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Old 03-22-2013, 07:19 AM   #21
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what kind of charger do you have? AGM batteries require a lower charger voltage then other batteries. I read once that large alternators can over charge AGM batteries.
I don't believe that is true. AGM batteries are installed in boats and vehicles routinely with no change to the alternator or shorepower charger. Gel batteries are the ones that require adjustments.
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Old 03-22-2013, 07:29 AM   #22
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I am sorry to say but this is very wrong, as is portager's premise that series is "better" The big disadvantage of series driven banks is that if one cell goes bad in any battery you must replace all the batteries. Otherwise you will kill them all soon enough by misbalanced charging. Once you have put them into series all you have done is create one big battery. ..............
I'm not going to argue that series is better or worse than parallel. In a technical sense, series wins out, but both configurations work just fine. You have a valid point about having to replace all the batteries in a series configuration if one fails.

I think a lot of people don't understand the importance of your last sentence "Once you have put them into series all you have done is create one big battery".

A six volt battery is three two volt cells in series. A twelve volt battery is six two volt cells in series. The only difference between two six volt batteries wired in series and a twelve volt battery is that the connection between cells #3 and #4 is external, not internal.
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Old 03-24-2013, 04:10 PM   #23
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I am sorry to say but this is very wrong, as is portager's premise that series is "better" The big disadvantage of series driven banks is that if one cell goes bad in any battery you must replace all the batteries. Otherwise you will kill them all soon enough by misbalanced charging. Once you have put them into series all you have done is create one big battery. Please read Nigel Calder's "Boat Owners mechanical and Electrical Manual" an essential document, for a fuller explanation than I can give here. My boat has four major series-driven banks, so this is something I have had to pay a lot of attention to.
The reasons that I said series banks are better is;
1 Historically series banks provide a longer service life than parallel or serial/parallel.
2 Serial banks are easier to trouble shoot and maintain.
3 If a single battery fails in a series bank you only need to replace the failed battery.

Although I believe Nigel Calder's "Boat Owners mechanical and Electrical Manual" contains a lot of useful and accurate information it isn't perfect. He made an error on page 21 when he said, "In a series installation, if one battery fails, you have to replace all the batteries." In a series configuration all the batteries receive the same current, therefore charging is inherently balanced. You can only get "misbalanced" charging in parallel or serial/parallel configurations. Therefore, in a series configuration when one battery fails, you only need to replace the failed battery, but the replacement must have identical capacity.

The main disadvantage with a serial bank is when a battery fails you must replace that battery, but with parallel you can disconnect the failed battery and continue to use the remainder of the bank with reduced capacity. If your planning a long passage or a trip to a remote area and you consider your battery bank essential, you may want to carry a spare battery, which is what Steve Dashew does.

The main problem with parallel banks is it is very difficult to diagnose a battery failure and a failed battery can prevent the parallel legs from getting fully recharged and it can discharge the other legs following charging. For these reasons series banks tend to last longer than parallel banks.
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Old 03-25-2013, 06:30 AM   #24
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So maybe the old '60's setup of 10 , 12V batts in series to create 120V house current and the selection of universal motors, std house lamps, toaster, made sense?
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Old 03-25-2013, 09:34 AM   #25
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Brooksie says: "The cost / benefit between flooded, gel, & AGM needs to be worked out on a case by case basis I think."
Attached is a recent analysis for my new accessory battery bank.
Very interesting, big flooded cell fanclub member here...
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Old 03-25-2013, 10:11 AM   #26
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Very interesting, big flooded cell fanclub member here...
Why? Is it because they're cheaper to buy?
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Old 03-26-2013, 06:49 AM   #27
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Why? Is it because they're cheaper to buy?

The biggest advantage of AGM is their more rapid charge rate.

Few folks are willing to spend the $$$$ to be able to bring a 50% SOC set of house batts to 85 or 90% SOC in a short time.

With out 200+ amps of temperature monitoring charge rate aboard , why pay for what cant be used?

I would rather spend the bucks on bigger LA wet batts.

For the truly affluent the newest LI batts can take a huge charge in 15 min , IF you have the charge amps, and $20 Grand for the batts.
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Old 03-26-2013, 07:04 AM   #28
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Why? Is it because they're cheaper to buy?

The biggest advantage of AGM is their more rapid charge rate.

Few folks are willing to spend the $$$$ to be able to bring a 50% SOC set of house batts to 85 or 90% SOC in a short time.

With out 200+ amps of temperature monitoring charge rate aboard , why pay for what cant be used?

I would rather spend the bucks on bigger LA wet batts.

For the truly affluent the newest LI batts can take a huge charge in 15 min , IF you have the charge amps, and $20 Grand for the batts.
I know all the advantages and disadvantages and agree FF.

Sort of like all the other discussions about everything from anchors to oils.

My best friend has a nearly new $300,000 42 foot Catalina. Everytime he goes to a boat show...new toys and new systems and upgrades...new anchors, Mobil 1, expensive inverters, new genset ,,,etc...etc ...and is chattering away solar and wind power (never married, no kids...). In the 4 years he has owned the boat he has maybe 100 hours and ZERO nights at anchor).

He bought it from the other guy who swore it would be "his last, retirement, cruiser" who took a job in India and never really cruised the boat....and he bought it with every option possible and was adding stuff as he sold it to my friend.

Two guys who "love" gadgets. My buddy doesn't even understand most of how his systems work and certainly not how they work or not together. Yet he is the perfect candidate to "be sold" on anything new.

I see a LOT of boaters who are exactly the same way...maybe for different reasons...but wind up with the same stuff, boating the same ways.

I spend a lot of time sitting down with these types and penciling out the cost advantages of one system over another...then usually lose then trying to explain why the advantage is lost when they don't upgrade something else...but I'm usually wasting my breath as it happens because they LOVE to talk anbout their new XYZ at happy hour....which is usually back at the home dock and not the cruising grounds.

Oh by the way...the $300,000 outfitted to the teeth boat....when we moved it to Charleston...I had to bring MY PLB along as one thing the boat doesn't have is an EPIRB...go figure...
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Old 03-26-2013, 08:09 AM   #29
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The reasons that I said series banks are better is;
1 Historically series banks provide a longer service life than parallel or serial/parallel.
2 Serial banks are easier to trouble shoot and maintain.
3 If a single battery fails in a series bank you only need to replace the failed battery.

Although I believe Nigel Calder's "Boat Owners mechanical and Electrical Manual" contains a lot of useful and accurate information it isn't perfect. He made an error on page 21 when he said, "In a series installation, if one battery fails, you have to replace all the batteries." In a series configuration all the batteries receive the same current, therefore charging is inherently balanced. You can only get "misbalanced" charging in parallel or serial/parallel configurations. Therefore, in a series configuration when one battery fails, you only need to replace the failed battery, but the replacement must have identical capacity.

The main disadvantage with a serial bank is when a battery fails you must replace that battery, but with parallel you can disconnect the failed battery and continue to use the remainder of the bank with reduced capacity. If your planning a long passage or a trip to a remote area and you consider your battery bank essential, you may want to carry a spare battery, which is what Steve Dashew does.

The main problem with parallel banks is it is very difficult to diagnose a battery failure and a failed battery can prevent the parallel legs from getting fully recharged and it can discharge the other legs following charging. For these reasons series banks tend to last longer than parallel banks.
You are just plain wrong about this. In a parallel bank you can just replace one battery and pretty much get away with it. In a series bank you will only get away with it for a very short time until the other batteries are dead, and the new one is dead too. I suppose if one never leaves the dock or cruises less than an hour or two from a dock, you can get away with this ultimately very expensive practice. Mr Calder is right, I am right, and you are wrong. I suggest you read the first three chapters of his book thoroughly and then maybe you'll "get it". With two 32 volt banks each consisting of four very large and expensive 8v batteries, one 24v inverter bank of 4 large and expensive 6v batteries, and a 24v thruster/wash down pump bank of two 12v 8D batteries, this is no trifling matter to me.
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Old 03-26-2013, 09:23 AM   #30
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While I agree in principle with FF that wet batteries are a "better buy", The big advantages of AGMs are (1) minimal (no) maintenance enables them to be stuffed into (almost) inaccessible spaces; and (2) if you anchor out a lot for extended periods, they charge faster which translates into less run time on the generator -- less fuel, less wear.
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Old 03-26-2013, 09:56 AM   #31
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Why? Is it because they're cheaper to buy?

The biggest advantage of AGM is their more rapid charge rate............
For me and a few other folks, the biggest advantage of AGMs over flooded cell is the low/ no maintenance. Replacing my flooded cell batteries with AGMs means I no longer have to remember to climb down beside the engine or prop shaft and use a mirror and flashlight to try to determine the electrolyte level every month. And then figure a way to add water to the correct level.

It's worth the cost for me, better performance is icing on the cake.
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Old 03-26-2013, 10:28 AM   #32
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While I agree in principle with FF that wet batteries are a "better buy", The big advantages of AGMs are (1) minimal (no) maintenance enables them to be stuffed into (almost) inaccessible spaces; and (2) if you anchor out a lot for extended periods, they charge faster which translates into less run time on the generator -- less fuel, less wear.
based on the generator operation hours thread...many more people need to run their genset more anyway....
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Old 03-26-2013, 11:32 AM   #33
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One big advantage to AGMs is no off gassing thus little terminal corrosion from acid.
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Old 03-26-2013, 03:47 PM   #34
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Batteries, their power reserve, charging time, and DC longevity! I keep it simple / productive / cost-wise!

Some times we hang at hook for 3 to 5 days… or longer. On our 34’ Tolly Tri cabin we keep 6 batteries at the ready (all batts new early 09 – still doing great in 13!). We’re often out for days; cruising and hooking. Never stay at dock in decent weather.

Battery Bank:

- 4 – Flooded, lead acid, “semi no-maintenance”, deep-cell, BCI Group 31 batteries: Each 105 amp hrs / 650 cold crank amps / 182 minutes reserve capacity. These batteries are used for engine starting and also general usage. They are charged by motor alternator or by Pro Mariner charger on boat when Kohler genset runs, or by the same charger when hooked to dock AC.
- 1 – Flooded, lead acid group 27 starter battery: For Kohler genset. It is kept charged by solar panel attached to fly bridge front (so genset can always start - to charge any batteries if/as needed); and/or by 1 amp charger mentioned for next battery, or by genset alternator.
- 1 – Flooded, lead acid group 27 starter/deep-cell battery combo: A reserve, completely independent battery hooked to nothing and stored in a separate battery box. It is kept on top charge by a 1 amp trickle charger that sits inside this battery’s box and is activated upon Kohler genset use or dock side AC whenever the 120 in-boat outlet breaker is turned on. The 1 amp charger also has its own easy access on/off switch for if we were to keep boat on dock power for extended period with 120 breaker on.

Total battery cost (early in 2009): $595.00 – Including all 6 batteries, 1 amp charger, large single battery box and taxes. I plan to keep these batteries in good condition for years. Ya just gotta love “Batteries Plus” stores!

Long and short of it… I’m a simple boater who uses DC power (as well as most/all other items) carefully and sparingly on a boat.

When at anchor: We usually run the Kohler genset in morn for about 30 to 60 minutes so we can use the stove for bacon, eggs and coffee; we simultaneously turn on other breakers; e.g., 120 outlets to charge our VCR player’s battery / refrigerator / battery charger / hot water heater. And, we run the genset for approx same length of time in eve to cook dinner as well as to turn on the same breakers. Of course when we cruise battery charging of our 4 mains is well handled by the engines’ alternators.

This schedule affords us all the battery power we need and keeps our other features in useful conditions.

BTW – I don’t use float chargers. Have before, but from experience I feel they too often over charge the batteries and can considerably shorten their life. If batteries are in good condition, fully charged and have all sources of power drain shut down when leaving boat… they will remain substantively charged for months on end. Therefore I always turn every item off; Perko main switches included, and do not even have need to leave our AC dock line plugged in. Upon arriving at boat we immediately plug in dock power, turn on battery charger breaker as well as several other breakers and flip the Perkos on. Works great for us… Everything’s ready by the time we’re set to pull out for days on end of exciting Tolly Fun!!!!

Simple is as simple does! We do love our Tolly Time!! - - > Cruisen, partyen, swimmen, diven in SF Delta’s warm fresh waters – YUM!
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Old 03-26-2013, 04:54 PM   #35
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If you cycle your house bank a lot, as in a cruising and anchoring out full time lifestyle, then the cheapest and best battery is LiFePO4 cells. 3000 cycles at 80% DOD vs 500 cycles at 50% DOD, minimal voltage sag under heavy load, and almost zero Peukert effect along with the highest charge acceptance. I've used golf cart 6 volt batteries, L16's, 2 volt 700 a-hr AGM, and none are anything close in performance to the LiFePO4 cells I'm running now. Also 1/3 the weight per given energy density.

Just the difference between 19th century technology and 21st.
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Old 03-26-2013, 05:25 PM   #36
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If you desire some math to support my claims, lets start with the best lead acid for this purpose, the 2 volt 900 a-hr AGM, currently available at Lifeline GPL-6CT-2 Volt 900AH AGM Battery for $381.97, so for a 12 volt (10.8 KW-hr) bank $2292. But you have to remember that 900 a-hr rating is based on 20 hours and is quickly derated to less than 800 a-hr at typical inverter loads, i.e. Peukert effect. Now your bank is 9.6 KW-hr, but since you want those 500 cycles you can't discharge deeper than 50% DOD. Usable energy from this house bank is 4.8 KW-hr.

(4) 700 a-hr LiFePO4 cells run $2240. These cells in a 20 hour rating give 25% more than their rating, my cells do and everyone on the Cruiser's Forum report the same. They are very conservative in their ratings. Since Peukert is nil and DOD is 80% for a life of 3000 cycles, you can see the cost savings, not to mention not having to change out batteries for 15+ years.

AGM lead acid, $2292 for 4.8 KW-hr usable, for 500 cycles

LiFePO4 lithium $2240 for 7.3 KW-hr usable, for 3000 cycles.
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Old 03-26-2013, 05:59 PM   #37
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Where are you finding the LiFePO4s for that kind of price? TIA. Here's the best i could find, almost 3 times that price for 600ah.

http://www.lithiumion-batteries.com/...on-battery.php

By the way you can cycle good AGMs down 60-70%. I'm a wet cell man myself save the generator start battery; my batteries are extremely easy to service. I got the sam duty cycle out of my wet cell L16's (4 for 24v) of identical capacity to your illustrated 12 volt AGM system. They run about 1200 in todays money. So I think you are underselling the AGMs a bit.
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Old 03-26-2013, 06:10 PM   #38
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George,

Here is the link to the wholesaler and he sells to the retail market. Balqon - Advanced Transportation Solution

I have had very good service from all the AGMs that I have used over the years. I used to race an EV I built that used the little Odyssey PC680s, and I pulled over 400 amps on a regular basis from those 15 lb batteries. I have nothing but good things to say about AGM, but there is a much better and cheaper battery out there.

On the Cruiser's Forum we have a thread that has gone to 2488 posts just on LiFePO4 cells for housebanks. About a dozen members there jumped on the Balqon clearance sale when I posted it, and they are flat out loving their battery upgrade. I've never seen outside of my EV group such a passion on batteries as on the Cruiser's Forum. LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks - Cruisers & Sailing Forums
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Old 03-26-2013, 06:29 PM   #39
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To give you an idea of how much energy density we are talking about using LiFePO4 cells, I had a recent, very small project for my electric kayak. A group 27 battery would give 16~18 nm on a charge, not near good enough for kayak camping. I put together (2) 12 volt 100 a-hr LiFePO4 packs for the kayak that weigh just a bit less than the single group 27. What I got in range is around 80 nm, more than enough to cruise the entire 75 mile shoreline of Lake Tahoe and still have enough power for my Engel fridge and Coleman LED lantern.




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Old 03-26-2013, 06:35 PM   #40
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What are the charging parameters for the LiFePo4 batts?? Dp you charge them as "wet", "AGM" or "gel". I do not have a LiFePO4 setting on my charger??
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