Yamaha 2400 generator's on-board 12V charger

MrWizard wrote:
Accept the fact, that you did it correctly, exactly for what it is intended for an Emg charge to start the vehicle
It is not intended to be a stand alone battery charger, or to be left alone unattended, or to be a 12v power supply for other devices

Yes, fact accepted. It has been and will continue to be my 3rd or 4th ranked option for battery charge behind solar and generator-shore power cable-TT converter. Thus me never having even tried using it before despite having the generator for 3 seasons now. I think I would pick the generator's 12V charger over firing up the truck and hooking up the trailer cable because it would probably be higher amps and certainly use less gas.

Accept the fact, that you did it correctly, exactly for what it is intended for an Emg charge to start the vehicle
It is not intended to be a stand alone battery charger, or to be left alone unattended, or to be a 12v power supply for other devices

2manytoyz wrote:


You must accept that the built-in charger is merely a nice to have feature.

Almost any standalone external battery chargers connected to this generator will outperform the built-in charger... but it does work!

Words of wisdom buried at the bottom in the last sentence............

19 words are worth 1K of pictures, LOL!..:W

.

ewarnerusa wrote:
I was expecting the charger to provide a regulated constant voltage in the high 12's to low 13's. Instead, the voltage reading across the terminals continued to rise.

Initially the dead battery was pulling down the voltage as it absorbed what the generator put out.

As the battery charged, it pulled down the voltage less. Until the generator voltage is reached, it will keep pulling up the battery voltage. Eventually, that is a bad thing for the battery.

Thanks for the responses and explanations. I've known that the gen's 12V charger was last resort charger. That's why I've never used it, but I thought trying it out to deal with the lawn mower battery was a good excuse to see how it works. I actually started out with it jumpered to my truck battery and letting the alternator charge it. Then I got motivated to change the oil in the generator in the meantime and did that, then I remembered the 12V charger on the generator, then I started tinkering...

ewarnerusa wrote:
I was expecting the charger to provide a regulated constant voltage in the high 12's to low 13's. Instead, the voltage reading across the terminals continued to rise.

if it was 12 to low 13 volt...you might still be waiting for your battery to charge.

The charger output on this and possibly all small generators is unregulated and unfiltered. It's produced from an AC winding run through a full-wave rectifier, and nothing else. Depending on the voltmeter, it might read the peak, average, RMS, or almost any other voltage that it decides the DC voltage of this output is. When connected, the battery acts as a filter and changes the output to better DC, still with a lot of AC ripple, and different voltmeters will still interpret this differently. The Honda eu-series manuals say the charger output should be used to charge automotive-type batteries, and nothing else. They also admit the the output is unregulated. I've read at least one publication that suggests using the unfiltered output would bring a fairly quick death to an AGM battery. A FLA battery is apparently perfectly happy with the dirty power, and low end battery chargers have been providing this since the dawn of battery chargers.

You must accept that the built-in charger is merely a nice to have feature. You 'can' recharge a 12V battery with it. It will supply up to 8 Amps.

That said, here's what we're dealing with:



Without connecting the cables to a battery, there's some AC ripple on the waveform - should be flat:



Before starting, the voltage on my battery was 12.64V. Upon connecting it to the charger...



Please understand this is not unusual for a cheap grade charger. The voltage is not well regulated, but the current is limited, which prevents boiling an automotive battery.

I have used this setup many times to put a charge on our boat that was in storage (no power there):



Almost any standalone external battery chargers connected to this generator will outperform the built-in charger... but it does work!

Smaller generator ROB the alternator's (Generator's) FIELD VOLTAGE which usually 18-volts on these micro gens. Voltage is sent to the external plugs. Depending on the generator current is limited to around four to eight amperes.

Field voltage is what is utilized in the rotating "rotor". The excitation is direct current. My Kubota/Kato uses 36 volts at 2 amperes in the primary exciter which is a rectified generator winding in itself. 20 amperes @ 110VDC feeds the main rotor winding.

2oldman wrote:
Page 18 of the owner's manual has some interesting information.

Consulting the manual would have been a great idea, I guess I figured it wouldn't be complicated enough to warrant it! Murphy's Law.

I did try pushing the DC Protection button in but it wouldn't budge.

So does anyone know if, when operated properly, the voltage reading should remain constant when using the generator's 12V charger?