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Old 11-10-2014, 13:48   #121
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Re: 12vdc generators - any good ones out there?

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Originally Posted by pbiJim View Post
I know that a lot of the portable 110/220vac generators out there also have a 12vdc output on them, but that's not what I'm looking for. I'm looking for a small gas or diesel powered generator (or alternator) that puts out 12vdc only. I'm looking for something in the 50-100 amp range. The last time that I saw one of them was probably close to 20 years ago. Do they still exist anywhere in the US retail market? Has anyone used one lately? Can anyone give me some performance reports?

Thanks,
Jim
Jim, Check out: tmmarineelectronics.com. This site may have what you are looking for. Dave
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Old 16-10-2014, 22:43   #122
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Re: 12vdc generators - any good ones out there?

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Originally Posted by pbiJim View Post
I'm looking for a small gas or diesel powered generator (or alternator) that puts out 12vdc only. I'm looking for something in the 50-100 amp range.
First, here, there's an Earthquake 110v 800w inverter generator that runs a ProMariner 40 amp installed 3 stage charger very well. ProMariner says that charger needs 660w input at 110v. I like this generator because it's priced right, starts and runs good (alcohol-free gasoline only!!), it's quiet, it weighs 21 pounds and is thin.

Second, for you build-it-yourselfers, here's a 1.5 hp diesel (sort of) engine to start you off....

http://www.southernagro.com/petrol_k...engine1.5l.htm

And finally, the book 'Living on 12 Volts with Ample Power' says the thing to do is get a 110v inverter generator and run a 110/12v transformer with simple diode rectification full tilt, hooked up to the batteries. That's a bare bones charger with no regulator. When you want to charge your boat's batteries you want those batteries charged. You don't want the three stage regulator screwing up the charge and wasting gasoline and time, and you're there standing around watching the charging process and can take the charger off when the batteries are charged. Or boiling. This looks like a good idea and it's on my projects list so I'll let you know how it works out when I get to it....the way things are going that'll be in about 2016 sometime...
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Old 16-10-2014, 23:23   #123
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Re: 12vdc generators - any good ones out there?

I'm liking that small diesel generator idea. Time to break out my drafting kit, + my Heavy Duty - Build & or Mangle - Tool Box.
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Old 17-10-2014, 11:10   #124
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Re: 12vdc generators - any good ones out there?

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Originally Posted by Seymore View Post
First, here, there's an Earthquake 110v 800w inverter generator that runs a ProMariner 40 amp installed 3 stage charger very well. ProMariner says that charger needs 660w input at 110v. I like this generator because it's priced right, starts and runs good (alcohol-free gasoline only!!), it's quiet, it weighs 21 pounds and is thin.

Second, for you build-it-yourselfers, here's a 1.5 hp diesel (sort of) engine to start you off....

http://www.southernagro.com/petrol_k...engine1.5l.htm

And finally, the book 'Living on 12 Volts with Ample Power' says the thing to do is get a 110v inverter generator and run a 110/12v transformer with simple diode rectification full tilt, hooked up to the batteries. That's a bare bones charger with no regulator. When you want to charge your boat's batteries you want those batteries charged. You don't want the three stage regulator screwing up the charge and wasting gasoline and time, and you're there standing around watching the charging process and can take the charger off when the batteries are charged. Or boiling. This looks like a good idea and it's on my projects list so I'll let you know how it works out when I get to it....the way things are going that'll be in about 2016 sometime...
I've run charging without a regulator... but not for too long! All you need is a big rheastat in the field wire to your alternator. Frankly though, I thinks it's a PITA to monitor what's going on and you'd better not get distracted!
I've built 3 12V charging systems on Kubota based diesels... they all worked quite well. Eventually I just decided using the main engine was cheaper and simpler though.
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Old 17-03-2015, 10:25   #125
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Re: 12vdc generators - any good ones out there?

FWIW, we have been using our home-built Kubota DC generator for several years now. Based on the Kubota EA-300 and drives a large alternator as well as the HP pump for our watermaker.

I also developed an integrated controller / alternator regulator to manage the engine (starting, stopping, speed control) as well as the alternator regulator. One of the features is it is able to monitor (and hence regulate) current produced - maintaining a constant load on the engine, but also allows for 'de-rating' of the alternator output. This prevents what seems to be a chronic overloading of these small diesel engines, and also reduced overall generator run time by maintaining a constant load on the engine as the batteries recharge. Another is the ability to change engine speed to match load - so as the batteries are in their final staged of charging am able to slow down the engine RPMs before auto-stopping.

Am currently experimenting using a vastly over-sized alternator and spinning it at lower RPMs to pick up efficiency - initial results look promising.

We are full time cruisers (8mo out of a year or so) and dependent on our generator for a significant part of our energy supply.

More on the DC generator here:
mv.VikingStar: Kubota DC Generator

The controller is open sourced, based on the Arduino IDE and documented here:
Arduino based Alternator Regulator and Small Engine Control


(Watermaker details are here if anyone is interested:
mv.VikingStar: Water Maker )

-al-
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Old 14-11-2015, 05:23   #126
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Re: 12vdc generators - any good ones out there?

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Originally Posted by thomasow View Post
FWIW, we have been using our home-built Kubota DC generator for several years now. Based on the Kubota EA-300 and drives a large alternator as well as the HP pump for our watermaker.

I also developed an integrated controller / alternator regulator to manage the engine (starting, stopping, speed control) as well as the alternator regulator. One of the features is it is able to monitor (and hence regulate) current produced - maintaining a constant load on the engine, but also allows for 'de-rating' of the alternator output. This prevents what seems to be a chronic overloading of these small diesel engines, and also reduced overall generator run time by maintaining a constant load on the engine as the batteries recharge. Another is the ability to change engine speed to match load - so as the batteries are in their final staged of charging am able to slow down the engine RPMs before auto-stopping.


More on the DC generator here:
mv.VikingStar: Kubota DC Generator

The controller is open sourced, based on the Arduino IDE and documented here:
[url=http://smartdcgenerator.blogspot.com/]Arduino based Alternator Regulator and Small Engine Control[/url
Awesome work with the controller!!!

It would be a godsend to be able to buy one of these controllers ( or something similar) off the shelf. There looks like a fare bit of work involved to print pcb, build, programme and commission one.

I'm not in the market for one just yet, but when I am I want to go down the 2 cylinder diesel DC generator path, possibly with a dive compressor attached.

If someone sold a marine DC/AC generator with dive compressor I reckon they would be popular as there isn't anything like it out there.
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Old 14-11-2015, 20:13   #127
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Re: 12vdc generators - any good ones out there?

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Originally Posted by Moonos View Post
Awesome work with the controller!!!

It would be a godsend to be able to buy one of these controllers ( or something similar) off the shelf. There looks like a fare bit of work involved to print pcb, build, programme and commission one.

I'm not in the market for one just yet, but when I am I want to go down the 2 cylinder diesel DC generator path, possibly with a dive compressor attached.

If someone sold a marine DC/AC generator with dive compressor I reckon they would be popular as there isn't anything like it out there.

I initially thought about a DC genset but after a bit more thought decided to go the AC route as it works better for me

I bought a Next Gen 5.5 kW genset and am using it to drive a HP watermaker pump. This is not something that Next-Gen can accommodate so I am machining a dual sheave front pulley to mount to the Kubota front crank pulley.

Perhaps you could that for a dive compressor. You will likely have to change the pulley OD from the 107mm that I need, so I have here is the Kubota drawing you need to mate to:
Attached Files
File Type: pdf Genset Kubota front pulley.pdf (492.0 KB, 15 views)
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Old 14-11-2015, 23:00   #128
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Re: 12vdc generators - any good ones out there?

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I initially thought about a DC genset but after a bit more thought decided to go the AC route as it works better for me

I bought a Next Gen 5.5 kW genset and am using it to drive a HP watermaker pump. This is not something that Next-Gen can accommodate so I am machining a dual sheave front pulley to mount to the Kubota front crank pulley.

Perhaps you could that for a dive compressor. You will likely have to change the pulley OD from the 107mm that I need, so I have here is the Kubota drawing you need to mate to:
Thanks for that.

How do you plan on automatically increasing the engine rpm to account for the load from the pump?

I'm now thinking I might look as using a mini Plc with analogue output connected to a actuator which drives the throttle. I would enjoy building it, and see how to fine tune the control loop. I'm currently studying plc's.
If the Plc ever broke I can still use it manual mode.

Roughly...
switching on the compressor will add 50% to the output actuator position.
The load from the batteries or inverter will also add % to the actuator driven state.
If the compressor is on, this will limit the max the alternator is allowed to supply.
Normal operation will limit actuator max drive to 75%.
Boost mode will allow actuator to go to 100%.
Manual control will allow adjustment of actuator with a rotary dial.

Just need to find a cheapish, small, solid state Plc with analogue output which I can mount in waterproof enclosure.
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Old 14-11-2015, 23:35   #129
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Re: 12vdc generators - any good ones out there?

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Thanks for that.

How do you plan on automatically increasing the engine rpm to account for the load from the pump?

It is an 5.5 kW AC genset and runs at a constant 2800 RPM. Easy to calculate the belt pulley ratio to spin the watermaker pump at design speed of 1750 RPM
Pump load is 2.58 HP on a 10 HP engine

The plan is to load the genset when battery charging, and then when the load drops off to make water. Or indulge in 1 aircon and make water, 2 aircons etc....... A bit of finger/brain operated load management

1-2 hours per day will do it unless she deems a need for aircon or just to sweltering here in the tropics at night to sleep
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