Aqua Marine's MyTGen 12 Volt Genset

[nhschneider]

I suppose I should post my thoughts on the Aqua Marine MyTGen as ours has been installed for four years now and we've cruised almost 22,000 miles with it. Overall, I've been happy with it but it's not without issues.

First, is the overall design. The engine uses electric pumps for both the coolant and raw water. The water pump">raw water pump failed after only 200 hours but the replacement pump has been fine after almost another 1,000 hours. I wish I had gone with a belt-driven rubber-impeller raw water pump.

Installation was time-consuming. The engine did not come with a wiring harness (the instructions that came with the engine recommended hiring a marine electrician to do the job) nor did it come with motor mounts. There was an error in the wiring diagram. I had ordered my genset with the optional high coolant temp/low oil pressure shut down but no diodes were sent with the engine although, a phone call to Dan, the owner of Aqua Marine, resolved that issue quickly.

The engine is very noisy and there's no sound shield available. Even though Rutea's engine room is very well insulated, the genset makes more noise than our Beta Marine 90 running at cruising speed.

On the other hand, we do get a full 150 amps of current out of the alternator and the engine only uses .39 of a gallon of fuel running at full throttle, full load. The engine has not used any oil nor does it leak. It always starts easily (I don't even use the glow plug). The oil sump only holds one liter of oil and there is no oil filter. I change the oil every 100 hours. Dan, the owner, has been pretty good about responding to my emails although when the genset recently blew an oil seal (made a monumental mess all over my once-clean engine room), he recommended that I stop in at the local Kubota dealer. At the time, we were in a remote part of Borneo.

I guess the bottom line question is: Would I buy the MyTGen again? I think I probably would. It's small and light and the price/value ratio is very high but there have been some compelling posts here on CF about people building their own and having good success with them. Frankly, when I was searching to buy a genset, I found very few choices in the DC-only arena.

Fair winds and calm seas.

[Cheechako]

There have been a few builders of this basic format over the years. Ample Power built one also. I have built 2 on that engine base. For mine I attached the alternator to the side on the cast arm that came as part of the engine. with a double sheave I used a bronze impellor pump on the opposite side of the engine for raw water. This required a welded frame under the engine. The fan and radiator from the factory unit was usually discarded and a small heat exchanger/tank could be purchased to bolt on the top of the engine in place of the fan/radiator. No pump was neede to circulate the antifreeze/coolant. I debated using an electric cooling pump but decided it would be a bad idea for reliability. Originally Ample power used a bronze belted pump as I did. Not sure what they've done later on. These units were very quiet... not sure why yours is so loud... maybe due to the fan/radiator still on it?
Is yours configured with the fan and radiator still on it?

[nhschneider]

Cheech-
The MyTGen comes with a remotely-mounted heat exchanger (no radiator/fan). I did splurge and bought very expensive stainless steel motor mounts which were suppose to help control the engine noise but I guess I'll never know if they were worth it. The electric coolant pump has been trouble free.

Fair winds and calm seas.

[Hoghead]

I am thinking of one of these
Any more feedback

I am familiar with small Yanmar diesel engines on iron buffaloes and they are loud.
How about the Aqua marine

[sailnow2011]

Originally Posted by Hoghead

I am thinking of one of these
Any more feedback

I am familiar with small Yanmar diesel engines on iron buffaloes and they are loud.
How about the Aqua marine

We have the same engine driving a 120volt generator. They are loudish.
Ours runs at 2600rpm, so it is a little more quiet.
The reason you do not want a 12volt gen is as follows.

Inefficient. you will need huge cables to make the run from the generator to the bank, and there will be losses at 12 volts. The generator will deliver full current at cold temps, but once it starts to warm up it will put out less and less, as they all do. Converting 12 volts to 120 volts can be done at no more then 90% efficiency, so another loss there. If you are storing this energy in a battery you will have losses during charging.

Glazing. As the batteries get more and more full they take less and less of a charge. Once you approach 90% the load on the generator will be so low, it will start to run cold. Running cold means it will glaze the walls of the cylinder, and it will burn oil.

The big deal is how inefficient it is. You are better off with a phasor or nexgen 3.5kw unit. use it when you need it. When charging batteries after they hit 90% and you want to go to 100% you can make hot water, you can run an air conditioner, update your blog ECT.

[exMaggieDrum]

I have a Balmar DC genset with a 275 amp large frame (better be) alternator with direct drive based on a two cylinder Yanmar motor and a remote panel with full alarms. Sweet little unit. But it is aft of my main engine on my 42'boat and it is therefore stern heavy. I am going to remove and sell it once I figure out how to remove it. It was put in behind the main engine when the main was out for a rebuild.

It is the PC 750 model. Balmar no longer sells them. It was offered as a combo genset/watermaker but the PO did not install the watermaker but he did get the optional high volume takeoff pump that is to be installed on the front of the motor. The alternator is on the rear. The pump was never installed. The pump is solid and heavy but I don't plan on installing it although it would be a dandy dewatering pump in an emergency.

It only has 16 original hours and has been serviced annually anyway. The oil is clean, clean, clean. So I will be selling it when I can figure out how to get it out of the engine room. I have not figured out how much to offer it for. I may have to partially disassemble it to remove it. Or take out my main again along with the binnacle, steering, and cockpit floor - yikes.

[Cheechako]

Originally Posted by Hoghead

I am thinking of one of these
Any more feedback

I am familiar with small Yanmar diesel engines on iron buffaloes and they are loud.
How about the Aqua marine

Aqua Marine: The engine is good, I built two and my buddy built one using that engine. I am confused by Aqua Marine's pictures though. One unit shows the standard air cooled engine with the fan and little radiator, the other picture shows the air cooling stuff removed. Both show a wet exhaust elbow, but I don't see a water heat exchanger on either.
There is (was) a water heat exchanger/tank available that bolts on top in lieu of the air exchanger. With that, you will not have heat build up in the compartment the unit is used in.
Our units were quiet and great. The nice thing about the 12V system is you can run it maybe 1500-1700 rpm to start, and after the initial 15-20 minutes of heavy amp output, throttle it back to a real quiet rpm for the float charging. The Kubota is much quieter than those air cooled Yanmars for sure.
None of ours were built over 150 amp alternators. I would look for someone that builds them with the water heat exchanger.


I would look at the Ample Power Genie shown here. You can see the black heat exchanger on top in the pic:

[Hoghead]

Originally Posted by sailnow2011

We have the same engine driving a 120volt generator. They are loudish.
Ours runs at 2600rpm, so it is a little more quiet.
The reason you do not want a 12volt gen is as follows.

Inefficient. you will need huge cables to make the run from the generator to the bank, and there will be losses at 12 volts. The generator will deliver full current at cold temps, but once it starts to warm up it will put out less and less, as they all do. Converting 12 volts to 120 volts can be done at no more then 90% efficiency, so another loss there. If you are storing this energy in a battery you will have losses during charging.

Glazing. As the batteries get more and more full they take less and less of a charge. Once you approach 90% the load on the generator will be so low, it will start to run cold. Running cold means it will glaze the walls of the cylinder, and it will burn oil.

The big deal is how inefficient it is. You are better off with a phasor or nexgen 3.5kw unit. use it when you need it. When charging batteries after they hit 90% and you want to go to 100% you can make hot water, you can run an air conditioner, update your blog ECT.

Point taken and the run of heavy 12V cables is an issue.
Output loss with rise in operating temperature is not such a big concern as I would "amp limit" the output to 85A but again I see your point

Once I hit 90% charge I would likely turn it off and let solar and wind top the bank off so cylinder glazing is not a big worry.

Price for DC VS AC seems comparable

[Cheechako]

Glazing wont be a problem on a 10HP diesel, actually hasn't been on truck diesels or main boat engines even.

[SV THIRD DAY]

We had a home-built version using the Kubota when we first left for Mexico with 160A alternator and Hp water maker pump, fondly named "The Frankenmaker" ...but OMG the noise from that Kubota was unreal.

After multiple issues we ditched the Kubota in exchange for a $950 Honda 2000 Generator, and 75A batter charger, and 1.0Hp electrically driven water maker Hp pump.

In fact, that is how Cruise RO was started from an anchorage in Mexico....