DC Power Solutions

DC Power Solutions

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Can My Batteries Freeze?

You may have survived winter, but did your batteries?

Man climbing out of frozen river

So can they?

As temperatures have been well below freezing this winter you may be wondering if your lead acid batteries can freeze. The simple answer is yes. Here's why, if your battery is partially discharged, the electrolyte in a lead acid battery can actually freeze. When a battery is fully charged the electrolyte will not freeze until the temperature drops to approximately -92°F; however, if there's only a 40% state of charge the electrolyte will freeze when the temperature drops to approximately -16°F. There's some good news though, battery operating time will increase somewhat for temperatures above 77°F. And the flip side being that the operating time will be decreased, significantly in some cases, for operating temperatures below 77°F.

The charging voltage is a function of the electrolyte specific gravity and will be indicated on the battery label. Batteries with an electrolyte specific gravity of 1.280 to 1.300 should be float charged at an average voltage of between 2.25 and 2.30 volts per cell.

The sulfuric acid (H2SO4) in the electrolyte is actually one of the three active materials in the battery. By increasing the percent acid, or specific gravity, of the electrolyte it increases the high rate performance and ampere-hour capacity of the battery. However, increasing the electrolyte specific gravity will also increase the open circuit voltage and required charging voltage of the battery.

Do lead acid batteries discharge when not in use?
All batteries, regardless of their chemistry, will self-discharge. The rate of self-discharge for lead acid batteries depends on the storage or operating temperature. At a temperature of 80°F. a lead acid battery will self-discharge at a rate of approximately 4% a week. A battery with a 125-amp hour rating would self-discharge at a rate of approximately five amps per week. Keeping this in mind if a 125 AH battery is stored for four months (16 weeks) winter without being charged, it will loose 80 amps of its 125-amp capacity. It will also have severe sulfation, which causes additional loss of capacity.

If you have noticed reduced capacity in your batteries please contact us or Request service.
We will test, service and repair your industrial lead acid battery.