V42 charging system

[Alphadug]

Hi gang, I searched for this topic and didn't find anything. Has anyone rewired a 2015 V42's convoluted alternator charging system? I'm getting different ideas from my local "experts". I would like to remove the bow and stern thruster batteries and supply power from the house bank (460Ah AGM). This would involve removing the 2 ECS Alternator charge splitters and devote all of the Alternator output to the house bank. I would need to run some rather large wire to the bow and stern thrusters to power them. I would probably use some sort of Echo Charger or B2B Charger to keep the start battery charged. If I can make this new configuration work I'll eliminate 4 batteries and make the house bank bigger. I have 610W of Solar Panels that work great while at anchor for extended periods.

Thoughts? or am I crazy?

Thanks,
Doug

[tiger79]

You'll need to run some huge cables from the house bank to the thrusters; the cables will be costly and difficult to thread through the boat.  Plus you'll need big fuses or breakers to protect the cables.  Assuming the original system works, why change it?

[symphony2]

Not sure what you are hoping to achieve by doing this. You already have the "best" setup which works. The alternator should always charge the its own start battery first a it is critical that this receives the first charge before any excess alternator output is directed towards the other banks.

[tiger79]

The alternator should always charge the its own start battery first a it is critical that this receives the first charge before any excess alternator output is directed towards the other banks.

This is a popular belief, but It doesn't do this - the alternator output is shared between the various batteries, which each accept current according to their state of charge.  Starting an engine removes very little charge from the starter battery, so it is rapidly replaced.

[symphony2]

The suggestion was to devote all the alternator to the domestic bank then maybe charge the engine start with a B2B which means that the engine battery will only get charged when the domestic reaches the state of charge that is et on the B2B. Hence my question about what he is trying to achieve as he is losing a direct charge from the engine to its start battery.

[Alphadug]

Hi again, thanks for your input and ideas. I figure that the charge lost to starting the D240 is negligible. I probably use more power for the glow plug. If I get worried about the state of charge in my start battery I could run the inverter and the start battery charger.

Yes, the cables to the thrusters/windlass will be large, probably 4/0. My options are to replace the batteries every 8 or so years at a cost of $1200 to $1600 (Canadian) or install big copper wire once. I need to make sure I can find a short route from the house bank to the 2 thruster banks, probably not going to be easy, but I'm a boater and love a challenge. There's good space around the H/C water lines. Unfortunately the wire costs about $15.00 per foot (unless I can work a deal or find a better supply). Won't an Echo Charger or B2B turn on when the motor is running as the voltage will be high going to the house bank?

The reasons this whole mess came up is 1) my house bank is totally shot and I want to enlarge it when I replace it. 2) The bow thruster bank does not get adequate charge from the alternator and will shut down due to low voltage. It doesn't get charged from the solar array.

Again, thanks for your input/ideas.

Doug

[tiger79]

Yes, the cables to the thrusters/windlass will be large, probably 4/0. My options are to replace the batteries every 8 or so years at a cost of $1200 to $1600 (Canadian) or install big copper wire once.

If you plan to keep the boat a long time, this may be worth doing.

Unfortunately the wire costs about $15.00 per foot (unless I can work a deal or find a better supply).
 

You might look at using welding cable, which can work out cheaper.

Won't an Echo Charger or B2B turn on when the motor is running as the voltage will be high going to the house bank?
 

Depends on the charge state of the house bank.  If it's low, it will pull down the alternator voltage.  But as the charge state rises, the voltage will rise and the echo charger will kick in.  Starter batteries don't take much to recharge.

The reasons this whole mess came up is ....2) The bow thruster bank does not get adequate charge from the alternator and will shut down due to low voltage.

Why not? If it's being fed from the charge splitter it should have the same charging voltage as the house bank.  Could the battery be faulty?

[Alphadug]

Good question. I think the battery sense wire is on the ECS. The wire running all the way to the bow carrying the charge current is only #10 AWG, #8 at best. I feel there is a bit of voltage drop occurring. Could be too little to worry about though. I hope to get to the boat next week and check the actual size and where the sense wire is connected.

Doug

[JEN-et-ROSS]

Hi again, thanks for your input and ideas. I figure that the charge lost to starting the D240 is negligible. I probably use more power for the glow plug. If I get worried about the state of charge in my start battery I could run the inverter and the start battery charger.
Doug

Since our 'Domestic' Battery bank and the 'Engine Start' battery use the same 'Common Ground'...
I simply added a heavy Interconnecter between the 'Positive' poles of the Domestic bank and the Positive pole of the Start battery with a very high capacity switch between the two...
This switch is normally 'OFF'.. But to start the engine with a dud start battery, just switch it 'ON'....................Bill.

[tiger79]

Since our 'Domestic' Battery bank and the 'Engine Start' battery use the same 'Common Ground'...
I simply added a heavy Interconnecter between the 'Positive' poles of the Domestic bank and the Positive pole of the Start battery with a very high capacity switch between the two...
This switch is normally 'OFF'.. But to start the engine with a dud start battery, just switch it 'ON'....................Bill.

That's not a great solution, because you are putting a flat battery and a charged battery in parallel - the charged battery will discharge into the flat battery.  Better wiring options are available.

[JEN-et-ROSS]

Since our 'Domestic' Battery bank and the 'Engine Start' battery use the same 'Common Ground'...
I simply added a heavy Interconnecter between the 'Positive' poles of the Domestic bank and the Positive pole of the Start battery with a very high capacity switch between the two...
This switch is normally 'OFF'.. But to start the engine with a dud start battery, just switch it 'ON'....................Bill.

That's not a great solution, because you are putting a flat battery and a charged battery in parallel - the charged battery will discharge into the flat battery.  Better wiring options are available.

Indeed....
I guess I didn't make it clear that the adaptation was made to deal with the rare event that the 'Start' battery didn't have sufficient juice to start the engine..
Then, and only then could you, at the turn of a switch, rapidly and easily redirect oodles of power to start the engine (and possible get out of trouble) and immediately disconnect the two banks again....
Much, much faster than trying to find, unfankle and connect a pair of 'jump leads' in a panic...
No. the Start and Domestic bank would never ever be left connected..........Bill..

[tiger79]

Indeed....
I guess I didn't make it clear that the adaptation was made to deal with the rare event that the 'Start' battery didn't have sufficient juice to start the engine..
Then, and only then could you, at the turn of a switch, rapidly and easily redirect oodles of power to start the engine (and possible get out of trouble) and immediately disconnect the two banks again....
Much, much faster than trying to find, unfankle and connect a pair of 'jump leads' in a panic...
No. the Start and Domestic bank would never ever be left connected..........Bill..

Rather than putting the emergency switch between the positive poles of the batteries, you should have put it between the positive pole of the house bank and the engine side of the start battery isolator.  If you find the start battery won't start the engine, turn off the start battery isolator and turn on the emergency switch.  When the engine is running, turn on the start isolator and turn off the emergency switch.

[JEN-et-ROSS]

Indeed....
I guess I didn't make it clear that the adaptation was made to deal with the rare event that the 'Start' battery didn't have sufficient juice to start the engine..
Then, and only then could you, at the turn of a switch, rapidly and easily redirect oodles of power to start the engine (and possible get out of trouble) and immediately disconnect the two banks again....
Much, much faster than trying to find, unfankle and connect a pair of 'jump leads' in a panic...
No. the Start and Domestic bank would never ever be left connected..........Bill..

Rather than putting the emergency switch between the positive poles of the batteries, you should have put it between the positive pole of the house bank and the engine side of the start battery isolator.  If you find the start battery won't start the engine, turn off the start battery isolator and turn on the emergency switch.  When the engine is running, turn on the start isolator and turn off the emergency switch.

Yes, I could have, but since the 'House Bank' and the 'Engine Start' battery are mounted side by side under the port saloon seating, it made sense to keep the cable as short as possible and mount the emergency switch on the outside of the settee between the 'house' and 'engine' batteries....It was just convenience as the isolator switches are mounted above the Nav table ( about 2m away )....Bill.