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Old 11-11-2010, 15:17   #16
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I use an amp hour meter (link 2000R) to track battery usage. I assume I have 800 amp hours of capacity (8 x 100ah batteries). When the meter says I have taken out 400ah I know Im at or about 50%. I then run the engine or plug in until the meter goes back down to zero with some give and take. For instance on a weekend cruise I will wake up to about -80 amp hours, then as we get going and motor some it will come back up, I may anchor for the night around -20 or -30 amp hours. Cumulatively if we dont run the engine long enough the amp hours add up and we go further in the hole. Not always though, we may end up motoring for a full day if there is no breeze and then things end up prettty well topped off. As we design our live aboard system I intend to add (4) 135watt solar panels that will hopefully keep us from having to run the engine much but for now we are slaves to the balmar.

Is there anything wrong with using the amp hour approach? I always figured was easier than trying to find out how far I was discharged by looking at a volt meter and then figuring out whether the batteries were really resting or not?
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Old 11-11-2010, 15:28   #17
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I used to use my Link 2000 and watch the amp hours. A funny thing used to happen though. I used to charge it up to maybe -20 amps and when I stopped charging that -20 used to reset to 0. So I did not really trust the damn thing. Do that for 5 days in a row and you've somehow lost 100 amps. I could never understand it and finally gave up. The 2000 crapped out after four years so now I use it only as a volt meter and a switch for the inverter and charger. I am thinking of installing a Victron battery monitor this year. I am sick of Zantrex and their Links. By the way the same thing used to happen on a friend's boat so it wasn't just me.
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Old 11-11-2010, 15:39   #18
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Interesting. Mine only resets to zero if after charging it has gone above zero. So for instance lets say Im down 50 ah and I plug into shore power. After a while the meter goes from -50, -25, -5, +5, +10 etc. So I may end up after sitting on shorepower for a few days with the meter saying +10 -+15 ah. Once I unplug shorepower it resets to zero. But if Im charging off the engine I dont think I have ever gone over zero and so its never reset.

I will say though that I dont fully trust the link as I have seen them crap out on many other boats and in the case of the 2000 R model it has taken out the alt. regulator and left us with no charging capability... I carry a spare alt regulator and plan to get a replacement for the link for when it takes a crap.
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Old 11-11-2010, 18:41   #19
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Hard to do when living when living on the hook. I go down to 50%. I find I'm using the band from 85% to 50% as the last 15% takes a lot of time to charge up.
I found it easier after installing a solar booster and LED lights all over the boat.

Used to be down -80 amp hours after a night @ anchor, but half that now even with the 12 Volt fridge/freeze kicking in now and then.

Been using a Xantrex Battery Monitor for 5 years and found it very useful and an eye-opener for learning 12 Volt managment.

If it gets down to 75% after a few days for anchor and little sun, I run the engine in reverse gear for 20 minuttes or so.
If the sun is baking every day, the two 75 watt panels will keep up with demand.
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Old 11-11-2010, 21:27   #20
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Just a note for cruisers who charge a little here and there and maybe only to 80 percent.
Do not waste your money on AGM batterys. That treatment will kill them quicker than you can say"the flooded batterys were so much cheaper"

I have been using AGM's and they are great, but only when they are charged as full as possible every time.
The situation where you shut down the generator to go to the beach before the charge is complete will cost you two years of life.
Been there.
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Old 13-11-2010, 07:02   #21
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Highlander40's comment #20; +1

And, in fact, this holds true for all lead acid batteries. The demise of flooded and gels is just not as dramatic as for AGMs.

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Old 13-11-2010, 07:32   #22
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Originally Posted by Highlander40 View Post
Just a note for cruisers who charge a little here and there and maybe only to 80 percent.
Do not waste your money on AGM batterys. That treatment will kill them quicker than you can say"the flooded batterys were so much cheaper"

e.
Yeah, been there done that. Went to AGMs a few years ago. Very big disappointment. Am back to flooded. Trojan 1275s. 12v Trojans.
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Old 13-11-2010, 12:22   #23
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Don't get the wrong idea

Just to be clear. AGM battery technology is great for the right use.

Higher storage density,slower resting discharge rate, faster recharge and longer life when cared for properly.

When I roll out of bed, the first thing is to start the generator.
The generator is sized small so that the charger will provide enough load.
Cooking, heating water and air heating/cooling are planned to spread out the time that the generator is running and charging the house bank.

I like to run awhile in float phase too. Usually 3 hrs is good for the entire cycle twice a day.

This points up a design question. A huge house bank that cannot be charged up in a normal generator run is doomed to fail early.

This all depends on the boat and how much power is used daily.
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Old 13-11-2010, 12:36   #24
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Just to be clear. AGM battery technology is great for the right use.

Higher storage density,slower resting discharge rate, faster recharge and longer life when cared for properly.

When I roll out of bed, the first thing is to start the generator.
The generator is sized small so that the charger will provide enough load.
Cooking, heating water and air heating/cooling are planned to spread out the time that the generator is running and charging the house bank.

I like to run awhile in float phase too. Usually 3 hrs is good for the entire cycle twice a day.

This points up a design question. A huge house bank that cannot be charged up in a normal generator run is doomed to fail early.

This all depends on the boat and how much power is used daily.
Just a reminder that the majority of cruisers do not have a generator. Running a generator six hours a day is not my idea of fun.
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Old 13-11-2010, 14:02   #25
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By definition, the voltage used to gage a battery's state of charge is the "resting voltage" that means no load for a few minutes.
considerable longer perhaps

Measuring A Lead Acid Battery State of Charge Photo Gallery by Compass Marine at pbase.com
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Old 13-11-2010, 14:41   #26
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RH, We have a maintenance routine that includes checking the batteries on the first of each month, or close to it. We find that when in heavy use, they will usually take some but not a lot and be sure and use ONLY distilled water. Any time I find myself in the compartment with the batteries, I remove one or two caps and have a look. The monthly check has been fine for us. We do a lot of cruising and the batteries go through a lot of charge and discharge cycles. We use 6 volt Interstates and we get about 7 to 8 years from a pair. When we replace them we replace the pair. 50% is usually our limit, but I must admit there have been times when we have discharged deeper. A regular equalization charge helps also. Chuck
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Old 13-11-2010, 17:41   #27
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The comment on resting voltage assumes that charging was finished 12 hours ago and you shut off any present loads in order to get a good idea of charge state.

Are you really going to watch the meter for 12 hours?
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Old 13-11-2010, 17:45   #28
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For those without generators. DO NOT buy AGM batterys.

A properly installed generator does not wake the 8 year old or the 47 year old wife.

Fuel consumption .5 to 1 ltr/hr, so close to zero it doesn't matter.
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Old 15-11-2010, 15:08   #29
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Get yourself one of these.
It stops filling at the proper level.

Battery Filler Bottle

Filling to the collars is ok, but not if you're going to equalize.
The batteries will blurp out electolyte.
Don't ask how I know.
Also available is the Flow-Rite Pro-Fill battery filling system. While originally intended for golf carts, they work just as well for golf cart batteries aboard a boat. Aboard our boat, I have an 8 battery bank using US Batteries. I can water all 8 batteries from a single quick connect using a hand pump. The Pro-Fill system replaces the battery caps with a new cap with a float valve and a manifold connects the caps together. The manifolds are then plumbed together and terminated with a quick connect. To fill the batteries, one connects a hand pump (bulb much like an outboard priming bulb) to the quick connect, and simply pump until the bulb is firm. The float valves shut the water flow off to each cell when the proper level is reached. The Flo-Rite system was less than $200 for 8 batteries/24 cells. Features | Flow-Rite

No affiliation, just a happy customer .
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Old 15-11-2010, 15:15   #30
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For those without generators. DO NOT buy AGM batterys.
Would that it were this simple. If any of you have ambition to race your boats in any sort of offshore racing, ISAF regs no longer allow you to carry anything except AGM batteries.

While I understand the logic behind this rule change (safety), it sure is an expensive one for those of us with larger battery banks. If I do any further offshore racing on Insatiable, I will probably take batteries out and just go withAGM for 1 x cranking and 1 x house
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