8KW Onan MDKD DC power requirements

Yes the generator needs DC power but it is making it's own not using the battery. Could be many things. The field to the broken alternator, electric gauges, fuel solenoid. It wouldn't take much to drain a battery in 60 hours. If making AC power, why not run the battery charger?

That was user error I forgot to plug it in.

Vyndance said:

Yes the generator needs DC power but it is making it's own not using the battery. Could be many things. The field to the broken alternator, electric gauges, fuel solenoid. It wouldn't take much to drain a battery in 60 hours. If making AC power, why not run the battery charger?

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Don't bother re-instating the genset's baby alternator. Get a Balmar Digital Duo Charger and connect this between House bank and Genset Start battery. It will put out up to 30A, plenty to quickly re-charge the genset start battery & maintain it in good condition.

Many folks will use a jumper cable set or rotary switch to enable a main engine start from the noisemaker battery.

Might work for you in reverse?

Go back to OEM on the unit , as it will be the easiest to repair in the future with an OEM wiring diagram.

FF

I am in the process of replacing my 7.5 KW GENSET with a 8KW genset. I made sure it has it's own alt. and battery. Plus I can start the genset with my main start batteries or house batteries.

As you indicated in your original post it appears that the charging circuit is not working on the generator.

The generator needs 12 volts to operate. This voltage keeps the injection pump solenoid operating, or on the old Onan units there is a solenoid thay pulls in allowing the fuel rack to operate.

Where you get that 12 volts is up to you. I prefer to have the generator alternator working. As indicated you can also use a stand alone charger. This can be a 120 to 12 volt charger, or it can be a ghost charger which uses 12v to 12v.

I actually have both on my boat. The generator has a alternator, and I have a 12 volt Charles Industries charger that keeps the gen, and both engine start batteries charged. It also serves as a backup to the large inverter/charger in case that fails.

Whatever method you choose you need the 12 volts.

Gensets use DC to power their fuel pump and sometimes the run solenoid. Both willl draw 2-3 amps.

Genset's internal alternators are somewhat mickey mouse and often have poor regulation. So if it is not working then leave it that way and use an AC charging source.

Since your trickle charger isn't going to keep up with the ongoing DC loads, you have a couple of options:

1. Upgrade the trickle charger to a higher capacity unit. Guess makes one for about $75.
2. Your main AC charger may have two or more isolated outputs that you can use to charge your genset battery.
3. You can use an ACR (combiner), Echo Charger, Duo Charger, etc to supply charging current from your main AC charger to your genset battery.

David

Thanks! I have an older Freedom 2500 inverter/charger. Looking through the docs from the previous owner some time ago ge removed the Echo charger going to the genset battery. I have no idea on why this was done but it looks like something I need to look into. The only issue I see is that the house and main start are AGM and the generator is wet.

djmarchand said:

Gensets use DC to power their fuel pump and sometimes the run solenoid. Both willl draw 2-3 amps.

Genset's internal alternators are somewhat mickey mouse and often have poor regulation. So if it is not working then leave it that way and use an AC charging source.

Since your trickle charger isn't going to keep up with the ongoing DC loads, you have a couple of options:

1. Upgrade the trickle charger to a higher capacity unit. Guess makes one for about $75.
2. Your main AC charger may have two or more isolated outputs that you can use to charge your genset battery.
3. You can use an ACR (combiner), Echo Charger, Duo Charger, etc to supply charging current from your main AC charger to your genset battery.

David

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The Echo Charger built in to the Freedom would be an ideal way to keep the genset battery charged. The Echo Charger is current limiting so you don't need a fuse at its end, but be sure to put a fuse at the genset's battery. Use at least 12 gauge wire which will easily carry the EC's 15 amps max.

Don't worry about mixing AGM and flooded cell batteries. Their charging voltage characteristics are close enough.

David