School me on some batteries

[ranger58sb]

Originally Posted by NorthernMac

They are group 27!!
12v
Oops

Pin down exactly how much space you have, first.

If you have two BCI Group 27s, perhaps each in a tray... you MIGHT have room in the trays for 12V Group 31s, a slight capacity improvement.

OR...

If you have additional space -- for four BCI Group GC2 (6V golf cart batteries), which are also slightly taller, wired in series/parallel to 12V -- you might be able to get a much better capacity improvement. (Only two GC2s may or may not be an improvement, and if one battery goes south, you don't have a 12V get-home system).

Once you know space possibilities, then you can worry about whether flooded lead acid, AGM, Carbon Foam AGM, etc. would be most viable at least expense. Pros and cons for each. Then you can worry about brands. I'm not conversant with the lithium options, so other folks can talk to that.

-Chris

[daletournier]

Originally Posted by boatpoker

He said "two" panels to make the 300watts. My point it is simply not necessary for the typical systems on a 30 footer.
We run music, refrigerator/freezer and a separate freezer 24/7 on 175Watts.

You are obviously a very knowledgeable professional thus my comments are given with respect, but I find it hard to believe 150w is sufficient to run a fulltime cruising boat that never plugs in if running a fridge computer etc, its borderline imho. I suppose it all depends on what one believes full is, this is often disputed here.

And of course your right, doing a power audit and working out ones needs is the only way to be sure.

Imho batteries are abused more than any other system on a fulltime cruising boat. One example recently is a mate of mine (circumnavigatior) dosent believe in equalizing because when he did it he swelled the cases of his T105's, of course he didnt start the process from full but believed he did, no solar, charges from genset everyday and the batteries never see more than 14.2v, t105's will never get to full at that voltage.

Once again, no disrespect intended.

Cheers.

[GordMay]

Many experts recommend that batteries be equalized periodically, ranging anywhere from once a month to once or twice per year.

However, Trojan only recommends equalizing when low or wide ranging (variation between cells) specific gravity (>0.030) are detected, after fully charging a battery.

[NorthernMac]

Ended up getting a pair of west marine 800cca flooded 27s

I agree with a oops on these hurting less than lithium

[rbk]

Those are starting batteries and will live a short life as your house bank.

[NorthernMac]

Originally Posted by rbk

Those are starting batteries and will live a short life as your house bank.

They were listed as a dual or hybrid type

[Adelie]

If they are 800cca then they are probably starting batteries or at best dual purpose not deep cycle and can expect relatively short life from these batteries.

[rbk]

Originally Posted by NorthernMac

They were listed as a dual or hybrid type

I would try and return them if you can, for some true deep cycle. Or better yet two deep cycle and keep one of those for a dedicated start battery.

[NorthernMac]

Originally Posted by Adelie

If they are 800cca then they are probably starting batteries or at best dual purpose not deep cycle and can expect relatively short life from these batteries.

This

https://www.westmarine.com/buy/west-...91?recordNum=1

[rbk]

Originally Posted by NorthernMac

This

https://www.westmarine.com/buy/west-...91?recordNum=1

They’re more designed for power boats with lots of electronics where they’re almost always being charged but can’t take a deep discharge well, like say running a refer, lights gps for an evening at anchor after a day of sailing. I would buy a dedicated start battery or one of those booster packs as you may find yourself lacking starting power. But it really all depends on your power budget...you did figure that out right?

[NorthernMac]

Originally Posted by rbk

They’re more designed for power boats with lots of electronics where they’re almost always being charged but can’t take a deep discharge well, like say running a refer, lights gps for an evening at anchor after a day of sailing. I would buy a dedicated start battery or one of those booster packs as you may find yourself lacking starting power. But it really all depends on your power budget...you did figure that out right?

So swap one out for a straight deep cycle? I can always return one.

I’m not reading the snark well, so I spent too little? I was about to put two lithium batteries in the boat and everyone was like bad idea, toss two dual purpose, man you just can’t win around here!

[rbk]

Originally Posted by NorthernMac

So swap one out for a straight deep cycle? I can always return one.

I’m not reading the snark well, so I spent too little? I was about to put two lithium batteries in the boat and everyone was like bad idea, toss two dual purpose, man you just can’t win around here!

No snark intended. What you need to do is sit down and figure out how much power you need, example:
https://newcontent.westmarine.com/do...%20Budget.xlsx
Figure out what you’re running and for how long, don’t be cheap on this, better to have more reserve than not enough. Then size your bank. Best to have a house bank and a dedicated start battery or you will very likely find yourself at anchor one morning unable to start your engine. At that point you have severely drained your batteries and have shortened their life. Figure that out then post your findings.

[NorthernMac]

Originally Posted by rbk

No snark intended. What you need to do is sit down and figure out how much power you need, example:
https://newcontent.westmarine.com/do...%20Budget.xlsx
Figure out what you’re running and for how long, don’t be cheap on this, better to have more reserve than not enough. Then size your bank. Best to have a house bank and a dedicated start battery or you will very likely find yourself at anchor one morning unable to start your engine. At that point you have severely drained your batteries and have shortened their life. Figure that out then post your findings.

Ok, will do, so right now I have a selector for off/1/2/both, I’d set up say 2 as a couple deep cycles, 1 as a high CCA, start on one, anchor on 2, and shore power charge on both? I also understand that the system won’t take kindly to starting on 1 and switching to both after start up?

Would adding a alternator switch help? I’m used to starting with the alternator off and switching it on after the engine starts, switching it off before shutdown.

Budget wise, I’m already planning on spending more on the refit than the purchase price, that’s both because I got a good deal on the boat and also not wanting to half arse things.

Apologies for questions guys, I lived aboard for a good chunk of my childhood, sailed a ton too, but recently most of my water work has been professionally and seaplanes, I’ll pick up quick, just forgive the slight delay

[basssears]

NorthernMac, don't take it as "just can't win", just go with the flow on your original title, you're now "going to school" on batteries.

Won't repeat the suggestions above but there are good ones, particularly coming up with a power budget and figuring out how many batteries of what type you need, that is the best long term solution.

That being said, I have been right where you are (multiple times, camper vans and boats) where you have an existing set of batteries, they need to be replaced, you don't know that much about the rest of the setup yet and d*mnit this is my new toy and I want to play with it!!

I think you made a good call with going lead acid for now, lithium is definitely a big step up in complexity, I would recommend getting a well proven setup going first and then considering upgrading later.

If you're set on just getting two new batteries so you can go out and play (and there's NO judgement in that sentence, it's just different plans for different folks... some people would buy a new boat, haul it and just tinker and fine tune for a year... others, myself included, want to get out and play while fine tuning things), here are some thoughts:


1) As pointed out above, those are "dual purpose" batteries you bought, supposed to be a hybrid start and house battery. Like many hybrids, they're bad at both. Anytime you see the first spec as "CCA" (cold cranking amps) you're looking at something designed to deliver a rush of power to turn over an engine, not deliver a trickle of power over a long period. That being said, these things claim 80AH although I doubt that claim (I inherited some Interstate dual batteries that are similar spec and I bet I don't even get 60AH).

2) The "AH" in #1 is "amp hours"... the quoted amp hour is usually the 20 hour rate, that means these batteries claim to provide 80 amps over 20 hours (that doesn't mean they could provide 80 amps in one hour, too fast a draw). Since these are 12v batteries and amps*volts = watts, 12 * 80 = 960 watts, so these claim to provide 960 watt hours or almost 1 kilowatt hour. BUT, they're really more like ~60 or 65AH's, and you only want to drain flooded lead acid to 50% at most, so you'll really get ~500 watt hours out of one battery. Over 20 hours that's 25 watts an hour, so a few LED lightbulbs and maybe charging a phone. Granted, that's babying the battery, but you can see how you're not getting an epic amount out of this battery.

3) Now take a look at the Trojan 27TMX, also a group 27 battery, so same size. 20 hour rate is 105 amp hours. At 50% use that's 57.5 amp hours, at 12 volts that's 690 watt hours... almost 40% improvement. And they're cheaper than Worst Marine's. If you can find Trojan's locally and can return the West Marine's I would go that route. You're looking for batteries that start their specs with amp hours not CCAs.

4) Sounds like you have space for only two batteries, is that correct? Conventional wisdom is you have a battery switch that switches all power supplied to your boat between bank #1 and bank #2. Traditionally one of these banks is your "house" bank, which is multiple deep cycle (AH not CCA) style batteries to provide power for all your living functions (instruments, lights, charging things, blenders etc). When your engine is not running you turn battery switch to your house bank. The other "bank" is really just one battery, a start battery (CCA not AH) that you switch to to start your engine. When engine is running you switch to "both" so your alternator charges both (same with when you're connected to shore power assuming you have a battery charger). The theory is even if you forget you should only drain your house bank to 50%, and you drain it all the way (your batteries are dead, no lights, no nothing) you can still switch to your start bank (which hasn't been affected) and start your engine and recharge all your batteries. FWIW this is house my system is setup, 1 start battery and 3 deep cycle house batteries.

5) Given that #4 above is your traditional setup, if you only have space for two batteries it can be challenging. You would have one start battery that is an insurance policy but rarely used, and one seriously overworked house battery. Given how good the jump start battery packs are these days, another alternative would be to skip the multiple banks and just have one house bank of two batteries, then be careful about how far you drain them, and if you drain them so far you can't start you engine you use your start pack. Not ideal, and the time you need to dig out the start pack is going to be the time you REALLY need the engine to start right now (Murphy's law), but it's a way to do it. Two Trojan 27MTX would give you almost 1,400 watt hours over a 20 hour period and you would still have only drained your batteries 50%, should still start your engine, and in the meantime you can be running a draw of almost 60 watts per hour for a 24 hour period (we're ignoring the non-trivial fact that you'll be adding to this with solar)... that's enough to run an energy efficient fridge, lights, charge devices etc. I get by quite well (with some solar help, although only 130 watts, and we're very energy conscious) with ~90AH of usable power, so less than what you'd get with two Trojans (need to upgrade to those) and we run an Engel 12v cooler as a freezer, lights, music, Wallas heater at night.


If you go down the route of #5, two thoughts... one, even with a separate start battery those jump start packs are a nice insurance policy... I carry one even though I have a start battery because someone else might need it, or you might forget to turn the battery switch from "All" to the house bank when you shut the engine off and then you drain both banks of batteries. Also, regardless, if you get a jump start pack they're not all the same, make sure it's spec'ed to start your style engine (plenty of them will start a little 2.0 liter gas engine, not so many will start a diesel particularly if it's larger).


Good luck, if you have more questions as you go down this slippery slope post 'em, we have all had to learn this stuff the hard way too.

-- Bass

(P.S. Just the usual caveat, this is my opinion and my experience, I'm no expert, trust but verify)

[basssears]

Originally Posted by NorthernMac

I also understand that the system won’t take kindly to starting on 1 and switching to both after start up?

This shouldn't be a problem. Notice I emphasize shouldn't. A good quality (like Blue Sea) battery switch should be make before break, meaning when you switch from "1" to "All" it makes the new connection before breaking the old, so there shouldn't ever be a time when neither 1 or All is connected (which would, as you're fearing, fry your alternator).

But before you risk your alternator, you can test your switch simply. Turn on a few lights, then very slowly switch the switch back and forth between 1, All, and 2... if the lights ever flicker then you're switch is breaking before making and needs to be replaced or you need to guarantee you never use the switch while the alternator is running.