Reply
 
Thread Tools Display Modes
 
Old 07-16-2012, 09:24 AM   #1
Senior Member
 
Gulfstar 36's Avatar
 
City: Kent Island
Country: USA
Vessel Name: Sundowner
Vessel Model: Gulfstar 36 MrkII
Join Date: Jul 2012
Posts: 226
Question 8KW Onan MDKD DC power requirements

The previous owner rigged up a 1.5AMP battery charger to the generators starting battery. This is the only way it will charge. The generator does have an alternator but I assume that it no longer works and someone just put the F-it sticker on in. Last weekend I ran it for about 60 hours without even thinking of plugging in the charger. Yesterday the starting battery was dead. My question is does this generator have a 12volt DC requirement while running that drains the starting battery?
__________________
Advertisement

Gulfstar 36 is offline   Reply With Quote
Old 07-16-2012, 11:22 AM   #2
Senior Member
 
Vyndance's Avatar
 
City: Ventura, CA
Country: USA
Vessel Name: Vyndance
Vessel Model: 48 Californian CP
Join Date: Aug 2010
Posts: 154
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?
__________________

Vyndance is offline   Reply With Quote
Old 07-16-2012, 11:31 AM   #3
Senior Member
 
Gulfstar 36's Avatar
 
City: Kent Island
Country: USA
Vessel Name: Sundowner
Vessel Model: Gulfstar 36 MrkII
Join Date: Jul 2012
Posts: 226
That was user error I forgot to plug it in.



Quote:
Originally Posted by Vyndance View Post
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?
Gulfstar 36 is offline   Reply With Quote
Old 07-16-2012, 02:23 PM   #4
Guru
 
Aquabelle's Avatar
 
City: sydney
Country: australia
Vessel Name: Aquabelle
Vessel Model: Ocean Alexander Flushdeck
Join Date: Jun 2012
Posts: 538
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.
Aquabelle is offline   Reply With Quote
Old 07-17-2012, 07:00 AM   #5
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,531
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
FF is offline   Reply With Quote
Old 11-26-2012, 02:56 AM   #6
Veteran Member
 
khhayes's Avatar
 
City: San Mateo
Country: USA
Vessel Name: Cha Cha
Vessel Model: 43' Gulfstar MK1
Join Date: Jul 2012
Posts: 41
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.
khhayes is offline   Reply With Quote
Old 11-26-2012, 09:34 AM   #7
TF Site Team
 
ksanders's Avatar
 
City: SEWARD ALASKA
Country: USA
Vessel Name: LISAS WAY
Vessel Model: BAYLINER 4788
Join Date: Feb 2011
Posts: 3,956
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.
__________________
Kevin Sanders
Bayliner 4788
Seward, Alaska
www.mvlisasway.com
ksanders is offline   Reply With Quote
Old 03-25-2013, 08:54 AM   #8
Senior Member
 
Gulfstar 36's Avatar
 
City: Kent Island
Country: USA
Vessel Name: Sundowner
Vessel Model: Gulfstar 36 MrkII
Join Date: Jul 2012
Posts: 226
I'm pretty sure the generator alternator is not working. Re-commissioned the genset yesterday and once it was running I was only seeing 12.10 volts on the battery. So it looks like I will leave the 1.5 amp trickle charger plugged in when the generator is running.
Gulfstar 36 is offline   Reply With Quote
Old 03-25-2013, 10:50 AM   #9
Guru
 
djmarchand's Avatar
 
City: East Greenwich, RI
Country: USA
Vessel Name: Bella
Vessel Model: Mainship Pilot 34
Join Date: Aug 2012
Posts: 2,882
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
djmarchand is online now   Reply With Quote
Old 03-25-2013, 01:04 PM   #10
Senior Member
 
Gulfstar 36's Avatar
 
City: Kent Island
Country: USA
Vessel Name: Sundowner
Vessel Model: Gulfstar 36 MrkII
Join Date: Jul 2012
Posts: 226
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.


Quote:
Originally Posted by djmarchand View Post
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
Gulfstar 36 is offline   Reply With Quote
Old 03-25-2013, 01:40 PM   #11
Guru
 
djmarchand's Avatar
 
City: East Greenwich, RI
Country: USA
Vessel Name: Bella
Vessel Model: Mainship Pilot 34
Join Date: Aug 2012
Posts: 2,882
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
__________________

djmarchand is online now   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 10:04 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012