How can you till if it's time to replace your batteries?We have two Trojan T-105s that are about 5 years old. They are usually charged by AC but a couple times a year we will overnight at a Wal-Mart.We're getting ready to make a long trip and may use Wal-Mart for a few overnights. I don't want to replace them if they still are healthy and have plenty of life left in them, but I don't want to take off and have them fail on the trip either.Thoughts?

Take them to an auto parts store. They have test machines that can test them and let you know the health of the batteries. I use Advance Auto Parts and they test them for free.Dave

jcpainter wrote:How can you till if it's time to replace your batteries?We have two Trojan T-105s that are about 5 years old. They are usually charged by AC but a couple times a year we will overnight at a Wal-Mart.We're getting ready to make a long trip and may use Wal-Mart for a few overnights. I don't want to replace them if they still are healthy and have plenty of life left in them, but I don't want to take off and have them fail on the trip either.Thoughts?Why not try a simulation run in your RV in your driveway for a few days and see what happens? You could charge them up by plugging in, and then degauss them, and check them with a meter or hydrometer, but a live test might give you a better idea of what they will or won't do in the field. If they fail, replace.

A simple pass/fail is if you can see the sides bulging. If they are then it's time to replace.

Use a hydrometer to check the specific gravity. You want to see it in the high range if they are charged but a big variation between cells is an indication of needing an equalize charge or old age

An adequate solar system will fill them by noon or so. Then you’ll be unconcerned with where you camp regarding batteries.

Battery replacement | Good Sam Community

MEXICOWANDERER
Explorer
Apr 19, 2018
I believe you will find the SUN VAT numbers to be VAT 33, and VAT 40

The 40 could load to 800 amperes. The first to have that green inductive pickup.

And a three volt full scale AC volt scale to detect STATOR DIODE

Remember :) ?

Auto Meter now makes a top drawer carbon pile at a top drawer pricetag.
grizzzman
Explorer
Apr 19, 2018
4
Chum lee wrote:
In my first professionally taught auto tech class we had a Sun Professional Battery tester in the shop. It had two meters on it and two heavy cables to attach to the +- battery posts. It had a variable load cell inside it along with a volt meter and a separate ammeter. Provided it passed a visual test, (posts, leaks, cracks, bulges, etc.) and the electrolyte was above the plates and within about 1.250 to 1.280 specific gravity, we were taught to test 12 volt wet cell batteries with a 250 amp load for about 10 seconds while reading the voltage on the meter with the load connected. Less than about 9.0 volts under load (for most batteries) meant the battery went in the trash. Within a minute, the voltage must return to within .5 volts of the pretest voltage after the load is terminated. The battery was charged first if the electrolyte was below the minimum specific gravity and below about 12.2 volts nominal. It's pretty hard to fake your way through that test and you can easily replicate it with simple previously mentioned tools and by using the starter motor as your load. (remove the fuel pump relay, the coil wire, or engage some other kill system to prevent engine ignition)

This information is a little dated, but . . . .

The instructors were a senior technical representative from Delco-Remy and a German guy with a masters degree in mechanical engineering and 10 years engineering experience in the engine/drive train department at Porsche in Germany. So, . . . if all of the resident experts disagree, you are disagreeing with them! (not me) YMMV!

Chum lee

in the day 70s it was the vat45 and then the vat 60 battery testers however they don't test for capacity they were built for starting batteries.
azrving
Explorer
Apr 19, 2018
azrving wrote:
Chum lee wrote:
In my first professionally taught auto tech class we had a Sun Professional Battery tester in the shop. It had two meters on it and two heavy cables to attach to the +- battery posts. It had a variable load cell inside it along with a volt meter and a separate ammeter. Provided it passed a visual test, (posts, leaks, cracks, bulges, etc.) and the electrolyte was above the plates and within about 1.250 to 1.280 specific gravity, we were taught to test 12 volt wet cell batteries with a 250 amp load for about 10 seconds while reading the voltage on the meter with the load connected. Less than about 9.0 volts under load (for most batteries) meant the battery went in the trash. Within a minute, the voltage must return to within .5 volts of the pretest voltage after the load is terminated. The battery was charged first if the electrolyte was below the minimum specific gravity and below about 12.2 volts nominal. It's pretty hard to fake your way through that test and you can easily replicate it with simple previously mentioned tools and by using the starter motor as your load. (remove the fuel pump relay, the coil wire, or engage some other kill system to prevent engine ignition)

This information is a little dated, but . . . .

The instructors were a senior technical representative from Delco-Remy and a German guy with a masters degree in mechanical engineering and 10 years engineering experience in the engine/drive train department at Porsche in Germany. So, . . . if all of the resident experts disagree, you are disagreeing with them! (not me) YMMV!

Chum lee

Sounds like SG was important to them. So they were saying that a dead battery can't be tested. Well, it can but the auto parts guy will just watch the voltage drop and then tell you that your battery is no good. ;)
azrving
Explorer
Apr 19, 2018
Chum lee wrote:
In my first professionally taught auto tech class we had a Sun Professional Battery tester in the shop. It had two meters on it and two heavy cables to attach to the +- battery posts. It had a variable load cell inside it along with a volt meter and a separate ammeter. Provided it passed a visual test, (posts, leaks, cracks, bulges, etc.) and the electrolyte was above the plates and within about 1.250 to 1.280 specific gravity, we were taught to test 12 volt wet cell batteries with a 250 amp load for about 10 seconds while reading the voltage on the meter with the load connected. Less than about 9.0 volts under load (for most batteries) meant the battery went in the trash. Within a minute, the voltage must return to within .5 volts of the pretest voltage after the load is terminated. The battery was charged first if the electrolyte was below the minimum specific gravity and below about 12.2 volts nominal. It's pretty hard to fake your way through that test and you can easily replicate it with simple previously mentioned tools and by using the starter motor as your load. (remove the fuel pump relay, the coil wire, or engage some other kill system to prevent engine ignition)

This information is a little dated, but . . . .

The instructors were a senior technical representative from Delco-Remy and a German guy with a masters degree in mechanical engineering and 10 years engineering experience in the engine/drive train department at Porsche in Germany. So, . . . if all of the resident experts disagree, you are disagreeing with them! (not me) YMMV!

Chum lee

Sounds like SG was important to them. So they were saying that a dead battery can't be tested. Well, it can but they will just watch the voltage drop and then tell you that your battery is no good. ;)
Chum_lee
Explorer
Apr 18, 2018
In my first professionally taught auto tech class we had a Sun Professional Battery tester in the shop. It had two meters on it and two heavy cables to attach to the +- battery posts. It had a variable load cell inside it along with a volt meter and a separate ammeter. Provided it passed a visual test, (posts, leaks, cracks, bulges, etc.) and the electrolyte was above the plates and within about 1.250 to 1.280 specific gravity, we were taught to test 12 volt wet cell batteries with a 250 amp load for about 10 seconds while reading the voltage on the meter with the load connected. Less than about 9.0 volts under load (for most batteries) meant the battery went in the trash. Within a minute, the voltage must return to within .5 volts of the pretest voltage after the load is terminated. The battery was charged first if the electrolyte was below the minimum specific gravity and below about 12.2 volts nominal. It's pretty hard to fake your way through that test and you can easily replicate it with simple previously mentioned tools and by using the starter motor as your load. (remove the fuel pump relay, the coil wire, or engage some other kill system to prevent engine ignition)

This information is a little dated, but . . . .

The instructors were a senior technical representative from Delco-Remy and a German guy with a masters degree in mechanical engineering and 10 years engineering experience in the engine/drive train department at Porsche in Germany. So, . . . if all of the resident experts disagree, you are disagreeing with them! (not me) YMMV!

Chum lee
2oldman
Explorer II
Apr 18, 2018
jcpainter wrote:
So, we played it safe and just ordered two new T-125s to replace the 5 year old T-105s.
Good. The time to replace batteries is when you start wondering if you should.
DrewE
Explorer II
Apr 18, 2018
Smitty77 wrote:
OP - Go have some fun:)! The T-125 will give you just a tad more AH's available then the T-105's. (240AH vs 225AH for about .066% more juice.).

...

Have a good trip:)!
Smitty

You of course mean 6.6% (or 6.7% if you want to round properly). Still not a huge difference, but at least measurable under other than pristine lab conditions with expensive highly accurate test equipment.

And yes, I also hope it's a great trip.
Smitty77
Explorer
Apr 18, 2018
OP - Go have some fun:)! The T-125 will give you just a tad more AH's available then the T-105's. (240AH vs 225AH for about .066% more juice.).

Our first 'used' Bounder, had two mixed GC batteries - both were bulging. Still remember the 1st owner commenting 'Well, those batteries might need a look at.':)! Only had room for X's GC2 batteries. Wanted to fit the T-145's, but just not enough head room. So, X's 2 T-125's went in.

I sold that Bounder to a neighbor 6 years later. He replaced that set at age 10, because he thought he should:)! Due to very poor access to the top, I added the the turkey baster squeeze ball watering system. KISS it was. About once a month I'd go squeeze the ball until firm, usually not even a full squeeze was required. Very seldom did it ever require a partial second squeeze. (That's battery water techie talk, to say in our application they did not consume much water:)!).

Have a good trip:)!
Smitty
MEXICOWANDERER
Explorer
Apr 18, 2018
I hope this makes you smile because I would have done exactly the same thing
Some folks on this forum are not experienced with load testing I fear
It is difficult to LOAD TEST a single golf car battery
Both batteries have to be tested at the same time and they have to be connected for 12-volts while testing
The only valid load test for a golf car battery is to load it with 250 amperes for a full 30-seconds
Who has such an adjustable carbon pile load tester? There are very few of these
An electronic impedance tester would work but you would spend time and money finding someone with such a tester and then take the batteries in to be tested
The main point is you are going on a long trip and you are dead set against having battery problems
And being a world class cheap skate I too would have chosen Trojan over warehouse club batteries. Testing batteries to reveal an accurate guess as to remaining lifespan is beyond the capability of retail stores
IMHO you did the most assured action
I blow-up if I have a battery go bad while traveling
I have sero-tolerance for it
Best of luck on your trip!
jcpainter
Explorer
Apr 18, 2018
Lady OP here, Golly Gee Willikers . . . I sure didn't mean to start a heated discussion. Both a well respected auto parts store and the local Trojan dealer advised us that there is no true way to accurately measure how much GOOD life a battery has left in it.

So, we played it safe and just ordered two new T-125s to replace the 5 year old T-105s.

Thanks to those of you that offered friendly suggestions and hopefully they will benefit others that find themselves in this quandry.