Adding More Batteries

[Randyonr3]

I'm adding to my house bank.. At the present, I have 10 of the Lifeline
4d's aboard and am adding 2 more..
The 2 I'm adding will be mounted in what was the forward head area and now houses the watermaker and closet..
My question is,
what size cable do I need to run to the main part of the house bank as its about 20 feet from the intended placement of the new set?
At the present, I have 4 of the 4d's under the nav station, 2 4d's under the windless up front conected with 4ga. wire in paralel. another 2 of the 4d's under the galley area, and 2 more just forward of that in the main soloon, all with 6 ga. wire..
I was recently told that due to the large bank already in existance, All I really needed to run was 10 ga. with a 10 amp fuse in line to protect the line if for some reason, the house bank went poof.
The whole Idea was to create small banks of batteries at the "need for the Power"... and connect the smaller banks as one large bank..

[forsailbyowner]

I thought I had a large house bank with 8 golf cart batteries. When I added the four under vberth I used 1/0 cable with a 100amp fuse on both ends of the cable. Didn't research or anything,just thought bigger is better. 10 amp fuse?

[David M]

That sounds reasonable given you have batteries elsewhere that will also be providing power at the same time. The idea is to gauge for at least the largest draw or the largest charge to the battery you are adding, whichever is greater.

[Randyonr3]

David,
we're think the same way...the origional set up was a small bank of 4-4d's at the nave station.. Burnt out the windless and found out that even though I had 13 volts at the house bank, I was down to 9 something out at the front of the boat, about 35 feet forward of the nav station, when the windless was being used. and I have 4ga wire running to the front.. So I mounted 2 more 4d's in the forward hatch under the windless which now gives me a full 13 volts at the windless and the batteries under the windless are tied paralell to the house bankl under the nav station.. I did the same thing to the pump systems and now want this (mini-bank) to set at the watermaker...... so the main draw on these batteries (watermaker) is only inches from the batteries.
BUT, my concern is they are also linked to the house bank which drives the windless in sorts..

[Mike Sibley]

I thought the general rule was that all batteries that are permanently connected in parallel need to be the same type and the same age. Otherwise, they will have slightly different voltages and one group will be constantly discharging into the other, eventually leading to the deterioration of them all. Is this incorrect?

I have two separate house banks (one aft and one forward) but they are connected only when there is a charging source.

[David M]

If you are looking for the perfect system that maximizes its efficiency, then yes...such as if you are dependent on solar panels and want to maximize their ability to store power. But if your batteries mostly get charged by the charger while at the dock or by the alternator when underway then don't worry about those last few percentages of efficiency. Its okay to mix and match standard lead-acid batteries of different amp-hours. What you do not want to do is mix in AGM's with gel-cells with standard lead-acid batteries.

You will find out that there is lots of discussion about having ultra efficient battery systems. Quite often getting that extremely high efficiency costs a disproportionately higher amount of money. For some it is worth it and for others it is not. It really depends on how you use your boat and your budget.

In thinking about it, I would go up to a larger wire gauge. I'm thinking 6 or 8 gauge with a fuse that is gauged to the AWG and the run with a maximum 3% voltage drop. This will give you some built in leeway in case the maximum draw or charge changes for some reason. Ten gauge wire just seems too scrimpy for a 4-D battery

[goboatingnow]

I would not advise mixing batteries ( parallelling) of different amp-hours. The chargng regime can easily chronically over or under charge this type of setup.

[S/V Illusion]

The cable size is a function of the max current draw - it has nothing to do with the size of your battery bank or the batteries.

[HobieFan]

Originally Posted by S/V Illusion

The cable size is a function of the max current draw - it has nothing to do with the size of your battery bank or the batteries.

That's not entirely true when referring to cables that solely are used to "parallel" the batteries (rather than to run a load).

If you have 2 batteries in parallel and have a load drawing 20 amps, each battery will supply 10 amps.

If you have 20 batteries, each battery will supply 1 amp.

I suspect the resistance of the wire between the batteries may cause issues.

In other words, a small wire induces a lot of resistance and will drop the voltage. This suggests to me that it's BEST to use the largest wires you can justify as it will keep the entire bank charging evenly and discharging properly.

With a small wire running to some batteries, those batteries will be chronically undercharged and will not be used and will have a shorter life.

I would say larger wires are always preferred, from an efficiency standpoint.

[David M]

Now we are getting in to the last few percentages of efficiency for a lot more money that I was describing.

I have never had any problems with putting different amp-hour batteries on the same circuit. Internal resistance and volts per cell for a standard lead-acid battery is the same regardless of cell size. One will charge faster perhaps but they all eventually get charged up. Electrically, the battery knows no difference between a large wire attached to it or a small wire, provided it is receiving the same current and potential.

[btrayfors]

Randy,

Maybe I'm not understanding you right. You say you have 10 Lifeline 4D batteries now, and are adding 2 more.

By my calculation, that makes 12 batteries @ 210AH each for a total of 2,520AH. As each one weighs in at 135lbs, that's 1,620lbs of batteries and @ about $500 each that's $6,000 worth of batteries.

On a 42' Beneteau?

Why????

Bill

[MarkJ]

Originally Posted by btrayfors

Randy,



On a 42' Beneteau?

Why????

Bill

on a 42 foot racing Beneteau.

What kinky things you guys up to?????

Saturday night dancing with disco balls, smoke machines and strobe lighting?
Hydroponic Majuana growing?

I got it! You installed a TURBO BATH!!!!!!!!!!!!!

[mesquaukee]

For even controllable charging of batteries (to maintain the “health of them”) they should all be together in one spot joined together using a connecting cable pattern so each battery "sees" the same voltage when being charged or discharged. This is simply done by using the same wire size and ensuring that the total length of wire to and from each battery is the same to where they tie together feeding the house systems and/or receive a charge.
That is the priority not the “need for power” at some spot.
What is happening to your layout is when you are charging from any source being wind, solar, shore or alternator the closest (read resistance here not proximity) battery will get most of the charge or overcharge. You may just end up cooking it (an alternator will easily do that, followed by a shore charger), perhaps that is why you have an 2100 AmpHr battery bank that you feel you must add to as some of them are dead (as in throw it overboard for use as an anchor or as internal ballast).
I would suggest you load and capacity test all of your present batteries first before extending your “grid” with more batteries. Disconnect them from the “grid” first though.

[jdoe71]

I find this incredible. Our last boat had 2 X 115 amp/hr batteries and the current one has 2 X 4d's of 215 amp/hr each. I cannot imagine what we could possibly want 10 of these monsters for? Or how we would ever charge them? If I needed that much energy I'd just stay home. Different strokes, but really...

[ka4wja]

Randy,
I'm with most of the others here, since I cannot figure what you're trying to accomplish, nor who informed you that you could use such small wiring????
Even the 4ga and 6 ga wiring is too small, but now someone told you to use 10ga wiring for adding more batteries????
Oh boy!!!!

(Just as an eaxmple, with my 825 A/H house bank, I use 00ga wiring for the batteries, and to master breaker panel, and then to windlass......)

In addition to Bill's elegant query,

Originally Posted by btrayfors

Why????

, and others incredulity, I think Mesquaukee set it out pretty clearly for you.....
Follow Mesquaukee advice, and you'll probably find a bank of 4 - 4D's with some 00ga wiring will be all that you'll need!!!!
(And, you have a LOT more room on board, and sail faster as well!!!!)

In all honesty, I wasn't even sure your post was serious......if this was April 1st, I'd have smiled, but it's Septemeber.....


Fair winds...

John