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4 Tips for Maintaining Batteries

Maintaining batteries in machinery sitting idle over the winter requires some sort of strategy if their cranking power is to be preserved. 

In the past, you removed batteries and connected them to a trickle charger. As equipment employed bigger and heavier batteries and even groups of batteries, manufacturers often buried these units deeper into machinery, making removal difficult. 

The advent of onboard computers has made off-season storage even more complicated. Since many on-board electronic devices have a low but steady electrical system draw, batteries that stay in vehicles may need to be periodically recharged. 

Some manufacturers recommend removing the batteries or disconnecting the negative cable when machinery is stored over 60 days. Other firms specify leaving the battery group in and recharging every six weeks. 

These different recommendations require a strategy that extends battery life by dissolving accumulated sulfate from the surfaces of the lead plates. This is a process called sulfation, which occurs when batteries lose their charge and sulfur attaches to the charge plates. 

The ideal tool for managing a battery is a battery maintainer. This device should not be confused with a trickle charger or a low-rate charger. A purpose-built maintainer has circuitry that utilizes a tricky, high-frequency pulse technology that, over time, causes some of the built-up sulfate to dissolve. This helps restore the effectiveness of the lead plates. Solar-powered maintainers are also available for use in storage sheds or even outdoor storage when no electrical power is readily available. 

Here are four essential steps to maintain batteries through the winter. 

1. clean up

Clean all dirt and residue off the battery and out of its case. Accumulated dirt and chaff aren’t so bad when the machine is in daily use. However, that same dirt can draw enough moisture in storage to turn the mixture into a conductor and slowly discharge the battery over time.

2. check water levels

Check the water level in each cell and add distilled water as needed. Only use distilled water because it does not contain minerals that, over time, can coat a battery’s internal plates. 

3. charge ’em up

Charge the battery with a low-rate charger until the at-rest (float) voltage is at or near 13 volts. Not all battery maintainers can bring an undercharged battery group up to full charge. They are only capable of maintaining a fully charged battery. So it’s important to precharge the battery with a low-rate charger before connecting the maintainer. 

4. maintain charge

Connect the maintainer to the battery or battery group. Maintainers can be used with a permanently installed plug-in wiring harness or connected with clips similar to a battery charger. If a permanent wiring harness is used, it should always have an in-line fuse and be installed in such a way that it’s protected from damage while the machine is in operation. It should also be noted that one maintainer can service multiple machines if the machines are close to each other in storage. 

Custom-built extension cords (built from bulk cord) can be employed to deliver maintenance power from one maintainer to batteries on multiple machines scattered across a shed. Jumper cables (extension cord size) can be used to connect several machines in parallel to one maintainer, as long as the voltage of the battery groups is the same. 

Of course, each battery in each individual machine should be brought to float voltage by a low-rate charger before multiple machines are parallel-connected to a single maintainer for long-term storage. Because of the tremendous amperage available from the battery groups, every wiring harness that is used (either clip-on or permanent) should have an in-line fuse installed on the positive wire where it connects to the machine. The harness or maintainer wiring harness can be connected anywhere on the machine. It may be more convenient to connect to an external positive and negative than directly to the battery. 

About the Battery Doctor DAVE MELLO

Dave Mello is a former engineer and electrical systems maintenance consultant who left the West Coast and is now living in Libertyville, Iowa. The retired Mello is always being pressed into service for both operating and maintaining equipment on a friend’s farm located near Batavia, Iowa. You can contact Mello at

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