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Old 17-05-2014, 17:41   #16
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Re: Switching Batteries - Charger Question

We have 12 x Trojan T105's and charge happily with a Freedom 25. For best battery life on these do not exceed 12% of total cap as charge rate. The Freedom is infinitely programmable, via a Link 2000 etc...Of course we are 24v boat, but that makes 675 A/h.
We have 460 watt solar, MPPT controller, 250 Watt Wind, and 3x alternators 30, 40 and 60 Amps, all controlled via Hueco external controllers. Keep the Freedom!
Get used to maintaining your battery, every month we check water, every 3 months we check water, per bat voltage, temperature, and SG, its all recorded. When you see a variation, chuck that one bat out and replace it. Clean your batteries monthly, keep the terminals tight. You can get a centralized watering system, with one hose joining all cells, and automatically filling till shut off of the float valve.

Tight sheets to ya.
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Old 17-05-2014, 18:05   #17
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Re: Switching Batteries - Charger Question

Lotta myths to explode here! Well meaning, but wrong.

Haven't got a lot of time right now to fully explain, but all this has been hashed and re-hashed on this and other forums for years.

First, to answer the OP's concern about whether or not his charger is sufficient for dockside use, the answer is YES. Virtually any charger is fine, if you're going to stay at dockside and have it plugged in long enough. The larger-size chargers are handy for maximum rate of charging if you're out cruising and, e.g., want to overnite at dockside. Or, if you have a generator-driven charger, then the larger the better.

Next, charging acceptance rates vary depending on battery type and battery chemistry, as well as state-of-charge (SOC). An AGM battery can accept a hell of a lot of current, depending on its SOC. For example, a 200AH Lifeline AGM can accept well over 200 amps charge when 50% depleted. When much more deeply discharged, it can accept 1,000 amps or more!!!

But, these high rates of charge acceptance will dial down as the SOC comes up. How quickly this will happen depends on the size of the charger. With AGMs, they can almost certainly take all the charge you can throw at them.

Flooded LA batteries can't take such fast charging. More like 20-25% of rated capacity is all they'll take. And, they'll dial back quickly.

Here's the key point to remember: the battery itself will determine how much charge it will accept. It doesn't matter a whit if you have a charger that is capable of putting out, say 200 amps if the battery will only accept, say 50 amps. It will accept those 50 amps -- and ONLY those 50 amps -- even if you have a 1,000 amp charger.

Moreover, there's evidence that the higher charge rates are actually good for batteries and for their health and longevity. The oft-cited 0.1C type of thinking is mostly just urban myth, and is based very roughly on the size and chemistry of the battery and its "average" charge acceptance over the whole charging cycle.

Finally, the size and type of charging capability you have aboard depends very much on not only the batteries but the type of cruising you do. If you're at dockside most of the time, ANY regulated battery charging size/type will do, so long as it's big enough to overcome the self-discharge rate of the batteries and the average load on them.

If you're out cruising or on a mooring, you need something different: you need the ability to get your battery bank up to full charge often and, if mostly with mechanical means, to feed the batteries as much amperage as they'll take in order to minimize charging time and cost.In many/most cases, this means solar or wind in order to get the batteries fully topped up since it is very costly and annoying to do this with engine or generator.



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Old 18-05-2014, 03:35   #18
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Re: Switching Batteries - Charger Question

Originally Posted by deckofficer View Post
Capt Mike is the cool one, he has electric propulsion.
Thanks for the accolade Deck Officer but, while I was helping to push electrons out the door in TV studios for years you were out on boats enjoying those sunrises and sunsets out on the oceans and getting paid too! I'm a little envious. In addition your post has also inspired me that after six years with the current electric propulsion setup it may be time to tweak things a bit. I've been doing well with the Zivan NG-1 charger with it's 16 amp (900 watt) output for bulk charging and also using it for electro sailing on windless days moving the boat along a 3 knots until the Honda 2000 runs out of gas. But, I could always use a few more amps. So this season I think I'll be adding a 48 volt 600 watt power supply into the mix in addition to the current Zivan charger. This will add about another 12 amps for charging and also for electro sailing but, still be under the continuous operating rating of the Honda 2000i generator. Should decrease charge time at least through the bulk charge stage while at anchor. That's the nice thing about electrical systems is you can change and modify things as needed.
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Old 19-05-2014, 01:56   #19
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Re: Switching Batteries - Charger Question

Originally Posted by btrayfors View Post
Lotta myths to explode here! Well meaning, but wrong.

The "best" advice should always be use the battery manufacturer's recommendation, not always what you read from just one poster.

Trojan are one of the few who recommend 0.1C, for longest life!!!! 0.2C is more normal, so a charger with an extra 5% is needed to cover house loads and charge at the same time. So 0.25C is what to aim for.

Lifeline AGM recommend a MINIMUM of 0.2C charging current, which many people fail to reach.
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Old 19-05-2014, 04:45   #20
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Re: Switching Batteries - Charger Question

Originally Posted by DDabs View Post
So I am in the next phase now of my battery refit. I am going from having two AGM 12V batteries (200ah bank) to six 6V batteries (630ah bank).

The boat came with a Heart Interface/Xantrex battery charger/inverter. My main question is, will this system be adequate to charge the new batteries? of course and if on shore power even a small charger would do it as it just takes time, but you have a large solar bank and for the most would only be floating if on shore power I am not as much concerned about the inverter, because I am hardly ever going to use it,you may wish to rethink as I find I use my inverter fairly often to run power tools etc. as an example it is a lot easier to use my power inflate my dinghy than spend 20 minutes hand pumping
be sure to check the programing on your charger (an engine alternator regulator) when switching over to the FLA from the AGM
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Old 19-05-2014, 17:34   #21
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Re: Switching Batteries - Charger Question

as long as the charger is still working it'll be fine. those are getting old and starting to die. I've seen some only putting out 10-30 amps not 100.

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