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Old 08-29-2014, 02:31 PM   #21
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Originally Posted by le.breeze View Post
I think we will buy 2 good 12 volt batteries for now and then think about adding the monitor.
Please note that true deep cycle 12v batteries are far less plentiful than true deep cycle 6v's. This is the main reason most people think that 6v's are better...their not necessarily comparing apples to apples. If a battery has any mention of CCA's, then it's NOT a true deep cycle...it's probably a hybrid or "marine" battery.

In my opinion, the best value comes from a pair of 6v golf cart batteries from your local Costco, Sam's Club, or Walmart. Trojan batteries are nearly twice the cost and they absolutely do not last twice as long. Especially if you are the type that may abuse your batteries.
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Old 08-29-2014, 02:54 PM   #22
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Quote:
Originally Posted by GreenImp View Post
Please note that true deep cycle 12v batteries are far less plentiful than true deep cycle 6v's. This is the main reason most people think that 6v's are better...their not necessarily comparing apples to apples. If a battery has any mention of CCA's, then it's NOT a true deep cycle...it's probably a hybrid or "marine" battery.

In my opinion, the best value comes from a pair of 6v golf cart batteries from your local Costco, Sam's Club, or Walmart. Trojan batteries are nearly twice the cost and they absolutely do not last twice as long. Especially if you are the type that may abuse your batteries.
Again, you've got to be sure you're comparing apples to apples. When I priced them out, a Group 24 generic dual purpose marine/RV vs a Trojan Group 24 (24TMX) the price difference was about $40. Well worth the extra to go with something billed as a true deep cycle over a dual purpose.
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Old 08-29-2014, 08:59 PM   #23
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Oh...it may be too late, but I forgot to mention the most important thing. Whatever type of battery you decide on, you must check the date! You do NOT want a battery that has been sitting around on the shelf for months or possibly even longer. And you cant automatically assume that the fresh ones are in the back...you must read the dates. I recently saw a battery shoved to the back of the shelf that was almost 2 years older than the ones in the front. The store employees are obviously not rotating their stock. Eventually, some poor unsuspecting buyer is going to end up with that battery and when it fails they will surely blame the manufacturer for making a bad product.
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Old 08-29-2014, 11:59 PM   #24
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I will try to answer the OP's various questions posed in this thread:
1. If you ONLY plan on TWO house batteries get 12VOLT deep cycles. Buy NOTHING that says anything about cranking amps on the label...you are not looking at a true deep cycle! Try a marine store if you can't find it in the auto stores. Why 12V and not 6V....because with ONLY 2...if one 12V fails you can still run the coach...not so with a single 6V.
If you plan on FOUR batteries then 6V will give you more bang for the buck while still providing failure redundancy.
2. When parked for EXTENDED times...fully charge your batteries and then disconnect the negative wire. They will stay perfect and discharge about 10%-15% a month so you can go 3 months that way. LONGER in the winter since there is less self discharge the colder it gets. Fully charged batteries freeze at -96 degrees!! You are good to -16 degrees with a 60% charge. A 40% charge freezes at +5!! You should never keep a battery on float full time...because of charger failure risks and cell failure risks PLUS it is WAY better to put on a bulk charge once every few months to stir things up and reduce sulphation. A charger with an EQ setting is the best of all but most coaches don't have them.
3. You keep your battery over 50% by getting a battery monitor like the Trimetric mentioned above. I like the Victron BMV700 myself. A real monitor you can use has a SHUNT. No voltage reading monitor in use will give you an accurate reading of your true battery state...you need to know AMP HOURS remaining...not voltage.
4. As a rough estimate...lets say you have 200 amp hours of battery bank. This means that when discharged sufficiently they will ACCEPT a charging current (AMPS) of 40 to 45 amps maximum. (20%of capacity.) If you recharge when you hit 50% discharge...that means you have to put back in 100 amp hours from your generator and battery charger. The charger will take about 2 hours to put in the first 80 amp hours (at 40 per hour) ...then another 2 hours to get in the last 20 amps because it gets HARDER to load up the battery as it gets more "full". Most people don't want to run the genny for four hours....so they'll just put back in the 80 amps in 2 hours. That is fine...but it leaves you with only 80 amps to operate on till you need to "refuel" again. Batteries like to be 100% charged...so you can get away shortchanging the charging process on a short trip...but on extended boondocking with WET CELLS...I'd put on the full 100% charge once a week. If you have AGM's ...they really hate partial charging so I don't recommend anything other than 100%.
5. When people complain that their batteries died young...I tell 'em it wasn't from natural causes...They wuz murdered!! Check the water...fill with ONLY distilled....charge fully and never discharge below 50% and properly and give them a good long bulk charge every few months if you don't have an EQ cycle.

Hope this helps along with all the other advice above.
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Old 08-30-2014, 07:29 AM   #25
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Originally Posted by camaraderie View Post
1. Why 12V and not 6V....because with ONLY 2...if one 12V fails you can still run the coach...not so with a single 6V.

2. When parked for EXTENDED times...fully charge your batteries and then disconnect the negative wire. They will stay perfect and discharge about 10%-15% a month so you can go 3 months that way.

5. When people complain that their batteries died young...I tell 'em it wasn't from natural causes...They wuz murdered!!
1. That's a little misleading. You're talking about 2 x 12v batteries vs 2 x 6v... the rough equivalent to 1 large 12v. If you only have 1 12v then in either application, if it fails, you're not going no where. Apples to apples... 2 12v would be 4 6v, so if half your batteries fail, you can still power up.

2. That's kind of where "you get what you pay for". 10-15% off gassing per month for a 12v is pretty common, but your 6v's are not designed equally. Mine 6v's off gas at 2% per month. Just to help illustrate that the internals in a good quality 12v are not typically designed to match up to the same specs of a decent 6v. The intended applications are not the same and they are constructed accordingly. (plate sizes, composition, internal connections)

3. All good advice.

4. It's important to remember though that bottom line.. getting the best performance out of your deep cycle battery (of any type) is largely dependent on every other component in your charging system. I think the biggest misconception is voltage at the battery does not equal "capacity". In other words, it's not so much about what charge state you can get into your house batteries, but how long your batteries are capable of providing that charge. A typical RV charging system is highly inefficient and is not capable of charging a true deep cycle to 100% capacity. Your charger and battery meter may be saying you are at 100%, but it tain't so.

Typically, you're looking more at around 70-85% of capacity... so really only 20-35% of usable capacity. Of course... it's pretty common knowledge that deep cycles don't really like that, so from word go they are slowly dying.

You can still expect a good 3-5 seasons out of your system, and 20-35% of a 200ah battery still, by far, trumps what you'll get out of 100ah 12v. It's not terribly expense... for the majority of recreational users it's "still" a step up in usable power... and let's face it.. how many people really maintain their batteries the way they should during the 11 months out of the year when not in use? Deep cycle batteries like to be cycled.

5. Absolutely! It's a hard life being a house battery.

Just to keep things in perspective. Camaradaries info is very useful and pretty much the norm for recreational users and basic solar setups. My remarks are geared more to those that absolutely depend on their battery banks and are willing to put in the time and expense it can require.

So you have to replace your batteries every 3-5 years or so, enjoy a pretty decent power availability, it's not terribly expensive, didn't take a lot of brain work and you kept the focus on having fun. I call that a win!!

For some few, even investing in a decent meter, and only getting 20-35% (in a typical RV setup) of actual capacity... meh... not so much.

Even in the majority of a lot of "professional" solar setups, it's better, but your system is only going to be as good as the weakest link.

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Old 08-30-2014, 09:08 AM   #26
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With any purchase, price should be a consideration, unless your the gov't of course. So, take this information into account.

Average battery life has become shorter as energy requirements have increased. Life span depends on usage; 6 months to 48 months, yet only 30% of all batteries actually reach the 48-month mark. You can extend your battery life by hooking it up to a solar, trickle charger, during the off months. Source: BatteryStuff.com Please don't shoot the messenger.
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Old 08-30-2014, 10:07 AM   #27
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With any purchase, price should be a consideration, unless your the gov't of course.
x2. My post was TMI. I just get on my soapbox when we are perpetuating the widely accepted myth that you just can't expect to get anything near a batteries rated capacities. It's not their fault.

With a little care, getting a couple 2 or 3 seasons off a couple costo/wallyworld 6v'rs for $150-200 is more than a reasonable expectation with a stock electrical system.

My 4 - 6v cells are in use 8 or 9 months out of the year. They cost more around $350 a pop, but with a properly engineered system I expect to get 10+ years of use out of them (so about $140 a year for 440ah). My last set I had for 9 (a friend took them over and is still using them the past 3 years), but switched to AGM's with this new rig in order to get some weight off the hitch and to upgrade to 2/0 gauge. That ain't cheap, but the cable runs are more like 2 feet at most and my entire power system sits neatly under the foot of my bed. In a proper system, 7-9 years is not in the least uncommon... 10-12 years isn't unheard of, and 15 years is doable. Of course, mine provide roughly double the amount of usable ah's over what you typically see in a stock RV setup, but I also don't discharge all the way down to 50%.

It's not for everyone, but there is a big difference in buying a battery knowing it's going to be badly abused and disposable in just a couple of years, then blaming the battery industry. Your expectations have to be reasonable.Garbage in garbage out.
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Old 08-30-2014, 06:28 PM   #28
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We learned so much from everyone's input....thanks again! I think we decided to go with 2 Trojan 24 TMX batteries. We will keep them on trickle chargers when not being used.
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Old 08-30-2014, 10:09 PM   #29
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Yarome... Agree with everything except your comments about my #1:
Quote:
1. That's a little misleading. You're talking about 2 x 12v batteries vs 2 x 6v... the rough equivalent to 1 large 12v. If you only have 1 12v then in either application, if it fails, you're not going no where. Apples to apples... 2 12v would be 4 6v, so if half your batteries fail, you can still power up.
No it is not at all misleading...I am comparing two batteries in both cases where the total amp hours offered by the PAIR is the same or approximately so. We could also compare by weight of lead and end up the same.
2 Group 31 12V = about 210 ah's
2 T105 6V's= about 210 ah's at 12V
Apples to apples...but my comment on a 2 battery system as better in 12V stands. As I said...if I had room and budget for 4 batteries...I'd go with 6Volts.
I also think AGMs are a good choice for full timing, reducing generator run time and winter storage in any climate as the self discharge is 1-2% rather than 10x that amount with wet cells.
Of course there is a price to be paid... but as you point out...you can amortize it.
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le.breeze....good luck with it all...good choices. Get the monitor when you can!
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Old 08-30-2014, 10:51 PM   #30
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Talking batteries is like talking politics or religion. Points to remember: the draw down and recharging is what takes a toll. For batteries wired in parallel volts stay same-amps are added, IE; 2) 12 volts in parallel w/212 amps = 12 v/412 amps. The opposite is true for series wiring, IE: 2) 6 volt in series w/242 amps =12 v/24r2 amps. Consider the maintenance when choosing; 2 6v = 6 cells to maintain. 2 12v =12 cells to maintain. We always boondock and have had great success with the following setup: 2)Trojan T-105, group 27, 242 amp hr., deep cycle golf cart batteries in series. I have added an onboard solar panel (1.5 w) for trickle charging. I have 4) 2.9 amp solar panels wired in parallel and ran thru a charge controller to re-charge during the day for 17.9 volts @ 11.8 amps (we run 2 CPAP machines off the setup thru a Samlex 2000w inverter). I have also installed "solar battery vent caps" that trap the vapor from charging and put it back into the battery. I hope to post some pic's of the solar charge/inverter/charge control setup soon. Selling the WolfPack to upgrade to a larger toy hauler and will set it up with 4) T-105's. Goog luck and happy Camping!
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