Battery System Maintenance and Repair: Page 2 of 4

Intermediate

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Battery System Maintenance and Repair
Regular care of your renewable energy system’s batteries will help ensure that they can provide years of high performance.
Add distilled water to the batteries
Add distilled water to the batteries to about 1/4 inch below the bottom of the fill tube. Always wear eye and skin protection.
Corrosion
Corrosion between a battery terminal and the metal frame of a battery rack creates a potential path for current, which could create a ground fault or shock hazard.
Excessively corroded battery connections
Excessively corroded battery connections can have enough resistance to affect a battery’s performance, both when charging and discharging, and result in reducing a battery’s performance and life.
Clean all battery terminals and cable lugs
Take the time to make all battery terminals and cable lugs clean and bright before connecting the cables.
Petroleum jelly can protect terminals against corrosion
Petroleum jelly can protect terminals against corrosion, but also may attract dirt and makes using a wrench on them messy.
Always use insulated tools when working with batteries
Accidental short-circuiting between battery terminals can damage a battery and result in severe injury—always use insulated tools when working with batteries.
A battery meter
A battery meter is crucial to monitoring your battery bank’s electrical state.
Keep good records
Keeping good records is part of good battery maintenance, and can help you identify trends and spot problems if they occur.
Overcharging can result in excess gassing
Overcharging can result in excess gassing and loss of water. Exposed plates will oxidize and the battery will be permanently damaged.
Undercharging can result in electrolyte stratification
Undercharging can result in electrolyte stratification and/or sulfation (shown) and a damaged battery.
Battery System Maintenance and Repair
Add distilled water to the batteries
Corrosion
Excessively corroded battery connections
Clean all battery terminals and cable lugs
Petroleum jelly can protect terminals against corrosion
Always use insulated tools when working with batteries
A battery meter
Keep good records
Overcharging can result in excess gassing
Undercharging can result in electrolyte stratification

Before reconnecting the battery cables, wire-brush the terminals until the lead is shiny, tighten the connection, and then cover the terminal and cable with an anticorrosion coating—the best is a spray-on type that dries upon contact. Common petroleum jelly can also be used, but it can attract dust and dirt, and will be a sticky nuisance to deal with when checking the terminals for tightness.

Checking Connections

The bolt and nut connection needs to be tight enough to fully compress the split-type lock washer (which should always be included, along with two flat washers). The bolt should be tight enough that the cable lug cannot be moved on the terminal when pulled. Battery manufacturers will specify torque values for their terminals. Typical torque levels for 1/4-inch hardware is 6 foot-pounds; for 5/16-inch hardware it’s 11 foot-pounds. Be careful when using metal wrenches on the battery as it is very easy to accidentally cause a short circuit to adjacent terminals. Using specially made, insulated tools or, at the very least, wrapping the handle of the wrench with insulating tape, is highly recommended. Some tips for making battery connections are:

  • Always use stainless-steel hardware to connect cables to terminals.
  • Always clean the terminal posts and cable lugs so that they are shiny prior to installing the connections.
  • Always include flat washers to prevent the bolt and nut heads from digging into the soft lead terminals and copper cable lugs (but do not place them between the cable lug and the battery terminal).
  • Always include a split-type lock washer to help keep the bolted connection tight.
  • Always use an anticorrosion coating over cleaned connections, and reapply the coating after retightening or replacing cables.

Recharging & Equalizing the Batteries

One of the most critical factors in maintaining good battery health is regularly charging the battery to a full state of charge. Ideally, this should be done once a week.

No matter the cause—an undersized PV array, running excessive loads, or not having a secondary energy source for extended cloudy periods—undercharging batteries can permanently harm them over time. When batteries are not fully charged, sulfate crystals form on the lead plates’ surfaces. This reduces the contact area between the lead and the electrolyte, decreasing the battery’s capacity. Sulfate crystal buildup can become an irreversible condition that will worsen until the battery is unusable.

An intentional overcharging—called equalization—helps remove the sulfation from the battery’s plates. Equalization charging is a process where the battery is intentionally overcharged to bring weaker cells up to parity with stronger cells and should only be done with FLA-type batteries. During equalization, the battery’s cells will gas vigorously, mixing up the electrolyte and eliminating stratification. Most sophisticated inverter/chargers and PV charge controllers have an equalization function, which allows the charging source to charge the battery for a timed period and achieve a preset, high-voltage setpoint. During equalization, closely monitor the electrolyte’s level and temperature—and be prepared to shut down the charging when the equalization is finished or if the temperature exceeds 125°F (52°C).

Comments (8)

Marsha Robison's picture

I hear you Eric. But I am in a very harsh environment. Temps range from 0 in the Winter to 109 (sometimes) in the Summer. One day can have ranges of 70 degrees. My battery banks just don't preform as expected, even with diligent maintenance.
Please let me know your expert opinion on the Lithium as an alternative. I have been watching this technology but want to wait till it is perfected. Are there any other options.

Ed Mahoney's picture

Marsha,
I've supplied thousands of systems thoughout the world; many in extreme temperature environments. Your problem is not unique.
In high temperatures batteries will suffer extreme loss of useful life and in cold temperatures their capacity is diminished.
If the air temperature canot be controlled the best method of solving the high & low temperature extremes is to BURY the batteries in a container. Getting the batteries a couple of feet undergroung will minimize the temperature effects. You can reduce the battery's temperature by 25 F. in hot summer months and increase it by 25 F. in cold winter months.
In addition, use a battery temperature compensated charge regulator to optimize the charging voltage.
By doing this your battery will last at least 50% longer and help provide it's maximum capacity.
If you need further assistance please let me know.
Ed Mahoney

eric roberts's picture

Hi Just a point to Jim and Elaine stack? Lithium batteries have no history yet? we do not even know how to dispose of them yet, they can be highly toxic and a fire hazard, but i understand what you mean about, lead acid batteries, which are incidentally 95% recycled now. thanks eric roberts

Jim and Elaine Stack's picture

Use lithium batteries and you never need to water, they last much longer and are non hazardous. It's the 21st century and we have taken lead out of paint and even gasoline so don't use it.
Just mining it kills us. People say it gets recycles but that is a poor excuse since it gets in the air and everyplace. LEAD is one of the worst containments ever used.
Solar City used Tesla Lithium batteries for backup. Tesla is building a new battery factory that will make them 30% better or more in a few years. Invest in the future not the past.

Paul Hancock_2's picture

Great article!

I was recently moving my inverter and inadvertantly the pos and neg battery leads touched momentarily causing some sparking while they were on the ground. I know this is not good for the battery bank (I have 12 surrettee S-530s) but is there any specific way I can test the batteries to see if they sufferred any permanent damage?

Michael Welch's picture

Hi Paul. Just minor quick sparks? Should not have affected the batteries at all.

Paul Hancock_2's picture

Thanks for the reply Micheal. The sparking was just for a second or so but did melt a bit of the copper connector on the end of the cable. Batteries seem to be performing as usual but would you recommend any maintenance or testing I should be doing after this incident?

Thanks again.

Michael Welch's picture

Just go ahead and use your batteries. Rest easy, you have not harmed them.

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