DC generator to charge my RV house batteries?

[PNW_Steve]

Hello Everyone,

I am installing solar and upgraded house batteries in my RV. I will have a 24v - 370A/H battery bank and need backup charging for times when solar production is not adequate.

I have come across a diesel 36v generator. Basically a small diesel motor with a 36 volt alternator.

What I am considering is using the 36 VDC generator to feed a 40A MPPT charge controller to charge my 24v battery bank.

My RV is diesel and I don't want to have to carry gasoline. Otherwise I would buy a little Honda inverter generator.

What do you all think of this plan? Suggestions?

Thanks.

S.

[Sunking]

You do not need any charger or MPPT if the genny has a 36 volt DC output. Only real issue is 36 volts DC is a bit to low to charger with on a genny, and no charge or controller is going to fix that, just make it worse and take longer. Besides a MPPT controller would not work.

[Mike90250]

You will need to configure the MPPT controller to work with a Wind Turbine. That changes in interernal IV curve to work with copper windings and not PV panels.. Not all MPPT controllers are adaptable.
What's the 36V amperage ? Age of the engine? sometimes lightly loaded diesels will Wet Stack and get gummed up under light loads

[PNW_Steve]

You do not need any charger or MPPT if the genny has a 36 volt DC output. Only real issue is 36 volts DC is a bit to low to charger with on a genny, and no charge or controller is going to fix that, just make it worse and take longer. Besides a MPPT controller would not work.

Not sure I understand your reply.

It appears to me that the voltage is quite high and needs to be reduced to the appropriate voltage to charge my battery bank.

Edit: Now I understand.... In my original post I stated that I have a 24V 370 A/H battery bank. Later in the post I mistyped 36V where it should have been 24V. Sorry for the misunderstanding.

[PNW_Steve]

You will need to configure the MPPT controller to work with a Wind Turbine. That changes in interernal IV curve to work with copper windings and not PV panels.. Not all MPPT controllers are adaptable.
What's the 36V amperage ? Age of the engine? sometimes lightly loaded diesels will Wet Stack and get gummed up under light loads

The generator has a 60 Amp alternator. I am not sure of the age of the engine. It is a common Yanmar air cooled single cylinder.

Should I use the generator as a "last resort" when the batteries get low enough that the charging process will place a significant load on the engine?

Thanks.

S.

[Sunking]

Not sure I understand your reply.

It appears to me that the voltage is quite high and needs to be reduced to the appropriate voltage to charge my battery bank.

No problem, the battery regulates the voltage. As long as the generator DC output is at least 36 to 40 volts.

A charge or controller does not regulate voltage other than to limit current so it does not burn up the electronics. The only time the charger limits voltage is when the battery is just about charged up. then SLOOOOWS down so it takes another 6 to 12 hours to finish charging slowly so you you do not have to watch it and turn it off. Just slows things way down. You do not want that with a genny that has a DC generator or alternator. You want it to charge as fast as possible, then stop only after the battery is fully charged. Give it a try. Start the generator up and measure the output voltage with nothing connected. If the output is 36 to 40 volts you are good to go and give it a try. Stop charging when current drops to 10 amps and measure Specific Gravity.

[PNW_Steve]

No problem, the battery regulates the voltage. As long as the generator DC output is at least 36 to 40 volts.

A charge or controller does not regulate voltage other than to limit current so it does not burn up the electronics. The only time the charger limits voltage is when the battery is just about charged up. then SLOOOOWS down so it takes another 6 to 12 hours to finish charging slowly so you you do not have to watch it and turn it off. Just slows things way down. You do not want that with a genny that has a DC generator or alternator. You want it to charge as fast as possible, then stop only after the battery is fully charged. Give it a try. Start the generator up and measure the output voltage with nothing connected. If the output is 36 to 40 volts you are good to go and give it a try. Stop charging when current drops to 10 amps and measure Specific Gravity.

OK. Now I am really confused.

Do I understand that you are telling me that I should charge my 24 Volt battery bank with the 36 Volt alternator without any other changes?

[Sunking]

OK. Now I am really confused.

Do I understand that you are telling me that I should charge my 24 Volt battery bank with the 36 Volt alternator without any other changes?

Is the generator output voltage 36 volts or made for 36 volt batteries?

[PNW_Steve]

Is the generator output voltage 36 volts or made for 36 volt batteries?

Made for 36 Volt batteries.

[PNW_Steve]

Well ... I took a gamble that I can make it play... I bought it.

[PNW_Steve]

Any thoughts?

[PNW_Steve]

Some pics:

[PNW_Steve]

I contacted Mechron before I bought the generator. My contact there told me that he could send me documentation if I sent him the serial number.

Bought the generator, brought it home and emailed the info to Mechron. I received one reply to my email . No documentation though.

Now the guy at Mechron is not answering his phone or responding to voicemail or email.

Anyone here have any knowledge /info on the alternator shown in the picture?

I am hoping that I may be able to track down the actual manufacturer of the alternator itself.

Thanks.

[Bala]

If it is an alternator , an auto electrician may be able to fit up a 24v regulator. If you van get an adjustable regulator you can set a higher voltage to increase charge rate. That will be a noisy engine.

[bcroe]

I would start by determining if the alternator has a voltage regulator feeding brushes, or a
permanent magnet rotor, or what. It has 3 phase rectifiers? Bruce Roe