Generator- one or two batteries?

[RJM]

Dumb question; I bought our 53 last year and this weekend we discovered that the battery charger/tender for our Onan generator has crapped out. Shows charged but the battery is at 7.5 volts. The charger is a Guest Charge Pro 10A 5/5. The battery box is for 2 batteries but only has one (12v). Am I right to conclude that there were 2 batteries in parallel in the initial setup? Should I replace the charger with a similar charger and a second 12V battery? Current battery is lead acid. What is the current (no pun-well maybe a little) think on this. What battery charger do you like?

Thanks

 

[Pascal]

A single G31 works fine for these size gen. I really like ProMariner ProNautic chargers. Have two of them, one 24v for house and one 12 V for mains and Gen.

 

[racclarkson@gmail.com]

Dumb question; I bought our 53 last year and this weekend we discovered that the battery charger/tender for our Onan generator has crapped out. Shows charged but the battery is at 7.5 volts. The charger is a Guest Charge Pro 10A 5/5. The battery box is for 2 batteries but only has one (12v). Am I right to conclude that there were 2 batteries in parallel in the initial setup? Should I replace the charger with a similar charger and a second 12V battery? Current battery is lead acid. What is the current (no pun-well maybe a little) think on this. What battery charger do you like?Thanks

How about the genny’s alternator? I’ve got a smaller than Grp 31 on my NL 20KW. It is also not connected to a charger. While I carry a 12V charger onboard, I’ve never needed it.

 

[SeaEric]

The original config on my Hatt had the 6kw Onan Gen starting off the stbd engine 8D battery. There was an "on/off" battery switch in the Gen feed. When I replaced the Gen with a 9kw Beta Marine, I wanted a stand alone battery for Gen starting which we added. We changed the On/Off battery switch to a 1/2/All so if the Gen battery is dead I can still ulitlize the stbd battery to get her going. I have had to do that only one time. The dedicated Gen start battery does only that, and is not connected to a battery charger. It's about the size battery you would see on a lawn mower. I've repalced it once in 8 years.

 

[Captain Ralph]

The few Hatts we have worked on, the gen-sets were 24Vdc and used the stb main engine battery bank.
I never liked this and on one later model, we installed a separate 24V bank for the gen-sets.
The battery charger had a third tap and it went to this dedicated bank. Also installed a battery switch for that just in case scenario.

The last 12V Hatt we worked on was a fine ole gasser.

So, question 1; is your gen-set 12 or 24V based?
On one Hatt we removed the ole 20 and installed new NL 20 & 12kw sets.
Both 12Vdc systems. A better 4D battery makes the starting battery.
A battery switch is still used for those just in case scenarios to the stb bottom battery.

Question 2; Does your gen-set have a battery parallel switch Back to one of the mains banks? Was it started this way before?

Question 3; Your battery measures 7.5 volts. Was that with the charger on during this reading?

I would question the battery AND the charger for failures.

If it can fit your battery box, A sealed combo G31 battery should offer great service and life for your gen-set.
I don't think anybody makes a bad charger, but MasterVolt, Pro-Marinier and Victron make fine lil chargers.

 

[Jammin']

I have a separate automotive size battery for my 8K Westerbeke that was only charged by the generator when it was running. I added a small 4 amp CTEK charger just to keep it topped up during expended periods of disuse.

https://www.amazon.com/CTEK-40-206-...pd_rd_i=B00CD44RQO&psc=1&ref_=pd_bap_d_rp_1_t

 

[RJM]

Thanks for the replies. Unfortunately I am off the boat until later this month. I downloaded the charger manual which I didn't have and found that the green light that I see on the charger could mean either a battery failure or a fuse failure on the charger. I plan to take one of my car chargers down with me to charge and stress test the battery independent of the charger. Clearly I have more diagnosing to do. I also found out that the charger can be wired for either one or two batteries, so maybe it only had one from the start. Still, since the battery box and the charger will both take another battery I am wondering about the usefulness of having another 12V battery charged and ready to go as a redundant. Just a thought.

 

[racclarkson@gmail.com]

I am wondering about the usefulness of having another 12V battery charged and ready to go as a redundant. Just a thought.

That's my plan. I have four additional 12V batteries available that can be pressed into service. Maybe not the most convenient back-up, but I've also never needed to go there in 6 years of ownership.

I'd still want to know why my battery was discharged and if my generator's alternator was in the pink.

 

[sdowney717]

That's my plan. I have four additional 12V batteries available that can be pressed into service. Maybe not the most convenient back-up, but I've also never needed to go there in 6 years of ownership.

I'd still want to know why my battery was discharged and if my generator's alternator was in the pink.

When you get your gen started, check the voltage at the gen start battery to see if the gen is charging the battery. I recently got rid of my gen battery and ran two gauge 2 wires from engine start battery bus bar to gen, and it has worked fine. I also bought a new Victron IP22 30 amp 3 bank charger. you can view the charging on your phone using bluetooth, very easy to setup.
One less battery to worry about, a gen takes little power to start.

Starting the gen also now charges the starter bank, so if its low and you can get gen started it will help get the starter bank charged up again.

My starter battery only starts all engines. I can flip a rotary switch and join house bank to the starter bank and also rotate a switch and turn off the starter bank. so can combine both together or run whole boat on either bank with other bank disconnected.

 

[RJM]

I need to correct an assumption; I have always assumed that my start batteries are the same as my house batteries. I assumed that one bank (32V) was for each engine and that the 32V for the house came off of one bank, although I didn't know which one. Other than making sure that the batteries were topped off with water and that the charger was working I've given it no more thought to this point. Do I have this wrong? Is one bank for start and one for house? Which bank is for which, starboard and port?

 

[Avenger]

"Usually" there's one battery for each engine, but the port battery is used for house loads and the stbd battery is reserved exclusively for starting. That way if you run the house battery down you can parallel in the start battery to get engines running.

 

[sdowney717]

"Usually" there's one battery for each engine, but the port battery is used for house loads and the stbd battery is reserved exclusively for starting. That way if you run the house battery down you can parallel in the start battery to get engines running.

Yes except reversed on my boat. Port is engine starting, now all 3 of them. And starboard for house, two 6 v golf cart GC15 batteries. I have found no problem with 1 battery to start multiple engines.
And the 2 golf cart batteries can start the engines by themselves. Batteries are frequent expensive consumables, does not make sense to have too many on the boat, for me anyway.

The start battery does have 2 of the 5 bilge pumps wired directly to it I found out, through an 80 amp fuse and a 6 gauge wire, part of the charging circuit, alternator and victron charger joined and then each pump has a smaller fuse for it's smaller wire after that.

The other 3 bilge pumps are on the house battery. Turning off the rotary battery switch does not turn off power to the bilge pumps, which is a good thing.

 

[Pascal]

I would never use online fuses on pumps. You only know they re blown when you need the pumps. Visible breakers are a must

I like redundancy and keeping systems separate. I have a single 8D for each 12 v engine, a G31 for the gen and a separate 24 v house bank made of 2 8Ds

 

[sdowney717]

I would never use online fuses on pumps. You only know they re blown when you need the pumps. Visible breakers are a must

I like redundancy and keeping systems separate. I have a single 8D for each 12 v engine, a G31 for the gen and a separate 24 v house bank made of 2 8Ds

Let me think and describe my setup regarding fuses and breakers and bilge pumps.
All bilge pumps are on breakers, a Rule 2000, runs from house side getting it's power from the 150 amp MEGA fuse that supplies the house DC power, it runs a branch line to a manual reset breaker to the pump.

The two pumps on the start battery, Rule 2000 and a Rule 500 are also breakered, they get their power from the 6 gauge battery charging wire and an 80 amp fuse protects those feed wires.

The entire house side is fused with a 150 amp mega fuse, then has many breakers on branch lines, half are breaker-on - off switches, the other half have to be manually reset.

There is one 6 gauge wire running to a 50 amp breaker feeding an always on buss.
On the buss, are two Rule 3700 pumps.

If I somehow lost the house 150 amp fuse and the 80 amp charging fuse, still have the two Rule 3700 on a breaker at the always on buss block.

The 2 Rule 3700, I run on float switch and also a single manual switch, They run together, at same time, I think. Been awhile since I did that. I use a 70 amp DC relay to save the switch from wear as it is just too many amps for that one switch. I almost never use those pumps.