Portable DC Generator

[Skinny]

Hey guys

Been awhile since I've been on the forum, trying to finish up my 8.1 1 ton square nose Suburban project and maybe actually drive my CUCV this summer. I started up a side company making these portable DC generator kits.

I built it to be similar to a Honda EU2000 in size, output, and fuel consumption but for the DC world. I have an EU2000 but wanted an alternative to charging batteries and running DC and AC loads (using my inverter of course). 1700 watts of power at an assembled price of under $600 without all of the complexities or costs of a fancy inverter generator. Probably not needed on a rig that uses the main engine to charge your battery bank if running it all the time but certainly a great backup if your solar can't do the job on a cloudy day or have a stand alone trailer.

You can use any type of Delco 10si or 12si alternator so basically anything from 6v to 48v from a basic one wire to a fancy externally regulated unit if you need the extra capability with different battery types.

www.affordabledcgenerators.com

 

[john61ct]

Fantastic, have always loved the concept.

Other alts to consider, obviously need more HP with increased kW output

Eco-Tech, top notch design, can output rated amps 24x7, allows for a low 1800 rpm.

Zena 200A, doubles as an off-grid arc welder

American Power HPI

Leece-Neville Heavy Duty as used in fire trucks & ambulances, go for cheep on eBay, they used to also have a "weldernator" but my link broke.

This big Kahuna

C E Niehoff and Co Alternator/generator 28v 570amps 76761-n1609 for sale online | eBay

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at 15kW can power your whole mobile boondocking village, big enough LFP bank just run a couple hours per week

 

[john61ct]

For proper load and setpoint regulation, converting to a specialized external VR that can regulate current as well as voltage is a good idea, critical IMO for getting the most out of a large LFP setup.

The mainstream choice is Balmar's MC-614


The cutting edge: Wakespeed is the recently commercialized version of Al Thomason's open-source SAR / VSR Very Smart Regulator / "Smart Alternator Regulator" project

Wakespeed Charge Smarter - Wakespeed

Intelligent Engine-BasedCharge Control Wakespeed is leading the charge in RV, marine, and commercial transportation applications. Offering smart DC charge control systems, Wakespeed’s advanced alternator regulator, the WS500, is the first of its kind and delivers unsurpassed quality and...

www.wakespeed.com

others:

APS-500 http://www.americanpowerinc.com/aps-blog/aps500-top-5-q-a-on-our-new-regulator/

Mark Grasser

Sterling Power

 

[Skinny]

Eventually I want to make an on board welder set up with it. Have too many other things going on to tackle that right now.

That is a big mammer jammer alternator, going to take more then a Honda GC160 to spin that over!

The nice thing about my kit is that you can outfit with an alternator and external regulator if you want the advanced charging capability. That controller is almost the entire cost of my kit so you can see that I'm not going to include that unless everyone were to require it. A one wire alternator will bulk charge a battery at 14.5v just fine which is what it's intended to do. If you want to upgrade, the end user can spend accordingly.

Good news is that you can field swap the alternator with a couple of wrenches in five minutes.

Sent from my Moto G (5) Plus using Tapatalk

 

[Hillbilly Heaven]

And find it at any auto part store

 

[john61ct]

Yes, was not suggesting including any of that gear.

But having different plate sizes / hole layouts for these super-high quality high-output alternatives,

one day, if the base idea sells enough to sustain expansion.

It seems most setups require an extra horse for every 20A at nominal 12V (call it 300W).

So that big Hummer alt needs 40+HP !!??

 

[john61ct]

Note also that a lead bank won't be worth charging much past 90% SoC with any ICE source, as amps acceptance tapers down.

So unless shore power is available once or twice a week for overnight topping up,

have to run your ICE charging for getting up to that point in the morning, and use solar for the long tail - without much load currents running

in order to get longevity for a big expensive bank.

Or go LFP, which is when those precise VRs really become necessary. Or use a Sterling DCDC to do tge same thing.

 

[luthj]

Given a 4.6hp (3.4 kw) engine output, I would think the unit could support a larger alt? Or maybe there is stalling issues?

 

[luthj]

I would also suggest getting belt guards made. Even if its just a vacuum formed piece of plastic. Losing a finger would be a problem.

 

[john61ct]

Given a 4.6hp (3.4 kw) engine output, I would think the unit could support a larger alt? Or maybe there is stalling issues?

75 - 100A @12V actual loading continuous would be my guess, lower is better without active cooling

yes torque is an issue, but better VRs have a slow-start ramp up

 

[luthj]

In open air, the backing plate would block most of the cooling air from the engine, so I would guess the alts should be able to handle 90% of rated output. Its when you get engine heated air, or ambient temps over 100F that the alternators start to struggle.

It would be interesting to see a kit based on a 7hp engine model, that supported some of the newer bosch or denso alternators (many up to 180A, or even 250 aftermarket wound). These alternators generally have a serp belt style pulley, and use a side mount, which would require a bit more fabrication to mount. They are however a bit more efficient than the older designs. Some have integral digital monitoring, so they do a short ramp up, and have temp de-rate built in.

 

[DaveInDenver]

Given a 4.6hp (3.4 kw) engine output, I would think the unit could support a larger alt? Or maybe there is stalling issues?

For a GC160 (rated 5 HP max @ 3600 RPM, which would be wide open throttle) seems about right conservatively assuming 50% alternator efficiency with belt and conversion loss to run it at ~6,000 RPM. The industry standard is to assume 65% to 67% for a baseline alternator efficiency in a vehicle (e.g. engine load for fuel economy and emissions), which a Delco 12si would be pretty much the baseline. So doesn't this seem likely where the engine fuel consumption would be at a fairly high HP per liter?

 

[Hillbilly Heaven]

I like the idea and design concept as it lends itself to be adaptable.

Gasoline, Propane, or Diesel are limited resources. One can only carry so much.

Fuel efficiency hasn't been discussed.
Which is more fuel efficient?
2KW generator with an attached battery charger vs the portable alternator. Which is going to make the most efficient use of fuel? Will adding additional charging hardware to the portable alternator be needed?

 

[DaveInDenver]

Which is more fuel efficient?
2KW generator with an attached battery charger vs the portable alternator. Which is going to make the most efficient use of fuel? Will adding additional charging hardware to the portable alternator be needed?

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

This generator would be as good as that, since that's all that's inside of a generator like that - a motor turning an alternator, which in turns powers an inverter to create the 120VAC. The EU2000 gives you a 12V tap I think, which is just the output of the alternator and is essential all this is.

Running that 120VAC into a charger is incurring another level of losses, so there's no reason to do that. The improvement for it would be to more completely condition the batteries.

But in terms of converting gasoline into electrical current there's not much improvement available. You could run a DC-DC charger straight from the alternator output if you wanted a highly intelligent charging and it would be a slight dink to efficiency. Less than running a 120VAC charger from a 12V generator, though.

If you mean a generator that is actually generating 120VAC directly then it's a wash. You would need a charger to do 12V and that's some loss you wouldn't have with this.

Overall value, this unit is definitely the best approach to charging batteries. Cheap, simple, easy to fix/upgrade/modify, pretty good efficiency. If you ignore subjective size and portability the only thing is it might lack an ability to intelligently idle down under light load. At rated load it'll be just as good on gas, so you just run it when you need a charge and shut it off when they are topped. There's no reason to let it idle.

 

[luthj]

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