The Midland ER310 and Midland ER40 do the same core job: they bring in NOAA weather alerts from the National Weather Service and keep working when the power is out, charged by the sun or a hand crank. The differences are in battery size, backup power and extras. Here's how they compare, based on Midland's published specs.
ER310 vs ER40 at a glance
| Midland ER310 | Midland ER40 | |
|---|---|---|
| NOAA weather alerts | Yes | Yes |
| AM/FM radio and clock | Yes | Yes |
| Charging | Solar, hand crank, USB | Solar, hand crank |
| Rechargeable battery | 3500 mAh lithium-ion | 2600 mAh lithium-ion, replaceable |
| Runtime (Midland's figure) | Up to 45 hours of normal use | Not published |
| AA battery backup | Yes, 6 AA (not included) | Not listed |
| Flashlight | Cree LED, 1400 lux, low/high settings, SOS beacon | LED with SOS strobe |
| Ultrasonic dog whistle | Yes | No |
| Display | Digital clock display | Large, backlit LCD |
| Phone charging | Emergency top-up only, by USB | Emergency top-up only, by USB |
| Size | 8.0 x 3.4 x 2.4 in | Not published |
| In the box | Radio with battery, micro USB cable, manual | Radio, 2600 mAh battery, wrist lanyard, manual |
What they have in common
- NOAA weather alerts. Both radios sound an alert when the National Weather Service issues one on your local weather channel. That's the main reason to own one: you get warned even when the cell network is down.
- Off-grid charging. Both charge their internal lithium-ion battery from a built-in solar panel or the hand crank.
- AM/FM radio and a clock, for news and entertainment.
- A flashlight with an SOS signal, for power outages and signaling for help.
- An emergency USB phone top-up. Midland says these radios were designed to give older phones an emergency charge, and they protect their own battery for alerts. On a modern phone, expect a few percent at most, so carry a power bank for real charging.
- No license needed. They only receive, so there's nothing to register.
Where the ER310 pulls ahead
- Bigger battery and a published runtime. The 3500 mAh battery gives up to 45 hours of normal use, according to Midland. The ER40's battery is 2600 mAh, and Midland doesn't publish a runtime for it.
- AA backup. The ER310 can also run on 6 AA batteries (not included). If the lithium battery is flat and there's no sun, fresh AAs get you back on the air without cranking.
- A brighter, adjustable flashlight. A 1400-lux Cree LED with low and high settings, so you can save battery when you don't need full brightness.
- Ultrasonic dog whistle. Midland says it may help search and rescue teams find you in an emergency.
- Charging cable in the box. It comes with a micro USB cable.
It's also our best-selling Midland radio, and CNN named it a 2025 All-Star emergency radio, as Midland notes.
Where the ER40 wins
- Lower price. It costs less than the ER310 and still covers the essentials: weather alerts, solar and crank charging, a flashlight and an emergency USB phone top-up.
- Large backlit LCD. Midland highlights an easy-to-read screen for finding channels in total darkness.
- Replaceable battery. Midland describes its 2600 mAh battery as replaceable, so a worn battery doesn't mean a new radio.
- Wrist lanyard in the box, for carrying it around camp.
Which one should you buy?
| If you... | Pick |
|---|---|
| Want one radio for the main RV emergency kit or evacuation go-bag | ER310 |
| Might be without power for days and want the longest runtime and an AA backup | ER310 |
| Want a brighter flashlight and the dog whistle | ER310 |
| Want the essentials for less | ER40 |
| Want a second radio for the tow vehicle, a camp bag or a family member | ER40 |
| Need to read the display in the dark | ER40 |
Our take: for an RV, the ER310 is the better main radio. Its bigger battery and AA backup matter most during a long outage or evacuation, when you can't count on sun or shore power. The ER40 is a good, lower-cost choice for a second kit, or if you mainly want weather alerts and a light.
Using either radio in an RV
- Keep it charged and in your go-bag by the door, not buried in a cabinet.
- When you arrive somewhere new, tune to the local NOAA weather channel and turn on alerts.
- Charge it from the sun on the dash or a window while you drive.
- Pair it with the rest of your kit. See our RV emergency kit checklist.
For two-way radios to talk between rigs, see GMRS vs FRS. All the Midland radios we carry are on our Midland page.
FAQ
What's the main difference between the Midland ER310 and ER40?
The ER310 has a bigger 3500 mAh battery rated for up to 45 hours, a 6 AA backup, a brighter 1400-lux flashlight and an ultrasonic dog whistle. The ER40 costs less and has a large backlit LCD and a replaceable 2600 mAh battery.
Do both radios get NOAA weather alerts?
Yes. Both sound an alert when the National Weather Service issues one on your local weather channel.
Can the ER310 and ER40 charge a phone?
Only a little. Both have a USB port for an emergency top-up, but Midland says modern phones have much bigger batteries than these radios were designed for, and the radios protect their own battery so they can keep sounding alerts. Expect a small top-up at most. For real phone charging, carry a power bank or a portable power station.
Can the ER310 run on regular batteries?
Yes. It takes 6 AA batteries as a backup. They aren't included.
Is the ER40 battery replaceable?
Yes. Midland describes its 2600 mAh lithium-ion battery as replaceable.
Do I need a license for these radios?
No. They only receive, so no license is needed.