Tuesday, March 21, 2023


RVelectricity – Just Ask Mike (J.A.M.): All about portable jump starters

Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM. Today I discuss portable jump starters.


Dear Mike,
Have you done a story on these portable battery jumpers? What does it take to jump a battery in a motorhome engine or a big diesel truck? In my opinion, RVers should have one of these aboard. We have one in our Honda Fit and it saved us from calling AAA one time—worked perfectly. And what other ways might they be of use? —CW

Dear CW,

I haven’t done any real testing of these portable jump starters, just yet. But I have 50+ years’ experience of jump starting cars in general, so let’s explore this a bit and see what might work as a boost starter for your toad or even your tow vehicle or large RV.

Back in the day, if you wanted to jump start a car with a dead battery, you would have to park another car nose-to-nose and get a set of jumper cables. Or you could schlep a donor battery over to the dead car, being careful not to spill battery acid on your clothes. Also, be careful to connect positive to positive, and negative to negative. Doing it backwards for even a second can result in an exploded battery or destroyed electronics in the vehicle needing a jump start.

Enter the portable jump starter…

Let’s fast forward to the future and see what lithium battery technology can do for us. Instead of a big lead-acid battery that could weigh 40 or 50 pounds, what about a portable lithium battery pack that weighs only a few pounds and even some of the smaller ones that can fit in your pocket? And since there’s no lead-acid chemistry, then there’s no acid to spill. They also are short-proof and won’t damage anything if you accidentally get the polarity reversed.

How to select one…

Okay, it should be obvious that if you need to start a little car, then you can get by with a little portable jump starter. And if you need to jump start a big vehicle with a dead battery (like your RV), then you’ll need a bigger portable jump starter.

I haven’t personally tested these products for operation, but NOCO seems to be the leader of this type of technology. They include ratings for the size of gas or diesel engine a particular model can start successfully. For example, here’s what they say about the GB40 model which is rated for gasoline engines up to 6.0L and diesel engines up to 3.0L.

GB40 – 1,000-Amp UltraSafe Lithium Jump Starter

The GB40 is a portable lithium-ion battery jump starter pack that delivers 1,000 amps for jump starting a dead battery in seconds. It features a patented safety technology that provides spark-proof connections and reverse polarity protection, making safe and easy for anyone to use. It’s a powerful battery booster that doubles as a portable power source for recharging USB devices, like a smartphone, tablet and more. It’s designed for a car, boat, RV, truck and more with gas engines up to 6 liters, and diesel engines up to 3 liters.

  • Compact, yet powerful lithium jump starter rated at 1,000 Amps – up to 20 jump starts on a single charge.
  • An ultra-safe and mistake-proof design with spark-proof technology and reverse polarity protection, which allow it to safely connect to any battery.
  • An ultra-bright 100 lumen LED flashlight with 7 light modes, including SOS and emergency strobe.
  • Recharge your personal devices on the go, like smartphones, tablets, e-watches and more – up to 4 smartphone recharges.
  • Designed for gas engines up to 6 liters and diesel engines up to 3 liters for cars, boats, lawn mowers and more.

What else can you do with a portable jump starter?

Many of these portable jump starters also include a trouble light and SOS strobe as well as a USB-C charging port for your phone. So, that’s additional great safety features you could really need if you find yourself lost with a dead battery in your RV.

Will I be testing them?

Perhaps…. I’ve asked for some test samples, and sometimes it’s a real push to get any action. But if I can get my hands on a few of them I’ll try starting a few vehicles with dead batteries and report on them, just for grins…

OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.

Let’s play safe out there….

Send your questions to me at my new RVelectricity forum here.

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.

You don’t want to miss Mike’s webcasts on his YouTube channel.

For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign



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10 months ago

I have a JUMTOP model N12. Says it has 20800MAH capacity to jump a 10 cylinder. I have a Ford E350 so I think it will work for me but I’ve never had to put it to the test. It also has a flash light that will strobe and 2 output USB ports which I’ve never utilized because this thing is for emergencies. Is there a way to test it?

Mike Sokol
10 months ago
Reply to  cee

Of course the strobe and USB ports are easy to test, just try out the light at night and plug in a dead cell phone. The trick is how to test them to start an engine with a dead battery without actually discharging the battery in your vehicle. But I have an idea that might shed some light on that question.

10 months ago
Reply to  Mike Sokol

Thanks Mike. I know it works, there are 4 blue lights telling you its fully charged & I’ve tested the USB ports. I’d like to know if it will REALLY jump my motorhome if my chassis battery is dead⚰️
Will stay tuned for your idea.☮️

8 months ago
Reply to  cee

go to a parts place and ask them if you can borrow a ‘dead’ battery for a quick test. If they are curious to see if your jump start can actually work, they will probably say sure and may even help you swap it for the test. 🙂 They may also have a load tester for batteries that may be able to see what the max output from the jump pack is able to do.

Last edited 8 months ago by Turtlewax
8 months ago
Reply to  Turtlewax

Great idea, thanks

10 months ago

I bought a 3000A Rugged Gear jump starter. Good price and reviews.

10 months ago

My alternator was intermittent and I found my battery dead in the lumber yard lot. A guy noticed my hood up and brought over his Schumacher 1200a pocket size jumper .. I laughed and said that little thing won’t work
I was wrong, it cranked my 6.0 gas like a fresh battery!!

Don murray
10 months ago

I carry a portable battery charger and when needed, I start my generator.

10 months ago

I’m definitely a  proponent of this type of jumper. I got one for my TJ Jeep about 7 or 8 years ago when they were kinda new to the market. After using it a couple of times, not for me but for others, I decided to get one for all of the family vehicles including the gas motor home. But now I have a 6.7 diesel! Not sure if it has enough poop to start the beast. I’ll check it to see if it’s rated for that size engine! So thanks for the information, especially all the different capacities for the jumpers!

10 months ago

A dead battery in modern vehicles can lock you out. Remote door lock fob will not work if battery is low enough. So the hood cannot be opened either. If you are willing to get dirty, slide under the vehicle with your jump-starter and clamp on the positive cable of your starter and then on the engine metal with the ground. Now you can unlock your doors.

Diane Mc
10 months ago
Reply to  D K

We have a key in our fob for all our cars. One is a 2008. You can open the door the old fashioned way. But a nifty tip that even my knows everything cars, including his race cars husband, didn’t know. Thanks.

10 months ago
Reply to  Diane Mc

Yes if you have a key that pops out of your FOB, you most likely have a key hole in your door handle. However it may NOT be visible as you have to remove a cover that hides the key hole. Most car manuals that come with your car explains on how to do this!

Mike Sokol
10 months ago

I would think that the DOT would require all vehicles to have some sort of physical key entry system, but as noted it might be hidden. Best to figure this out before you really need it…

Gregory Brott
10 months ago

Purchased a NOCO Boost HD GB70 2000 Amp for our Toad and have needed to use it only once, however it worked quickly and efficiently and within <2 minutes I had the engine started.
Next purchase will be for our DP Coach and will be the NOCO Boost X GBX155 4250A. If I were smarter I would have purchased the 155 first as it will charge up to a 10L gas and 8L diesel and I would have only needed one.

10 months ago

I have an Autogen 3000 lithium jump starter. It starts the e350 V10 instantly. I’ve also used it to help out other folks at campgrounds.

Bob p
10 months ago

They do work, the thing I’ve noticed is it’s not like a car to car jump start where you connect the cables and start the car. You connect the cables and wait for the batteries to normalize somewhat. The two I have after connecting the batteries I wait several minutes until the green light appears indicating enough charge to crank the engine. If I try to crank it as soon as I connect the cables I get the dreaded click-click. So it doesn’t have the cold cranking amps of a regular battery but it will put enough into our battery for a start.

Mike Sokol
10 months ago
Reply to  Bob p

Correct…. Basically they act like a fast charger, so after 2 or 3 minutes there’s enough charge in the vehicle battery to provide the hundreds is amperes needed by starter motor.

10 months ago

Purchased one after having a flat battery at a rest stop. Friends were there, one walked over with his “little” jump package. RV started immediately. Next opportunity, I purchased one. It lives in my toad.

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