Review my charging system changes please

[jr_spyder]

I’ve been evolving the charging system on my boat for better efficiency, safety, and with the ultimate goal of running my generator a lot less. Also both my alternators were dead/dying so it was the right time to start over. My inquiry started with this thread: https://www.cruisersforum.com/forums...rs-218898.html. I’ve read all the relevant resources suggested and learned a lot, and made some changes. I’m down to some last details and would like a sanity check. Here’s an overview diagram of my current system:



Note missing from this is that each alternator has an MC614 regulator with the voltage sense wires connected to the house battery side of the isolator (not ideal). I also have a Balmar SG200 battery monitor. It’s good but not perfect. Once I drew it all out I noticed a few things. 1: There is a distinct lack of fuses on main cables. 2: There is no way my charger/inverter will ever charge my start battery. 3: If I run my generator without the engine switch on it will not charge my starter battery. Also there seems to be a lot of opinion that a diode-based battery isolator is not efficient and sometimes troublesome.

I’ve decided to eliminate the Promariner 2-130-2 isolator, add a Balmar Digital Due Charge unit, and add a lot of fuses. This is the plan I’d like reviewed. Here:



The things I’m changing:
1. Notice both alternators’ positive outputs now connect to each other (and are fused) just before the Main switch. Is this a non-no? I never run the generator and engine at the same time, but I don’t know if there is any risk of one alternator’s output feeding back into the other alternator. The old isolator did not allow this. I don’t think it’s a problem, but just a nagging question. I have not seen a diagram of this sort of setup anywhere.
2. I will move the regulators’ sense wires to the positive terminal of the house bank, and the negative power wires for the regulators to the negative terminal of the house bank so all line voltage drops are compensated for.
3. Adding the Digital Duo means my charger/inverter will now charge my starter battery.
4. I’ll also be adding Sterling Alternator Protection Devices to both alternators.
Other notes: I upsized the new alternators and limited them to lower capacities. The regulators are set to BAL=4 (20% reduction). Both regulators have temp sensors for batteries and alternators. They should stay happy.

Input welcome!

Thanks, JR.

[smac999]

I would run both alts to the always on bus.

2 alts to same house bank is how most 2 engine boats are done and is totally fine.

make sure the voltage settings in the balmars and the inverter charger are the exact same.

for both regulators. you want the voltage sense off the house battery but the power from the start battery. I commonly see the power from the house which will screw you if the house is ever totally dead. because then the alts will not start up.

[YANDINA]

Balmar Duo Charge $225 for 30 amps. Warranty 2 years if purchased from Balmar dealer and installed by qualified installer, 10 year parts warranty limit.
Yandina Combiner 100 $70 for 100 amps Unlimited warranty, currently up to over 25 years free repair/replace.

[jr_spyder]

Thanks for the input. I've spent some time adding more detail to my diagram. It's pretty complete now.

[two-rocks]

Interesting that your multi-bank battery charger is not wired correctly. Or I have it wrong, mine charge the various batteryies but not through the battery switch, which may also be wrong. Factory setup, seems to work.

I'll add that generator run time has many factors to consider - so piling on the money in some areas vs. others may be less than cost effective. Lots of ways to skin a cat. I can't imagine having no solar power, even if you think it's not 'enough'.

[smac999]

The inverter charger needs a battery switch too. For service disconnect.

[two-rocks]

What about a charger, not inverter/charger. I don’t need (or want) the combo....

[jr_spyder]

Originally Posted by two-rocks

Interesting that your multi-bank battery charger is not wired correctly.

Right, I was always suspicious the charger wasn't giving any juice to the starter battery but wasn't sure. Once I chased all the wires and sketched this out I realized I was right, and why. It hasn't been a problem in that the starter battery does very little work and would just hold it's charge with an occasional boost from one of the alternators via the isolator.

Originally Posted by two-rocks

I'll add that generator run time has many factors to consider - so piling on the money in some areas vs. others may be less than cost effective. Lots of ways to skin a cat. I can't imagine having no solar power, even if you think it's not 'enough'.

Understood. So far I haven't spent any money on things that didn't need replacing anyway, but have done those things in a smarter way. The biggest impact on reducing my generator/charging time so far was tweaking the AC side of the generator to put out more volts. It was giving me right around 110vac and with that my old charger/inverter might push 80 amps in bulk mode. I noticed the charge did much better on shore power at 120+vac, so upped the output of the generator to 124vac and now the charger pushes almost 120 amps (full spec) to the batteries. That improves the bulk phase and seems to shorten the full charge cycle.

If my future included a lot more blue water and living on the hook I'd add solar, but my time in the Caribbean is ending this season and I'll be back north and marina based. That shore power cord will get the job done, and 3 to 4 week periods on the move will be fine with the generator. My older classic styled boat just doesn't want solar panels. For the record I do have a small solar panel to trickle charge the batteries when I have to leave the boat on it's own for a while and no loads are on except the bilge pump circuit.

[jr_spyder]

Originally Posted by smac999

The inverter charger needs a battery switch too. For service disconnect.

Good idea. Easy to add.

[Stu Jackson]

Originally Posted by two-rocks

Interesting that your multi-bank battery charger is not wired correctly. Or I have it wrong, mine charge the various batteryies but not through the battery switch, which may also be wrong. Factory setup, seems to work.>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>

I agree, the alternator output(s) should preferably be run directly to the house bank.


Any switch(es) in alternator outputs should be clearly labeled as service disconnects and only opened if working on the alternator(s).