AGM Battery Care: Getting Full Range and Longer Life

Your battery is the part of an electric utility vehicle that decides how long a workday lasts and how many seasons the machine stays useful. It's also the part most owners guess about. The good news is that sealed lead-acid chemistry is well understood and predictable. Once you know how it behaves, getting full range out of a charge and years out of a pack comes down to a handful of habits that take almost no effort.

This guide covers what's in the pack, why your range moves around, the one habit that matters more than all the others, and how to charge and store a pack so it lasts.

What's actually in the pack

The StepRanger All-Terrain runs a 48-volt system built from four 12-volt, 25-amp-hour sealed lead-acid batteries wired in series. That's roughly 1.2 kWh of stored energy, and it's good for 15 to 17 miles of range on a charge. Add the second battery set and you have eight batteries in two parallel strings: 48 volts at 50 amp-hours, about 2.4 kWh, and roughly 30 to 34 miles.

These are deep-cycle traction batteries (AGM/gel), not car starting batteries. A starting battery is built to dump a huge current for three seconds and then get topped right back up. A deep-cycle battery is built to give up most of its capacity slowly and be recharged hundreds of times. Same chemistry family, very different construction, and the care instructions are different too.

We don't sell lithium packs. Sealed lead-acid is heavier, but it's rugged, it ships without hazmat surcharges, it handles cold storage without drama, and it's serviceable by any owner with a wrench.

Why your range isn't a fixed number

Two owners with identical trucks can see very different mileage on the same charge. Three things explain almost all of the gap.

How hard you pull

Battery capacity is rated at a slow discharge. Our cells are rated 25.0 Ah at the 20-hour rate, 23.2 Ah at the 10-hour rate, 22.6 Ah at 5 hours, and 20.0 Ah at 2 hours. Same battery, 20 percent less usable capacity when you empty it in two hours instead of twenty.

That's Peukert's law, and lead-acid feels it much more than lithium does. Internal resistance rises with current, so a hard pull wastes a larger share of the stored energy as heat. In practice: steady moderate throttle covers more ground than repeated hard acceleration, and a heavy load up a long grade eats range faster than the distance alone suggests.

Temperature

Cold reduces capacity. Warm restores it. Roughly, against a 77°F baseline of 100 percent, expect about 85 percent at freezing and about 72 percent at 5°F. At 104°F you'll actually see slightly more than rated capacity, near 106 percent.

This is normal chemistry, not a fault. If your winter range is noticeably shorter than your summer range, the pack is fine. The operating window runs 5°F to 122°F. The charging window is narrower, 32°F to 104°F, which matters for storage and is covered below.

Load, terrain, and tires

The All-Terrain carries 1,000 pounds plus the operator and climbs grades up to 30 degrees (about 58 percent). It will do all of that, but a loaded climb pulls far more current than a flat run. Stay in Low gear on grades. Low trades speed for torque and keeps the motor out of the high-current region where Peukert bites hardest.

Tire choice matters too. Mud and snow tires and high-flotation turf tires both roll heavier than the stock all-terrain set. If you're running an aggressive tread on hard ground for range reasons, you're paying for traction you aren't using. More on matching machine to job in our electric wheelbarrow buyer's guide.

Depth of discharge is the whole ballgame

If you take one thing from this guide, take this: how deeply you drain the pack determines how long it lives, and the effect is enormous.

Our cells are rated for roughly 400 to 600 cycles at 100 percent depth of discharge, and 1,200 or more cycles at 50 percent depth of discharge. Draining the pack halfway instead of flat doesn't cost you half the cycles. It roughly doubles or triples them.

The mechanism is sulfation. Discharging forms lead sulfate on the plates, and recharging is supposed to convert it back. When a battery sits deeply discharged, those soft sulfate crystals harden into a form that no longer dissolves. The plate area is permanently lost. That's why the single most damaging thing you can do to a lead-acid pack isn't heavy use. It's leaving it sitting empty.

Two practical rules follow:

• Plan your work around half the range, not all of it. On a single-battery truck, that's about 7 to 8 miles of real work between charges. Most property work never comes close.
• The dual-battery set isn't only about range. For the same day's work, twice the capacity means half the depth of discharge, which means a much longer pack life. If your days routinely run the pack low, the second set earns its keep twice over.

Charging

The included charger puts out 48V at 2.8A from any standard 110V household outlet. Typical recharge is 5 to 6 hours, so a full charge fits inside an overnight. The charge port is on the left side.

Charge after a good day of use. You do not need to leave it plugged in all the time. There's no harm in topping off, but it isn't required between every short trip.

Don't let it sit drained. A pack left low for weeks is the classic way to kill one. If the truck is going to sit, charge it first.

Single-battery trucks: the right-side battery box's charge port is non-functional. It's pre-wired for a future second set, that's all.

Dual-battery trucks: both exterior battery switches go up to run, so the motor draws from both banks. To charge, flip both breaker switches down and charge each bank independently until full. One charger can charge both sets through the parallel link with the switches up, but charging the banks independently now and then keeps them in sync. A second charger cuts total charge time in half and is worth having on a dual setup.

Never tap 12 volts off a single battery in the string. The four batteries are in series. Pulling 12V from one of them unbalances the string, damages the pack, and is not covered under warranty. If you want onboard 12V for lights, USB, or a small inverter, use a 48V-to-12V step-down converter wired to the full pack on its own inline-fused circuit, never through the motor controller. Keep continuous accessory draw at or below about 600 watts on a single bank.

Winter and long-term storage

Sealed AGM and gel batteries handle cold storage without damage. There is no need to haul four batteries into the house.

1. Charge to 100 percent before lay-up.
2. Leave the truck in the shed or garage with the batteries in place.
3. Flip the main battery switches off (down) to isolate the pack. No parasitic draw.
4. Top off in spring once temperatures are back above freezing.

Expect to lose charge slowly while it sits: roughly 90 percent remaining after 3 months, 80 percent after 6 months, and 60 percent after 9 months. A mild winter lay-up needs nothing but a spring top-off. A long northern winter is worth a mid-season charge.

Leaving the charger plugged in for the season is an option only if the storage space stays above freezing. The charger doesn't operate below 32°F.

Rain is fine. The pack lives in an enclosed box and normal weather exposure is expected. Don't submerge the box and don't pressure-wash into it.

A five-minute routine

• Charge the same day you work it, not the next week.
• Check tire pressure. The functional range is 10 to 62 PSI for this application. The 116 PSI molded into the sidewall is the tire manufacturer's raw rating, not ours. Never run them there.
• Check lug nuts and battery terminal connections a few times a season.
• Switches off any time the truck will sit more than a couple of weeks.
• In storage, top off roughly every 3 months.

When a battery actually needs help

If a pack gets too low to accept a charge, don't buy replacements yet. A deeply discharged sealed lead-acid pack can often be recovered. Call or email us and we'll walk through the recovery procedure first. If a battery genuinely won't come back, it's covered.

Every StepRanger carries a 2-year warranty against defects in materials and workmanship, including damage that affects performance or safety. More common questions are answered on our FAQ page, and you can find us at our locations page.

Who builds it

StepRanger designed the electric micro-truck form factor and introduced it to the US market. First units were produced in 2023 and sold regionally in California and Montana before we took the machine nationwide online in 2025. Lookalikes came after us.

We work directly with our factories, not through trading companies. A co-founder is on the factory floor regularly and we keep an independent engineer onsite overseeing production and QC. We're founder-led, headquartered in California with a second location in Montana, and every truck ships fully assembled from California. When you call or email, a co-founder answers.

If you're new to the category, start with what an electric micro-truck actually is, or see how it compares against the other ways people move heavy loads around a property in our 5-acre hauler comparison and our horse barn guide.

Ready to see the machine these batteries live in? Here's the StepRanger All-Terrain.