How long do you run your batteries?

It also helps to use a hydrometer -- a very low tech device -- to test the specific gravity of each cell. When one cell starts to show a different reading than the others, this is a time to replace the battery. There is probably a way to revive a bad cell, but I would not want to take a chance on being stranded with a bad battery.

My last set of group 31 12 volts lasted for five years, with careful maintenance, and I used them about 70 or 80 nights per year. A lot of cold-weather boondocking. But I never ran them down below 12.1 volts, I always checked the water, and I always kept them on a battery minder when not in use.

Now that I have a portable solar panel, the batteries rarely get below 12.3 when in use. I think that might help extend their useful life, but I am just guessing.

The one thing that I do not do is an equalizing charge. I have been told by folks who really are experts (hi, Mex and Niner!!) that equalizing is a good idea. But I do not have a charger that will give me that capability, and the cost of really good charger may outweigh the extra battery life that I would gain. It is a matter of dollars and cents.

(Has anyone done that calculation, by the way? How much does a good charger cost, and how much extra life would you get by equalizing? Does it pencil out??)

Unfortunately we seem to be stuck on Years of use when actually the best way to judge batteries is cycles. That is why a truck that is used lightly, like mine, the batteries will last many years. My OEM Ford F550 batteries lasted 9 years. Where a heavily used battery in snow and cold, everyday starts last maybe half that time. Are they bad batteries, not neccessarily.

Batteries are are on a path of decline from the beginning. Just like going down a hill. When they cycle often, 12.4v to 14.9v each day, they are cycling at a hard rate. If they maintain a 12.8v majority of the time they will last longer. Then when they are subject to deep drain use, running A/C, Microwaves, Engine Starters, they will impact the batteries harder. All factors in how long the batteries will last. The more you abuse them, not keeping them topped off, deep drains and failing to keep connectors clean and water fluid filled, impacts too. As well as using batteries and storing batteries in extreme heat and cold.

Due to my heavy use, my use factor is about 5 to 6 years for AGM & FWC batteries. I have no info on the Lithium batteries nor will as long as they are at a high $$$$. The way I judge my batteries for replacement is that I keep track of their daily power use and charging. When I see that the batteries are not holding a charge consistently, resting rate overnight comes down to 12.3v or less, rather than 12.6v-12.7v of a newer battery, I know that their SOC is no longer viable and the batteries are in need of replacement. I can usually detect these batteries decline 3-4 months before replacing and can then decide where along my route to replace due to cost and sales tax, or lack of tax.

Just keep an eye on your battery resting SOC each morning and it will tell you what your battery status is. If the battery is no longer maintaining a charge easily, replace it. Unlike a car battery, subjected to hard starting requirements, a RV battery often dies a slow death and if you are keeping aware of it, you will be able to see it before it completely dies, as my AGM did after 7 years of abuse and use.

b

That's what we do with our older batteries. My batteries are not Trojans but are the standard issue cheap GP24 12VDC Interstate batteries the dealers provide in most RV trailers.

I know from experience what performance to expect on how long these batteries produce 12VDC power over the extended time before they get down to their 50% charge state when camping off the grid. When this starts falling back I will start more dedicated charging routines...

If you take care of the batteries they will last a long time... When camping off grid I monitor my batteries all the time with my meter panels and physical inspections looking for over heating of the battery cases and boiling out of fluids etc...

I installed mine in late 2008...

When camping off the power grid my batteries are being used 24/7 with a three hour daily charge period starting when they drop back to their 50% charge state. The three hours charging routine brings them back up to their 90% charge state where I can expect a good 99% of the performance capacity once again. By experience I can do a good 12-14 cycles of this 50% to 90% charge states before having to do a 100% charge state which in my case takes a good 12 hours or more of smart mode charging. Keeping within these guideline I don't seem to be doing much harm to my batteries...

Roy Ken

8 to 10 years is not uncommon for properly cared for Trojan's.

Maybe.. if they seem weaker, if you've often discharged them over 50%, if you use high-wattage appliances often, if they're swollen or leaking.. etc.

Mine are seven years old and still working great. When they stop holding their charge I will replace them.

Too much of the equation determining effective battery life is based on their "care and feeding" that there really is no standard rule.

Best advice is to occasionally check their SG (Specific Gravity) and/or load test them.