Alternator monitor

[romantic comedy]

Neil, I dont go in for any of those electronics. I was just wondering though. I see a lot of guy who have all the stuff and it is often broken.

I still have points!!

[joe_db]

The various battery monitors that do a running total of AH in and out can be somewhat temperamental.
I used to sell and install them. Besides for outright breaking, the biggest issue is eventually drifting off track and not knowing when the battery is full. I like to experiment, so there are a couple I might try. Generally, given an accurate voltmeter, ammeter(s), and some experience you can get a pretty good feel for your battery condition without the AH totalizer.

[Al Schober]

I'm leery of this 'Chinese' instrumentation. Had a couple of digital voltmeters that I ended up putting in the trash - couldn't get them to agree with my other meters. Like they say with nuclear disarmament - Trust but Verify.

[ndutton]

Here, compare and contrast (view outboard as a generic engine with alternator). One battery switch or four?

[joe_db]

My hit rate on Fleabay Chinese meters is about 75% good and 25% trash. At $10-$20 or so per meter, it works out OK in the end.
OTOH Victron makes well respected meters and they can be had for about $150 or so on Fleabay. Search for BMV700.

I'm leery of this 'Chinese' instrumentation. Had a couple of digital voltmeters that I ended up putting in the trash - couldn't get them to agree with my other meters. Like they say with nuclear disarmament - Trust but Verify.

[Bratina]

Welcome back, Russ!

We missed you. Now if we can just figure out where Mo went....

Bill

http://www.moyermarine.com/forums/showthread.php?t=9960

Woo hoo!

[toddster]

Here, compare and contrast (view outboard as a generic engine with alternator). One battery switch or four?

[ATTACH]12175[/ATTACH]

[ATTACH]12176[/ATTACH]

It appears to me that one might simplify that a bit by substituting circuit breakers for the three on/off switches and their associated ANL fuses. (At least for our A4 -sized systems.)

Then consider other high-amp loads not shown there, that are too big for the house panel. Windlass, SSB radio, inverter... One ends up with a main service panel fed from the main hot bus. Well, unless you have a really beefy house panel.
Edit: Wow, I see those Blue Sea panel breakers come in sizes up to 50 amps!

[joe_db]

I use a 150 amp breaker instead of a switch for my alternator service disconnect. My SSB runs from the house panel, but the 1000 watt inverter has its own switch and another 150 amp breaker.

It appears to me that one might simplify that a bit by substituting circuit breakers for the three on/off switches and their associated ANL fuses. (At least for our A4 -sized systems.)

Then consider other high-amp loads not shown there, that are too big for the house panel. Windlass, SSB radio, inverter... One ends up with a main service panel fed from the main hot bus. Well, unless you have a really beefy house panel.
Edit: Wow, I see those Blue Sea panel breakers come in sizes up to 50 amps!

[ndutton]

Is it because we can?

Both diagrams are essentially for battery management, both are managing only two banks. If we ignore the shore power charger, solar and the bilge pump in the complex drawing, both systems achieve the same end result, starting the engine and charging the battery banks. Both have the means to disconnect the alternator, both can start and charge either bank or combine them.

For my tastes one is a little too simple, the other too complicated for a simple result. My boat's battery management system favors the simpler design but with slightly more complication. I manage three banks independently or in any combination, have the ability to isolate an engine starter battery and disconnect the alternator and I use only two 1-2-Both battery switches, half the number in the complex drawing that manages only two banks.

It seems to me one design is unnecessarily complicated, intended to impress. Impress who? I dunno, maybe a paying customer?

[toddster]

Dunno. Other than level of detail and plus or minus a few toys, the main difference is separation of the house and starting loads. If you had large diesel engine(s) and large house loads, you might want to use separate battery banks with different characteristics for these tasks. (Well, you could do that with the first system too, with a lot of manual switch-flipping.) But for our engines, I doubt that it would make any difference. To me, the second battery is just there as an emergency backup.

My system is also somewhere in between the two examples. But it has suffered from the sins of growing over time. Sometimes I think that I should spend a Sunday making a large drawing that shows how every possible gadget that I might add in the future would link in. So at least there would be a plan to follow.

I might want to add solar panels and a charging relay at some point in the future. But I can't seem to find any enthusiasm for running separate cables to the alternator. Also looks like a goof in the second diagram because the bilge pump is the only load that can't be run from the reserve bank, in the event that the primary bank dies.

[ndutton]

Other than level of detail and plus or minus a few toys, the main difference is separation of the house and starting loads.

I've engaged the author of the complex system drawing numerous times on numerous topics. One of our points of contention is charging automation (ACR's/combiners). He argues for automation because it eliminates the need to turn battery switches for charging and the inevitable error of switching through 'Off' resulting in poofed alternator diodes, also argues automation charges battery banks faster and better. The example of guests fiddling with the battery switch is always brought up. Then, he comes up with a design with FOUR battery switches despite the ACR!! Sounds like someone isn't listening to his own arguments.

[toddster]

Even with some automation for charging, you need some way to switch the reserve battery in. I'd think the main failure mode for the full manual system is forgetting to decombine the batteries after killing the motor, then leaving something on that drains both banks. But as noted above, I agree that the switches are redundant, unless you just don't like switchable circuit breakers for some reason.
Also, in my thinking, a battery terminal fuse, sized for the largest wire, can eliminate a lot of those downstream fuses, as long as you carry that gauge to all the major components. Which shouldn't be a problem for Atomic-4 based systems.

BTW, the only time I needed the reserve battery in the last couple of years was when a guest flipped on the cockpit instrument light switch, which went unnoticed in the summer sun, and drained the main battery during the week.

Um... OK, I may have left the VHF on once. Because it's very quiet where I live.

[joe_db]

YMMV a lot depending on what you are trying to do.
I had a lot of customers, myself included, that do not want to deal with transient voltage spikes throughout all the navigation and comm gear when starting the engine. Others are not bothered by this or don't have enough to worry about.
Another thing is when battery banks get large, alternators get large, and you have battery chemistry that can charge at 1/2C, you really don't want to route well over 100 amps of charge current through the little start battery on the way to the huge house bank. I had customers with twin 160 amp alternators and over 1000 AH house banks.

Even with some automation for charging, you need some way to switch the reserve battery in. I'd think the main failure mode for the full manual system is forgetting to decombine the batteries after killing the motor, then leaving something on that drains both banks. But as noted above, I agree that the switches are redundant, unless you just don't like switchable circuit breakers for some reason.
Also, in my thinking, a battery terminal fuse, sized for the largest wire, can eliminate a lot of those downstream fuses, as long as you carry that gauge to all the major components. Which shouldn't be a problem for Atomic-4 based systems.

BTW, the only time I needed the reserve battery in the last couple of years was when a guest flipped on the cockpit instrument light switch, which went unnoticed in the summer sun, and drained the main battery during the week.

Um... OK, I may have left the VHF on once. Because it's very quiet where I live.

[ndutton]

That's how mine is. I start on a dedicated start battery completely isolated from all other systems, engine only. This is easily managed through a simple 1-2-Both battery switch. When the engine is warmed up I switch in the house banks for charging and switch off the engine starter battery - in that order.

[BadaBing]

I use a 150 amp breaker instead of a switch for my alternator service disconnect. My SSB runs from the house panel, but the 1000 watt inverter has its own switch and another 150 amp breaker.

Is it safe for the alt to turn these switches on and off while the engine is turning and the alt is producing?