Part Three: A not-too-technical discussion of solar & RV batteries.

3-way charging.
A 3-way charging system does several things to extend the life of your batteries. First, if the batteries are low then the charger charges at a higher rate to get the batteries full. Typically the Freedom series inverter charges at a rate of 100 amps to get the batteries in the “safe zone” quickly. This high rate diminishes as the batteries get close to full. When the voltage of the batteries gets close to a full state of charge then the charger switches to “absorption” mode. This means the voltage remains at a set point that charges the batteries at a much slower rate, similar to a “trickle” charger. After the batteries show full then the charging system switches to “float” rate which is electronically controlled to give the batteries just the right “top-off” zaps to further lengthen the life and storage capacity of the battery bank. There’s more to it than that, but you get the idea: charge quicker when needed and no overcharging.

Solar is good.
By their nature, solar modules provide a fairly low rate of constant charge and most solar controllers provide batteries the “good” charge cycle similar to a 3-way system.

Am I supposed to be a battery expert?
Well, not exactly, but if you want your batteries to last longer or you are dependent on them for your power while you are out “boon-docking” then you will probably need to learn more. It may seems like a lot to learn but there’s actually more you should do to optimize the life of wet cell batteries. This chart is a quick review with some do’s and don’ts, but you may still have a few questions after reading it.

More FAQ’s

Why can’t I replace one new battery in my older battery bank?

Older batteries will make a new addition old too. All batteries in a bank should be replaced at the same time. I usually tell people if the old ones are only a few months old it is OK to add new batteries.

What is the proper level for battery fluid at different states of charge?

A discharged battery should have the electrolyte level just above the plates. The fluid in a battery expands as it gets charged and if overfilled there is danger of overflow which will change the electrolyte composition and cause irreparable damage greatly shortening the life of the battery. A fully charged battery should have the fluid level just below the dip tube at the top of the cell.

How do I moderate my batteries temperature?

Temperature extremes are bad for batteries, especially heat. Care should be taken not to let batteries sit in the hot sun or get too hot in an enclosed compartment. Insulation may help, as well as ventilation, but sometimes it takes some creative ideas to moderate temperatures.

What voltage adjustments should be made in extreme weather conditions?

Many solar controllers and inverter/char-gers have a battery temperature sensor which will help regulate the voltage being sent to the battery bank. Batteries should be charged at slightly different voltages in the cold or in hot climates. Chargers with temperature sensors will automatically adjust the voltage but if you plan on taking a trip to Alaska after spending time in the Mojave Desert, then you will want to consult your controller operating manual for manual setting changes.

Do I have the same amount of power (amp-hours) to use during cold weather and warm weather?

No. Up to 40% of your stored amps are lost in cold climates. This should be taken into consideration when using your batteries in winter months. Our customers with solar power not only have less power stored in their batteries, they have less power flowing from their solar panels in winter months.

What does equalize batteries mean and how do I do it?

The Equalizing battery charging cycle is used when the electrolyte has different readings in the cells of a battery. It is a cycle which applies a higher than normal voltage for controlled periods of time when needed. Great care must be used when using this cycle because excessive explosive gasses are formed. Sometimes a battery can get hot and the cycle must be stopped. Many inverter/chargers have this manual feature and all safety precautions must be taken. Special precautions must be observed when equalizing wet cell (flooded) batteries. Thoroughly read and understand your instruction manual before performing an equalizing cycle.

How often should I equalize my batteries?

I have heard monthly, every other month, yearly, etc. After the battery bank has been fully charged Trojan Battery says that when the electrolyte reading in a battery is low or wide ranging (+/-.015) between cells, and after being fully charged, is the time an equalization cycle should be performed. The electrolyte level is measured with a hydrometer.

What does de-sulfation mean and how do I de-sulfate my batteries?

Basically all batteries collect sulfates on the metal plates during their life. Older or heavier use batteries will have more than newer batteries. Some newer automatic battery chargers have a de-sulfation cycle where a voltage is applied in rapid pulses thereby loosening buildup which falls to the bottom of the battery or re-mixes with the solution. Typically solar controllers, inverter/chargers do not have this feature. The equalizing cycle uses a different method (higher voltage) to accomplish de-sulfation.

Do I really need a hydrometer?

Best get one and learn to use it. It will give you another level of understanding your batteries. Voltmeters are a help in knowing what is going on with your batteries, but they do not tell the whole story.

Should I stick to distilled water to fill my battery fluid?

I think all battery manufactures suggest distilled or de-mineralized water for filling battery cells. I have been told that in a pinch it is better to put a good filtered (no minerals added) bottled drinking water in the cell rather than let it go dry.

I’ve heard that a battery will go dead or rapidly discharge if left on the floor of my garage.

This is an old-wives-tale. It used to be true when battery cases were made out of bakelite. They would slowly discharge to ground when placed on a cement floor. Modern battery cases are made out of plastic materials which do not conduct electricity so there is no capacity loss when placed on the ground. Actually, in hotter climates like here in Las Vegas, it probably is better if the battery were placed on the cooler cement floor during warm weather. It is recommended that the battery be placed on a mat or catch basin so that any spilled or leaking acid is contained.

I’ve heard that batteries are dangerous. What precautions should I take?

Batteries are very dangerous and a healthy respect for safety precautions must be vigilantly observed.

What are the fuses and breakers for?

Where should they be in relation to the battery? Okay, if you are asking this question then you may need a professional do your wiring. All wires or cables (circuits) must be fused for the wire size and expected amp (current) draw. This goes for 110vac in your house and 12vdc in vehicles. All wires will melt if too much current flows through them. The fuse or breaker must be placed as close to the battery bank as possible. Often a fuse block is used with a larger positive feed wire coming from the battery. In addition to each small branch wire having a fuse, the large feed wire must be properly fused close to the battery. If it’s attached to the battery it better be fused properly!

I want to run a small inverter off my cigarette lighter plug. Can I do this?

Well, you can try. If the inverter is a small one (50 to 350 watts) then you probably are okay. I have found that the guy who wired the cigarette lighter didn’t think about the huge current draw of inverters so he put in too small of a wire. Most inverters should be connected to the positive (+) and negative (-) terminals of the battery bank directly with proper connectors and fuses inline. Most inverters instruction manuals will tell you wire sizes and maximum length allowed. Please follow these instructions carefully. Try to go less than maximum allowed on distance from battery to inverter if at all possible.

I want to run a larger inverter through my cigarette lighter plug. Is this possible?

Heck no. The same goes for large inverters (above 350 watts) as small ones. Make sure you have the correct size wire, connectors, disconnect, fuse (or breaker), and keep the distance from battery to inverter at an absolute minimum. It is very important to follow the manufacture instructions for these parameters. You can go with larger size wire if needed and you will need a recommended “disaster fuse” on the positive cable connecting to the battery. Most large inverters do not come with a proper fuse in the box when making a purchase. If you do not know what size to use, contact us for suggested specs. We carry several options when it comes to larger amp draw fuses and disconnects.

Where do I find out more about battery care and maintenance?

We generally keep a supply of a brochure ‘Deep Cycle Battery Maintenance’ (Expanded Edition) that is distributed by the Trojan Battery Company. Stop by Vegas Trailer Supply to pick one up for your library. You can find great info and videos at the Trojan Battery web site: www.trojanbattery.com. Look under Tech Support or Battery Maintenance.

Additional information can be found through the solar living pages at www.vegastrailer.com and www.solarforemergencies.com