Boats are going into storage, and our phones and inboxes fill up with the same question every fall: how do I store my MillerTech batteries for the winter? The answer is simpler than most people expect. Charge them full, disconnect everything, and put the boat away.
In the video below, Lester Miller, Founder of MillerTech, walks through the questions we hear most this time of year. Here’s what he covers.
The Short Version
- Charge the battery to 100%.
- Disconnect the charger and every load: trolling motor, graphs, all of it.
- Store the boat. Heated or cold, it doesn’t matter.
- Charge the battery to full again in the spring, or at six months, whichever comes first.
Do I Need to Take My Batteries Out of the Boat?
No. Storing batteries at room temperature is nice, but it isn’t a must. Most boats have a lot of wires running to the batteries, and there’s no reason to spend an hour pulling them out. If your boat is under a cover or in an unheated building, your batteries can stay right where they are.
Should I Store My Battery Fully Charged?
Yes. Charge the battery to 100%, then disconnect the charger. A lithium battery loses only a little charge each month, so you can go six months without recharging.
If you want to get technical, 50% is the ideal storage charge. But we’ve done a lot of testing, and the extra battery life you’d gain over one winter isn’t worth the hassle of running it down to 50%. As Lester puts it: “Fully charge it, pull the charger off, and you’re going to be perfectly fine.” Your Sport Series battery is covered by a 10-year warranty either way.
What If I’m Storing It Longer Than One Winter?
For long-term storage, say a few years, 50% is worth the effort. Discharge the battery to 50%. When it drifts down to 30%, recharge it back to 50%. That’s the sweet spot for a battery that’s sitting for the long haul.
Should I Disconnect My Charger?
Absolutely. Even when it isn’t plugged into the wall, a charger still draws a little power from the battery. Every MillerTech charger has a quick disconnect, so just pull it apart and you’re done.
While you’re at it, unhook the trolling motor and remove every other wire connected to the battery. Nothing should be drawing on it over the winter.
How Cold Is Too Cold to Charge?
Your battery can sit in the cold all winter. It just won’t take a charge when the temperature drops to 28°F. That’s by design, to protect the cells. Once the battery warms to 32°F, whether the weather turns or you bring it inside, it starts charging again.
That’s why the simple routine works: charge it full in the fall, and charge it again when it’s warm enough in the spring. If you need to charge on the boat in freezing weather, ask us about our heated Sport Series models. A built-in heater warms the cells so they can take a charge in the cold.
We know cold-weather charging matters to a lot of anglers in northern states, and we’re always testing new battery technology. We’ll share updates as we have them.
Keep It Simple
Winterizing a MillerTech battery comes down to a few steps. Charge it full, take off every wire, and put the boat away, cold or heated. At six months or when spring comes, charge it full again and you’re ready to fish.
Got a question about your setup? Call 855-MAX-LITH (855-629-5484) and a real person will pick up. You can also email [email protected] or visit millertechenergy.com/.