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Choosing the Best RV Battery: Which is Right for You?

Most of us have at least a nodding acquaintance with the battery that start our cars, but what about the batteries used in our Recreational Vehicles?

Are they the same?

All RV’s have a set of “house” batteries that power the lighting, water pump, and other 12 volt needs.

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Multiple RV batteries may be wired together to make a single power source. These house batteries have different characteristics than the batteries used to start an engine.

Motorhomes, of course, have an engine and require an engine starting (chassis) RV battery, but this is always separate from the house battery system.

The starting (chassis) battery in a motorhome is the same type as used in a car, though often with a larger CCA (Cold Cranking Amps) rating because the engine is larger.

Choosing the right RV battery is simply a matter of getting enough CCA to do the job and generally that means replacing the battery with another of the same or larger CCA rating, the same as you would do for your car.

House RV Battery

The best house RV batteries are a different breed altogether.

Starting batteries are designed to provide a huge amount of power (amps) in a short burst (a few seconds) to get an engine going, but house RV batteries are designed to provide a much smaller amount of amps but over a long period of time, hours instead of seconds.

Furthermore, the house RV battery is often heavily discharged before being fully recharged again, what is known a “deep cycling”.


A RV battery designed for lower power and deep cycling will last longer and perform better than an engine starting battery. The best deep cycle batteries will last three to four times longer than a starting RV battery under the same conditions.

Deep cycle battery capacity is measured in AH (Amp-Hours), meaning the total number of amps of power it can deliver over a 20 hour period.

An alternative measurement is called RC (Reserve Capacity), which is the number of minutes the battery can sustain a 25 amp load.

You don’t have to understand the method of measuring to know that “more is better”, so a battery with a larger AH or RC rating is better (more capacity) than a smaller one. Unfortunately, there is no meaningful way to compare AH and RC values, so make sure you compare apples to apples.

Marine Batteries

So-called “marine” batteries are an attempt to make a compromise design that combines the characteristics of starting and deep cycling. As with most compromises, they aren’t great for either need, but they may be suitable for some RV battery situations.

A marine battery trades a lower CCA rating for somewhat better deep cycle performance. It’s main advantage is that it is a variation of a starting battery and can be produced by the same manufacturing process, making it a less expensive battery than a true deep cycle.

Useful Technology for a RV Battery


Currently, all RV batteries use lead-acid technology but it comes in different packages.

The basic package is called a “flooded cell” battery, in which the lead is bathed in a liquid water/acid solution (the electrolyte).

This type loses a little of the solution each time it is charged, so requires the addition of some water once in awhile.

So-called “maintenance free” batteries attempt to reduce the loss of electrolyte by sealing the cells except for a tiny vent hole, but this isn’t effective under the frequent heavy charging that is typical of deep cycle use.

It is not a good choice for a house RV battery. AGM (Absorbed Glass Mat) batteries retain the electrolyte solution in a sponge made of glass fibers and are totally sealed except for a safety valve. This type is very effective in reducing the loss of electrolyte during charging and is an excellent technology choice.

Gel type batteries use a thick paste electrolyte and are also fully sealed, so they are a good choice as well. However, AGM has largely replaced Gel technology for RV use.


6 Volt Golf Cart Batteries

rv battery bestA popular choice for an house RV battery is the 6 volt size designed for use in golf carts.

It is an extremely rugged, deep cycle design and two of them can be wired in series to form a 12 volt battery that works extremely well in RV applications.

Golf cart batteries must be used in pairs, so you need space for 2 or 4 or 6 of them. They are available in both flooded cell and AGM types.

44 thoughts on “Choosing the Best RV Battery: Which is Right for You?”

  1. Hello Gary, awesome info here, also follow your comments on IRV2, thanks for sharing. My question is I have 4 12v workaholic U2200 that are ready to replace they have treated me very well. They came with the coach new, which was build 5/2008 and I purchased 01/2010. I have 42,000 miles and 2100 hundred hours on genset. I boondock alot. I thinking about going with the Trojan T105 6V to replace 12V. Do I replace with 2-6V for every 1 12V? ….meaning do I go with 8 T105’s

    Thanks Justin

  2. Seriously……I have 3 house batteries that are Trojans from 2004. Stay at 13.4 and never skipped a beat. Great pieces of equipment.

  3. First time RV’er. We just purchased a 2005 Itasci Meridian 40 ‘It has 2 new batteries for the engine but the 4 house batteries are the question. We have to run the Generator all night so the AC and other things work.
    When we push the switch to see the house battery voltage and it has been 4.6 to 6.4 and when we turn off the generator everything shuts down. We have it at home to try to learn things before we start to travel. We have a 50 amp service just for the RV and keep it plugged in and still have to use the generator. Any idea or should we replace the house batteries and what kind do you recommend?
    Thank you for your help

  4. Hi Gary,
    Thanks for the excellent info. I was wondering what you could recommend for a battery setup + Solar + Inverter for a small dodge promaster conversion. Below are a list of needs and considerations

    Running: 2 Laptops charging, microwave, fridge, lighting, coffee pot, the occasional power tool.

    Set-up – Use of alternator, not planning to hook up to shore power but would like to have an outside plug-in just in case. What solar panel/s would you recommend?

    battery type – We are planning to teach classes in over 30 states for a year (pretty much none stop in the van) but then do not plan to keep the van afterwards. So keeping the cost of the battery low, little to no maintenance would be nice. We want to make sure we have plenty of power. Don’t want to have to replace a battery on the road though.

    Haven’t seen a great solution for a heater? What would you recommend?


  5. Hi Gary

    I had 3 GE 100Amp solar panels, a Magnum Pure Sine Wave Inverter/Charger ( MS-2012), a MPPT 500 Solar Controller installed on my 2004 Allegro motorhome just 2 years ago. Batteries are 4-6 volt Delcro Duracells (EGC2), also new at the time of the install. My monitoring system is the Trimetric 2025 meter by Bogart. I have the 3 panels tilted to 40 degrees here in the desert for the winter months, and there are absolutely no shading issues with the panels by roof vents, antennas, ladder tops, trees,etc.

    I use a 2000 watt Honda portable generator to recharge the batteries as needed and also occasionally will use the RV’s house generator.

    When boondocking I am very conscious of power consumption and normally watch 4 hours of TV on my 32 inch LCD LG TV and use my 2009 24 inch iMac computer for another 4 hours ( these tend to be my maximum use rates). The Trimetric shows 7 amps of power flowing when I use the computer and 5 amps when watching TV. My refrigerator is on gas only, not set to auto, my water heater also is set to gas. I never use the toaster oven or microwave unless the house generator is running. I even have the TV and peripherals and the computer and peripherals each set up on their own power strips and keep these strips unplugged unless I am actually using them.

    My batteries have never been drawn down below 12.2 volts and really never even get below 12.3, measured at rest when the inverter is turned off. A hydrometer test of all 12 cells of the batteries when at full charge shows them all to be in good shape.

    My understanding ( limited I will admit ) is that the battery bank fully charged should give me 220 amp hours of power ( 50% of 4 x 110 amphours ). Knowing that nothing in the system is 100% efficient and that the inverter itself consumes power, say I have only 150 amp hours available at full charge.

    My problem is that 3 or 4 hours of the computer running alone will drain the batteries down to a 12.3 reading. On a bright sunny day with the solar panels generating power ( readings on the solar controller of 5.4 PVA and 19.5 BA ) with the Trimetric meter starting out at 13.0 volts, my computer use alone still drains the system down to where I need to either stop using the computer or I need to start up the generator.

    My Trimetric meter reading at night when I retire and turn off the inverter is the same the next morning so I think that eliminates the possibility of some phantom draw being the problem, so where should I be looking for a solution to my problem?

    Over the 2 years the batteries have been cycled probably 100 times more or less and I find I never have to add much distilled water when I check them. Am I correct in assuming that the batteries need replacement?

    If so, based on a future fulltiming lifestyle consisting of much more boondocking vs. park camping, do AGM’s make sense $wise? If so, what brand would you recommend?

  6. Gary,

    On this rainy day in Edgewater, FL, I’ve been reading about batteries and found your article and comments interesting and enlightening because I’m currently looking for two good RV AGMs. I do boondock quite frequently.

    Currently, I have mismatched batteries, one deep cell about 3 years old and an auto battery about 2 years old. I modified my TC by adding the second battery, an inverter, and a 140w solar panel. All worked well last spring while my wife boondocked in a cow pasture while volunteering for the workshops at Sun ‘n Fun in Lakeland. They still work well as long as we don’t intend to use the inverter for the coffee maker or the microwave.

    Currently, I’ve been Impressed with the specifications and warranty of the Batteries Plus SLI34AGMDPM. The price to me is somewhat scary as I have seen in the past, rebates by manufacturer and store totaling about 10%.

    Do you have any specific knowledge or recommendations for this or any other similar battery?

    As a side note, I’m fairly active as a member on

  7. I have a 100 watt solar panel and would like to add another one. The voltage output is about 16 volts. The solar charger can handle another solar panel but the 8 gauge wiring to the batteries I believe will limit me to only another 100 watts when in full sun with max output. Since I don’t know the type of solar panel or the brand can I get any 100 watt panel with an output of about 16 volts and physically about the same size? Can I mix a 100 watt and a 150 watt?

    Thanks for your guidance in advance!

    Kind regards,

  8. Yes! It would pay to make sure you do a discharge test over a few hours to proove it ok.
    Battery in series or Paralell?
    But you should never put a new with old.
    Putting a new with old is un equal – the older battery constantly drains energy from the newer one. Normally it’s just one cell that dies (battery is dead) Because the cell is dead and can never be fully charged the rest of the cells work to charge something which never charges makng all batteries connected useless.

  9. Gary: I don’t own a RV, but I have a small solar system for charging batteries for backup sump pumps and power converters- one for house use ,and the other a pure sine inverter for the computer and t.v.. I’ve learned more about batteries and how to buy/use/charge/maintain, etc, from your articles and comments than any other source to date. Keep up the good work and thanks for all the info.

  10. I love reading about electrical systems. Currently run a 6-pack of Trojan 125s in 38 ft Alpenlite. I have gravity fed watering system in it. I have 720 watts of solar on roof with options for 30 and 45 degree angles depending on winter or summer usage.From the roof, I ran single aught welding cable down. My goal was to lose the least amount of voltage drop in the distance they needed to rfun gto get to the controller. . I have a 45 amp Controller and a Magnum 2800 watt Inverter. I have produced 37 amps under noon sun and get 9 more than I would off a 30 amp pole in most RV parks. My little travel trailer has a set of new Trojan 125s in parallel with LED lighting through-out. The twin Honda 2000 power the AC in summer and also charge the system.
    Lastly, I just installed brand new twin Interstate 2200s in my little 24.5 fifthwheel that I use on the rivers and creeks where ever I go. I have 1 triple panel 45 watt charging system from harbor freight I use to keep the batteries up daily as I will discharge accordingly at night. Just in case, I drag the twin Hondas along for the worse case scenario”
    When I read about systems, anywhere, I get psyched! Your going to love what options are available, whenever your able to purchase them. My biggest asset…to me anyway, is the LED lighting systems in all three RVs. Yes, they can be a bit pricey but like I did, I bought them separately and my expense level until I was completely LED loaded. Good luck on whatever systems you run and happy travels.

  11. This answer refers to Trojan batteries (model T105), they are frequently found in RVs and probably what you have. You can find them pretty cheaply on eBay. They’re hard to find elsewhere online though.
    Although this answer does conclude that wiring in series will prolong battery life compared to the parallel setup, Trojan says that either setup is fine. People typically buy two 6 Vs because they’re cheaper and smaller than a 12 V battery.
    “It would appear that there is no significant difference in capacity and voltage between these two examples.
    But this really is not the case, and the reason has to do with the engineering and materials used to construct the batteries.
    The plates designed for the T-105 use the same active material and alloy of the group 27 deep cycle batteries but both the T-105 negative and positive plates are 60% thicker than those found in the deep cycle 27 group sizes. The significance of this is that these 6 Volt batteries should have a longer lifespan than the two deep cycle 27 group sizes, if properly cared for.
    While the capacities are similar (220 versus 225 Amp Hrs.), battery longevity favors the two 6 Volt batteries. Why? Because a major cause of deep cycle battery failure is the shedding of active material from the battery plates.”
    And here’s a wiring guide from Trojan that doesn’t state any preference for one setup over the other. Trojan does state that most people prefer series wiring due to the cost and space advantage.

    Hope this helps,

  12. Quick question, I just bought a used camp trailer and it had two six volt Trojans in series. Is that better than having two 12 volt batteries parallel???? Any advantage?

  13. Most motorhomes will charge the house battery from the engine alternator once the chassis batteries reach full charge, but a few do not and I’m not sure about your ’87 Gulfstream. An easy way to tell is to check the house batteries with a voltmeter while the engine is running and no shore power hook-up. If the house battery voltage is above about 13 volts, it is being charged.

    Don’t disconnect the house batteries while parked with shore power on – the charging system will keep the house batteries up. Do, however, check the water in the battery cells regularly – the old charger in your coach will tend to boil away the water. Use distilled water to top up the cells as needed.

  14. Yes, you can, as long as you are confident the other battery is still “good”. You should verify that voltage remains good at rest and under load, and so a specific gravity (hydrometer) test of the cells on a flooded cell type. Use a battery of the same AH capacity and type (flooded, AGM, etc.)

    Mixing old and new batteries is risky because any substantial difference in performance will decrease the capacity of the new one and might even cause damage to it as the charger strives to bring the poorer battery up to par and thus overcharges the good one. The safest course of action is to replace all batteries at the same time, to assure they have identical characteristics.

  15. Can you hook up a new 12v deep cycle battery parallel to one that is the same kind and tests good, but is not new.

  16. Our motorhome house batteries are two Lifeline GPL 24T batteries connected together (parallel). One went bad so we purchased a new one. They are quite expensive. We were told that we should purchase a second new one even though the existing one tested fine. Is that true?

  17. Just bought a used gulfstream motorhome and not sure if when the engine is running if the engine alternator charging both batteries at the same time? I know it’s suppose to charge the engine battery but not sure about the deep cycle. Also should I disconnect the house battery when the rv is parked for a couple of weeks? I’m having charging issues! I’ve had the alternator checked out good and both batteries are new. I changed the starter relay solenoid and it charged real good for awhile and now the gauge reads about 10 volts when she’s running. ’87 Sun Vista 34ft.

  18. Aaron,
    Sure that sounds like it would work fine. As long as the voltage is the same for both, you should be OK alternating their use. Although it depends on your battery needs for your style of camping, there’s probably no need to go buy another battery just for the sake of having the exact same model. Congratulations on your new Thor Tahoe trailer and thanks for visiting the site.

  19. well, I am a greenie when it comes to buying RVs and working with them. So, I didn’t think anytging about getting the same battery that the previos owner had before. I’m wondering if it would be best to just use one at a time for now and then when one goes bad then switch over to the other one possibly so I don’t waste too much money and get to another 24 or 27

  20. Some one else might want to chime in on this, but you should only connect batteries in parallel that are the same rating. By wiring batteries in parallel {Parallel connections (+) to (+) and (-) to (-)} you’re increasing the amp hours but not the voltage. The problem with the AH mismatch is that the batteries won’t be evenly discharged / charged. And eventually you’ll have badly imbalanced batteries that could cause a problem. Any reason you didn’t want to go with two of the same type?

    Here’s an article at Camping World. They sell Exide batteries online.

  21. I just bought a used 1997 thor tahoe camping travel trailer a few weeks ago and the previous owner had a 24 and 27 battery. Both of the batteries were shot. I picked up a new 27 and a new 24 up hoping that that would be okay instead of having like two 24 batteries.

    my question: is it ok to combine those two sized batteries together? And if so, should I hook 24 up first or the 27th deep cycling battery up first and then combine them?

  22. I think you are referring to the RC – Reserve Capacity – rating of the battery? Coupling two in parallel will doubles the RC minutes, which means they last much longer.

  23. if batteries show just say 380 min @25 for one then if you have two if will not put as much of a draw on the batteries, or will it allow them to go longer

  24. You can’t get a “larger” DC 24 battery – the 24 represents the case size and that is the limiting factor. You could change to a size 27 or a 30/31, either of which would increase capacity somewhat, about 20% more for the 27 and 75% more for the 30/31 sizes. But your best bet is to switch over to a pair of 6v GC2 batteries, which will nearly triple your capacity and probably have a much longer lifespan than the 12v you are using.

  25. My 5th wheel house battery runs out overnight (about 4 hours) running furnace, fridge (on propane) and some connected electronics. I have a deep cycle, one year old DC24 CA 690 RC 135, that the dealer says tested good. I would like to gain 3 more hours of capacity. Would I be best served by an additional DC 24 or switch to a large 24?, Or two 6 volts in series?

  26. Sometimes a new battery can be bad, so maybe its worth having it load tested to be sure. Since this is a diesel RV, you probably have two engine starting batteries connected in parallel. If one of them has a bad cell, it drags the voltage down in both of them.

    You are correct that the house and chassis battery systems are supposed to be separate, but sometimes somebody, even a dealer tech, may connect some “house” function to the chassis battery, or cross-connect the two systems when attaching an accessory, destroying the isolation.

    Another possibility is that your entry steps have a light underneath (many do) and it is staying on. Take a look at night – it’s easy to tell then.

    By the way, there is generally no need to start a diesel every week, but you should probably continue to do so until the battery issue is solved. Are you letting the engine run long enough to recharge the chassis battery each time? It takes a lot more than a few minutes. You might also be able to charge them by running the generator or shore power, but that depends on the year/make/model of the coach.

  27. Gary
    Great information, thank you!
    Wondered if you could give me some ideas as to why a new 12V starting battery won’t hold a charge. I start the Diesel RV weekly but keep having to jump the RV to get it started. Would dead house batteries effect the able to start the RV? It shouldn’t right, it is on a separate system I thought.

    I appreciate anyone’s input.

  28. The two 6v batteries will be connected in series (see diagram in the article above), which effectively makes them one large 12v battery, so the voltage will be no different than what you now have.

    If you add more batteries, the only effect is that it takes longer to re-charge if all the batteries are low. Your charging system can only produce so many amps, so if you double the amount of battery capacity, it may take up to twice as long to fully charge. Think of a water hose (your charger) and two water pails (your batteries): if both pails are empty, it takes twice as long to refill as it would just one pail. However, if both are half-empty, it takes no longer to refill than if you had only one pail that was completely empty. So most of the time it makes no difference, but if you actually use both batteries until they are dead, remember that re-charging will take a long time.

    If you frequently encounter long charge times, you can replace your RV’s converter/charger with one that has a higher amp rating.

  29. I currently own a 2012 Heartland Elkridge 5th wheel with a single 12v battery and am thinking of converting over to at least one bank of 6v batteries. Is there anything I need to do with the onboard charging system to accomidate for the change in battery voltage? Also, I easily have the space for at least two banks of 6v or two 12v batteries, would the addition of that many batteries change the charging system at all?

  30. Gary, I continue to be amazed by people like you who take the time to write such informative and educational articles! Thank you, as others have said. This information has taken the stress out of my first time replacement of RV house batteries. Now if you can get my gas milage to be just a bit better… 🙂

  31. In answer to Jengle’s question about Li Batteries being used in RVs. We have been in close contact with Rob Jones who was the first to install Li batteries (Technomedia).

    We have a 34′ Open Range 5th wheel. Son Cary has been in solar/alternative energy for 22 years (currenJengltly under contract to install panels and low voltage for a 1.5 megawatt system for power company). He wanted to see if he could design a fabricate an autonomous solar system for our trailer. This system has 1.4 kW of solar, 9.8 kW hours (720 amp-hours at 12 V) of lithium iron phosphate batteres, 4.0 kW PSW inverter and the associate controllers, , conveters and other peripherals. We have not had to utilize shore power or generator since June except to exercise/test the system. We have been able to run a/c for 3.5 hours on combination of battery and solar. Since Lithium Iron Phosphate batteries can utilize 90% of power storage, this is equivalent to about 1300 amp-hours at 12 V of lead sulphide batteries. The LFP batteries weigh a total of 160 # as opposed to over 1000# for equivalent storage by PbS. LFP are extremely expensive but would not be able to install equivalent PbS in 5th wheel due to weight limits and then, where the heck would we put them. Have dumped the 50 amp power cord and now just have a 15 amp cord if we ever have to plug in again. Son Cary installed two battery chargers so we can use our 1.0 kW Honda (really only puts out 0.6 kW). These are 1.0 and 0.6 kW. The 0.6 kW is for the generator and both would be used in parallel with 15 amp cord if we ever do choose to tie-in to line power. These battery chargers also permit using really bad line power such as we have experienced in Baja and the Yucatan (burned out microwaves in both places) since the power goes directly to battery and then to 110 V ac via inverter. We still use a surge protector. Surprisingly, power in Belize was excellent.

    We were caught in a snow storm last November and had 8″ of snow on roof (it was so slick on top I could not sit down without sliding off) and decided not to try to uncover the solar panels. We still got about 12 amps at 12 V from the panels and the LFP batteries were still at 60% capacity after three days of running the forced air heater. We could have gone for another three days.

  32. The high inverter power draw needed to operate the coffee maker is probably going to cause the battery voltage to drop below the inverter’s safe operation threshold, meaning it likely will shut itself off within several seconds. A second battery is recommended to share the amp load and help keep the voltage up.
    The second 12v battery must be connected in parallel, not series. The email incorrectly identifies the pos-pos, neg-neg connection as series, but that is in fact parallel wiring. It will not hurt his existing system in any way. Also, there is no harm in trying to operate with just one battery and see if it is sufficient, but odds are heavy that it is not. The inverter will simply shut itself off if the voltage gets too low.


  33. Hello,

    I have one 12v house battery on my 2007 Winnebago Itasca 32′ motor home. I purchased a 1500 watt inverter for early morning coffee (before I can run generator). Should I add another 12v battery in series (pos-pos,neg-neg) in this? The fairly new battery I have marine deep cell w/20 AH rate 75. Will adding another battery hurt my current 12v system?

  34. And where does Lithium Ion fit in? I am seeing more articles about Li3 being used for RVs – with longer life and much less weight.

  35. The traditional wisdom is that the AGMs don’t spend enough time under alternator charging to worry about the voltage excess, but I haven’t seen any battery manufacturer state that. From my own experience I can offer this:
    1. My car starting battery is an AGM and gets nothing but alternator voltage. It seemed to last about as long as flooded cell car batteries last here in Florida, about 4 years.
    2. I have 4 x Group 31 Trojan AGMs in my coach that are 5.5 years old. They have seen about 45,000 miles of alternator charging and still seem ok, but I can’t say whether they would have been better without the higher charge rate. For what it’s worth, my inverter/charger doesn’t have a charge profile for AGMs either, so they always get a bit higher voltage than Trojan recommends.

    But, your mileage may vary…

  36. I use 6 golf cart batteries with a large solar array (used to be solar dealer myself). Noting acid problems on battery mounts, I would consider switching to AGM when these fail. But AGM must hav lower charge voltage limits. Of course I can set the solar and the 3-stage charger for AGM needs, but what happens when the vehicle charging system takes them to wet-cell limits? Any standard cure for that?

  37. Very good article, the last two 6 V deep cycle (golf cart) batteries were from Costco about three years ago. They still perform very well. I do like the Trojan batteries, but at the time the cost was more important. If the Costco batteries last 5 years I’ll buy them again. One way to make adding water easier to the batteries is to add a watering system especially if they are hard to get at like mine are. Once a month it is very simple to pump water into both batteries, takes just a few minutes. Always use distilled water also no tap water.


  38. Gary,

    Thank you so much for this well-written, informative article. I’ve learned more in the last five minutes than I ever expected. This topic was a bit intimidating to me, but now I feel I have the foundation to continue my research. Much appreciated!


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