Batteries; type, configuration, & use

[Marc]

Okay guys, since tis is the place to get the best answers here we go.  I am shopping for batteries,  I am wanting to get two and wire them in parallel, so I have lots of 12 V,  what do you all consider the best and what brands.  I'm planning on LED lighting for my boat and a 55 watt solar panel to charge, and to allso start my engine.  There will be an inverter large enough to charge my laptop and perhaps a TV.  I will also have VHF, AM/FM CD radio but no amplifier and of couse depth finder and speedo and compass lightin.  So what do you guys think?  Thanks a lot Marc

[skylark]

Two Trojan T105 's, 6V each in series

Lower cost:

Two deep discharge marine trolling motor batteries from WalMart or similar outlet, 2 12V batteries in parallel.

[Joe Pyrat]

That's what I've got, two T105 6V golf cart batteries in series which is fairly common on boats, but not the only option (output 12V/225AH).  The rule is parallel doubles the amp hours, series doubles the voltage.  Here's a site with an explanation of the series vs parallel setup. 

http://www.zbattery.com/Connecting-Batteries-in-Series-or-Parallel

Here's what Don Casey says in Sailboat Electrics Simplified regarding golf cart batteries.

GOLF CART BATTERIES are of interest to sailors because they are designed to be discharged all day then given a charge to prepare them for the next day's gaggle of duffers--a use pattern remarkably similar to what a sailboat's house battery experiences.  Good-quality golf-cart batteries last three or four years in this service.

What makes golf cart batteries particularly notable is that they are readily available at very attractive discount prices.  The well-respected Trojan T-105, for example, can be purchased for as little as $60.  That makes the cost of a 12-volt, 225-amp-hour bank $120.  A marine-quality deep-cycle 8D battery of equivalent capacity will run more than twice that amount.  An 8D might deliver more cycles, but probably not twice as many (the T-105 is independently rated at more-than-respectable 750 full discharge cycles).  This makes a good-quality golf-cart battery the best value in terms of amp-hours for the dollar over the life of the battery, with no -to-be-dismissed advantage that if some life-ending misfortune befalls your batteries--you forget to keep the water level up, an unnoticed regular failure boils them dry, a stuck bilge pump float submerges them--replacement costs is far more palatable.

http://www.amazon.com/Sailboat-Electrics-Simplified-Don-Casey/dp/0070366497/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1232933565&sr=8-1

[newt]

I would put the hydro-caps on them too. People swear they cut the maintenance in half.

[Joe Pyrat]

Newt, that's interesting as I just checked the water level in my batteries this morning (good timing :) ).  I Googled them and found this.

http://www.ecovantageenergy.com/catalog/items/item33.htm

The Hydro-Caps sound like more trouble than Water Miser caps, but I'd never heard of either until you mentioned it.  Reducing the water loss on my T-105s would be a good thing though.  Anyone have any experience with these things?

[AdriftAtSea]

If you're only able to fit TWO batteries into the boat for the house bank, I would highly recommend not using T105 or other 6VDC golf-cart type batteries. If one develops a bad cell or goes dead in any other way, you're left with NO HOUSE BANK.  If you want to use 6VDC batteries, please use at least FOUR of them, so that you have some battery redundancy for the house bank.  If you parallel two 12 VDC batteries, and one goes bad, you can pull the wires from it and run the house loads off of the other....if you have two 6 VDC in series, and one goes bad, you've got a good 6 VDC battery that is useless.

[maxiSwede]

I just found myself the happy owner of three more 12 V // 75 Ah deep cycle batteries. The guy who sold them thought they had gone bad, but it turned out to be his charger that was crappy...

So, no we have got 6 of these in all, pretty similar adding to a total 450 Ah. ) i know, that IS luxury for those of you that simply can't find any room for such an abundance). On Röde Orm we have 3x 30 W solar panels that we move around (lifelines, cabin top, hung on the booms dependent of conditions and if we are at anchor or at sea. This should be sufficient. The man power consumers on board are the radar (3 Amp) and a bit sadly the computer(s). (4-6 amps)At sea the computer is used with chart software and at anchor for e-mail and web browsing and picture editing as well as music and occasionally a movie or two.


Now to my question:

I have done some reading on the subject and decided to install all six in ONE bank, with a Marine Priority Start as a low volt Guard. It automatically cuts the circuit f the voltage under load goes under 11,9 V, thus leaving enough juice to still make it possible to crank the engine (3 cyl. Yanmar)

I was very happy with this arrangement for three days.  8) then a friend said - what if yo accidentally short one battery? a metal object falling on it or slowly work it's way to end up over the two posts.... and BOOM - 6 DEAD batteries and no motor, no chart reading etc.... NO GOOD.

Hmm, sounds like a maybe unlikely scenario but anyway,,,   ???

Maybe I should connect them in two separate banks instead, and if so, how? I guess I would need a manual switch then to use one bank at a time, thus having to keep track of charging etc....


I like the simplicity  about on bank only, but of course it's prudent to have options even if when the worst thing happens.

Thoughts on this issue???

[AdriftAtSea]

IMHO, you should have a large house bank and a separate emergency starting battery.  To simplify charging, you can use an echo charger or a battery combiner to keep the emergency bank charged whenever the house bank is being charged.

The small emergency battery doesn't require much space or maintenance, and could even be as simple as an external "jump start pack", since the small diesel engines on most sailfar type boats do not actually require much in the way of energy to start them.

I'd also point out that the batteries are supposed to be enclosed in battery boxes for a reason.  If they are properly enclosed in a battery box, the chance of something falling across the terminals is very remote. 

The reasons for keeping the house batteries in a single large bank are quite good. 

First, the house bank is more efficient and lasts longer if it is larger relative to the loads placed on it.  This is primarily due to the Peukert factor that affects lead-acid batteries.  This is also why the 20 hour rating on a battery is higher than the 5 hour rating—the larger the load relative to the battery, the less capacity the battery effectively has.

Second, you can go longer between having to run the engine to recharge the house bank if the batteries are all combined in a single bank.

Third, you only need one run of the heavy cables to connect the house bank to the boat's main DC panel, rather than two.

[s/v Faith]

I like to have one bank, but I don't have an inboard to start.  That said I would probably do as you are planning to do and add the new batteries in a separate bank.

I like Dan's idea for the reasons he cited, but will differ with him for reasons I bet he will agree with in this case.

 Since you are adding batteries that have a different 'history' then the rest of your house bank, I think you would be wise to use a switch, and keep them separate.  Mixing new and old batteries in a large bank can cause problems.

 It is important for batteries of a differnt mfg. or age to not be kept in parallel.  As a battery ages, you can develop slight difference in the 'internal resistance' of the battery.  It is kind of a 'new wine in old win skins' problem.  If your newer batteries have a different internal resistance, you will have current flow (very small amount) from the new to the old.  This process will effectively limit the life of the entire bank to the life of the oldest battery.

 If the batteries you are adding are the same age / mfg. as what you have you may be ok... but will take a risk.  If you simply treat the new batteries as a new bank, and use a combiner for charging, you will gain the advantage of the separate starting battery that Dan is advocating, without adding another new (devoted starting) battey to the mix.

 Just another consideration.

[Auspicious]

My tendency would be to stay with one large house bank, age of batteries not withstanding. In the real world it just doesn't make much more difference than usual manufacturing variance.

My suggestion is to get small, motorcycle-type start battery an engine start battery and an echo charger or similar to keep it topped up. I have a small gel-cell I use to start the outboard on my dinghy that will start the Yanmar 4JH4E main engine or my Mastervolt 6kW genset if needed (I do have a dedicated start battery for the engines as well). For me, the little battery is my tertiary system, but it would make a dandy start battery for a SailFar size boat.

sail fast, dave
S/V Auspicious

[maxiSwede]

Thanx guys for your answers. Some good points taken there that I will consider.

As a note to Dan's comment re. battery boxes. Obviously that's right but thosee boxes doesn't fit under the quarter bunk, where most of my bank is. The batteries do fit snugly w/o boxes though. I just need to keep that area free of metal objects that potentially could cause damage.... and as a further means of precaution I will make neoprene protective covers on top of the 'lead boxes'. After all, when they are in a row, it's not far between the +terminal on one to the -terminal on the next.

Auspicious MC batt idea as a back-up is definitely an interesting option that I haven't thought of before. If it cranks your 4 Cly. it should crank my tiny 3 cylinder too  ;D

[Marc]

As far as my restoration is, I'm starting to look at batteries.  I don't think I will need a starting battery, but , for my house batteries I'm looking at a pair of Trojan T-125 both are 6V.  What does everyone think?   Any suggestions?  Marc

[s/v Faith]

Marc,

  I went ahead and merged this into the earlier thread you had started on batteries. 

I went with a pair of Trojan T-105's.  IIRC, the cost difference for the 125's at that time was not favorable for the increase but the price for the Trojans was worth it over the cheaper brands.

  THere were some JC batteries sold by various retailers (Sams, WM, and others) that were as much as $40 each less... but they skimped on plate thickness and the golf cart guys (who use and abuse these batteries more then we do) said the $$$ saving was not realized over time.

[tomwatt]

Has anyone tried/used wheelchair batteries? Seems like they share a lot of the features of golf cart batteries, but are also built to be 'interior safe' against acid spillage, etc. Just curious.

[newt]

Funny how this thread got completely lost for me. I was in the process of getting a boat, and the survey, etc.... One of the boats I was interested in had hydrocaps, and the owner swore by them. But if I have to remove them everytime I am heavily charging the battery- sounds like too much trouble. Sorry Joe for not getting back to you sooner.

[nowell]

Wanted to add, that while doing research on electric drives (i've decided im going that route) I came across this little gem for you guys that are using flooded lead acid.

http://www.flow-rite.com/battery-watering/millennium-spw

[Pablo]

Wanted to add, that while doing research on electric drives (i've decided im going that route) I came across this little gem for you guys that are using flooded lead acid.

http://www.flow-rite.com/battery-watering/millennium-spw

Nowell, I love the idea of electric drive.  I hope you will share the details of your setup and any other details you may come across. 

[nowell]

Wanted to add, that while doing research on electric drives (i've decided im going that route) I came across this little gem for you guys that are using flooded lead acid.

http://www.flow-rite.com/battery-watering/millennium-spw

Nowell, I love the idea of electric drive.  I hope you will share the details of your setup and any other details you may come across. 

Intresting blog about a cruiser that uses an Electric Yacht kit (on my short list). At times a little preachy, but overall, great insight!

http://boatbits.blogspot.com/

Anyway, back on topic of batteries

[Godot]

Here's what Don Casey says in Sailboat Electrics Simplified regarding golf cart batteries.

What makes golf cart batteries particularly notable is that they are readily available at very attractive discount prices.  The well-respected Trojan T-105, for example, can be purchased for as little as $60.  That makes the cost of a 12-volt, 225-amp-hour bank $120.  A marine-quality deep-cycle 8D battery of equivalent capacity will run more than twice that amount.  An 8D might deliver more cycles, but probably not twice as many (the T-105 is independently rated at more-than-respectable 750 full discharge cycles).  This makes a good-quality golf-cart battery the best value in terms of amp-hours for the dollar over the life of the battery, with no -to-be-dismissed advantage that if some life-ending misfortune befalls your batteries--you forget to keep the water level up, an unnoticed regular failure boils them dry, a stuck bilge pump float submerges them--replacement costs is far more palatable.

Prices seem to have more than doubled in the past decade. :(