12V output from all these AC gensets is puny current, just designed for charging up a little a starter batt.

You would need a charger to do 12V and that's some loss you wouldn't have with this

The efficiency factor is not significant, the sophisticated inverter tech actually gets better efficiency that will make up for the separate rectifier losses.

The real reason to go this way is cheap and robust DIY with a stock alt you can replace ir get serviced anywhere.

Self-sufficiency for out in the boonies, especially if (when) the SHTF.

Lifespan of a crappy cheap motor like Harbor Freight or Northern Tool will mean the Honda's probably a better deal per hour per year if used a lot.

Unless it gets stolen, another huge advantage of this one.
 
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john61ct

Adventurer
This is not a new idea guys, been done as long as cars have charged batteries.

Fischer Panda makes high quality version, pricey.

yes several in Oz

Supercharger in the UK

Torcman in Germany

Supercheap Chinese versions, e.g. Shanghai Yangke

Balmar / APC

TM Marine Electronics

Aquamarine

Ample Power Genie

ZRD's ESD unit

Polar Power

Norwall

etc etc more come and go every year

Again, this item's USP is kit form, cheap motor, add your own alt, easy entry to the DIY approach, not rocket science.

I hope it's very successful and thus expands
 

shade

Well-known member
No, the 12V output from all these AC gensets is puny current, just designed for charging up a little a starter batt.
True. A Honda EU2000i provides 8A / 12VDC. I keep the 12V cord with mine for emergency vehicle battery charging, but I doubt I'll ever use it.
 

Skinny

Active member
I couldn't have said it better myself!

I wanted something that was rugged, inexpensive, and most importantly serviceable down the road. I want to be able to go and buy an alternator off the shelf for cheap money so I can have a spare, be able to find a drive belt in an auto parts store or Tractor Supply, and not be tied to having to buy it from a manufacturer at a jacked up price.

Everything in my kit is quarter inch aluminum plate, high grade fasteners, and Commercial quality components that you can swap out down the road because they are not built to be a customized generator, they are built to be universal parts that all work together.

I personally needed a DC generator to charge up batteries on vehicles that sit for extended periods of time where I do not have an electrical supply available for a battery charger. I also need it to charge batteries so I can run a portable refrigerator without having to idle my Honda generator all the time. I wanted to do this and not spend a crazy amount of money doing it.

I like to think of it as the Toyota Hilux of DC generators



Sent from my Moto G (5) Plus using Tapatalk
 
@Skinny Can you please check any data that came with the engine to see if the muffler is "Spark Arresting"?

If anyone plans on using this in National Parks or Forest and I sure most State areas it will have to have a certified spark arresting muffler.

I also wonder if the GC160 and GX160 are dimensionally the same as far as mounting and shaft location. GX has a larger fuel tank capacity, almost triple. There is an optional spark arresting muffler available for the GX series. GX is commercial rated and GC is residential.

I have not been able to find any sound specs on the engines. It is more dependent on it's use and enclosure. I don't think either of these engines would be as quiet as the EU2000 generator.
 

luthj

Engineer In Residence
Spark arrestors are option equipment on the GC/GX. I guess it would depend on the application.

GC160 dimensions from a google search.

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