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Discussion Starter #1
Hello,
I need to know if it is ok to replace an existing (bad) 12v wet cell battery with 2 golf cart batteries while still keeping a 12v wet cell starting battery?
If so, is there any particular wiring issue or simply put the 2 6v in series?
Thanks.
 

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Barking Dog
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Do a search on this site for battery and you will find a thousand different configurations, most of which are supported/correct. I think that the answer depends on how you plan or if you plan to have the existing wet cell connected to the golf cart (also wet cell) batteries.

I don't think that you can simply just slide the 2 new new batteries in series into place as it charges at a different rate than the existing battery.
 

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the simple answer is that you are fine if you isolate the new batteries as a house bank and use your good 12 V as a start battery and don't try charging them as a group unless your charger is properly configured to differentiate.

Some chargers can't tell what or how many batteries are in line and charges them regardless of their individual state.
 

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In the should and could category, you SHOULD have a bank of batteries that are composed of the same type and same capacity, ideally the same age batteries.
You could mix them up, doing so will cause them to charge and discharge badly (meaning damage them).
 

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What you should do is buy Nigel Calders book; complete guide to sailboat maintenance and repair. He goes into great depth on battery use, charging, configuration, etc. etc. etc. Everything you'll need to know. Well laid out in detail with all the facts and figures.

find out the real experts opinion.
 

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xort,
I just parrotted Nigel's opinion. He is my source of knowledge for all things electrical and mechanical on a boat.
 

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moderate?
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I am assuming the 6v batteries are wet cells as well.
You may simply substitute them for the dead 12V battery and wire them in series. There is NO issue as the regulator sees them as the same 12V load.
This assumes the existing starting battery is is excellent shape. It is not a good idea to combine a battery on its' last legs with new batteries.
 

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Telstar 28
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Should be fine.
 

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Discussion Starter #9
Wow, you guys are fast. Way to end the year!!!
Thanks.
 

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Discussion Starter #10
Ok, I guess I'm not quite done with this...
After reading more on the deep cycle batteries and going through Don Casey's book, I have further questions:
I will be using the house battery for the usual day sail requirements and occasional weekend overnight (anchor lights, water pump and eventually car stereo) in South Florida.
Since my motoring time is very short, I am worried I won't be recharging the battery enough between overnights (I currently do not have a way to chahrge the batteries at the dock). I do not know my alternator's capacity but will check on it later on. (Atomic 4, on a 30' O'day).
So, should I look into other types of batteries? I'm looking at the Dual Purpose batteries sold at WM.
Also, is an AGM for house ok if I have a wet cell Starting battery? I'm thinking not but I want to make sure as many batteries I see advertised seem to be AGM.
 

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the dual purpose batteries won't help. power taken out needs to be put back in. if you don't have shore power & don't run the engine enough to charge up, then you need solar panels or wind gen to put back used electricity. Even if you run the engine enough to recharge, you will slowly loose charge just by sitting. solar panel in your area would be good.

all this stuff should be in casey's book

AGM & wet cell batteries require different charge voltages. Most chargers do not have the capability of charging separate banks at different rates. Some don't even have the ability to be adjusted for different types of batteries. You need to check on what type of charge controller you have on your alternator to see if it can be set to the different voltage requirements of AGM.
 

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Discussion Starter #12
X,
Yes, the book talks about the solar panels and I will look into $that$ :eek:
I have an electric outlet available at the dock (normal household outlet). Is it ok to get a plug adapter for the shorepower hookup and then get a battery charger?
My current AC system is very basic and only runs two ac outlets in the cabin off the shorepower AC.
 

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Telstar 28
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A small solar panel may be capable of re-charging the batteries given enough time and no parasitic loads on the batteries. :)

YOu could use the AC at the dock and use a pigtail, but you want to be very careful doing so, since normal AC outlets do not twist lock. :) The outlet must be GFCI protected.
 

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Yes, you can get an adapter for the twist lock. You might only have 15 amps from the dockside power. You can use a bit of line to tie the plug to the post to keep the power cord from pulling out.
You need to do some research on what kind of charger you want. Look at ability to charge different types of batteries...wet, AGM, gell. Equalization cycles. Multiple bank charging capability. And match the battery output to the bank of batteries you have.

You need to do a power consumption analisys to determine how big a battery bank you need for house loads then buy a charger to work with that bank. Plus take a look at the engine charger system, if you don't want to make big changes there, that might dictate what you do. a whole system of stuff to mate together.
 

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Yes you can run a charger from a 15amp/120v circuit. Just use the right adapters from dock to boat as suggested above.
Get a 3 stage small charger in the 10-15amp range.
ONLY use wet cells...not AGMs in your situation. AGM's would be a waste.
Check the water in your batteries at least once a month if you leave 'em on dockside charging. You might check into getting water-miser caps if you have to refill frequently. Use ONLY distilled water or you will kill your batteries.
 
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