Batteries - 12 vs. 6

megalucky · 03-26-2018, 07:38 AM

I am in the process of having to replace my 12 volt coach batteries in my 2016 Precept 31ul. I decided to go with 6 volt as the replacement. Most all I have read and received opinions on, say this is the way to go. Has another precept owner done this and encountered any issues or concerns? Anything I should be aware of in the change over process?

Siamese · 03-26-2018, 08:32 AM

I don't know anything about the Precept, but.....

All they have to do is fit. 6v batteries are a little taller than 12v batteries, but they have about the same footprint. Once you jumper them together (in series), they will behave as a single 12v battery.

GrumpyDad · 03-26-2018, 11:13 AM

Just verify that you end up with more Amp-hours capacity with your 6V setup compared to whatever 12V deep cycle you can buy locally. Usually you do, but it's worth verifying. And remember with 2x6V setup you don't get to do 2x the Amp-hours.

Example, my Trojans are 225 Amp-hours, but with two of them I'm still at 225 amp-hours, just at 12V instead of 6.

Good luck.

geezerbob · 03-26-2018, 12:24 PM

Here is what I'm doing this year regarding batteries.
Replacing my Interstate Group 27 Deep cycle,
SRM-27 600 CCA 750 MCA, 160 minutes reserve capacity

With an Exide Nautilus 31 mdc
830 mca, 205 minutes reserve capacity,
115 amp hours @20 hours (not sure what that means)

The 31 mdc fits into the group 27 battery case.

**Mustang65** · 03-26-2018, 01:21 PM

Quote:

Originally Posted by geezerbob

With an Exide Nautilus 31 mdc
830 mca, 205 minutes reserve capacity,
115 amp hours @20 hours (not sure what that means)

The 31 mdc fits into the group 27 battery case.

As long as you understand that the battery you are going to purchase is not a TRUE deep cycle battery but a hybrid. Any battery that has a CCA or an MCA are hybrid batteries. True deep cycle batteries do not have this rating.

Don

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geezerbob · 03-26-2018, 01:51 PM

Is that true even if it says Deep cycle and it has mdc on it??

geezerbob · 03-26-2018, 01:55 PM

What makes it a hybrid and or what are the differences?

Robbbyr · 03-26-2018, 02:05 PM

Quote:

Originally Posted by geezerbob

What makes it a hybrid and or what are the differences?

Mustang65 is far more versed than I and I learn a lot from his posts. But I will try!

True Deep-Cycle batteries have thicker lead plates. Allows for longer service life, but they are not great at providing very large (but short term) amperage draws such as when starting a chassis engine. They are meant for longer-term moderate power drains. They do fine in a battery bank starting a generator engine such as in motorhomes, but they are not designed to start my Freightliner's Cummins diesel repeatedly!

Hybrid/Marine batteries have thinner lead plates which allow for the higher amperage draws needed to start an engine, but will "wear out" sooner than the far more substantial plates in a 6-volt true deep-cycle battery. Eventually in all lead/acid batteries the plates will degrade over time, but it takes far longer in a true deep cycle battery properly cared for because of the plates larger size.

geezerbob · 03-26-2018, 02:26 PM

Got it thanks for the explanation. I'll give this one a chance and see if it fits my needs for now.
I had considered 2, 6 volt batteries but a great opportunity came along for this one.
Bob

**Mustang65** · 03-26-2018, 03:58 PM

x2 What Robbbyr said.

Here is what Exide advertises about that battery:

"Exide® Nautilus™ Marine Starting batteries are designed to deliver high bursts of power for short periods of time to start marine engines", pretty much the opposite requirements of an RV's deep cycle battery

The main intent of this battery is for starting boats. If you plan on dry-camping you may want to think about your purchase.

Good Luck!!!

Don

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geezerbob · 03-26-2018, 04:34 PM

I have thought about it and decided to use it for now. I'm not ready to use it as a boat anchor yet.

geezerbob · 03-26-2018, 04:47 PM

Over a few years we have pulled a tt about 25,000 miles from Wi. to AK. a couple of times and have included dry camping in those trips. Our inverter/genny has bridged the gap when needed and our group 27 handled it a few times. That being said I will probably up our game with "real" deep cycle batteries and solar when the time comes especially if we head south.
I have a pretty good read on what I can get out of our "hybrid batteries" for now though.
Bob

Vicr · 03-26-2018, 05:24 PM

[QUOTE=Mustang65;622490]As long as you understand that the battery you are going to purchase is not a TRUE deep cycle battery but a hybrid. Any battery that has a CCA or an MCA are hybrid batteries. True deep cycle batteries do not have this rating.

Don

Don,not true in all cases. My Fullriver DC Series AGM batteries are true deep cycle batteries for various deep cycle applications which includes the sailing community. The CCA ratings are posted on their batteries as a point of fact for the sailing community if they have to use their battery bank to start the engine(s). A true deep cycle battery WILL in fact turn over the starter of an engine.

Vicr · 03-26-2018, 07:17 PM

There are many quality battery brands out there but few manufacturers. Yes you want a deep cycle battery. Trojan, Full River, Lifeline, Rolls are are premium quality you can’t go wrong with. First Interstate makes an excellent battery and is more affordable than the previously listed batteries. The choice comes down to cost vrs. Quality and where that happy medium is. A lot of people on the forums go to Walmart or Sams Club because they have the lowest cost. I shop batteries by specification to best fit my needs and budget. Batteries and electrical posts on the forums go viral with posts and “advice” if I were you I would shop at a battery store and listen to an expert. You’ll get 20 different replies here and as an electrician of 35 years the replies will be all over the board.

OutCole'd · 03-29-2018, 06:52 AM

I went to two 6V interstate Golf Cart batteries and noticed a huge difference. Much better than my original single 12V deap cycle.

**Mustang65** · 03-29-2018, 08:26 AM

[QUOTE=Vicr;622576]

Quote:

Originally Posted by Mustang65

As long as you understand that the battery you are going to purchase is not a TRUE deep cycle battery but a hybrid. Any battery that has a CCA or an MCA are hybrid batteries. True deep cycle batteries do not have this rating.

Don

Don,not true in all cases. My Fullriver DC Series AGM batteries are true deep cycle batteries for various deep cycle applications which includes the sailing community. The CCA ratings are posted on their batteries as a point of fact for the sailing community if they have to use their battery bank to start the engine(s). A true deep cycle battery WILL in fact turn over the starter of an engine.

I have not checked Fullriver website in years. And yes they now have the CCA/CMA ratings on ALL their batteries. I bet that all the other manufactures will eventually add these ratings to all their batteries for IE marine comparisons/increase sales.

The problem now is now where the line is between "Hybrid" vs "True Deep Cycle" batteries. It looks like they have different categories, but consider them all deep cycle. To the average person buying a battery for an RV it can become a nightmare.

RVers will need to find a way to separate these batteries in the future. Other than cutting open a battery to see what it really is, or depend on what a sales person has to say about it, is to check the battery model's "Life Cycle" chart, but unfortunately not all the battery models have individualized charts.

I did not check, but there may be a way to isolate the "True Deep Cycle" batteries form "Hybrids" by comparing battery case sizes (a deep cycle thicker battery plates will not fit in a standard size battery case, although a hybrid internals will fit in a larger true deep cycle case) or there may be a way to check CCA/MCA differences between these two battery types.

I am sure that the Battery industry will come up with a system to make it easier to identify the battery by specific needs.

Yes, I know you can start an engine using True Deep Cycle batteries. If you have enough 12volt 12ah security batteries in parallel you can start a car with them also. The point is that "True Deep Cycle" batteries life will be shortened as they are not designed for deep/fast loads, like regular starting batteries or Hybrids. As with a regular car starting battery where you can get thousands of starts (starting is only a 2-8% discharge) out of it. If you were to continually bring the automotive battery to the 50-40% level (RVing) you would only get around 150 to 200 deep cycles out of them before they will become useless. Hybrids life cycle is some where between the two extremes.

It will be interesting to see if the Battery Industry org, address this issue in the future.

Until then, I would recommend that you do your research and as mentioned check with an "Knowledgeable" battery expert and even then research what they suggest before laying down the big bucks.

Don
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RVing with SOLAR

Vicr · 03-29-2018, 10:24 AM

[QUOTE=Mustang65;623454]

Quote:

Originally Posted by Vicr;62257

Until then, I would recommend that you do your research and as mentioned check with an "Knowledgeable" battery expert and even then research what they suggest before laying down the big bucks.

Don
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I did, including a call to customer support at Fullriver. The DC series are true deep cycle batteries.

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