Your setup is almost identical to ours except we also have 220 watt solar and 200 watt wind. We don't use the wind (or solar obviously) at night so that adds nothing to this discussion. Our energy use is pretty low, the fridge being the only big draw (6 amps to start, tapers to 5) and it runs 1/3 of the time so that is about 50 amps in 24 hours. Other stuff adds another 20-30 amps so we are very close to your usage. We have the same alternator as you but with a Xantrex XAR regulator.

When we start the engine after a day on anchor we will typically see about 45-50 amps going in and that tapers off fairly quickly to the 20 range which is absorption. I understand Xantrex makes Balmar's regs, ours is very adjustable but I am using a standard flooded lead acid profile. Your amps going in sounds low compared to ours, I wonder if your charging profile on the reg is correct?

The solar and wind can top us up pretty much to float during the day, but the charging pattern I see is consistent anytime we start the engine after being at anchor for a night, it will always hit 45 amps and then taper off quickly. This was our third year on this setup and batteries and they seem fine to me. I understand that batteries will last longer with shallow cycles than deep cycles, though you can then get in to discussions of how many amps you get out either way versus cost, etc etc etc.

Perhaps you have a sulfate problem? Does your 110V charger do an equalize cycle? Our IOTA does a short one every 7 days if the batteries haven't been cycled in that time. The solar panel charge controller also does one every 28 days, or at least it tries to do one, 15 amps is not going to raise a 460 amp bank to much of an equalize voltage, maybe high 14 volts at most. You should be able to set your Balmar regulator to do an equalize, but that requires running the engine a lot and you need to monitor the batteries pretty closely as they are going to bubble pretty hard.

You could try discharging them more deeply and see how the regulator responds to that. I find our batteries are a little "lazy" in spring but once we start loading them again they are fine. I leave them in the boat over winter and let the solar panel controller look after them, so far that has worked better than anything I've ever done for winter storage of batteries. They seem to be in very good shape.

Bottom line, your amps going in does seem low compared to what I see with our near identical setup.

Mike,
What Bud said....It sounds like you have really done your homework, and the setup you have is as close to ideal as you can get, according to the electrical gurus on this site. You might want to check the settings on the Balmar regulator. There are several ways it can be "de-tuned" for lower amps, and might be limiting your output. From what I've read, only NiCads have a memory, and not lead-acid batteries, so I don't think that's your problem. I had a similar setup on Julandra and also on Juniper, and when I first start the engine after a night on the hook I see 50-60 amps.

[QUOTE=bstreet;14628] I understand Xantrex makes Balmar's regs, ours is very adjustable but I am using a standard flooded lead acid profile.[/quote]

Actually just the opposite. Balmar built the XAR regulators for Xantrex.

Some thoughts...

If you are only discharging to 80-85% then you are quickly into "voltage limiting" or absorption. Once out of bulk and into voltage limiting the regulator will control the field voltage/current to the alt so as to not over or under shoot the voltage set point.

1- Due to the way a regulator works, where you "sense" the voltage can become critically important. The voltage should be sensed at the batteries + terminal not at the alternator. This requires proper wiring because the sensed bank must also be the "fed" bank by the alt. If your 1/2/BOTH still controls where the alt output goes then you can not "sense" the bank correctly. Without knowing how the reg was wired up it is imposable to say whether voltage drop may be causing the low output... Voltage is pressure and if the batteries are only seeing 13.6V, at the bank, but the reg thinks they are seeing 14.4V then the batteries will accept a LOT less current at 13.6V than they will at 14.4V.

2- Your bank may not be as deeply discharged as you think. The monitor needs to be CAREFULLY programmed so as not to cause counting errors. Counting errors are like compound interest. The longer they go on the bigger the errors get. This is why monitors should be naually re-set to full when the banks are "known full"... Did you program the correct Peukert Exponent # for the batteries? Most don't and this results in poor "counting". Getting the right Peukert number from your battery maker is critical for good performance.

Also, if looking at the Ah's consumed (CE screen) and subtracting you may incorrectly assume you are at a lower overall state of charge than you really are due to Peukert. Without proper programming of the battery monitor then they simply can't count correctly.

The SOC screen is the correct screen to use, not "CE", on the Victron, BUT, it only works correctly when the device is wired and programmed correctly.

[QUOTE=mogline;14625]the monitor may show we are at around 80-85% or so state of charge (meaning we have used 70-90AH). [/QUOTE]

Here's where it gets confusing and I am going to guess your monitor is programmed incorrectly, based on the above statement. Try to follow me on this.

The Ah capacity used for deep cycle batteries in marine applications is a 20 hour Ah rating. Most all battery monitors need this 20 hour rating to be programmed correctly and most all reputable battery manufacturers of deep cycle batteries can supply you with the 20 hour Ah rating. They will also supply you with the Peukert factor for programming a battery monitor.

To figure the load your battery can support to deliver the same Ah's as the 20 hour rating you divide the rated 20 hour Ah capacity by 20.

100Ah Battery / 20 = 5A

So a 100 Ah battery can support a 5A load for 20 hours before falling to 10.5V which is considered dead for the 20 hour capacity test.

60Ah Battery / 20 = 3A

So a 60Ah battery can only support a 3A load for 20 hours before hitting 10.5V.

130 Ah / 20 = 6.5A

And a 130 Ah battery can support a 6.5A load for 20 hours before hitting 10.5V.

As you can see the "rated load" is entirely dependent upon the Ah capacity of the specific battery in question. A 60Ah battery can not be applied the same load as a 160Ah battery and hit it's rated capacity over 20 hours.

But there is a GOTCHA always is......

Here's the catch, it is called the Peukert Effect. In very simplistic terms it means that any load applied to the battery ABOVE the 20 hour rating will result in less Ah capacity. On the other hand any load below the 20 hour rating will result in more Ah capacity.

I think looking at the math will help. This is the math on a 100Ah battery.

[B][U]100 Ah Battery With A Peukert Factor of 1.25[/U][/B]

100Ah Battery - 80A Load = 50 Ah Capacity

100Ah Battery - 50A Load = 56.23 Ah Capacity

100Ah Battery - 40A Load =59.5 Ah Capacity

100Ah Battery - 30A Load = 63.9 Ah Capacity

100Ah Battery - 20A Load = 70.7 Ah Capacity

100Ah Battery - 10A Load = 84 Ah Capacity

[B][COLOR="DarkRed"]100Ah Battery - 5A Load =100 Ah Capacity[/COLOR][/B] (20 Hour Ah Capacity Rating)

100Ah Battery - 3A Load = 113.6 Ah Capacity

100Ah Battery With - 1A Load = 149.5 Ah Capacity

I highlighted the 5A load in red because that is exactly what the divide Ah capacity by 20 gets you too, as I mentioned above.

As you can see any load above the rated capacity at the 20 hour Ah rating results in less Ah capacity. Any load below the 20 hour capacity rating and you have more available Ah capacity..

This is why I almost always cringe when I see people wanting to use large inverters with 80A+ draws on the battery or bank. It can cut your available capacity and without a properly programmed battery monitor you'll not know it.

It is also another reason why a larger bank with smaller loads will survive better.

Take a parallel bank of four 100Ah batteries. You now have a 20 hour rating that can support a 20A load, or 5A per battery, X 4 = 20A. When you run this bank at an average load of say 8A you'll really have 503Ah bank.

If you add just one more battery and make the bank 500Ah's and you'll have a 25A support load, BUT, apply the same 8A load and you have a bank that can deliver 665 Ah's using an average of an 8A load.

Conversely, size your bank small at 100Ah, which would have a 5A support, and still apply the same 8A load and you really only have an 89 Ah bank. Bank size vs. load matters and the bigger the bank and the lower the load the less capacity you use and thus the shallower the discharge cycle. Shallow discharges are good for the battery bank and deep discharges are bad.

This should help explain why we humans, unless perhaps you're Stephen Hawking, can't keep track of Ah capacity by simply watching the amp screen on a simple ammeter.

A battery monitor will make all these calculations for you internally and then represent them as a % of bank capacity. This of course only works well if it has been programmed correctly. For proper programming, at a minimum, you need the banks total Ah capacity, at the 20 hour rate, and the Peukert factor for your specific batteries.

If we look at your 460Ah bank, and guess it has a Peukert of 1.25, and guess your average load is about 6A your bank would produce 643 Ah's before hitting 10.5V, or what the industry considers dead for the 20 hour test.. This means that to get to 80% SOC with a 6A average load you'd need to burn a lot more than 70 - 80 Ah's... The load on a 460Ah bank to hit the 20 hour rating is 23A. Anything less than 23A will result in the bank having more capacity. Battery monitors are only as good as the humans using & programming them...

My guess is that your overall SOC is higher than you think due to the programing in the Victron and the bank is taking what it will take...

Kudos to Maine sail. Impressively written. I learned a great deal from this response.

[QUOTE=mogline;14648]Mainesail,
Thank you. Those ideas make sense and I appreciate the explanation. I have the alternator output running directly to the positive post on one of the batteries and not thru the 12Both switch. But, I am sensing volts for the regulator off of the alternator so I'll change that to the bank. The victory is set with the default 1.25 Peukert factor but I'll contact the manufacturer and see if I can get the actual. One more question. [B]Does the Peukert exponent stay the same if 4 six volt batteries wired in series to get to 12v?[/B][/QUOTE]

Yes... It is basically the internal impedance of the battery so it will remain the same even with series / parallel.

If you are sensing the alt that is your likely culprit. Do you also have a direct wired 4GA neg from the alt to the bank? Engine/case grounds are often very poor and can result in voltage drop at higher currents.. Neg alt wire should always be the same size as the + feed and ideally go straight to the battery or stacked on the cable from engine block to battery. It should not ground to the block...

[QUOTE=Maine Sail;14652] Do you also have a direct wired 4GA neg from the alt to the bank? ...[/QUOTE]

Wondering whether 4ga is sufficient for this amperage in order to avoid a voltage drop. Its about a 20-25' round trip from the alternator to the house bank and back, with all the twists and turns (at least on our boat). On advice of others on this forum I used 1GA when I recently rewired to have a direct cable from the alternator to the house bank (was I oversizing?)

[quote=Chachere;14666]Wondering whether 4ga is sufficient for this amperage in order to avoid a voltage drop. Its about a 20-25' round trip from the alternator to the house bank and back, with all the twists and turns (at least on our boat). On advice of others on this forum I used 1GA when I recently rewired to have a direct cable from the alternator to the house bank (was I oversizing?)[/quote]

I don't think so, our 95's house wiring is all 2/0 and I'm sure it's OEM.

[QUOTE=Chachere;14666]Wondering whether 4ga is sufficient for this amperage in order to avoid a voltage drop. Its about a 20-25' round trip from the alternator to the house bank and back, with all the twists and turns (at least on our boat). On advice of others on this forum I used 1GA when I recently rewired to have a direct cable from the alternator to the house bank (was I oversizing?)[/QUOTE]

At 90A that will result in about a 5% voltage drop.. This is pretty band if sensing the alt but if sensing the bank the reg can overcome it.... Course you'll never be pushing 90A for long anyway....

Regulators simply "limit" voltage. If it is limiting voltage based on the back of the alt, and you have voltage drop in the wire, then the battery bank will see a lower "limited" voltage.

If you sense the bank then the regulator limits to that voltage and thus there is no voltage drop because the regulator actually compensates for the voltage drop in the wire.

[QUOTE=mogline;14758]Good call Mainsail. After changing the sense lead to the battery, not the alternator, amps out jumped up to 37 (initially) on a not real discharged house bank. Balmar's instructions state "the positive output of the alternator, the common side of a battery switch, or the positive post of the battery being charged will work best." [B]Anyone using the
MC 612 should ignore this direction and just wire directly to the battery.[/B][/QUOTE]

Glad I could help!!

For others reading this please keep in mind that UNLESS you also run the alternator directly to the battery being sensed that you SHOULD NOT run the sense wire to the battery bank.

Follow me on this;

You run the regulators sense wire to the house bank but leave the alt wired through the starter lug via the "C" post of the battery switch. You now decide to switch to bank #2 and fire up the motor. The alt does not sense any increase in voltage on the house bank and as such pumps out what ever it can and the voltage on bank #2 climbs to 17+ volts and cooks the battery..........

Only run the regulators sense wire to the house bank if the alternator is also run directly there. Seen a number of banks cooked over the years by folks not understanding what the manual was getting at. Most recently a $450.00 4D AGM battery....:eek:

[QUOTE=Maine Sail;14775]
Only run the regulators sense wire to the house bank if the alternator is also run directly there. [/QUOTE]

Maine -
This may be a stupid question, but, hey, I'm not proud:
As noted in an earlier post in this thread, I recently rewired so that the output of the stock Motorola 55 amp alternator (with its stock internal regulator) on our M25 is now directly fed to the house bank (rather than goes through the 1-2-both switch). Is there something that should be done with the "sensing" -- or it that a non-issue in this context?

[QUOTE=Chachere;14776]Maine -
This may be a stupid question, but, hey, I'm not proud:
As noted in an earlier post in this thread, I recently rewired so that the output of the stock Motorola 55 amp alternator (with its stock internal regulator) on our M25 is now directly fed to the house bank (rather than goes through the 1-2-both switch). Is there something that should be done with the "sensing" -- or it that a non-issue in this context?[/QUOTE]

Not stupid at all. With an internal regulator all you can really do is sense the alt. Some of the Moto alts are key excite and some self excite. The best you can do to avoid VD is to run larger + and - wires to the bank. People ALWAYS forget the neg wire and just assume the case ground or factory neg wire is doing its job, usually not.

See this for more on that: [B][URL="http://forums.sbo.sailboatowners.com/showthread.php?t=143814&#post942773"]Chronic Under Charging? - Check for Voltage Drop[/URL][/B]

[QUOTE=Maine Sail;14778]Not stupid at all. [/QUOTE]
Thanks for that!

At the risk of hi-jacking the thread, let me pose a somewhat related question:
After reading Mainesail's excellent "how to" on battery monitors, ([url]www.pbase.com/mainecruising/battery_monitor&page=1[/url]) I installed a Victron 602 monitor earlier this summer.
However, I noticed that when we are resting at anchor or sailing (i.e., no longer charging via either a shore power connection or the engine) and minimal load on the system (fridge off, etc.), the battery monitor will show maybe 1 amp coming in to the house bank!

I have 2 theories on this:

1) I have been unable to find out what is the Peukert factor for our batteries (a pair of West "SeaVolt" 6V deep cycle flooded) -- nothing indicated on the batteries and nothing on West's website. Could the lack compensation for Peukert factor cause a false reading of a phantom charge?

2) I notice that the cooling fan intermittently runs and indicator lights operate on the shore power charger even when we're off shore power (its an older WestMarine charger they no longer carry). The charger has separate outputs for the 2 banks (house and starter). Maybe its defective in some manner, and is leaking a charge from the starter battery over to the house bank?
Our battery banks are connected with a Blue Seas ACR, but I notice this phenomenon even with the ACR disabled.

Thoughts? Other theories?