battery question

[alwechs]

Perhaps this has been addressed previously. I'm looking to replace my house battery. I get I need a deep-cycle battery, but how vital is it that I stick with the numbers in my current battery? If I go with a higher number than the 750 cranking amps (at 32 degrees) that I have now will I get more performance? Or do I need the exact number that I have currently? Other thoughts? Thanks.

[Sebtown 1]

Purchase the largest deep cycle battery that will fit in your battery compartment. Don't waste your money on an RV/Marine battery. Deep cycle amp hours are more important that cranking capacity.

[Deano]

Genuine deep cycle batteries are not rated in cranking amps. They don't crank anything.
Best bang for the buck is a pair of 6 volt Golf Cart (GC) batteries connected in series for 12 volt, if they will fit.

[alwechs]

How do I know what "deep-cycle amp hours" are on the battery? Is that the same as "reserve capacity?" or "marine cranking amps?"

[Deano]

Reserve capacity and marine cranking are dual propose battery ratings. Deep cycle should be rated amp hour. The ones I 'm familiar with are marked on the battery.

[cruising7388]

Originally Posted by Deano

Genuine deep cycle batteries are not rated in cranking amps. They don't crank anything.

Say what?

https://lifelinebatteries.com/produc...ries/gpl-31xt/

[booster]

Originally Posted by cruising7388

Say what?

https://lifelinebatteries.com/produc...ries/gpl-31xt/

The CCA is mostly true in wet cells, but in AGMs they can pretty easily cover both starting and deep cycle without a problem. The Lifeline AGMs are one of the good ones in automotive type size 12v batteries. There are close no good 12v wet cells around for 12v anymore in automotive sizes. Even the used to be good DC24 and DC27 from Costco, Interstate, etc appear to have changed. We use them in the van for starting batteries as it is all warm weather, but the last one we got is pretty much junk. Reviews are reflecting similar issues.

[cruising7388]

Originally Posted by booster

The CCA is mostly true in wet cells, but in AGMs they can pretty easily cover both starting and deep cycle without a problem. The Lifeline AGMs are one of the good ones in automotive type size 12v batteries. There are close no good 12v wet cells around for 12v anymore in automotive sizes. Even the used to be good DC24 and DC27 from Costco, Interstate, etc appear to have changed. We use them in the van for starting batteries as it is all warm weather, but the last one we got is pretty much junk. Reviews are reflecting similar issues.

My point is that while it generally isn't cited, every 12 volt lead acid AGM battery can express a CCA rating. Concord does cite them and they are impressive.

I wasn't aware that Interstate battery quality has degraded. But even assuming that, considering that the duty cycle of a starting battery is so low, I'm surprised to hear that you are experiencing early failure considering that you are starting a gasser., not a diesel.

IMO starting batteries fail less from normal starting patterns and more from parasitic loads that fully discharge them to the point of hard crystal plate sulfation.I've used AGMs for a starting battery for decades without issues. I think the conventional rule of thumb for replacing a flooded cell with an AGM is to bump up the battery size for, more or less, a 15% increase, i.e. replace a flooded cell 24 with a 27AGM or replace a 27 with a 31.

Considering how important starting and house power is for an RV, I would stick with Trojan flooded cells and Concord lifelines. Considering that at least part of the time your RV is out in the middle of nowhere, I think choosing low price batteries is akin to choosing the low bidder for your heart surgery.

[Deano]

The OP was talking about his house battery, and as far as I know, the only thing it starts would be a generator, not the vehicle engine.
So, OK, I sit corrected. My research was 5 years ago and was primarily limited to 6 volt deep cycle coach batteries as a pair of GC were rated higher than any 12 volt I found.
The search I just did found all of the 12 volt deep cycle batteries that have cranking and reserve capacity listed are actually dual use, marine starting/deep cycle batteries. However, they are not true deep cycle batteries in spite of being called that.
The 12 volt actual deep cycle batteries I found, do not have cranking/reserve capacities listed.
As for AGM, while they have advantages over flooded the expected life is less and they are more expensive. I realize they may be required in some motor homes due to location and/or off gassing.
If you can use a pair of GC 6 volt, I stand by my previous post.

[booster]

For reference on what they call them and the specs that they give for their batteries at Interstate.


Actually even the GC batteries don't have AH ratings on them anymore.


https://interstatebatteries.com/recr...ies/deep-cycle


The DC24, or 24DC depending on where you, are mostly called marine starting batteries now. IIRC that is what Costco says.


I have been assuming a single 12V house battery as the OP said battery and 750 CCA. If that is the case, going to a pair of GC batteries is probably not a desirable option to them, even though it would certainly be a good thing.


The Trojan GC wet cells are some of the best batteries around in general and IMO way better than ANY 12v wet cell that I know of but I haven't heard much about the Crown 12v which some claim are very good but not used much in RVs.

[Sebtown 1]

My last Trojan group 27 wet cell lasted 5 years. I just replaced it and was able to fit a Trojan group 31 and pick up a few more amp hours. Can't be more firm in recommending a true deep cycle battery as opposed to a marine starting/deep cycle.

[Bud]

Originally Posted by Sebtown 1

My last Trojan group 27 wet cell lasted 5 years. I just replaced it and was able to fit a Trojan group 31 and pick up a few more amp hours. Can't be more firm in recommending a true deep cycle battery as opposed to a marine starting/deep cycle.

Is that because you have tried to think of an application for a marine battery and failed. Or you did not try? Or there are NONE?

Bud

[Sebtown 1]

Actually Bud, I tried a Diehatd Marine battery and found it ok but it did not have the longativity of the true deep cycle Trojan. I'm happy for you that you experience with marine batteries has been different than mine. I've owned camper vans since the mid 70's so I speak from my own experience.

[booster]

We had the unique "opportunity" to experiment with using a 3 battery system to see how it would work. It consisted of two 6v Trojan GC 260AH batteries and a 12v Trojan SCS200 which is touted as deep cycle, but really behaved more like a combo battery.


The SCS charged faster, discharged first, came to higher specific gravity, and used much more water. It also required equalize about 4X more than the GC batteries.


When we ditched that system for the 4 Lifeline AGMs, I capacity tested all the batteries. This was at 5 years of somewhat hard use because we were also doing a bunch of charger testing and learning.



The GC batteries tested as new after one equalize cycle, which totally amazed me. The SCS 200 tested at under 80% capacity after needing 3 equalization cycles to get there.



I am totally convinced that Trojan GC 6 volt batteries are really good batteries and handle abuse very well.


We could have gotten 5 years from the SCS batteries, I am sure, but the GC setup probably would have made 10 years.

[cruising7388]

Originally Posted by Deano

As for AGM, while they have advantages over flooded the expected life is less and they are more expensive. I realize they may be required in some motor homes due to location and/or off gassing.

If you can use a pair of GC 6 volt, I stand by my previous post.

The typical physical constraints of a class B makes convenient location more difficult. Coachmen briefly located flooded cell house batteries under chassis that made servicing them a major PITA. It didn't take long for them to switch to AGMs.

A distinct advantage of AGMs is that their local discharge rate during unattended operation is a fraction of the discharge rate of the flooded cell counterpart. A disconnected AGM can sit for the better part of a year without permanent damage. The rate is about 3% per month. Flooded cell local discharge is about 10% per month.

A pair of Golf Cart 6V batteries works fine as long as you can deal with the increased footprint. The Costco Interstate GCs are the best bang for the buck although Booster indicates that there are reports of a decline in the quality of Interstate batteries. For Booster: are these anecdotal user reports or objective test results?

[booster]

Originally Posted by cruising7388

The typical physical constraints of a class B makes convenient location more difficult. Coachmen briefly located flooded cell house batteries under chassis that made servicing them a major PITA. It didn't take long for them to switch to AGMs.

A distinct advantage of AGMs is that their local discharge rate during unattended operation is a fraction of the discharge rate of the flooded cell counterpart. A disconnected AGM can sit for the better part of a year without permanent damage. The rate is about 3% per month. Flooded cell local discharge is about 10% per month.

A pair of Golf Cart 6V batteries works fine as long as you can deal with the increased footprint. The Costco Interstate GCs are the best bang for the buck although Booster indicates that there are reports of a decline in the quality of Interstate batteries. For Booster: are these anecdotal user reports or objective test results?

The lowered life of the Interstate batteries was strictly limited to the 24DC and 27DC and anecdotally from peer reviews. What struck me was the amount of reviews from long time users of those batteries claiming the latest versions were hugely worse than the previous ones they had. I have found similar with our current 24DC and to a lesser extent with 27DC from maybe 5 years ago that the 24DC replaced.


I can't speak, but we have two fairly recent new, Costco starting batteries in our cars. One in DW's CRV and on one in my 96 Buick Roadmaster, so we will see how they hold up. If decent, they should last 7+ years as that is what the OEM ones normally do for us, or past Costco batteries.

[cruising7388]

Originally Posted by booster

I can't speak, but we have two fairly recent new, Costco starting batteries in our cars. One in DW's CRV and on one in my 96 Buick Roadmaster, so we will see how they hold up. If decent, they should last 7+ years as that is what the OEM ones normally do for us, or past Costco batteries.

Considering the normally low duty cycle placed on a starting battery, if fully charged and regularly watered, 7+ years of service life shouldn't be hard to obtain, other things being equal. But they rarely are. A perfectly good battery can be impacted by an alternator failure that will discharge the battery to the point that it won't even support ignition.

Decades ago I visited a battery shop owner that not only sold batteries- he built them from scratch and did numerous autopsies on dead soldiers. His conclusion was that a dead starting battery timely recharged while unmoved, caused little degrading but that jump starting a dead battery and typically immediately driving off subjected that battery to sufficient vibration to slough off amorphous lead sulfate to the bottom of the battery which in the best case is never converted to Pb during recharge and in repeated similar incidents shorts adjacent cells. His suggestion was when jump starting a dead battery, keep the vehicle stationary for five minutes or so.

It doesn't apply to your vintage Roadmaster, but I wonder if the emergence of the Canbus alternator charging protocol in the interest of increasing mpg has a better, or worse or no consequence on battery life.

[booster]

Originally Posted by cruising7388

Considering the normally low duty cycle placed on a starting battery, if fully charged and regularly watered, 7+ years of service life shouldn't be hard to obtain, other things being equal. But they rarely are. A perfectly good battery can be impacted by an alternator failure that will discharge the battery to the point that it won't even support ignition.

Decades ago I visited a battery shop owner that not only sold batteries- he built them from scratch and did numerous autopsies on dead soldiers. His conclusion was that a dead starting battery timely recharged while unmoved, caused little degrading but that jump starting a dead battery and typically immediately driving off subjected that battery to sufficient vibration to slough off amorphous lead sulfate to the bottom of the battery which in the best case is never converted to Pb during recharge and in repeated similar incidents shorts adjacent cells. His suggestion was when jump starting a dead battery, keep the vehicle stationary for five minutes or so.

It doesn't apply to your vintage Roadmaster, but I wonder if the emergence of the Canbus alternator charging protocol in the interest of increasing mpg has a better, or worse or no consequence on battery life.

The shake off of sulfate is a common issue from all I have heard. That is why they put the individual plate clusters into plastic bags on some batteries. I used to actually build the cell baggers for a machinery building company that made them for Gould National Battery, while I was in college. The sulfate would otherwise fall to the bottom of the battery and short between the cells, was the explanation we got then.


I have a scangauge on the Buick so have watched the alternator voltage control patterns, and it isn't bad at all. Not the old 13.0 all the time or the later 14.2 all the time stuff. The voltage rises and falls with amps and heat most likely and is very similar to what we say with stock alternator in the 07 Chevy van, but about 1/3 volt lower across the board, so seems to have a fairly modern control by 1996.

[cruising7388]

Originally Posted by booster

I have a scangauge on the Buick so have watched the alternator voltage control patterns, and it isn't bad at all. Not the old 13.0 all the time or the later 14.2 all the time stuff. The voltage rises and falls with amps and heat most likely and is very similar to what we say with stock alternator in the 07 Chevy van, but about 1/3 volt lower across the board, so seems to have a fairly modern control by 1996.

I'm not sure but I think that when Canbus determines that the battery is sufficiently charged, it shuts off alternator output making me wonder if there may actually be periods of battery discharge while the vehicle is operating.

[peteco]

Originally Posted by booster

I can't speak, but we have two fairly recent new, Costco starting batteries in our cars. One in DW's CRV and on one in my 96 Buick Roadmaster, so we will see how they hold up. If decent, they should last 7+ years as that is what the OEM ones normally do for us, or past Costco batteries.

Booster, a while ago we had talked about using our Ctek 7002 chargers on a regular basis (every 1-2 months) to fully charge our car batteries. Before the Ctek I used a Battery minder regularly. I got 10 years out of the original battery in my Camry
I think this goes a long way to minimizing sulfation.