Reel Repair by Alan Tani

Here's a link I use that's helps one know how long they can expect their device to run on batteries.

Especially useful when using a device, like a flashlight, that does not have low-voltage protection.

All you need is the amperage draw (measured with a multimeter), and the capacity of the batteries being used,(specd by manufacturer and measured in milliamp hours or mAh):

https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-battery-life

Devices; how to measure Amp draw with an I-pad or I-phone using a digital multi-meter?

Great question!

That's a tough one, given how dynamic the current draw is on those devices.. (insert stumped thinking emoji).

Androids have access to Google's on-device power measuring tool, perhaps Apple has something similar?

Thanks cbar —-

Good info.

As a coincidence, I am outfitting my little baby camper Tacoma truck with a full complement of gear and accessories for off grid camping, towing the travel trailer, and short one or two night trips.

Have solar, a 2200i Honda generator, and more.

But it needed a silent, fume-free power source to run the fridge/freezer, lights, electronic accessories, and more.

So I picked up a ECOFLO River 2PRO yesterday, after reading the dozens of other possibilities.  Didn't want to lug another battery around, or take a chance on running down the truck battery.  Didn't want to get overly technical on inverters and wiring.  Just wanted easy and flexible.

This will recharge in 30 minutes to 80%, and last a week of off-grid camping.  And it can be recharged with the Honda Gen, or the solar system, since it has all of the inputs and safety features both coming and going.  USB, USBC, AC, 12V, Solar plug-ins, all monitor screens, Bluetooth —- basically at 17 pounds, it does everything and more than I likely will need.  It will even recharge all of the iPods, phones, InReach device, MP3 players, speakers, earphones, and run the Ridgid chargers to recharge the 18V batteries.

5 year guarantee, #1 rated by Wirecutter for performance and value, 3000 cycle recharging, recharges in 30 minutes, battery supposedly good to 80% after 10 years. 

This will keep us stealthy and quiet, but with all of the comforts of home.  Both for fun camping, and also in emergency evacuation situations, travel trailer trips, or just for a quick power source at home.

Many folks have reported that during a power outage, this operates their refrigerator, TV, internet, and all electronic devices simultaneously. 

We have a large automatic stand-by generator for that —- but this is good for folks that don't have that.

Best, Fred

We used an older Duracell 400w power inverter during the recent storm. I was hoping it would run a small toaster oven but no-go; so opted for the propane-powered camp stove instead.

Specs on that unit look great. Lithium-Iron Phosphate is pretty much the safest and most durable battery chemistry you can get in a power station.

Plugging in the numbers for a mini fridge drawing 2 amps, it appears the River 2PRO can power it for ~32 hours straight—-quite impressive considering its 17lb weight.

Thanks for sharing Fred.

So you can go with the power rating on the device?
I used to have a Kilowatt meter; plug it into the wall outlet, then plug a device into it; either a demand appliance such as a refrigerator, or something with a switch such as a hair dryer. A demand appliance would give you your choice: watts or amps used over a day or week, or whatever.
Wondering how to determine the power usage of a battery-only powered device such as the I-pad or I-phone? Look at the back of the charging converter?

The non-charging reserve capacity of a vehicle battery(time) is listed on the label for how long you can drive with no alternator.

A toaster oven can draw as much as 1500 watts.

The most convenient camper refrigerator I had ran shore power or propane.

Quote from: Gfish on August 21, 2026, 07:45:53 PMSo you can go with the power rating on the device?

I think the charging adapter rating is just the amount of current being drawn to charge the device.

Amperage draw fluctuates with the processor load i.e., checking a text msg uses less iPhone battery than watching a movie while having multiple apps running in the background, at the same time.

An article at Science Direct lists 50 mA (.05 A) as the average power consumption of a smart phone at idle, and 500 mA (.5 A) during light use.

Quote from: cbar45 on August 21, 2026, 08:39:09 PMAn article at Science Direct lists 500 mA (.5 A) as the average power consumption of a smart phone at idle, or during light use.

Certainly not at idle. A typical smart phone battery is in the 3000-5000mAh region, so a phone that idled at 500mA would drain it in 6-10 hours. My iPhone will go several days on a charge if I don't use it at all.

Quote from: boon on August 22, 2026, 04:37:59 AM

Quote from: cbar45 on August 21, 2026, 08:39:09 PMAn article at Science Direct lists 500 mA (.5 A) as the average power consumption of a smart phone at idle, or during light use.

Certainly not at idle. A typical smart phone battery is in the 3000-5000mAh region, so a phone that idled at 500mA would drain it in 6-10 hours. My iPhone will go several days on a charge if I don't use it at all.

Thanks for the correction. Yes, that should have read 50 mA at idle, and 500 mA during light use.

Ha!
That's my biggest problem with the DDM use, converting the readings I get form decimal to straightforward Ohms, amps or volts and vice-versa.