Single engine DC setup

[Hawgwash]

Reading Dwight's thread, I realized almost all battery talk here relates to twins.

What is the most common and practical DC setup for a run of the mill 40 footer with a single engine and gen set?

 

[FF]

Rotary switch with field disconnect , 1 to start batt 2 to house batt, each only feeds starter and engine.

Rotate from off, start on #1 , rotate to both for trip, turn off after engine shutdown,

Rotary 1-both 2 switch from batts to feed house loads ., Usually on #2 most times.

120V charger to house .

IF lazy an $18 RV solenoid can be wired to the acc. position on the key switch , so no wrist movement from 1 to both after engine start is required .

KISS

 

[psneeld]

I have a single with a start battery, 4 golf cart batteries.


There is an on/off switch that connects the start batt and alternator with the house bank,


There is a 1,2, all, off switch to connect each 2 6volt box with the main DC buss.


At first I thought of only an on off switch but the 1,2, all, off switch allows me to disconnect 2-6volt batts for maintenance or wiring issues while still leaving 2 hooked to the main panel. I decided this as a liveaboard as often you want 12v power aboard even though maintenance is being done.


I think this setup does hamper proper charging of the entire bank and drives my Balmar charge indicator a bit crazy (think I have to move a ground to the far side of the second bank)...

It has worked OK for the last 2 ICW trips....but I really need to do some further testing to check charge/discharge rates on each 2-6v battery box. I may also add another 2-6V battery box so that will add to the checks.



And for all the worriers....I do have terminal fuses on all the hot leads.

 

[O C Diver]

Best setup by far is two alternators. The first only charges the engine battery and nothing else is on that battery. Second is a heavy duty truck type alternator (Leece Neville) with an external 3 stage regulator for your house battery bank. Add a battery switch to combine the two systems in the event of an alternator failure, and you have complete redundancy. The 2nd alternator on my trawler is 235 amps and am able to put over 200 amps per hour back into the batteries while cruising.

Ted

 

[Capt.Bill11]

In my opinion you should connect all the house batteries together for one large house bank.

Then set your charging system up so the output from your alternator is properly split to charge both your start battery and your house bank while keeping them isolated from each other. Then use a simple on/off switch to connected the start and house banks together to jump the house to the starting battery if needed to start the engine.

On shore power charge the house bank off a high amp charger or inverter/charger and charge the start battery off its own lower amp output charger. Get a two output charger for the start battery and that can keep the gen battery charged as well.

You could forgo the switch to connect the start and house banks together and just set a switch up to connect the start and gen batteries together if needed. Or you could have both switches for complete redundancy.

Of course if you could use two alternators. One high output for the house bank and one lower output for the starting battery.

 

[Ski in NC]

I went with simple. One start bank, one house bank. Engine connected to both with a 1-2-all switch. Gen connected to main engine starter cable through a on/off switch so engine and gen share a starting source.

Start engine on 1. Once started, switch to "all". Engine alt then charges both banks.

Easy to switch as batt sw is under galley sink right over batts in eng rm.

Edit: To clarify, the 1-2-all sw only controls the engine source. House bank has a breaker tied to house bank that leads to panel. This keeps volt dips when starting from affecting house bank and loads.

When anchored, engine sw back to "1", so start bank is isolated from house loads.

Thruster batt is stand alone, up near unit, only connection is a charge relay tied to house bank.

Now not sounding as simple!! But it really is.

 

[Larry M]

We went with one large house bank with it's own alternator and voltage regulator. The engine also has it's own battery with another alternator and voltage regulator. Two simple, separate systems with no interconnecting switches. We carry a spare alternator and voltage regulator than are interchangeable with either the house or start side.

The generator is independent with it's own battery and alternator which feeds the boats charger/invertor system.

Going on 9 years we've never had to jump from one side of the system to the other. We do carry cables just in case though.

 

[Hawgwash]

Two simple, separate systems with no interconnecting switches. We carry a spare alternator and voltage regulator than are interchangeable with either the house or start side.

I know, "it depends" but can a second alternator be easily mounted to most engines?

Larry, what is your "large house bank" and what size are your 3 alternators?

Also, the word "combiner" has not been used in this thread; does that go without saying or not used in a single setup?

 

[Pack Mule]

The PO put an extra on ours facing the engine .It is a
Leece Neville

 

[Ski in NC]

I know, "it depends" but can a second alternator be easily mounted to most engines?

Larry, what is your "large house bank" and what size are your 3 alternators?

Also, the word "combiner" has not been used in this thread; does that go without saying or not used in a single setup?

It truly depends on the engine, some are fairly easy to add a second alt, some are a real pita. And all second alts must be "engineered". I have seen a number of hack jobs and that does nothing for system reliability.

Combiners can be used, but can add other failure modes and problems. The diode based ones have a voltage drop which screws up charging. The relay based ones are much better in that regard. I chose not to use one in keeping with my "simple" design theme. That's also why I put the batt sw under the galley sink for easy access from helm. Same with second alt, as my engine is in the pita category.

 

[Larry M]

I know, "it depends" but can a second alternator be easily mounted to most engines?

Larry, what is your "large house bank" and what size are your 3 alternators?

Also, the word "combiner" has not been used in this thread; does that go without saying or not used in a single setup?

Ted on O C Diver, has a John Deere. There's a thread about his upgrade that shows the alternators I believe. We have a FL SP135.

Our house bank has 10 Trojan T-105s. The alternator (s) are 110 amp single pulley with Ample Power voltage regulators and temperature sensors.

We don't have a combiner but had one on our last boat. In 10 years we never had an issue. That was also made by Ample Power.

 

[Hawgwash]

The alternator (s) are 110 amp single pulley with Ample Power voltage regulators and temperature sensors.

Thanks Larry. So if one alternator packs it in, you just buy a new spare?

In 10 years have you had to use the spare and if kept properly would an unused spare deteriorate over time?

 

[markpierce]

Self explanatory:



But rarely have the parallel switch at the "on" position.

 

[Larry M]

Thanks Larry. So if one alternator packs it in, you just buy a new spare?

In 10 years have you had to use the spare and if kept properly would an unused spare deteriorate over time?

If I can't rebuild it (I carry bearings and brushes), I take it to an alternator shop. Last year a stator failed. I was able to buy a new "rebuilt" for $225 with the core trade in.

In 17K miles, I've only changed bearings and brushes once on each alternator. The bearings were getting loud in one so I put the spare on. When we got back to the states, I changed brushes and bearings on both. Changing the bearings and brushes is pretty easy.

On most of our engines, the alternator and engine cooling water pump are driven from the engine's main pulley from the same belt. If you loose the engine's alternator because of a bearing failure, you can't run the engine.

I store the spare in a box under our berth and so far moisture has not an issue.

 

[Hawgwash]

Larry, thanks for taking the time.

 

[O C Diver]

Some pics of my setup:

There is a second serpentine belt pulley added to the crank. The alternator is mounted to a plate off the engine mount.



We had to fabricate the engine mounts anyway. So in the process, we made them extra heavy duty. The plate is 3/8" stainless steel. It's rock solid, no flexing at all.



There are 2 grey boxes in the center of the picture. Top one is a Guest battery switch for disconnecting the house battery bank. Lower box is a switch to combine the batteries and alternators. Insert the red key and 1/4 turn. The red box all the way to the right is the Sterling external voltage regulator for the second alternator.



Ted

 

[Wxx3]

In my opinion you should connect all the house batteries together for one large house bank.

Then set your charging system up so the output from your alternator is properly split to charge both your start battery and your house bank while keeping them isolated from each other. Then use a simple on/off switch to connected the start and house banks together to jump the house to the starting battery if needed to start the engine.

On shore power charge the house bank off a high amp charger or inverter/charger and charge the start battery off its own lower amp output charger. Get a two output charger for the start battery and that can keep the gen battery charged as well.
.

Yep. That works well. My Balmar smart Regulator charges both the house bank and starter battery.

I have two sets of Perko switches, so can run house/start in any combo.

I never switch it though, everything is happy as it.

I have additional 120/240v chargers for house bank and Gen battery.

Lastly, I have a pair of jumper cables should any of the above not work.

 

[Wxx3]

If I can't rebuild it (I carry bearings and brushes), I take it to an alternator shop. Last year a stator failed. I was able to buy a new "rebuilt" for $225 with the core trade in.

In 17K miles, I've only changed bearings and brushes once on each alternator. The bearings were getting loud in one so I put the spare on. When we got back to the states, I changed brushes and bearings on both. Changing the bearings and brushes is pretty easy.

On most of our engines, the alternator and engine cooling water pump are driven from the engine's main pulley from the same belt. If you loose the engine's alternator because of a bearing failure, you can't run the engine.

I store the spare in a box under our berth and so far moisture has not an issue.

All good ideas.

On Larry's advice, I have a spare alternator, but not a "real" one! It's a Hitachi also built by Neville ?? and has the same bracket and pulley as the real one. The only difference is that being for a car, it weighs about 1/3 as much.

Which means that I can not use it to recharge house bank, but then if needed for long tern, I can run the Gen to do that.

I keep ti stored in plastic tupperware in the ER as it is the driest place in the boat.

 

[Bay Pelican]

We went with one large house bank with it's own alternator and voltage regulator. The engine also has it's own battery with another alternator and voltage regulator. Two simple, separate systems with no interconnecting switches. We carry a spare alternator and voltage regulator than are interchangeable with either the house or start side.

Similar set up to Larry. Although my main, wing and generator all start off of the house bank. I have a separate under the helm 12 volt battery which is used to power the SSB. It is independent and isolated except when charging.

It can start the generator if need be. It and its predecessors have started perhaps six engines on other boats where the batteries were dead. I just pick up the separate battery, add jumper cables and go off and play jump start.

Gotten a few bottles of wine and new friends for my troubles.

 

[Panhandler]

Is there a reason why voltage sensitive relays aren't used on single alternator boats instead of the traditional Perkins style 1/2/all/off switches? For instance, Marinco/BEP makes a VSR that automatically charges the start battery until it hits a certain voltage then charges the house bank. There is a manual switch to combine banks in case of emergency. I believe blue seas makes a similar product.

 

[JDCAVE]

I have a single alternator, charging the house bank. It's an Amptech 125. I have an identical,one as a spare, still in its box. It's an easy fix if the alternator fails. I have a Balmar digital duo charge, that in theory looks after the starter bank, but currently isn't functioning properly and work on it is on the spring"to do" list. The PO has hooked up the Blue Sea smart charging relay with remote switches for the helm. I don't use this setup to charge the starter batteries as they are Group 24's and the house bank comprises 10 T105's. So, the start batteries are not combined with the house bank unless the windlass is in operation. The starter batteries have a dedicated charter when on shore or generator power. Still there's a bit of work to do here.



The Genny also has a dedicated start battery, that is separately charged. The bow thruster is 24 volt and also has a dedicated charger and separate AGM bank under the master berth.


Jim
Sent from my iPad using Trawler Forum

 

[FF]

"Is there a reason why voltage sensitive relays aren't used on single alternator boats instead of the traditional Perkins style 1/2/all/off switches? For instance, Marinco/BEP makes a VSR that automatically charges the start battery until it hits a certain voltage then charges the house bank. There is a manual switch to combine banks in case of emergency. I believe blue seas makes a similar product.


Cost , complexity and reliability.

Why bother ????

when for nothing you rotate a switch one notch, or for $18 you don't have to rely on unrepairable transistor toys that require a mechanical backup?

 

[Panhandler]

"Is there a reason why voltage sensitive relays aren't used on single alternator boats instead of the traditional Perkins style 1/2/all/off switches? For instance, Marinco/BEP makes a VSR that automatically charges the start battery until it hits a certain voltage then charges the house bank. There is a manual switch to combine banks in case of emergency. I believe blue seas makes a similar product.


Cost , complexity and reliability.

Why bother ????

when for nothing you rotate a switch one notch, or for $18 you don't have to rely on unrepairable transistor toys that require a mechanical backup?

Gotcha, thanks

 

[Capt.Bill11]

Gotcha, thanks

Well, there are used and they work quite well and reliably. At least the ones I've installed or been associated with have.

 

[Panhandler]

Well, there are used and they work quite well and reliably. At least the ones I've installed or been associated with have.

Yeah, I've got one on my center console that's been awesome. But it's a smaller setup...

 

[psneeld]

definitely have to be careful of the mismatch of house bank size versus engine start...not just any VSR will work.