RV Battery Life Expectancy

[markopolo]

RV Battery Life Expectancy
By Mark Polk

The life expectancy of your RV batteries depends on you. How they’re used, how well they’re maintained, how they’re discharged, how they’re re-charged, and how they are stored all contribute to a batteries life span. A battery cycle is one complete discharge from 100% down to about 50% and then re-charged back to 100%.

One important factor to battery life is how deep the battery is cycled each time. If the battery is discharged to 50% everyday it will last twice as long as it would if it’s cycled to 80%. Keep this in mind when you consider a battery’s amp hour rating. The amp hour rating is really cut in half because you don’t want to completely discharge the battery before recharging it. The life expectancy depends on how soon a discharged battery is recharged. The sooner it is recharged the better.

What does all of this mean to you? That depends on how you use your RV. If most of your camping is done where you’re plugged into an electrical source then your main concern is just too properly maintain your deep cycle batteries. But if you really like to get away from it all and you do some serious dry-camping you’ll want the highest amp hour capacities you can fit on your RV.

Deep cycle batteries come in all different sizes. Some are designated by group size, like Group 24, 27 and 31. Basically the larger the battery the more amp hours you get. Depending on your needs and the amount of space you have available, there are several options when it comes to batteries. You can use one 12-volt Group 24 deep cycle battery that provides 70 to 85 amp hours or you can use two or more 12-volt batteries wired in parallel. Parallel wiring increases amp hours but not voltage.

If you have the room you can do what a lot of RVers do and switch from the standard 12-volt batteries to two of the larger 6-volt golf cart batteries. These pairs of 6-volt batteries need to be wired in series to produce the required 12-volts. Series wiring increases voltage but not amp hours. If this still doesn’t satisfy your requirements you can build larger battery banks using four 6-volt batteries wired in series/parallel that will give you 12-volts and double your AH capacity.

Happy Camping,

Mark

Copyright 2006 by Mark J. Polk owner of RV Education 101

RV Expert Mark Polk, seen on TV, is the producer & host of America's most highly regarded series of DVD's, videos, books, and e-books. http://www.rveducation101.com/

Mark Polk is a retired U.S. Army Chief Warrant Officer Three, specializing in wheeled and track vehicle fleet maintenance operations. In addition to owning and operating RV Education 101, (based in North Carolina) since 1999, Polk also has a very extensive RV background working in RV service, sales and management. Polk has a degree in Industrial Management Technology and his 30 plus years of experience in maintenance includes working as an RV technician, a wheeled vehicle and power generation mechanic, an automotive maintenance technician, Battalion and Brigade level Maintenance Officer, an RV sales manager and also in the RV financing department as the Finance & Insurance manager. http://www.rveducation101.com/

Article Source: http://EzineArticles.com/?expert=Mark_Polk

[weather command]

I am brand new to RV land and have zero knowledge and am sweating it a bit...I just bought a coach 31 group battery and live in Delaware. Can I leave the battery in the coach throughout the Winter? I have about 109 questions honestly. Thanks

[Bruceper]

If the battery is charged, it will be fine.

[booster]

Good article, although I would as usual disagree with part of the statement about depth of discharge vs life. He states the "normal" 50% rule we all have heard forever, that a battery lasts twice as long if discharged to 50% rather than 80% which isn't exactly correct IMO.

What is true is that a battery will last twice as many recharge cycles at 50% discharge compared to 80% discharge, but number of cycles isn't how most batteries are used. How they are used is to store energy and reuse it later, and if you look how much energy you can put into a battery and take out again, the difference in life is much less different and closer to 10% difference, and that is assuming an 80% discharge every cycle. Cycle life averages so shallow cycles increase the cycle life beyond what it would be at 50%.

The big advantage of going to 80% when needed is that you get 60% more usable power from the same amount of batteries, so your bank can be smaller, which also means lighter and less expensive. This is very important, especially in class B's.

There are several discussions of this on this forum that include lots of supporting data based on the manufacturer life charts, which are very good reads if you are into the how and why of things like this.

All the information I have seen would indicate that as long as you have good charging equipment to get back full, 80% discharges have a small effect on life of batteries.

IMO, the 50% rule is one of the most commonly repeated misunderstandings in the RV world.

[Davydd]

Most Class B RV's with lead-acid batteries have at most one or two batteries and really no controls to tell you how much SOC there is but guessed at idiot lights and no controls to prevent totally depleting your batteries. With few amp hours available it is very easy to deplete. Just accidentally leave your absorption refrigerator on 12v DC mode for instance and you might wake up to a battery depletion alarm in the middle of the night. Unless you are super observant and obsessive about battery use you could discharge your batteries more than you realize.

[GeorgeRa]

Having a critical appliance like fridge powered by 12V it would be advisable to invest in a SOC (State of charge) monitor to know the state of the battery. As pointed above excessive draining of battery(s) has a direct impact on longevity. The following are a few of battery monitors. Installation requires placing a shunt between the negative battery(s) post and the ground/loads. The actual monitor can be place anywhere for good visual access.
Gaining popularity recently - https://www.victronenergy.com/battery-monitors/bmv-700

It’s precursor was a venerable Link 10, good unit - Battery Chargers | LinkLITE Battery Monitor | Xantrex

A lot of folks like it, it still looks like was design in the last Century -http://www.bogartengineering.com/products/trimetrics/

One of the better units, OLED display, possible to be mounted on the positive battery post - https://www.bluesea.com/products/1830/M2_DC_SoC_Monitor

Don’t know much about it Clipper Marine Instruments

There are more shunt based battery monitors including the ones which are often available if your invertor is integrated with a charger such as Magnum.


Simple installation video.

https://www.youtube.com/watch?time_c...&v=MRljOaTdc3s

[Saldar]

Originally Posted by GeorgeRa

Having a critical appliance like fridge powered by 12V it would be advisable to invest in a SOC (State of charge) monitor to know the state of the battery.

Any thoughts on this bluetooth system that reads out on an app? It looks like a simpler installation, and can use a shunt. It has a 50mA draw, but has an on/off switch.

Wireless Multimeter Bluetooth Battery Monitor
https://www.amazon.com/dp/B0184XHL1K

When you have battery boost, does your shunt amperage have to take that surge into account? A really big shunt means your monitor precision goes down, I think.

[GeorgeRa]

Originally Posted by Saldar

Any thoughts on this bluetooth system that reads out on an app? It looks like a simpler installation, and can use a shunt. It has a 50mA draw, but has an on/off switch.

Wireless Multimeter Bluetooth Battery Monitor
https://www.amazon.com/dp/B0184XHL1K

When you have battery boost, does your shunt amperage have to take that surge into account? A really big shunt means your monitor precision goes down, I think.

This unit is limited to 30A shunt, not much. If you want information shared via Bluetooth you can use Victron, just get their Bluetooth transmitter.

[gimpy666]

I wish North America had batteries of the quality of the Varta brand that comes with a new Sprinter. My 2006 RV engine battery from new is still performing well and when I bought a new Mercedes 240D in 1975 that Varta battery lasted 13+ years and that was my daily driver.