Top Ten Battery Blunders and How to Avoid Them: Page 3 of 4

Intermediate

Inside this Article

Big battery, big mess. Don’t try this at home.
Big battery, big mess. Don’t try this at home.
These batteries have definitely seen better days.
These batteries have definitely seen better days.
Wrong Battery Type
Starting batteries work great in your car, but will quickly fail if used in deep-cycle applications.
Improper Size
A large battery bank requires a large charging source.
Improper Watering
An extreme result of battery neglect.
Many Small Batteries in Parallel Strings
Use bus bars to parallel multiple series strings.
Failure to Prevent Corrosion
Notice the parallel connections on the left side of the photo—the worst corrosion is at these stacked cable lugs. Batteries with corroded terminals will receive less charge, and will fail early.
Lack of a Protective Environment
A beautifully installed 48 V battery bank—sixteen 6 V batteries connected in two strings of eight. These big Surrette batteries have two holes on each terminal, so cable lugs don’t have to be stacked. The peaked battery enclosure allows for excellent hydrogen venting.
Lack of Proper Charge Control
Proper controller settings are critical for battery longevity.
Modern battery monitor
Example of modern battery monitor (amp-hour meter).
Modern battery monitor
Another example of modern battery monitor (amp-hour meter).
Big battery, big mess. Don’t try this at home.
These batteries have definitely seen better days.
Wrong Battery Type
Improper Size
Improper Watering
Many Small Batteries in Parallel Strings
Failure to Prevent Corrosion
Lack of a Protective Environment
Lack of Proper Charge Control
Modern battery monitor
Modern battery monitor

BLUNDER #6 Lack of a Protective Environment

Lead-acid batteries temporarily lose approximately 20 percent of their effective capacity when their temperature falls to 30°F (-1°C). This is compared to their rated capacity at a standard temperature of 77°F (25°C). At higher temperatures, their rate of permanent degradation increases. So it is desirable to protect batteries from temperature extremes. Where low temperatures cannot be avoided, buy a larger battery bank to compensate for their reduced capacity in the winter. Avoid direct radiant heat sources that will cause some cells to get warmer than others. The 77°F temperature standard is not sacred, it is simply the standard for the measurement of capacity. An ideal range is between 50 and 85°F (10–29°C).

Arrange batteries so they all stay at the same temperature. If they are against an exterior wall, insulate the wall and leave room for air to circulate. Leave air gaps of about 1/2 inch (13 mm) between batteries, so those in the middle don’t get warmer than the others. The enclosure should keep the batteries clean and dry, but a minimum of ventilation is required by the National Electrical Code, Article 480.9(A).

A battery enclosure must allow easy access for maintenance, especially for flooded batteries. Do not install any switches, breakers, or other spark-producing devices in the enclosure. They may ignite an explosion.

BLUNDER #7 Lack of Proper Charge Control

When installing new charge controllers or inverters in your system, make sure to program the appropriate charge setpoints for your specific battery type. Battery-based PV systems will usually have a solar charge controller and an AC battery charger, for use with an engine generator or the grid. The AC charger will typically be built into your inverter. Voltage settings appropriate for your type of battery must be programmed into these devices. If incorrect charge setpoints are chosen, sealed batteries can be overcharged and lose their internal moisture. Flooded batteries will be deprived of a full finish charge and will deteriorate if charge setpoints are too low.

When batteries are cold, they require an increase in the maximum charge voltage to reach full charge. When they are warm, they require a reduction in the voltage limit to prevent overcharge. Choose a charge controller and inverter/charger for your system that includes temperature compensation. To use it, you must have a temperature sensor located at the batteries. You may need a temperature sensor for each charging device (including the inverter), but networked systems communicate the temperature from a single sensor to all charging components. Some small charge controllers have temperature sensing built in. In that case, be sure the controller is located where its temperature is similar to that of the batteries. Otherwise, it will be “fooled” into setting improper charge limits.

BLUNDER #8 Lack of Monitoring Devices

Battery management is sometimes called a “black art.” That’s true only if the user (or supplier) is in the dark. Have you ever driven a car without a fuel gauge? It can be frustrating! Yet, many battery systems don’t have an equivalent device to show the state of charge (SOC), the level of stored energy.

Metering is not just bells and whistles. It provides crucial information for battery management, which in turn significantly increases battery longevity. Use a digital monitor, like the TriMetric (Bogart Engineering), IPN­ProRemote (Blue Sky Energy), or XBM battery monitor (Xantrex). These devices keep track of accumulated amp-hours and display the charge status of the battery bank. They also display other data that can be useful for maintenance and troubleshooting.

Install your monitoring device where it can be seen easily—in a central place in your home. Be sure the device is programmed properly, based on the parameters of your system. This needs to be done just once, during meter installation.

Comments (7)

bob tarzwell's picture

one trick for number 4 ie lots of batteries in parallel strings is to balance the charging with final wire size , I had acquired 80 good golf cart batteries and have 10 parallel strings in a 24 kw system , I balanced by voltage and current so each string gets very close to the same charging /discharge, I did it by reducing down a bit on the wire to higher groups , been 3 years now and still working great ,this year I will do a big charge and rearrange batteries in new strings to continue there life. in my other system its 120 volts 10 kw and two sets of 20 rolls s530's so not much to balance , works great especially when you get the charging right and charge hard.
ps after years of solar install I don't trust anyone's cable crimping I always scrimp and solder my connectors.

Woody Petrea's picture

Cool. Thanks for that. :)

Woody Petrea's picture

Was this article originally posted elsewhere?

Michael Welch's picture

As far as I am aware, only in our magazine. If it is out there elsewhere, it is most likely in violation of our copyright.

Woody Petrea's picture

It was just the way the article read. Under item #3 blunders, it states, "The photo at right shows a system that was ignored for more than two years." I noticed that all the images are at the top of the article.

Good read. Thanks to the author and to HP for posting it.

Scott Russell's picture

Fixed that text, Woody. We normally try to catch those references when republishing articles on the website, but they're easy to miss.

Michael Welch's picture

Ahhh. That's because the articles on our web site mirror the corresponding articles in the print version magazine. We generally try to avoid saying things like "to the right" and "on the next page."

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