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Old 30-04-2008, 06:20   #1
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Charging for 780AH @ 24V House Bank

I will soon be receiving my 6 new Fullriver DC260-12 AGM batteries each rated at 260AH at 12V

Just want to confirm that my basic calculations are correct and to get some advice on sourcing an intelligent Battery Charger and Large Case Alternator Systems that are balanced to recharge those AGM batteries as quickly as possible, without doing damage.

1. 6 x 260AH @12V = 1,560AH which = 780AH @ 24V……. Is that Correct?

2. Each Battery has a rated “Initial Charging Current of 52A at 25C temp. Does that mean that with my configuration theoretically it can only take 3 x 52A or 156A @ 24V as maximum charge? …. Is that Correct?


3. What I have read in other Threads and Books is that the rule of thumb is to size you’re charging system to 25% of you house bank. So that would mean 780AH/4 equals 195A @ 24V as the rating for a charger or large case Alternator.
….Which is correct 156A or 195A for sizing my charging system?

Here is a basic drawing of my series/parallel configuration; any advice would be greatly appreciated.
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Old 30-04-2008, 08:59   #2
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Pelagic-
I would assume the "initial" charge current reflects the fact that the batteries are new and need a few charge cycles at less than full rate in order to properly sort themselves out. So you would want a way to restrict the initial charge (perhaps the first half dozen or dozen cycles) to that rate.
The higher rate, the 25% charge rate, would be OK after that. When in doubt--contact the manufacturer directly to confirm rates for their specific product.

The drawing is fine with one caveat: When you are putting that much power through cables, if you daisy chain the batteries 1-2-3 the way you are showing, the battery at the far right will get less voltage than the ones to the left of it. Not much--but some, depending on your cabling or bus bars. Obviously with that much power you want low resistance in your cabling, but you might also splurge a bit and run three sets of identical cables to a common junction point, and then from that junction point to the alternator/inverter/etc. That ensures all three batteries are treated identically. The alternative is just using bus bars or cables heavy enough that there is "zero" effective voltage loss...because even 1/10th of one volt difference, is significant.

I saw an ad for Fullriver (I think in latts & atts) advertising a full five year warranty now. Very impressive. Assuming of course they're around to support it. (I'm doubly cynical of anything Chinese, but give them credit for standing up with that kind of warranty!)
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Old 30-04-2008, 10:07   #3
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Thanks Hellosailor,

I am honestly not sure what “initial” means?

Is it at the start of a charge cycle or as a break in period like you suggest? …. so I have emailed Fullriver to clarify what they mean by “initial charging current 52A or small”

Re wiring so as to give an even charge thru all of the 6 batteries, is what I have drawn below a way to solve that problem?
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Old 30-04-2008, 17:43   #4
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Hmmm...I suppose wiring them up that way ought to work, I never thought of doing it that way! The Honorary Missourian in me would still want to see it confirmed with a voltmeter to be sure,but I think it would work.

To me an "initial charge" (which in my limited experience, I've never heard of before) would mean the first time the batteries were charged. Or the first few times they were charged, to be conservative. But then again...I've seen some incredibly clever translations from Chinese companies that somehow just couldn't bother hiring someone to make good YnGlitch in their instruction sheets. To be safe, check with the company or their US distributor directly. Those batteries are too expensive to make assumptions.
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Old 30-04-2008, 21:19   #5
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Pelagic -

Both schematics are the same. I you don't use copper bus bars to connect the batteries just connect the power and grounds from the middle battery. This will worst case of one voltage drop. As wired the second battery would have one voltage drop and the third in line two.

good luck
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Old 30-04-2008, 21:30   #6
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Hi Pelagic,
You have it right. That amounts to a 780 amp-hour, 24 volt battery.

Not sure what an "Initial Charging Current" is but with a smart three stage battery charger you have a Bulk, Absorption and Float stage. As long as your three stage battery charger is put on the AGM setting and it has a temperature sensor (ideally but not a necessity), then you should be fine.

A smart charger will not cook your batteries. It knows if it is charging them too fast by the rate at which the voltage comes up. It will control how fast the voltage comes up by regulating the charge amperage. It will gradually drop the charging amps so the batteries have the time necessary to absorb the charge. On the AGM setting, your charger "knows" how to properly charge AGM batteries.

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Old 09-05-2008, 05:39   #7
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Thanks David and all.

Fullriver just confirmed what you were explaining that “156A @ 24V is the recommended charging current, but they say you can apply 195A @ 24V. as long as the system charging voltage is limited to be 28.8-29.8V. and the system has float charging period during the battery charging.”

Now my next question: What should be my primary charging for the 24v House Bank?

We live on board mostly at anchor on DC consumers and presently use the Northern Lights 12kw gen to charge the old 400ah House Bank with a Victron 50A charger.

This Gen was sized by the previous owner for the charter business to run 3 air cons, Dive compressor and water maker simultaneously.

Our use is much lighter as a home for 2 with no dive compressor and rare A.C. use. So the demands are mostly for powering the 50amp battery charger and making water. The Gen averages only 10-15amps and less as the batteries tops up. So it runs without much of a load (not good!)

My thinking is that as I have increased the House Bank to 780 AH (and I have room to further increase to 1040AH if needed)…. What if I were to install a Balmar Extra Large Case Alternator 98-24-220-BL onto this light load Generator? (Alternator puts out about 24V 210 Amps @ 3500RPM)

I would fabricate a 2 pulley PTO in front of the existing Crankshaft Pulley and mount this large case alternator underneath the Generators 12v Alternator.

I am asking Northern Lights if there are any Load or torsional vibration problems in doing this.

But assuming they say this is ok…… is this the way to go for a boat mostly at anchor rather than a series of electric battery chargers?

When motor sailing my existing 70 amp Balmar off the main engine should slowly top up the 780Ah bank. If not I could always increase the size or start the Gen.
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Old 09-05-2008, 06:24   #8
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Have you looked at the Zena alternators.
They look pretty tough


High Current Alternator Specifications
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Old 09-05-2008, 12:07   #9
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"as long as the system charging voltage is limited to "
Incidentally, your charger should have a battery temperature sensor or the option to add one. This is normally a little tab that gets bolted directly to a positive battery post and tells the charger what the temperature of that post is. If you don't have one--get one. That's the way that chargers cut back and limit overcharging under these conditions, since temperature and overcharge are very tightly related.
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Old 09-05-2008, 14:55   #10
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Well I contacted Dick Gee who is the VP and Engineering adviser for Northern Lights and he pretty much shot down my idea by saying:

"The problem is the tremendous side load imposed onto the nose of the engine crankshaft by the "V" belts when driving the alternator. We know from experience this can cause catastrophic failure. Based on this experience our 24v alternator limit is 40 Amps.

Also Nick, belt driven batter charging alternators are famously inefficient. On average they are 50% efficient.

Have you considered a very large battery charger that could use the AC power from the generator OR shore power?"

So I am now back to sourcing a very large battery charger.

The Fullriver battery people say they recommend max of 24v-156amps for my 760Ah bank. What I want to do is to reduce my generator hours by recharging the house bank as quickly as possible without damaging the batteries

The largest I have found so far is the Newmar Phase Three 24V-95amp charger.

Anyone know of a better solution or bigger charger?
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Old 09-05-2008, 20:34   #11
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I also found this new Victron Quattro 24/5000/120amp
combination Invertor/charger which seems to do it all.

http://www.victronenergy.com/upload/...rochure_EN.pdf

Any opinions?
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Old 09-05-2008, 20:54   #12
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Victron products are top-of-the-line. Very excellent build quality. I have a MultiPlus on my boat, and several friends have them as well.

The unit you're looking at is designed for 220Volts input and output, as well as 24V for charging batteries. Are you looking for a 220V unit? Is your boat set up for 220V??

Bill
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Old 09-05-2008, 21:39   #13
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I also will have a 24V house bank on 'Waratah'. Capacity 460 Ah. I am using a 24V 140A Balmar marine alternator on my Yanmar 4JH4AE (54 hp).
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Old 09-05-2008, 22:10   #14
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Another vote for Victron. The unit you found will do either 110v or 22v or both. It's a new unit but the web site says it will ship this quarter.

Your second battery diagram is correct. My understanding is that the positive and negative cables should be attached to opposite "ends" of the battery bank to insure equal charge and discharge of the batteries.

With that big a charge current be sure to use a temperature sensor on the batteries. The Victron has one.

Carl
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Old 10-05-2008, 04:13   #15
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My boat generator is 220Volt 50Hrz 12KW Northern lights generator which is oversized for my A.C. uses, so loading up with a big battery charger will be good for it.

The thing is; that Quattro is expensive! Costs about USD5,300.00 and will only give me a maximum of 120amps @ 24V where the Battery manufacturer says I can put in up to 195amps for my new 780AH house bank

We don’t really need a big 5000w inverter as the existing 1800 watt inverter is enough for the TV/Microwave and kettle.

What I am still looking for is a couple of smart battery chargers that can run together and safely monitor AGM’s to give me up to 195amps @ 24v and a fast recharge at anchor
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