Yamaha ef2000 charging the batteries

[Dalo]

We mostly dry camp. For years I have been keeping the batteries charged by plugging in the trailer power cord to a small Honda or my new Yamaha 2000 watt generator. Trailer has a 7355 Parallax converter. Never really had many problems but I've been reading on this forum about this not being the best way to maintain your batteries. I started looking more closely at the Parallax 7355 and I see that it has a max output of 55 amps but a typical battery charge rate of only .5 amps. WOW-that's nothing.
Here is my question. The Yamaha genny has a 12 volt outlet that puts out 8 amps. Would this be a better way to charge my batteries directly from the generator? The short 12V power cord that came with the generator has a very light duty looking cord. Wire is only 18awg (pretty thin).
I would much appreciate any comments. DALE

[Dalo]

Hi, My previous post about a 40 yr old Montgomery Wards portable charger (10amps @ 12.6volts) would seem to be too low of a voltage to do much good. I gather from reading the above comments I really need at least 14.1 volts minimum. Do I?
Been looking at the Progressive Dynamics and IOTA 60 Amp converter chargers and found them on Amazon for around $190. They sound like they would solve most of my problems. Some of the reviews for those were critical of poor quality and needing early replacement.

[time2roll]

Yes you can walk away for six hours.

[2oldman]

I have no idea

[red31]

2oldman wrote:

red31 wrote:
so how long does it take a 8A 'unregulated' charger to raise a 100 ah 50% dod batt's voltage to 15v?

50ah/8a

and would require no baby sitting for over 6 hrs?

[2oldman]

red31 wrote:
so how long does it take a 8A 'unregulated' charger to raise a 100 ah 50% dod batt's voltage to 15v?

50ah/8a

[red31]

so how long does it take a 8A 'unregulated' charger to raise a 100 ah 50% dod batt's voltage to 15v?

[road-runner]

MEXICOWANDERER wrote:
That 8 amp charging port ROBS field excitation electricity from the generator rotor.....Robbing the field for battery charging can rob the generator A.C. output potential from say 3,000 watts to 800 watts. This is a fact of life with any home generator with a field voltage tap.

Does this really apply with a permanent magnet rotor? The manual cautions that the power from the DC and AC outputs, when used simultaneously, cannot exceed the rated genset power. The DC output has its own dedicated stator winding.

[MEXICOWANDERER]

When the onboard charger slumps to 10 amperes, connect the manual charger and watch the amperage jump up. Where does some of this information come from? Jeez! That 8 amp charging port ROBS field excitation electricity from the generator rotor. Measure it open circuit. It will read something near EIGHTEEN VOLTS. My 5500 diesel Yamaha had a belt driven alternator I measured at at 21 amperes max at 14.1 volts regulated.

Robbing the field for battery charging can rob the generator A.C. output potential from say 3,000 watts to 800 watts. This is a fact of life with any home generator with a field voltage tap.

[SoundGuy]

Peg Leg wrote:
My Yamaha 3000 the 12v output is regulated to 12v.

Sorry to disappoint but that 12 vdc charging port on your Yamaha genset is unregulated, meaning it can easily overcharge your batteries and cause them to boil if you don't monitor the charging process carefully. No different than the 12 vdc charging port on many of these inverter style gensets, regardless of brand.

[scrubjaysnest]

Oasisbob wrote:
My Honda EU 1000 also has 8 amp charging. I find it much faster to bring along a plug in battery charger and charge at 15 or 25 amps. Takes 2 - 4 hours depending on how low the batteries went. I usually do this every three days or so. Better to charge briefly once a day rather than lettin them get too low. Hope my option works for you. It's cheaper than a new converter

We use a portable smart charger if there are three or four cloudy days.
15 amp is ok for a pair of 95 to 105 Ah 12 volt batteries but if you have GC-2's then a 25 amp is best.

[road-runner]

My Yamaha 3000 the 12v output is regulated to 12v. Computer type output not enough voltage for charging.

The wiring diagram in the EF3000iSE manual shows a dedicated generator winding going through a full wave rectifier, then a circuit breaker to the DC outlet. Same as almost all the other generators, unfiltered and unregulated pulsating DC.

[time2roll]

Dalo wrote:
OP here, Thanks for all the info. I have a 40 year old Montgomery Wards charger that I keep under my workbench. Label says 10 amp variable rate at 12.6 volts. Still works. I could hook this up to batts while boondocking. Not sure if 40 yr-old technology will help my case. BFL13 says I need at least 14.4 - 14.8 volts for optimum charging. Opinions?

Will not hurt a bit. Definitely give it a go while you decide where to upgrade.

[theoldwizard1]

Sandia Man wrote:
The way to go if your converter is a single stage charger is to upgrade to a multi-stage as that will serve you much better ...

Concur !

[Peg_Leg]

My Yamaha 3000 the 12v output is regulated to 12v. Computer type output not enough voltage for charging.