625ah Battery or 450ah and 400 Solar ?

[colemj]

Originally Posted by Maine Sail

Have you considered less expensive batteries such as the Deka/East Penn 6V batts sold at Sam's Club under the Duracell brand.

You sure they are Duracell? I think they are Energizer (although I haven't been in a Sam's Club in years). Wouldn't want to get that bunny pissed off...

Mark

[daddle]

I like the batteries to be big enough for a few days of continuous refrigeration, navigation and autopilot. To get thru a few days without sun. So charging can be skipped for a few days. Or in case the diesel has some problem that cannot be addressed right away.

But not so big that they cannot be charged in a few hours.

The actual size will vary depending on how much of a miser or pig one is.

[engele]

Thanks to both sides of this discussion. I hadn't considered cheaper batteries, though maybe I should. $80 each is a lot cheaper that $130 (assuming I still pay a $25 core charge). I just worried that the batteries would die six months out when we are least equipped to deal with it. It's great to read about other boats actual experience with a 450ah bank. I like some of the battery guys on this thread like the idea of being able to last a few days if need be without charge, but I am thinking that I should be able to do that with two more batteries unless we use the watermaker more than I expect (possible).

[s/v Jedi]

Make sure that your math assumes that you can only use 30% of the bank capacity. This is because you can't discharge below 50% and it's tough to charge much over 80%, plus you will loose capacity over time.

If you need 300Ah capacity, your bank becomes 1,000 Ah.

ciao!
Nick.

[Maine Sail]

Originally Posted by colemj

You sure they are Duracell? I think they are Energizer (although I haven't been in a Sam's Club in years). Wouldn't want to get that bunny pissed off...

Mark

Yes Duracell. The previous brand was Energizer, which some stores may still have, and they were made by Johnson Controls. The new batts are branded Duracell and a made by East Penn/Deka.. I've installed about 30 of them since they acquired the line in July.. They have the AGM's and wets and they are the identical battery West Marine sells for more than double the price..

[onestepcsy37]

maine sail - confirm that on the sam's batteries. i was in a sam's today. all of the batteries they are selling now are branded 'duracell' and clearly marked 'east / penn battery, lyon pennsylvania'. they were priced at $78. i did notice that the 20 hour rate is 210; it seems to me that the previous brand, energizer - the ones i bought last year - were marked 225. east penn is supposed to be one of the better makers. i don't like the cell cap arrangement they have on the new batteries but that's just my preference.

as colemj pointed out, my setup without controller is only workable because it puts out less amps than i consume, so no overcharge worries. it does have the advantage of being simpler and of sending full output to the batteries. but if i can ever come up with a satisfactory solution to mount a second panel i will have to add a controller.

he also mentioned lowering your amp draw. i'm gradually replacing all bulbs with led lights. i cut down on fridge draw by decreasing the size of the box by filling it in with insulation board. we found that six cubic feet was just too big. we're now using 3.5 cf which seems about right for us. and the insulation i used to cut down the interior size of the box also helps use less power.

for 120 volts i have a 700 watt inverter. i picked that size because it's big enough to run the small shop vac which the admiral uses for a vacuum cleaner but not big enough to run her hair dryer, which i'm sure she would use every day if she could.

[Maine Sail]

Originally Posted by onestepcsy37

maine sail - confirm that on the sam's batteries. i was in a sam's today. all of the batteries they are selling now are branded 'duracell' and clearly marked 'east / penn battery, lyon pennsylvania'. they were priced at $78. i did notice that the 20 hour rate is 210; it seems to me that the previous brand, energizer - the ones i bought last year - were marked 225. east penn is supposed to be one of the better makers. i don't like the cell cap arrangement they have on the new batteries but that's just my preference.

They have two "GC2" batteries. Sam's did not choose to label the batteries in Ah capacities, unless this changed recently. I simply called East Penn and got all the Ah ratings for the batts I would buy. The GC2 is claimed by Deka to be 215Ah and the EGC2 is 230Ah. The group Deep Cycle 29 is really a group 31 and is 105Ah..

[willardj]

?. I'm not to smart when it comes to this batt stuff, but the 6vt and 12vt ah's. How does the ah change from the 6vt to the 12vt? Do they just double? Y is the ah twice as high with the 6 vs the 12?

Thanks

[engele]

Two six volt batteries rated at 225 ah equals one 12v 225 ah battery.

[engele]

Okay,

I looked into the cheaper Duracell batteries. There is no Sam's Club closer than a 2 hour drive from here. Maybe worth it if they have the batteries. I also looked on Duracell's website and called the local dealer and he tried to sell me Crowne batteries. I know Crownes are great, but at that price ($155 or $170 before the core charge) I would stick with the Trojan's I know. I was toying with the idea of trying the Duracells at that price. Especially if they are just a rebranded Deka. I guess I need to keep thinking and maybe make the run to the Seattle area if they have them at the Sam's Club down there. Are there other good cheaper alternatives to the Trojans?

[onestepcsy37]

while i was in my local sam's club saturday i noticed another 'duracell' brand battery in the 'golf cart' section. it's 12 volt instead of the usual 6 volt. it's the same width as the 6 volt battery, a half inch taller, and about 3 inches longer. the amp hour rate for each battery is 155, meaning two would give me 310 ah as opposed to two 6 volt sizes giving me about 225 ah. it would also have the advantage that if one battery goes bad i can just remove the one; with 6 volt batteries i would have to remove two. something to think about.

the downside is that each battery weighs 90 pounds. i prefer dealing with 60 pound six volt batteries. anyway, i just bought new batteries last year so hopefully i won't have to make this decision for a few more years....

[goboatingnow]

Originally Posted by onestepcsy37

my boat is about the same size as yours (csy 37) and we use it about the same as you plan to do - living on the hook for months at a time. here's what's been working for us -

1) house bank is four golf cart batteries providing 450 ah - wet cells. we used to have t-105's and they lasted six years but when i went to replace them i decided they were simply too expensive so last year i replaced them with sam's club batteries at $75 each. i also have a size 29 (100 ah) 'starting' battey which is actually a deep cycle wet cell - also from sam's club and about $80.

2) 100 amp alternator on engine. it's a good backup for battery charging but i never use it just for that purpose.

3) solar panel. one kyocera 135 watt which puts out about 7 amps at mid day. figure about 40-50 amps per day. i would like to add a second panel. and now to debunk a myth; you don't have to have a controller at all. i haven't had one ever. my panel is wired straight to the battery bank with an on/off switch. the trick is to use more amps per day than the panel can produce, so you'll have no fear of overcharging. my fridge takes care of that. the panel can just about keep the fridge going so anything else i use guarantee's that i won't overcharge the batteries. the on/off switch allows me to shut the panel down when necessary. if i ever get to add that second panel i'll have to add a controller too.

3) honda 1000 generator and 35 amp 'smart' charger. every couple of days at anchor i have to run the honda for two hours to recharge the batteries. i could have installed an onboard charger but being 'thrifty' i bought a 'smart' automobile charger that starts at 35 amps and tapers off for $70. the boat came with an onboard charger but at 10 amps output it's not worth using.

that's it. a 450 ah battery bank and three independent ways of charging them. i use a digital voltmeter to keep track of battery state (for which i will be denounced on this forum) and i've never run the house down or overcharged it.

our daily usage is under 100 ah per day, the fridge being the biggest single draw. don't forget to include the autopilot when calculating your daily draw. on a long passage you can easily run your bank down without suspecting the source...

Of course you'll be lucky to get three years out of the " Sams club" batteries.

As to solar and controllers. Well if you like throwing away into 20 % of the potential energy you can connect them without a controller. Sure.

Dave

[engele]

The SAMs Club stores on the West Coast all carry "Energizer" brand batteries. So it looks like I am back to T105s.

[Jimbo485]

Rules of Thumb, Watson?

Your battery capacity Ah should be around 4 times your daily consumption. The theory says you don't want to go below 50% capacity and the upper 15% is difficult to charge, so you go down to about 60% and then back up to about 85%. That is 25% (85 - 60 or 90 - 65), so your battery capacity is 4 times your consumption. Some say 3 times or 33%. I prefer to be conservative.

But how reliable is your charging? If you have a generator, you can just burn some fuel and you do not need to depend on the wind nor the sun. So go for the rule of thumb of 4. Or 3 if you are a daredevil. But your choice of charging device will also adjust your estimation of the buffer your require. And the buffer is the battery capacity.

If you go through the numbers, wind generators just do not make the grade anymore for a typical tropical situation or tradewind RTW. Solar does. But you need to consider the sun / cloud cover and wind stats in your particular geographic location if you are anchored near Santa Claus or the penguins.

We had 340 W of panels and then bought an extra 630 W of panels from Sunelec for less than $1000 about a year ago. Pretty happy so far. Our total is currently 760 W because the last 210 W panel is lashed to the deck and still unconnected. When installed, yes, there will be a total solar capacity of 970 W. The 760 W at the moment gives us about 140 - 200 Ah per day in practice.

"Let's call it 180 Ah, Watson, which fits another rule of thumb about panel Watts and Ah produced per day. Divide your Watts by 4 should give you your average Ah produced daily. The theory is boring (W/20Vx5h = Ah/day. Divided by 20, not 17 for inefficiencies and it improves my lazy mental maths.) Just divide by 4 and accept it, Watson."

"Hmm," you interrupt me again, Watson, with your idle comments, "the other rule of thumb was also four for normal people and three for daredevils.... does that mean...?"

"Why of course, Watson, it is elementary! Simply calculate your daily Ah consumption with one of those Excel spreadsheet thingies, multiply the result by 4 and buy that quantity of battery Ah and that same quantity of Watts of solar panels!"

"What?" I hear you mumble.

"My dear Watson, I did say, and I will repeat it again, it is Watt. Not what! Or did you really mean how many?"

"Yes, I believe so, Sir."

"Ok, Watson, thank God we cleared that up. Our battery capacity is 880 Ah. The solar panels Watts you already know."

"Ahhh!," Watson ruminates like the fat cow he resembles, "So your battery capacity is currently a bit more than your solar panel wattage but soon it will be the opposite. WTF???"

And I say, "Very observant, Watson. You are correct! Please keep your acronyms to yourself. And the explanation is simple...no...logical?...no.... in fact I do believe it is elementary, my good man."

And then I continue, "Because we have no generator and our engines are generally out of action, stopped or very poor chargers when they do agree to spin their rotors, we need to account for a day or two of clouds. Not a week, Watson, because we are in the tropics, but a day or two, yes.

"So I assume the battery Ah can drop from, let's say, about 90% to 50% in a typical poor situation, which means 40% or 352 Ah. Are you following, Watson? Move quicker with that slide rule, please. That means, realistically 3 days, because if cloud comes in we can reduce our excessive consumption by turning off the second fridge, less water consumption for frivolous showers, dehydration avoidance, etc. So consumption of 150 Ah on day 1, and 100 Ah on day 2 and day 3 means a total of 350 Ah before we hit 50% battery capacity."

"But, Sir!"

"Approximately, Watson, these figures are approximate. So far this seems ok and has worked well in the real situations of those verdant isles in the New World.

"We looked into buying a Honda1000i or 2000i, Watson, but the money was better spent on more batteries and solar panels. With the difference saved, I bought you a truly excellent bottle of 28 year old whisky last Christmas and spent the remainder on 7 year old Cuban rum for my good self. Even if the monetary difference was not so notoriously in favour of batteries and panels, my good man, surely you must realize that the generator will only annoy us with the noise, petrol consumption, oil changes, smell, etc."

"But don't you think that...." he interrupts me with his ridiculous assertions.

"Yes, Watson, the petrol and oil consumption is not much. I do agree wholeheartedly. But I would still prefer to be hunting marine animals with a piece of glass on my face rather than proceeding with yet more maintenance on another infernal internal combustion engine. Those panels just sit there and produce energy. Almost a case of set and forget. For a lazy man who looks for efficiency in everything, that is great!"

.....

"No, I am not lazy, Watson! Damn your impertinence. I am efficient!"

........

"Our motors, Watson?? I already told you. Yes, they provide a few amps, 6 each to be precise, but it is insignificant.

"On your knees, Watson, pray to Ra!"

............

"What did you say? Who is Ra??? No more interruptions, Watson! Please, just STFU and pray!"

[cwyckham]

Awesome post!