One Starting Battery For Two Engines ?

[nnyerges]

Based on all observations, I will rethink the design, to create version 2.0. I have only two last questions:

1. In case of an emergency, if I need to use the battery to start the GENSET engines, can I leave the GENSET ON or Should I turn it off?

2. The ISOLATOR of my drawing is a 2ALT IN and 3BATT OUT type. The outputs are connected in parallel with the INVERTER/CHARGER. That’s OK. The question is: Can I connect the third remaining ISOLATOR output in parallel with the GENSET alternator?

[nnyerges]

Based on all observations, I will rethink the design, to create version 2.0. I have only two last questions:

1. In case of an emergency, if I need to use the battery to start the GENSET engines, can I leave the GENSET ON or Should I turn it off?

2. The ISOLATOR of my drawing is a 2ALT IN and 3BATT OUT type. The outputs are connected in parallel with the INVERTER/CHARGER. That’s OK. The question is: Can I connect the third remaining ISOLATOR output in parallel with the GENSET alternator (genset battery positive bus) all the time? I think its the same case as connecting a parallel switch between to starter batteries (paralleling a starboard & port engines alternators), but with the advantage of having a diode through them

[nnyerges]

Is a way to edit posted messages in this forum?
ERRATA ON QUESTION#1

Originally Posted by nnyerges

Based on all observations, I will rethink the design, to create version 2.0. I have only two last questions:

1. In case of an emergency, if I need to use the battery to start the GENSET engines, can I leave the GENSET ON or Should I turn it off?

2. The ISOLATOR of my drawing is a 2ALT IN and 3BATT OUT type. The outputs are connected in parallel with the INVERTER/CHARGER. That’s OK. The question is: Can I connect the third remaining ISOLATOR output in parallel with the GENSET alternator (genset battery positive bus) all the time? I think its the same case as connecting a parallel switch between to starter batteries (paralleling a starboard & port engines alternators), but with the advantage of having a diode through them

QUESTION #1 should be:

1. In case of an emergency, if I need to start the engines with the GENSET battery, can I leave the GENSET ON or Should I turn it off?

QUESTION #2 its OK

[nnyerges]

If my design where with the ideal of one starboard engine battery, one port stating engine battery and the house battery, it was a perfect match for using a dual VCR or ACR. My design is only with only one starting battery for both engines and one house battery, with two alternators charging the starting battery and the house battery. The third battery is only for the GENSET (depending of question #2). I want/need only 3 batteries, if I can use two independent batteries for each engine and the house battery and have the GENSET's starting from one of those batteries, I will be the happiest marine in the world and I’m sure I will use an ACR. I think the original post could take a 180 degree turn, analyzing how to connect the GENSET's to any of those three batteries.

[djmarchand]

nnyerges:

Since you asked me in a PM to comment on multiple charging sources hooked in parallel, let me throw my 2 cents into this thread. BTW I can't begin to follow the complexity of this thread so I am going to just offer some opinions, whether they are relavent or not.

I believe in one big house battery bank and one adequate size engine starting battery (whether for one engine or two). For redundancy you might want a separate Grp 24 starting battery for the genset, charged by the genset's DC output, but unless you are crossing oceans and TowBoatUS is unavailable, that is probably unnecessary.

If you do cruise outside of TowBoatUS and want some redundancy, there are several ways to get it. If you have a genset and a separate starting battery you can start the genset and then power the shore charger to charge up the house and main engine starting batteries. If you have solar panels you can hang out at anchor for another day or so (but maybe in the dark) and put juice directly into the engine/genset start battery (disconnect the house batteries and jumper directly to the start battery).

In an emergency when the starting battery is dead for some reason, the big house battery bank can start the engines with no harm done to them even if 50% discharged. A pair of battery starting cables can make this work, or you can invest in wire and switches.

I believe in combiners, ACRs, Echo Chargers (although I loathe Xantrex), etc. but not isolators- too much voltage drop and inaccurate charging although you can wire the alternator's voltage sense wire directly to the house and get accurate charging.

I think a boat's electrical system should designed so that on a routine basis it is "set and forget". I think that the house battery should be on the primary side of the combiner (the one tied directly to the alternator(s)) and the starting battery should be the one combined. This lets the larger and longer current sink (the house batteries) have first dibs at the alternator output. If for some reason the combiner fails to combine and the starting battery runs down, see above.

I much prefer simple on/off switches rather than one/two/all switches. If at all possible put them all in one place outside of the engine room so all batteries can be quickly killed in case of an electrical fire. And like I said above, on a routine basis, they never have to be touched.

And finally any multiple charging sources: solar, wind generator, genset, shorepower, etc should be fed to the house battery bank in parallel and then with the combiner, sent to the starting battery. The multiple charging sources will play nice together and find common ground. Well, than pun just snuck in ;-).

AFAIK, the foregoing is consistent with ABYC and good boat electrical design practices. But I have been known to be wrong.

David

[FlyingCloud1937]

Originally Posted by djmarchand

nnyerges:

Since you asked me in a PM to comment on multiple charging sources hooked in parallel, let me throw my 2 cents into this thread. BTW I can't begin to follow the complexity of this thread so I am going to just offer some opinions, whether they are relavent or not.

I believe in one big house battery bank and one adequate size engine starting battery (whether for one engine or two). For redundancy you might want a separate Grp 24 starting battery for the genset, charged by the genset's DC output, but unless you are crossing oceans and TowBoatUS is unavailable, that is probably unnecessary.

If you do cruise outside of TowBoatUS and want some redundancy, there are several ways to get it. If you have a genset and a separate starting battery you can start the genset and then power the shore charger to charge up the house and main engine starting batteries. If you have solar panels you can hang out at anchor for another day or so (but maybe in the dark) and put juice directly into the engine/genset start battery (disconnect the house batteries and jumper directly to the start battery).

In an emergency when the starting battery is dead for some reason, the big house battery bank can start the engines with no harm done to them even if 50% discharged. A pair of battery starting cables can make this work, or you can invest in wire and switches.

I believe in combiners, ACRs, Echo Chargers (although I loathe Xantrex), etc. but not isolators- too much voltage drop and inaccurate charging although you can wire the alternator's voltage sense wire directly to the house and get accurate charging.

I think a boat's electrical system should designed so that on a routine basis it is "set and forget". I think that the house battery should be on the primary side of the combiner (the one tied directly to the alternator(s)) and the starting battery should be the one combined. This lets the larger and longer current sink (the house batteries) have first dibs at the alternator output. If for some reason the combiner fails to combine and the starting battery runs down, see above.

I much prefer simple on/off switches rather than one/two/all switches. If at all possible put them all in one place outside of the engine room so all batteries can be quickly killed in case of an electrical fire. And like I said above, on a routine basis, they never have to be touched.

And finally any multiple charging sources: solar, wind generator, genset, shorepower, etc should be fed to the house battery bank in parallel and then with the combiner, sent to the starting battery. The multiple charging sources will play nice together and find common ground. Well, than pun just snuck in ;-).

AFAIK, the foregoing is consistent with ABYC and good boat electrical design practices. But I have been known to be wrong.

David

David...touche

Here is a recent setup I did. 2 alternators twin engine, all charging the big house bank, 2 MC614's and a centerfielder. One start bank maintained by a digital duo-charge. I did modify the attache schematic, and add an emergency parallel SW between the house start.

Lloyd

[nnyerges]

How about my new design, based on the three basic boat charging condition cases:
1. Cruising: I'll keep using my ISOLATOR (2INx3OUT) connected to the alternator of each engine. The outputs go to the starter battery, house battery and the third output, optionally the generator battery through a switch, to keep that battery charged, just in case that for some reason, do not count with both generators, which is quite unlikely, but can occur. Inverter / Charger OFF.
2. Anchored: Genset ON, as need it, charging his battery and connected to the house and starting battery using two ACR. Inverter/Charger OFF. Both ACR are going to be overridden by the engines starting ON switch, so both ACR's are disabled when engines are running (case 1), to prevent any issues of paralleling alternators.
3. ShortLine. Inverter/Charger ON for all batteries as need it.
NOTES:
1. Negative bus and other protections not show for simplicity
2. Optional two fuses or two ON/OFF switch or one OFF/1/2/1+2 selector switch, to avoir starter-solenoid shorts or failures
3. Optional In case of both gensets unavailable
----------------------------------------------
DIAGRAMS
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Original topic: Twin Engine + Genset + 3 Batteries Configuration
at Twin Engine + Genset + 3 Batteries Configuration

[nnyerges]

Happy New Year to all,

This is the definitive design for my 3 battery/2Engines/2Genset main DC switchboard. I start to connect the panel and planning to finish in the middle of February. Then I will upload some pictures of the installation. The following pictures are in los resolution, but I have uploaded a PDF hi resolution file for each of them.

Circuit diagram:

Simple working diagram:

Board Layout:

[osirissail]

The only glaring thing I can see is that you seem to have the batteries "hot-wired" (connected directly) to the battery switches. It is a very good idea for each battery to have a large bus fuse between the "hot-+" terminal of the battery and then "everything" connected off the downstream end of that bus fuse.

You may have smaller bus fuses thereafter for items like your ACR's, etc. The latest is to have a bus fuse in the engine starter positive lead to protect against stuck starter solenoids - which is a quite common cause of engine room fires.

Small item on the first diagram - the gensets have small (automotive-type) alternators and they are normally connected to the genset starting battery. That is not shown on that diagram.

[nnyerges]

Originally Posted by osirissail

.. The latest is to have a bus fuse in the engine starter positive lead to protect against stuck starter solenoids - which is a quite common cause of engine room fires.

According to ABYC standards (11.6.1.2.3): "except for those wires that are intended to carry starting currents, every positive wire in the DC main power distribution system must be protected by a fuse or circuit breaker". The American Boat and Yacht Council (ABYC) publishes voluntary standards for the type and placement of the fuse or circuit breaker to be used as a DC Main circuit protection device, but wires intended to carry engine starting currents between the batteries, the switch, and the starter, is not required to have main circuit protection devices installed.
It’s up to you if you what to place it. Yo can always add a Blue-Sea like MRBF Battery fuse, using the battery inline fuse block (5191 or 2151). Particularly for me, the block and the fuse have unnecessary voltage drop in the starting bus and it’s not necessary.

Originally Posted by osirissail

Small item on the first diagram - the gensets have small (automotive-type) alternators and they are normally connected to the genset starting battery. That is not shown on that diagram.

Yes you are right. I omitted it. Good suggestion. I should draw the two alternators in the circuit, since they are essential part of the charging scheme. That is the reason of ACR2 connected to the genset BAT2.

[Talbot]

Originally Posted by nnyerges

If my design where with the ideal of one starboard engine battery, one port stating engine battery and the house battery, it was a perfect match for using a dual VCR or ACR. My design is only with only one starting battery for both engines and one house battery, with two alternators charging the starting battery and the house battery. The third battery is only for the GENSET (depending of question #2). I want/need only 3 batteries, if I can use two independent batteries for each engine and the house battery and have the GENSET's starting from one of those batteries, I will be the happiest marine in the world and I’m sure I will use an ACR. I think the original post could take a 180 degree turn, analyzing how to connect the GENSET's to any of those three batteries.

My Privilege 37 has a single 1000 CCA battery to start both engines, a seperate generator battey, and 2 x 6v house batteries.

This works fine, but it is always better to start the engine in the same hull as the start battery first, as the losses due to long battery leads (even big ones) cannot be avoided.

[osirissail]

Originally Posted by nnyerges

. . . Particularly for me, the block and the fuse have unnecessary voltage drop in the starting bus and it’s not necessary. . . .

ABYC, as you stated are voluntary guidelines for the industry that are always changing (slowly). And putting a bus fuse in the engine starter line is not "yet" in the guidelines. And it is, as everything else in the boat - unless your have insurance - strictly your own decision as to whether you want to go with the minimum standards or a higher level of safety.

Of course to the three boat owners that I personally saw with burned out engine rooms due to stuck starter solenoids, having a bus fuse would have saved them mucho dineros and the heart ache of watching the boat burn.

There are even cases in threads here in CF that have shown burned out boats and the prime suspect was stuck starter/starter solenoid.

But as I have said before - it is your butt riding in the boat out there off-shore and therefore your decision.