What is a "Deep Cycle" Battery?

[INTJohn]

http://www.pbase.com/mainecruising/deep_cycle_battery

This is the best site I've ever seen to explain what really is a Deep Cycle Battery and also what isn't. The 2 main things to get from this link that probably apply to most here are

1- That group 24, 27 & 31 marine 12 volt batteries are NOT true 12 volt Deep Cycle batteries.

2 - That there are in fact true 12 volt deep cell batteries. Many rv'ers are under the impression that to really get big amp storage capacity you gotta go with 6 volt golf carts batteries . In my opinion for most rv'ers 12volt deep cells like the Trojan T-150 or T-1275 or the comparable US Battery US12V XC will supply the same big amp capacity for basically the same value or a better value as a combination of 6 volt batteries.

This link is from a marine perspective so basically where ever you read 'marine' or 'boat' think RV, etc...........  
Enjoy!................INTJohn

 

[John61CT]

Yes T-1275 is true deep cycle, one of the few 12v that is. But

If you look at the mfg specs for duty cycles vs DOD, you'll see the 6v cells are heavier duty compared to the 12v.

Go to 2V even more so.

Some cases just no room.

and yes Maine Sail is da man

 

[INTJohn]

Exactly! pretty much.

The 1275's are a little bit bigger ; I use the T-150's which are the 12 volt equivalent of the T-105 6 volt - same 2v cell; 1 in a 6volt box the other in a 12 volt box

3 of the 12 volt 150's = 450 amp hours  weight 3 at 80lb's ea = 240 lb's
4 of the   6 volt 105's = 450 amp hours  weight 4 at 60lbs ea  = 240 lb's

Price per amp hr is basically identical as well tho different retail places will vary somewhat; tho you'll need more cable to wire up all those 6 volts.

the big advantage to me - for me - is you can use the 12 volt T-150's INDEPENDENTLY; which gives me tremendous versatility with options of how I want to use them. e.g I generally only use 2 of them for the trailer 12 volt system - 300 amp hours; and the third I have an inverter connected to it - this third battery is recharged by my 120 watt portable fold up solar panel.
And I always have the option of connecting that thrid battery if I think I'm in need of some relatively lengthy use for 450 amp hours.

Obviously with 6 volt system you have none of this single battery independence & versatility; and if 1 of those 6 volts dies on you you're out of power & out of business - not so with a couple of 12 volts. 

Options & Versatility is one of the Secrets to Life!

My next set of deep cell 12 volts will probably be the US Battery US12V VX's as a buddy of mine run's owns an alternator/generator battery shop & can get me those US Battery made 12's for his cost and they are comparable to the Trojan 150's.

When buying a deep cycle battery - then besides the price:
What is the cycle life?
What is the amp hour rating?

............and for  peeps in vans, etc. they can be used as starter battery and then you have deep cycle capability which is what you're most likely using your starter battery for most of the time while parked anyway.

Thanx..............INTjohn

 

[John61CT]

Do those T-150's also show the same lifetime-cycles rating curve vs DoD%?

 

[INTJohn]

He shows all of the manufactures lab test graphs in that link if you wana wade thru it all. Like he says tho you can only compare same manufacturer with same manufacturer as there is absolutely no set universal standards with which to compare but Trojan &  US Battery are both about as reputable companies as what exists in the snake  oil business of making & selling batteries.
For specific data q's the only place one can really go is to the manufacturer themselves and they're going to give you only what their controlled lab data results showed which as is addressed in the above link  isn't going to have anything to do with 'real world individual usage'.

Hence I use the term 'snake oil'. I've always used true deep cycles in all of my vehicles after the initial starter battery that came with it croax. If one is only using their rv's for part time recreational use - camping every other weekend during summer and the once or twice a year week long camping vacation it probably really doesn't matter what type/kind of battery they use; or  if they're always or almost always on hook ups - if it were me in that case I would buy a new one every year as a part of the overall recreational expense.

But if one is living as a low expense fulltime boondocker now battery amp hours & cycle life along with versatility & option relattive to cost becomes critical as a matter of both Life & Lifestyle.  Hell I could buy new Trojan 150's every couple years if I wanted to but 3 of those T-150's is close to 500$ and to buy those every couple years would cut deeply into my annual gin budget.......

 

[Trebor English]

Manufacturers have labs, tests, and results. What gets published is what the marketers want to tell you. The latter may or may not have anything to do with the former.

 

[SternWake]

A "lab" Cycle has very little to do with a battery in actual usage, and their cycle lives are projected, not actual results by depleting a battery to 50% exactly, then recharging it perfectly before dischargnig it to 50% again, 1200 times then performing a 20 hour capacity test and seeing if it retains 80% of original capacity or not.

Projected cycle life = Educated guessing, and marketing is legally approved deceit, as much as they can get away with.

NO doubt the group 24/27/31s sold by trojan and USbattery and Rolls Surrete are Many miles ahead of Wally worlds group 27 or 29.

However no battery is immune to chronic undercharging and cycles attained for dollar spent before replacement is necessary, well the battery abuser would likely be better off with wally worlds lightweight marine batteries, but the person who can perform the 100% recharge every so many deep cycles would get their money's worth from Trojan or USbattery's marine battery options.

If I ever get a Flooded battery again for deep cycle Duty, it will be the Trojan T-1275.

In my Area I can get that battery for 190$, and the group 31 trojan is only 15$ cheaper, yet rated at only half the total 'lab cycles'

Kind of a no Brainer, but I have to do some modification to fit such a battery's greater height.

And I am kind of hooked onto the high$$ AGM's ability to greedily gobble up 65% charge rates Where as Trojan 'recommends' a 10 to 13% rate.

I'd not fear exceeding this recommendation in Van dwelling usage, as long as the battery was not allowed to exceed 110f. Which might be difficult if located in engine compartment.

The Lifeline GPL-30HT runs about 400$, but is the same size and capacity as the T-1275, and Likely has much higher CCA figures, if used for engine starting in cold weather, or powering higher inverter loads.

I like being able to take Hydrometer readings on Flooded batteries, but determining full Via an Ammeter while holding the battery at absorption voltage is actually easier in my opinion, at least with my tools and charging sources.

 

[INTJohn]

Good Stuff! SternWake..........

There really is no difference between the T1275 & the J150 (I just realized I been calling them T-150 - my bad) the 1275 has a slightly longer case but the reason I like the 150 is they come with handles.
http://www.trojanbattery.com/product/j150/
http://www.trojanbattery.com/product/t-1275/

The US Battery 12V XC has handles as well; main reason for my preference to those 2 particular models - at 80+ pounds apiece those handles make a big difference when moving them around. I use my trailer as a 'home base' if you will and toss one of the batteries in to my truck with my portable solar panel & an inverter and away I go camping out of the truck away from the trailer sometimes for 5 or 6 days. So I'm often moving 1 or more of them around - some1 else might hook em up & forget about em xcept when it comes to checkin the fluid levels.

I like the amp hours versatility and single battery 12 volt capability but everyone has their own style & usage. But yeah I'm with you, bro, for flooded deep cycles teamed with fulltime boondockin, can't beat the Trojan 1275's or 150's......... INTJohn

 

[John61CT]

Yes, I have found corroboration from Trojan that

T1275 and the J150 are exactly the same internally.

Also 50 amps charge rate is too much, 10 to 13% is the *maximum* rate, not just the 'recommended' rate.

So for max longevity they want unusually high charge volts, and not very fast acceptance.

Looks like an excellent product, but I'll keep looking at other premium marques due to those two issues.

In reality of course maybe they are more forgiving than their engineers think, obviously wouldn't matter in a PSOC situation.

 

[John61CT]

Wow Rolls will take CAR .2C, but wants 15V!

Isn't that high enough to actually cause problems with connected appliances and electronics?

Any other premium FLA out there with high CAR but lower voltage requirements?

 

[SternWake]

Any of these flooded batteries can handle higher charge rates when depleted to less than 60% charged, what the manufacturers 'recommend' is likely as driven as much by marketers, as engineers.


Mymost recent flooded battery was a group31 USbattery marine 'deep cycle'.  It regularly got everything my alternator could make at the very limits of its charge acceptance rate.  I got close to 500 cycles from it. It is still cycling, but not very deeply.

But that battery..
 On my solar alone, required 14.9v absorption for 2.5 hours, then a 15.3v finish for as long as possible when i was cycling 35 to 65AH of its 130AH rated capacity.  This battery in this usage still required a 16v equalization charge for about 45 minutes every 14 to 16 cycles.  If I went 30 cycles then the EQ could take 4 or 5 hours, once took 9 hours over 2 days, before SG maxed out on all cells.

That battery when driven mid to late morning for a few miles(ocean calls), and getting that 40 to 60 amps, then required much less time at 14.9v and 15.3v before SG maxed out.  I thought the high amperage and the physical agitation from driving were working together to significantly reduce solar absorption times, as 5 minutes of 50 amps does not really return the AH required to reduce that time on its own.

Now, having recent AGM temperature data when high amp recharging, I think the flooded 31 was likely heating significantly more in that 5 minutes of similar alernator amperage, and that,  combined with physical agitation of driving and high amperage when very depleted in early morning, along with egnine heat also warming battery, was why it reduced the absorption duration and finish charge duration required by a big factor.

15.3v did pose issues on my 400 watt PSW inverter a few times, triggering th ehigh voltge alarm, back when I used it to run a 50 watt heating pad heating my showerbag while I was surfing.  Now I use a 12v heating pad. But with my AGM I never go above 14.8 volts anyway.

I found that flooded USbattery to be a PITA, because the 15.3v, and the frequent EQ charges it required.  BUt also, when if I alternator high amp charged it, especially to a more distant spot along pacific, then the solar Absorption voltage settings were too much for too long, and water usage was increased as well, also Positive plate shedding.

What was weird was these overcharges were still not enought to stave off the needed EQ charges, nor extend the times between their applications. 

Around deep cycle 475, It was on its way to 14.9v taking 10 amps, and the cell closest to (-) battery post was heating excessively on the bottom. I then removed it from my Van, Switching ALL loads to my Northstar  AGM-27 battery.  That was June 2015.  Still my only battery, and I am on deep cycle ~470, and 38 months old.

Still starts my engine easily when depleted 60 of 90AH.  Still sucks up 65 amps for 20+ minutes when that discharged, and always holds a higher voltage than my flooded group 31 at 130AH capacity did.