EMD360
Tempe, AZ
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Joined: 01/18/2010
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I found this article on the trojan website that does a nice job of comparing batteries. The article is about a year old but it seems pretty up to date. I'm trying to compare prices to value for a set of new batteries and this helps.
Boat Battery Guide
I went to a Walmart that had the EverStart 27DC-6 Marine Battery in stock just to check it out. They are significantly cheaper than other batteries at the same rating @ about $69. These are rated at 115 amp hours but typically the test is at 20 hours and the battery states 115 amps at 1 amp/hour. I think that means the same thing but darned Peukert confuses things. Would this battery supply 5 amps for 20 hours as a typical 100 amp battery would? The article rates it for the full 115 amp hours and 160 reserve minutes.
I'm gonna say this is the cheapest option that I've found, cheaper than the 2 6v for 225 amps at Cosco, if I WERE a member. That would be about $170 but 2 12 v Everstarts should deliver 130 amp hours for $140 (plus tax and membership if Cosco). If the Peukert "exponent" is equal. I've never seen this number published for a battery though.
I like this explanation of Peukert. Especially the metaphor to pouring been in a glass. If you can think backwards anyway.
Quote:If you pour it in quickly, only a small amount of liquid is transferred: the rest is foam. The slower you pour the beer, the more beer and the less foam enters the glass. You may feel you need to test this a few times. (Hic – 'scuse me!) 
We're hooked!
2003 Itasca Spirit 22e
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skipnchar
Topeka or somewhere else
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Joined: 12/17/2003
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I have tried to use Everstart in an RV on several occasions and never got more than about a year from them. Keep in mind that I USE the batteries with lots of dry camping but have used the same set of Trojan T 105s for over 8 years and they cost about 2.5 times as much. Worth every penny as far as I am concerned.
2011 F-150 HD Ecoboost 3.5 V6. 2550 payload, 17,100 GCVWR -
2004 F-150 HD (Traded after 80,000 towing miles)
2007 Rockwood 8314SS 34' travel trailer
US Govt survey shows three out of four people make up 75% of the total population
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NewsW
US
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Joined: 02/06/2012
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You didn't say what you are using the battery for.
Batteries designed for starting have extremely high current rates, but very short life both in terms of discharge cycles and time.
Batteries designed for deep cycle are optimized for that function at the expense of starting current.
State your expected application, the load profile, and then see what is a batter deal.
Unless you are buying AGM, 7 change out of 10 the battery is made by the same company (Exide) and sold under different names.
But that doesn't mean they are the same.
Key difference to the consumer is the warranty.
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EMD360
Tempe, AZ
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Oh yeah, thanks for asking for clarification, these are for the coach. I already have 2 AGM's (Interstate DC100) in the dinette with a switch between those and the one in the outside battery compartment.
I bought a Vector 40 amp charger for those to run either from the generator or plugged in, and let the alternator and the converter charge the lead acid's. I had two 12v Interstates but one died about a year ago and the second just died about a month ago. I was waiting for that second one to die to buy two matching. So that is why I am shopping. The dead one is a group 27 Interstate Marine battery but is dual purpose and only rated at 75 amp hours.
In the article I posted the Everstarts that I'm looking at are marine but rated as "deep cycle" not "dual purpose" like some of the marine batteries. Just a few days ago someone posted (I can't find the post though!)that they called Johnson Controls and they both make these and rate them as deep cycle batteries.
While looking for that post I found that the 1 amp hour rating has been discussed in tech issues last August. 115 amps at 1 amp per hour translates to 95 amp hours at 20 hours according to KendallIP's Misleading capacity ratings post. His posted charts from JCI and Interstate seem to equate the Walmart Everstart to a deep cycle group 27 from Interstate.
So I'd get 190 amp hours from these and about 30 more amp hours for my extra $$ getting the 6v at Costco. Opinions on the Everstart vary widely, some saying they only got a year out of them and others saying they get 3 to 5 regularly. 2 GC's might be a little heavy for my plastic battery compartment which is another consideration.
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Bordercollie
Garden Grove, CA, USA
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Joined: 03/07/2002
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So, Is there a significantly cheaper but performance equivalent to the Trojan T-105 6 volt batteries used in series as house batteries in many Class C's ??
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NewsW
US
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Joined: 02/06/2012
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EMD360 wrote:
So I'd get 190 amp hours from these and about 30 more amp hours for my extra $$ getting the 6v at Costco. Opinions on the Everstart vary widely, some saying they only got a year out of them and others saying they get 3 to 5 regularly. 2 GC's might be a little heavy for my plastic battery compartment which is another consideration.
I don't believe in the validity of the calculation, as individual load profiles can widely vary life / charge behavior.
As for life, read and model the warranty --- and see what the claimed life really cost you when it is time to swap out the batteries.
For serious deep discharge work, AGM is the way to go.
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oldtrucker63
Harlan Kentucky
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skipnchar wrote:I have tried to use Everstart in an RV on several occasions and never got more than about a year from them. Keep in mind that I USE the batteries with lots of dry camping but have used the same set of Trojan T 105s for over 8 years and they cost about 2.5 times as much. Worth every penny as far as I am concerned. X 2 here
Without Trucks,....America Stop's
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pnichols
Santa Cruz Mountains
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Joined: 04/26/2005
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Quote:I already have 2 AGM's (Interstate DC100) in the dinette...
EMD360,
Those are the same AGM battery type that I have two-of in parallel for coach use in our 24 foot Itasca Class C. They are just a few months away from being used in our Itasca for six years. I only use the stock Parallax 7345 13.8 fixed voltage converter to both charge them when camping and to maintain them when in storage.
How have they been holding up for you and what charger or converter are you using to take care of them?
Phil, 2005 E450 Itasca 324V Spirit
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EMD360
Tempe, AZ
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The 2 AGM's are great but the are too big and heavy for the battery compartment so I have them in the dinette. Pnichols, you must have a larger compartment in the 24 footer if you can keep them there. Did you mod that compartment?
I think 2 trojans would be too heavy too. I have 2 that are about 10 years old from an old solar setup we had before we had the RV and they are shot. I just don't think the plastic compartment will carry that size battery. I could try to wrap it with metal I guess as they would fit in there but would be hard to maintain. It will fit 2 group 27's but non maintenance batteries would really be more convenient since the compartment is tight.
I was dry camping for a week for the first time ever at the rally. We just don't have the vacation time to get away for a week in the RV, so we mostly use it for weekends. Naturally it was at the rally that the 12 volt in the compartment decided it could no longer hold a charge.
For some reason when I moved the switch over to the AGMs alone I could not get power when the other 12 volt was dead. So I took one of the AGMs and put it in the compartment and ran off of that one night. The next day I charged the 12 volt and it charged up but it would not hold the charge. I put both of the AGM's back in the dinette and wired around the useless 12 volt and the switch worked fine. Somehow being hooked up to a dead battery did not let the second set take over? Or I was just confused!
I then charged them both together with the Vector for about 2 hours and they lasted the rest of the week--they were at about 12.3 when it was time to leave. They are great batteries aren't they? I was lucky to find them used. I've had them about a year, maybe a little longer.
I've left the blue sea switch on both banks when driving or running the OEM converter-the same 7345 Parallax. The Vector does a quicker job of charging the AGM's than the converter, that is all the difference I can see. I separated the banks because it was recommended to charge different battery types separately and I usually do that by leaving the switch on just the lead acids in the battery compartment or the AGM's in the dinette when driving or running the converter. Then I put the switch on both sets when not charging.
If you've been using just the 2 AGM for 6 years, I guess I don't NEED more battery now do I? So why am I shopping for 2 more for the compartment? 
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pnichols
Santa Cruz Mountains
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EMD360,
Even though we're retired, it sounds like we may be using our RV about the same as you are.
We rarely stay in one drycamp spot more than 3 or 4 days ... even on multi-week trips. Our two AGMs with 200 amp hours, total, gives us about 100 to 120 amp hours to use before recharging. (From everything I read deep cycle AGM batteries can be run down a bit deeper than deep cycle wet cell batteries can without harming them, so going down past 50% discharge isn't going to permanently damage them.)
They charge up pretty fast because of their low internal resistance ... into the 90%-95% range in about 5-6 hours using our converter with either of our generators ... which includes both the built-in Onan generator through the 7345 or our backup fuel sipping super quiet Honda EX650 through the 7345. They'll also come up to 100% charge in about 5 hours of driving from the Ford's 130 amp alternator. When camping I sometimes also idle the very quiet V10 for up to an hour before using only the 7345 and a generator to finish bringing them up to 90%-95%.
By the way when driving, our V10 engine's wet cell starting battery is automatically hooked up in direct parallel with the two 12V AGM coach batteries. I've been doing this "battery technology mixing" for over 5 & 1/2 years now and both the engine and AGM batteries seem to be doing just fine. I replaced the stock solenoid that does this interconnecting with a heavy duty one with silver alloy plated contacts to make sure there would never be any extra resistance (from contact oxidation and/or other corrosion) between the alternator's output and the AGM batteries when driving. This ensures that maximum alternator voltage is always available on the AGM battery terminals.
Most folks in the forums don't believe me when I mention how well (fast charging, etc.) these AGMs do with no special care on my part. I think reading the Lifeline verbage about their AGM batteries has scared some folks away from AGM batteries - thinking that they need ultra special treatment. One thing I never do is let them sit undercharged when in storage or keep them on the converter past full charge in warm weather. As a side note, remember that our Interstate AGM batteries are "motive batteries" intended for wheel chair and other electric vehicle use, so they're not really too exotic and intended for pretty much vanilla grade chargers and charging.
Our Itasca came fully wired with two Group 24 wet cell batteries under the coach step. (Two Group 24 batteries is part of Winnebago's Cold Weather Package.) This area under the step has only steel and air around it and is fully isolated from the interior. This battery storage area easily holds my two Group 29 12 volt AGM batteries and probably could hold a couple of Group 31 12 volt batteries ... BUT NOT two of the tall 6 volt golf cart type batteries under the step. Of course I paralled the two Group 29 Interstate AGM batteries with short lengths of heavy gage cables ... however, I also over-killed it by using TWO of these very heavy gage cables between each set of negative and positive AGM battery terminals. This further ensures that both batteries function under all conditions in sync as one large 12 volt battery with double the plate size of a single 12 volt battery.
I trust that comparing notes helps us appreciate our AGM batteries even more. When the time comes, I'll probably replace mine with the same Interstate AGM batteries if they're available. I believe these batteries used to be made for Interstate by C&D technologies ... not sure if that's still the situation.
P.S. I really enjoy your posts mentioning where you have taken that sweet little Itasca Class C you have. 
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