Battery switch does not kill power

[dlochner]

There was a previous post mentioning the danger of connecting the alternator to the 300Ah LiFe04 house bank. "Those three battle borns will demand 100 percent of your alternator and likely overheat it without some type of regulation. " - Heritage
I have only begun to research voltage regulators, so if there is a danger of damaging my alternator, I may need to hold off on rewiring the switch until I have the proper protection.

Somewhere back in the thread I seem to recall that you have a 50 Amp alternator. That it is connected to the starter and not directly to the house bank leads me to believe the alternator is the stock alternator. The stock alternator won't be burned up by the LiFe04 batteries because the regulator will cut back the voltage way too early. It also means the stock alternator won't do a good job charging the batteries.

To do a good job keeping those LiFe04 batteries charged it will be necessary to have a higher powered externally regulated alternator. Take a look at this article. Musings Regarding External Voltage Regulation

 

[Marrigoround]

I do have a stock 50 amp alternator. The fact that it is connected directly to the starter battery is a result of me doing so. I can just as easily connect it to the common post on the 1/BOTH/2/OFF switch.

I am considering an externally regulated alternator, however I plan to experiment on the efficacy of the solar panels as the main source of charge before diving down that rabbit hole. The alternator is connected directly to the positive post on the starter, which makes the starter cable perform both functions. Not sure if this is common or desirable...

 

[dlochner]

Hard to believe that there are rabbit holes on boats...

Connecting the alternator output to the starter is convenient for the boat builder because there are fewer cables to install. It is convenient for the engine manufacturer because it reduces warranty claims on fried alternators and is a marketing strategy, one less cable to run, so the install is cheaper and easier for your over worked employees; more profit margin or lower selling cost to the consumer.

The alternator to starter wiring ensures the battery that started the engine will get the benefit from the alternator and will charge first. However, starting an engine takes a lot of current for a very short time, as a result very little battery capacity is used when an engine is started. This is handy because it keeps the start battery charged. On the other hand, it causes problems with battery combiners because the alternator senses the start battery and reduces its output as a result the combiner cuts in and out and the house battery does not get the full benefit of the alternator charging. The process is more nuanced than this description, but my description is more or less correct. If the house and start batteries are equal and the 1-2-Both switch is used properly, this is not a big issue. However, when the house and start batteries are different sizes or types, connecting the alternator to the starter just doesn't cut the mustard on keeping both banks charged.

While electrons behave pretty much the same everywhere, on cars, boats, houses, and space ships. How they are controlled and directed varies a great deal on where they are; boats, cars, houses, and space ships have different issues. We won't even talk about the differences between wood, fiberglass, steel and aluminum boats.

Read and reread the articles on the Musings with MaineSail forum page and on MarineHowTo.com. There is a lot to learn, I'm thinking you know that by now.

 

[Stu Jackson]

So, it seems like I will need to rewire the switch thusly:
C - Distribution panel, charger/inverter, alternator
1- House Bank
2- Start battery

When you get the time to read the links, you'll find this is wrong. The C post should only be to the starter and DP. The AO should go to the house bank, and the start bank gets charged via the combiner/ACR. Ditch the isolator (again).

This ^^^ assumes you've upgraded to an external regulator regardless of what size alternator.

 

[Marrigoround]

Stu, thank you for responding to this specific question. I have read through the links and am still working on the best way forward.

1. Per one of your suggested links, the charger was recommended to be connected directly to the house bank. I have a Victron multiplus 3000. Can I rely on the switch on the unit, or would I need to install another emergency switch? I have a 400 amp fuse at the house bank.
2. In your suggestion, ditching the isolator would force the charging current through the small 12AWG wires of the Magnum Energy Smart Battery Combiner. It was my impression that the isolator (solenoid) provided that function with its 2AWG wires and 200 amp breakers on either side. Are you suggesting that this system is decidedly incorrect/non-functioning/unsafe or is it simply that I should have gone with the Blue Sea ACR in the first place, but what I have now is fine?
3. Do you have any suggestions on an external regulator for my 55amp alternator?

 

[heritage]

Somewhere back in the thread I seem to recall that you have a 50 Amp alternator. That it is connected to the starter and not directly to the house bank leads me to believe the alternator is the stock alternator. The stock alternator won't be burned up by the LiFe04 batteries because the regulator will cut back the voltage way too early. It also means the stock alternator won't do a good job charging the batteries.

To do a good job keeping those LiFe04 batteries charged it will be necessary to have a higher powered externally regulated alternator. Take a look at this article. Musings Regarding External Voltage Regulation

The problem with trying to charge LiFePo4 batteries with a stock internally regulated alternator is that the LiFePo4 battery will demand a high amperage and will do this without raising it's voltage enough for the regulator to reduce the alternators output. A lead acid battery's voltage under the same conditions will quickly increase and reduce the output of the alternator. That's why the your stock alternator needs some type of additional regulation to charge your house batteries. Either a dc to dc controller or an external regulator with a LiFePo4 setting.

 

[twalker H260]

Based on the magnum smart battery combiner manual and your original drawing it looks like you are wired for ampacity over 25amps which requires the combiner to have the battery connections be made through an appropriately sized and fused solenoid. (Wired as p8 of manual) using wire appropriate for the anticipated ampacity. (Others can likely say more definitively what this would be but I would base it on your alternator output with a bit extra - say 60amps.)

if it is a solenoid and not an isolator wired as shown on pg 8 Of manual (and in your diagram) Then you should be good - it may be that it is just a question of the terminology you’ve been using as in this case it isn’t acting as an isolator but rather as an integral part (switch) to the combiner. I think you indicated that wires from positive busses to the solenoid are 2guage? This is ample for current and likely any future size alternator. The only question I would have is are the breakers located a few inches from the buss bars And not just either side of the solenoid?

manual:

https://www.magnum-dimensions.com/file/2258/download?token=nih8T-F8

hopefully this helps clarify rather than confuse further!

 

[Marrigoround]

@twalker H260 Yes, thank you for your clarification. It is indeed a solenoid (link here) acting as an isolator.

The breakers are physically located a couple of inches above the solenoid and are wired according to the screenshot pasted below:

 

[Stu Jackson]

heritage is correct in what he wrote.

Per one of your suggested links, the charger was recommended to be connected directly to the house bank. I have a Victron multiplus 3000. Can I rely on the switch on the unit, or would I need to install another emergency switch? I have a 400 amp fuse at the house bank.

What switch on the Victron? If it is an I/C, then the heavy inverter wire goes to the house bank anyway and is used for charging with the power simply going in the opposite direction. I have a Freedom 15 I/C, 2/0 wire to the house bank.

In your suggestion, ditching the isolator would force the charging current through the small 12AWG wires of the Magnum Energy Smart Battery Combiner. It was my impression that the isolator (solenoid) provided that function with its 2AWG wires and 200 amp breakers on either side. Are you suggesting that this system is decidedly incorrect/non-functioning/unsafe or is it simply that I should have gone with the Blue Sea ACR in the first place, but what I have now is fine?

Sorry I haven't the time to get into the details of your Magnum as has twalker. But the CONCEPT is that with ALL charging sources going to the house bank, and the combiner serving only the start/reserve bank, the reserve bank only needs very little current, hence smaller wires.

Do you have any suggestions on an external regulator for my 55amp alternator?

Only two, both Balmar, but I'd go for the MC-614. The 614 replaced the 612.
Differences between Balmar MC-614 and ARS-5 Regulators 101

External regulation
Why oh why.......

Programming a Balmar External Voltage Regulator
Programming a Balmar External Voltage Regulator

You'll also need to read up on using the amp manager to avoid burning up your alternator.