Generator Battery

[Nassau Weekender]

In the process of putting the genny back in the boat. Never had one while Ive owned her but is plumbed and rigged for one. With the expection of batteries/starting. That has been messed with.

Got a Onan 4KW MCCK with closed cooling - original model to the boat I believe.

Anyways, where and which battery should I use for starting the genny.

Some threads I have read have an isolated one - just grounded to the main engines starting systems.

Others have used the battery that is isolated to one engine, and then others use the other engine and house battery bank.

I currently have my port engine isolated with a simple on-off switch - starts the port engine only.

Then I have two batteries connected to a 1-2-all switch for starting the stbd engine and house. And the emergency switch/solenoid system.

3 x GP31 in total down the center of the boat.

If I install an additional battery for the genny then I need to mount it somewhere new. Where ? What if genny battery goes flat. Is it ok to put a genny on a main engine system that has a alternator ?
If yes, then which - I'm thinking isolated port engine. Never being drained by house use and gets charged by the genny when its running - or may be not ???.....

I am confused... please help.


Thanks

 

[390x]

The best way, IMO, is to use a dedicated genny battery, that way if everything else goes dead, you can always fire the genny, which will fire the battery charger, and get your motors running.

 

[Nassau Weekender]

I get what you are saying but I will have the isolated port engine starting battery which can e conected to the stbd batts using the emergency switch. So even if I connect to house and run them dead I can still start the genny and stbd engine using the emergency switch.

 

[Nassau Weekender]

In the process of putting the genny back in the boat. Never had one while Ive owned her but is plumbed and rigged for one. With the expection of batteries/starting. That part of the installation has been messed with.

Got a Onan 4KW MCCK with closed cooling - original model to the boat I believe.

Anyways, where and which battery should I use for starting the genny.

Some threads I have read have an isolated one - just grounded to the main engines starting systems.

Others have used the battery that is isolated to one engine, and then others use the other engine and house battery bank.

I currently have my port engine isolated with a simple on-off switch - starts the port engine only.

Then I have two batteries connected to a 1-2-all switch for starting the stbd engine and house. And the emergency switch/solenoid system.

3 x GP31 in total down the center of the boat.

If I install an additional battery for the genny then I need to mount it somewhere new. Where ? What if genny battery goes flat - Jump Leads?.

Is it actually ok to put a genny on a main engine system that has a alternator ?

If yes, then which - I'm thinking isolated port engine. Never being drained by house use and gets charged by the genny when its running - or may be not ???.....

I am confused... please help.


Thanks​

 

[northern]

Does your generator have a 12 alternator to charge a battery. If yes then it can be a stand alone system. If not you need to use one one of your engine batteries to start it.
If you are worried about running all batteries down then get a portable jump start battery. It will have enough power to start the generator.

 

[390x]

What happens if you run the #2 battery dead? Also, if you run the house dead, and try to use the emergency start, it might not work. The dead batteries are immediately going to draw power from the good battery, rendering it dead as well, depending on exactly how dead the house batteries are.

 

[Nassau Weekender]

Genny does have a alt - 1amp output. I guess really what I am asking is.... is it ok to connect to an main engine staring system that already has an alternator in the loop (on the main engine) I cant wee why not, I just curious. Its only like having a trickle charge on it right ?

If it is ok, then which one? the isolated port engine system or the stbd engine and house system. I shoudl always have the emergency start system to cross over to good batteries.

If I go with a stand alone genny system then I'm into another battery, fabricating a home for it and an additional switch.

All in all more expense, time, maintenance and things to go wrong.

Maybe I am over thinking this, but I just want to do this one time. Once the genny is in its a PITA to change it.

Thanks

 

[Nassau Weekender]

Sounds like you are speaking from experience? How is your genny wired ?

So if I connect the genny to the Port engine isolated system I should be good right. Also this batt will be charged by the batt charger while on shorepower and engine alt when running- sol in theory always fresh. If the genny output is only 1amp how long do you need to run the genny for just to replace the energy used to start it ?

If I go isolated genny then I need to find/make and home for the extra battery and switch. I want/need to keep my house batts as they are as I can currently get a whole day at the beach and still start the engine without using the emerg start.

I have a small dilema which I am overthinking maybe ?

 

[390x]

My genny battery is isolated from everything else. It's self charging, but also hooked up to the charger. You're probably ok hooking up to the port battery, but there's a little bit of a risk there as you might run that battery dead if the engine was a hard start or something, and your house batteries were dead already. You don't necessarily need a switch on the genny battery. I don't have one, and many don't. As far as how long will it take to charge the genny battery, unless the genny is a hard start, I wouldn't worry about it. It won't draw much.

 

[MonacoMike]

Marine Max did the install on mine and they put in a stand alone battery that charges from the alt and 120v chargers. I like it as I have an isolated battery in the event of trouble.

MM

 

[390x]

+1 on Mike's method.

 

[Gunn]

I get what you are saying but I will have the isolated port engine starting battery which can e conected to the stbd batts using the emergency switch. So even if I connect to house and run them dead I can still start the genny and stbd engine using the emergency switch.

This is the way it's setup on a 280DA with three batteries. The starboard engine is connected to the house batteries pair. The port engine and generator share a battery. Or...did I get that mixed up?! Either way, one engine and generator have a dedicated battery to themselves.

 

[Nassau Weekender]

My charger only has three outputs. Currently each batt has its own charger connection. I think that is the deal breaker right there on the isolated circuit system.

If I isolate the genny battery (with no charger connected) - then even if I only exercise the genny for 1/2 an hour each week then its only going to put 1/2 an amp back in (1 amphr charge) and even I know its going to take more that 1/2 an amp to start it (it starts with no than 3-4 elephants of cranking).

But then.... I guess I could isolate it but also connect it to the emergeny start system with a simple inline on/off switch and keep it in the OFF position normaly so it is isolated but connected to something that can start it in an emerg ?!

Thoughts guys ?

Should this really be this complicated ?

 

[Nassau Weekender]

That sounds expensive.

But whats the plan if the your isolated genny battery fails ?

Stu

 

[MonacoMike]

That sounds expensive.

But whats the plan if the your isolated genny battery fails ?

Stu

What is your current plan if your primary battery bank fails before the addition of the generator?

As for cost, seems to me to be a battery and holding parts. You would already have to have cables no matter the power source.

MM

 

[MonacoMike]

Please only post a question once. You have members answering the same question in two threads. Most of us use the new posts 24 hours and will see it no matter where you put it.

MM

 

[MonacoMike]

Please only post a question once. You have members answering the same question in two threads. Most of us use the new posts 24 hours and will see it no matter where you put it.

MM

 

[390x]

My charger only has three outputs. Currently each batt has its own charger connection. I think that is the deal breaker right there on the isolated circuit system.

The three outputs is for three banks, (house, starting, genny), not three batteries. You hook up the output to a battery that is then connected to the other batteries in the bank. In fact, if you hook up two outputs from the charger to two batteries in the bank, I'd suspect it won't charge at all because both banks in the charger will sense that there's already a full charge and shut off. Hooking it up that way is definitely wrong. The isolated circuit is the best way to do it. Put in a dedicated battery for the genny, hook the charger up to it, and be on your way. Your genny battery won't go dead unless your genny doesn't work and takes a ton of cranking to start. It isn't this complicated. Just pick the way you want to do it, and go with it.

 

[MonacoMike]

My charger only has three outputs. Currently each batt has its own charger connection. I think that is the deal breaker right there on the isolated circuit system.

If I isolate the genny battery (with no charger connected) - then even if I only exercise the genny for 1/2 an hour each week then its only going to put 1/2 an amp back in (1 amphr charge) and even I know its going to take more that 1/2 an amp to start it (it starts with no than 3-4 elephants of cranking).

But then.... I guess I could isolate it but also connect it to the emergeny start system with a simple inline on/off switch and keep it in the OFF position normaly so it is isolated but connected to something that can start it in an emerg ?!

Thoughts guys ?

Should this really be this complicated ?

My emergency start up procedure, should the primary system fail involves battery cables. :smt043

This keeps the system fully isolated and cheap IMHO. MM

 

[Nassau Weekender]

What is your current plan if your primary battery bank fails before the addition of the generator?

As for cost, seems to me to be a battery and holding parts. You would already have to have cables no matter the power source.

MM

I guess at the moment I am cautious and take precautions (battery voltage alarm) knowing that I only have my emegency system to get me running. It ocurred to me that complaciency might set it thinking I "ALWAYS" have a genny to get me out the mire.