Battery Testing

[moosetags]

Lucy is now quickly approaching 5 years old (June 1) and we are still running on her original 12 volt batteries. How long are these batteries supposed to last? I have gotten the impression from reading other threads that you are lucky if you can get 3 years out of a battery. We have used Lucy a whole bunch (800 nights/70,000 miles) which may have something to do with her batteries' longevity.

What is the best way to test Lucy's batteries to see if they are still up to par or really need to be replaced?

Thanx for the help.

Brian

[Mexray]

Brian, You're on to something there...I usually tell my RV battery customers, "Use it or lose it!"....

If your batteries are maintained properly, the number of 'cycles' or discharge/recharge's are then the limiting factors...

Usually, well maintained batteries should retain usable life for at least 4-6 years...unfortunately, many RV'ers neglect their batteries during storage, etc., and so only get about 3 years (or less) useful life...use em' or lose em'...

You can have a battery specialist shop use a load tester on your batteries to get an idea of their 'status'...however, you will usually be tipped off it's time to change batteries when it's noticeable that your 12 volt stuff won't run as long as before - IE; diminished capacity...

Other than the above, it's really hard to make an exact prediction as to when they will give up the ship...

Being 5 years old, and if you are embarking an extended trip soon, it might well be worth it to change them out now. You can then shop around for what you need, and not be stuck on the road for some high priced alternative....

As for engine 'starting' batteries, I tell customers to run em' till you notice a slower starting response in the morning, after the battery has set idle overnight - If it sounds like it's starting slower, or 'labored', it's time to have the battery load tested, to see if it's time to replace, which it usually is 95% of the time, after those 'symptoms'!

[Jammer]

Five years is a long time.

I have developed a habit of replacing batteries in cars, trucks, etc. every four years even if they appear to be in good condition. The inconvenience and cost of having them fail at an awkward moment when it is not feasible to comparison shop is too great, especially in Minnesota, where failures usually occur during severe winter weather.

If you look at the cost per year or even per five year cycle you don't really save much money by trying to get one more year out of the batteries.

In a trailer it might be a big deal or might not. A fact to consider is that not all failures are gradual.

[masseyfarm]

My theory is to not replace stuff unless it shows signs of being on its last leg, or if I am upgrading to something better.
As mentioned above, there usually are some signs from the battery of age. Less juice over time, and harder and longer to charge.
If you SG test it on a regular basis and record the results in your log, you will know when the time is up, and you can start searching for the best replacement at the best price.
Where I live, there is little price competition on batteries, so I plan my buying with my off Island trips.
Theory does not always work, but you have to try.
How far you can make something last also depends on what you have for backup systems.

Dave

[Gene]

One factor is how the batteries were treated while on a dealer lot. Were they allowed to discharge too much? Were they overcharged?

I think our trailer was only on the lot about 4 months, but knowing what we learned about the dealer after we bought our Safari, I assume they may have abused batteries.

After 3 years of use (about 7 months each year) they seem not to be holding a charge quite as well, but they test ok with a cheap tester. I am conflicted. I want them to die so I can get better batteries that work better with our solar system and have more capacity than the cheapo OEM batteries. I don't want to have to buy new batteries.

Gene

[moosetags]

Lucy languished on the dealer's lot for 16 months. The early FB's were not a good seller. When we bought Lucy new in June of 2006, the dealer put in brand new fresh Interstate batteries (SRM 24/550CCA/690MCA) when she was delivered to us.

Brian

[2airishuman]

brian...

IF you've been regularly but LIGHTLY using this set, they could last a long time...

and if they are typically REcharged from a 70% or higher LOW point...

just keep on using them.

a simple test is furnace use (which is a bit of challenge in flo')

unplug the stream and set the furnace at about 20 degrees above interior temps...

then let the furnace cycle for 24 hours, check the battery level then run another 24 hours.

for folks that regularly use the furnace 2 days of use will deplete 2 grp 27s down to the 50% range (+/- 5%)

using actual voltage and furnace cycle times (with the known blower amps) can make this a reasonably accurate test.
_________

i once used a deep cycle battery on a 'stream for 12 years, yes 12 years.

and right now i've got a 9 year old german battery in an automobile,

and it still starts on the first tick (even at minus 10 morning temps) without hesitation.

this car sits UNdriven for months at a time, with a constant alarm load on the battery...

in other words the WORST possible abuse and it's still going at 9 years.

might replace it this spring, maybe.

the oem batteries in the 05 diesel truck (both of them) are also still going strong at 6 years ...

and the 2 agms in the 34 ftr are 6 years old this week, and still in daily use.
_____

so yes most folks may kill and replace every 3 years, but not all of us have that experience.

cheers
2air'

[GLMALM]

Yesterday I took my trailer batteries to my mechanic to check on their status (Sears Marine/RV). These were purchased 7/2004 just after I bought my trailer ('78 Ambassador). I keep them charged in my garage on a 900 m/A automatic charger when not on the road.

He used a Snap-on battery/load tester and both came up as "good" after a 2 tier load test. The reading on the second one I got as a printed readout (as follows) battery size (670 CCA), available amps (764 CCA), rated capacity % (114%), Initial volts (13.23 V), Final volts (12.36 v) Impedance (4.18).

Anyone have any thoughts as to how these numbers stand up to a similar "new" replacement (lead/acid) battery?

Gary

[Ag&Au]

Originally Posted by moosetags

Lucy is now quickly approaching 5 years old (June 1) and we are still running on her original 12 volt batteries. How long are these batteries supposed to last? I have gotten the impression from reading other threads that you are lucky if you can get 3 years out of a battery. We have used Lucy a whole bunch (800 nights/70,000 miles) which may have something to do with her batteries' longevity.

What is the best way to test Lucy's batteries to see if they are still up to par or really need to be replaced?

Thanx for the help.

Brian

Brian,

Other than just seat of the pants, they seem to be doing OK (that's what really counts anyway), the only good way to test them is under load over time. This is done with fairly expensive equipment. If you really want to know, take them somewhere and have it done. My advice would be to use them until they no longer meet your use requirements. I typically get 7-10 years out of batteries with decent care.

Regards,
Ken

[Gene]

I'm sort of repeating myself, but… Besides whether the batteries are done with, another factor is getting better batteries for boondocking. The OEM ones are cheap and don't have the capacity needed for boondocking for very long especially if you have to use the furnace. I understand there are better batteries for use with a solar panel.

So although ours are holding up, I'm thinking of getting better ones. This will mean I have to run the generator less often when boondocking. I hate listening to them at campgrounds and I think that being a good neighbor means buying better batteries this spring. This will be part of our constant upgrades to the trailer—I'll be installing self adjusting brakes too.

Gene

[SilverCabin]

Ours went t__s up at almost exactly three years. SG measurement confirmed it. I just attended a battery seminar at the Florida State Rally. The rep there from Exide said if you keep them on a battery tender or plug in no less than once a month, they should last until the advertised expiration date. He also recommended going to AGM batteries, but wait a couple of years for the price to come down.

Randy

[stephiejo]

We have a chance to buy a battery that's been sitting on a shelf (never used) in an auto parts store for a year, at a really good price. ($40)
Good idea? Bad idea? Any advice would be appreciated!

[lewster]

Originally Posted by stephiejo

We have a chance to buy a battery that's been sitting on a shelf (never used) in an auto parts store for a year, at a really good price. ($40)
Good idea? Bad idea? Any advice would be appreciated!

VERY BAD IDEA!!!!!

Any battery other than lithiums will lose a substantial portion of their capacity due to self-discharge over time due to internal resistance. Liquid cells will lose charge much faster than AGM batteries du to their higher resistance. If these batteries have been without a charge for 12 months, there is an excellent chance that the plates have sulfated as a result of not having the charge maintained. Sulfation is many times not reversible and drastically reduces the original capacities of any lead acid battery.

Even at $40........... you would be throwing your money down the drain.

Just my professional opinion....of course!!

[sgschwend]

You have landed on one of the challenges of lead acid batteries. You question of testing is a good one. The available energy is based on the plate surface area. Older batteries have less area and hence provide less energy even though the older battery will charge and display the correct voltages.

Not to make your head hurt but the following is how the test is done:

A capacity test takes a setup where a typical load is applied and the delivered current and voltage versus time is collect. The average current times the average voltage times the number of hours will become the energy capacity of the battery. For Amp Hours take the average current times the hours.

[thiel]

I'd love to see some actual data on self discharge. I see it quoted all the time as gospel, but I've heard contradictory points as well. I've heard that in cold weather things discharge faster too, and my own observations have shown that to not be true.

I pulled my batteries from the trailer in November and left them without cleaning the tops and with their dangly wires still on... and I purposely left them outside in what has been a typical New England winter. Since November, they have lost less than 0.3 volts in charge... and I bet if I cleaned the terminals and took the wires off the discharge would be even less.

If self-discharge is supposed to be extra bad in cold weather, based on my experience I would run a volt meter across that $40 battery and then snap it up if it was charged up.

Another point: people are telling me to upgrade my in-trailer charger--at the cost of a couple hundred dollars and some labor--in order to save my batteries. The batteries cost WAY less than a charger, and even with a new charger they need to be replaced some day... so even if I have to replace them a little more frequently its very close to breakeven (or better!) than switching out to a new charger.

All that said, people like Lewster know way way way way more about this stuff than I will ever know, so my crazy opinion should be taken as just that! I am just thinking about the practical economics of it to a garden variety dude, rather than the pure physics and optimal energy storage situation.... Batteries are easy to source when then run out, so I'm the type that uses them up!

[lsbrodsky]

One thing that is not being discussed is the affect of capacity loss. If you camp with hookups, you will never see the affect. Your TV charges the battery while you are towing, the charger does it while you are on shore power and everything 12v will work just fine, even after you unplug at your storage facility. They will sit at 12.6 volts or more, with no load, just fine.
However, if you dry camp you will see the affect impacting how long you can operate on 12v before you need to recharge your batteries. Old batteries can have dramatically reduced operating hours before the voltage drops too low.
I don't do a lot of dry camping, yet, but I saw this clearly when I had a sailboat and had to charge the batteries with the engine alternator. It became fairly obvious when I needed new batteries because I knew how long I should be able to sail/anchor between battery charges. Even good AGM's never lasted more than 5 or 6 years.
Larry

[stephiejo]

Thank you! That's what I thought, but needed some verification!

[Mollysdad]

Originally Posted by thiel

I would run a volt meter across that $40 battery and then snap it up if it was charged up.

You can't really test a 12v battery with a volt meter. I know, it reads 13.6v, but it has no load on it at the time and with a load it might be 11 v. in five minutes.
However, if it's at a battery dealer, he should have the means to test it.

I bought a "blem" from Interstate Batteries a few years ago. It was $40 while a new one was $120. The blem worked great for a year then I had to buy the $120 one.
If I was going to trade in the car next week, I'd consider it again, but not a good value.

[stephiejo]

Our buddy that works at the auto parts store said he tested the battery and it was at full charge, just found this out.
I think we're going to for it since it tested positive!
Thanks for all your feedback! Learning new things everyday thanks to all of you awesome AS lovers!

[cabinetmaker]

Brian, five years on the factory batteries is impressive.

Do you have the factory converter or did you upgrade? If that is with the factory converter then I''m even more impressed!