I have one of these that I purchased a few years ago. It wouldn’t start a car with a dead battery when I needed it multiple times but I was never sure if it was user error (me) or an issue with the device. I took it apart out of curiosity and learned that it has a relay in the plug-in the head with the somewhat flimsy jumper clamps that plugs into the end of the battery. As you said, they don’t use heavy gauge wire or a high current connector and I also noticed that the relay was not rated for hundreds of Amps, but rather only for 70A! I guess they get by because engines usually start before the wiring and the batteries in the jump starter get hot and fry or catch fire. I believe the purpose of the relay is to provide short circuit and reverse polarity protection. Another issue is the complexity of using these devices. The one I have requires you to push a small unlabeled button to energize the relay and connect the battery to the jumper clamps. You get blinking leds as status indicators and not so easy to read directions so it’s easy to get confused in an emergency situation or at night when you might need to use it. Plus, you need to remember to recharge them every few months which is just long enough that they can easily be forgotten. Mine is an older vintage and the new ones may be much improved but all things considered, I’m not getting rid of my 4 gauge jumper cables!
Try disconnecting the negative terminal and connecting the jump box to the cable. A bad battery will suck all the power instead of it going to the starter.
Great discussion and information, however I think most RV'rs with diesel tow vehicles are larger than 3 liters. I have yet to find a jump starter that will crank my 6.7. I still carry the old school jumper cables.
There are some pro jump starters that are rated for diesel engine. Not cheap or small, but would probably work for you when you can’t find someone willing to give you a jump.
Schumacher DSR Pro Series Schumacher DSR159 12V 4000 Peak Amp Jump Starter and DC Power Source, Black https://a.co/d/i0PtKxj
I have actually used a jump start pack to jump start house batteries! Some inverter/chargers require 12 volts from the battery to turn on. Even when running in charge mode, hooked to shore power or generator they won't charge the house batteries if they can't detect any voltage from those house batteries. (If they have been mostly discharged). Connecting my jump pack to the house batteries for a few minutes charges them up enough for the charger in the inverter/charger to see the battery voltage and start charging from shore power.
CR tested portable jump starters a while back. They have not tested them recently, so the models listed may not be available, but there's a good chance that the current model from the same mfr will perform similarly: https://www.consumerreports.org/cars/jump-starters/c37102/
The top rated ones were:
1) Antigravity Batteries XP-10
2) Spirit A8 Car jump starter
3) Bolt Power D28
4) New Brights Compact 12000mAH Mini Portable Car Jump Starter
5) PowerAll PBJS12000R
The others they tested were not recommended.
Car & Driver also reviewed them, but they may not be as objective as CR.
The technology with these things has markedly improved. I still have the SLAB booster from decades ago but it lives in the garage (just can’t get myself to get rid of it… still works). All my (spouse and kids) vehicles have one of these lithium boosters tucked inside and are recharged regularly. They take up very little space and are really easy to use. As mentioned, right-sizing is important. The booster for my 1.8liter vw 4 cyl is about the size of a deck of cards vs the one for my 6.7 Cummins diesel is the size of a kid’s lunchbox. All have been proven with dead batteries over the last few years and have gotten me out of jams. Highly recommend. My only real worry is a potential fire. There is a lot of energy packed in a small box. I keep all of our boosters protected in the original boxes or in one of those small “ammo” boxes sold in sporting goods stores. With this, they are kept from being crushed or damaged in every day life which could start a thermal runaway. IMHO, with proper care, the benefit far outweighs the threat.
Mike: I bought a cheap ($40) Chinese import a couple of years ago just to try. I have a Winnebago with the Ford V-10 gas engine and it had an old battery in it that I was getting ready to replace. It would hold a charge for about 24 hours and that's it. I ran the battery down to 11V and of course the starter didn't even try to engage. I hooked up this jump starter and put it in boost mode. 10 seconds later the RV was running!!! I was so impressed I ordered 4 more to give to my daughters and friends as gifts. I'm an Electrical Engineer and I can't figure out how they get that much current out of what seems to be a very small battery.
I have a Noco that I bought when my sister was having issues starting her Dodge Caravan. I have used it to start my Class A with a 454 Chevy power plant. It is usually hard starting but the Noco was up to the task.
Mike,we have a NOCO GB40, and love it. We have a parasitic drain on our "toad" that will kill the toad's battery in a short time. This thing is really "AWESOME" and hasn't failed us this past year.
Keep in mind that if the dead battery is totally out of action, the jump starter won't work because the bad battery sucks up all the power instead of it going to the starter motor. In that case, disconnect the negative terminal and connect the jumper directly to the cable end. That way the bad battery can't suck up all the juice. Also, you can usually run a car for a time, in an emergency, from a jump box without a battery if you keep the load to a minimum.
Mike, another variant worth investigating and reporting on are the ones based on super capacitors rather than lithium ion batteries. They have super wide operating temperature ranges and they say you don’t need to charge them because they can draw enough charge from dead battery to start it (unless it’s totally dead). I’d love to hear your take on these.
Limited-time deal: Autowit Super Capacitor Jump Starter, 12V Batteryless Jump Starter, 8.0 Gas&4.0 Diesel Car Jump Starter, Portable Jump Starter for Car Battery, Bulit-in Supercapacitor, No Need Pre-Charge https://a.co/d/371WAIU
Interesting idea Doug! I just read through the description.
The first/top 1-star review is concerning. It's titled, "Don't use it like most other battery packs."
I didn't read any further, but there is a high percentage of 1-star reviews (8%). Of course some are likely due to 'operator error' or are unjustified -- delivery was slow, the box was dented, the customer misread the description, etc.
One concern mentioned it the review is that if the battery is very discharged, it may not be able to charge the jump starter, in which case the mfr recommends using another battery. Needless to say, that is not always possible.
I like the idea of using a capacitor. In fact super capacitors are used for industrial scale energy storage. Perhaps there are other units that are more practical.
I have a 2017 Tiffin Allegro Bus on a PowerGlide chassis. The chassis batteries are 2 12 volt batteries connected in parallel. How would I connect a NOCO to start them? Would I connect to just one battery, or connect to a positive on one and the negative on the other?
Since they are in parallel, you can connect the pos(+) cable of the jump starter to either battery pos(+) and the negative cable to either battery neg(-).
Project Farm on You Tube did a thorough ttest on portable jump starters. Very informative.
https://www.youtube.com/watch?v=bMXyoIBJyJA
I have a NOCO and used it to start my motorhome, works like a champ.
REad the marketing material on the NOCO. 1000 Amp through that 12ga wire??? Seems "Ultra Safe" to me.
I have one of these that I purchased a few years ago. It wouldn’t start a car with a dead battery when I needed it multiple times but I was never sure if it was user error (me) or an issue with the device. I took it apart out of curiosity and learned that it has a relay in the plug-in the head with the somewhat flimsy jumper clamps that plugs into the end of the battery. As you said, they don’t use heavy gauge wire or a high current connector and I also noticed that the relay was not rated for hundreds of Amps, but rather only for 70A! I guess they get by because engines usually start before the wiring and the batteries in the jump starter get hot and fry or catch fire. I believe the purpose of the relay is to provide short circuit and reverse polarity protection. Another issue is the complexity of using these devices. The one I have requires you to push a small unlabeled button to energize the relay and connect the battery to the jumper clamps. You get blinking leds as status indicators and not so easy to read directions so it’s easy to get confused in an emergency situation or at night when you might need to use it. Plus, you need to remember to recharge them every few months which is just long enough that they can easily be forgotten. Mine is an older vintage and the new ones may be much improved but all things considered, I’m not getting rid of my 4 gauge jumper cables!
Try disconnecting the negative terminal and connecting the jump box to the cable. A bad battery will suck all the power instead of it going to the starter.
Great discussion and information, however I think most RV'rs with diesel tow vehicles are larger than 3 liters. I have yet to find a jump starter that will crank my 6.7. I still carry the old school jumper cables.
There are some pro jump starters that are rated for diesel engine. Not cheap or small, but would probably work for you when you can’t find someone willing to give you a jump.
Schumacher DSR Pro Series Schumacher DSR159 12V 4000 Peak Amp Jump Starter and DC Power Source, Black https://a.co/d/i0PtKxj
I have actually used a jump start pack to jump start house batteries! Some inverter/chargers require 12 volts from the battery to turn on. Even when running in charge mode, hooked to shore power or generator they won't charge the house batteries if they can't detect any voltage from those house batteries. (If they have been mostly discharged). Connecting my jump pack to the house batteries for a few minutes charges them up enough for the charger in the inverter/charger to see the battery voltage and start charging from shore power.
I’ve done something similar recently with a vintage Sears/Craftsman 2/12-amp charger
CR tested portable jump starters a while back. They have not tested them recently, so the models listed may not be available, but there's a good chance that the current model from the same mfr will perform similarly: https://www.consumerreports.org/cars/jump-starters/c37102/
The top rated ones were:
1) Antigravity Batteries XP-10
2) Spirit A8 Car jump starter
3) Bolt Power D28
4) New Brights Compact 12000mAH Mini Portable Car Jump Starter
5) PowerAll PBJS12000R
The others they tested were not recommended.
Car & Driver also reviewed them, but they may not be as objective as CR.
Thanks Mike
The technology with these things has markedly improved. I still have the SLAB booster from decades ago but it lives in the garage (just can’t get myself to get rid of it… still works). All my (spouse and kids) vehicles have one of these lithium boosters tucked inside and are recharged regularly. They take up very little space and are really easy to use. As mentioned, right-sizing is important. The booster for my 1.8liter vw 4 cyl is about the size of a deck of cards vs the one for my 6.7 Cummins diesel is the size of a kid’s lunchbox. All have been proven with dead batteries over the last few years and have gotten me out of jams. Highly recommend. My only real worry is a potential fire. There is a lot of energy packed in a small box. I keep all of our boosters protected in the original boxes or in one of those small “ammo” boxes sold in sporting goods stores. With this, they are kept from being crushed or damaged in every day life which could start a thermal runaway. IMHO, with proper care, the benefit far outweighs the threat.
Mike: I bought a cheap ($40) Chinese import a couple of years ago just to try. I have a Winnebago with the Ford V-10 gas engine and it had an old battery in it that I was getting ready to replace. It would hold a charge for about 24 hours and that's it. I ran the battery down to 11V and of course the starter didn't even try to engage. I hooked up this jump starter and put it in boost mode. 10 seconds later the RV was running!!! I was so impressed I ordered 4 more to give to my daughters and friends as gifts. I'm an Electrical Engineer and I can't figure out how they get that much current out of what seems to be a very small battery.
I have a Noco that I bought when my sister was having issues starting her Dodge Caravan. I have used it to start my Class A with a 454 Chevy power plant. It is usually hard starting but the Noco was up to the task.
Mike,we have a NOCO GB40, and love it. We have a parasitic drain on our "toad" that will kill the toad's battery in a short time. This thing is really "AWESOME" and hasn't failed us this past year.
Keep in mind that if the dead battery is totally out of action, the jump starter won't work because the bad battery sucks up all the power instead of it going to the starter motor. In that case, disconnect the negative terminal and connect the jumper directly to the cable end. That way the bad battery can't suck up all the juice. Also, you can usually run a car for a time, in an emergency, from a jump box without a battery if you keep the load to a minimum.
Mike, another variant worth investigating and reporting on are the ones based on super capacitors rather than lithium ion batteries. They have super wide operating temperature ranges and they say you don’t need to charge them because they can draw enough charge from dead battery to start it (unless it’s totally dead). I’d love to hear your take on these.
Limited-time deal: Autowit Super Capacitor Jump Starter, 12V Batteryless Jump Starter, 8.0 Gas&4.0 Diesel Car Jump Starter, Portable Jump Starter for Car Battery, Bulit-in Supercapacitor, No Need Pre-Charge https://a.co/d/371WAIU
Interesting idea Doug! I just read through the description.
The first/top 1-star review is concerning. It's titled, "Don't use it like most other battery packs."
I didn't read any further, but there is a high percentage of 1-star reviews (8%). Of course some are likely due to 'operator error' or are unjustified -- delivery was slow, the box was dented, the customer misread the description, etc.
One concern mentioned it the review is that if the battery is very discharged, it may not be able to charge the jump starter, in which case the mfr recommends using another battery. Needless to say, that is not always possible.
I like the idea of using a capacitor. In fact super capacitors are used for industrial scale energy storage. Perhaps there are other units that are more practical.
I have a 2017 Tiffin Allegro Bus on a PowerGlide chassis. The chassis batteries are 2 12 volt batteries connected in parallel. How would I connect a NOCO to start them? Would I connect to just one battery, or connect to a positive on one and the negative on the other?
Hi Helen,
Since they are in parallel, you can connect the pos(+) cable of the jump starter to either battery pos(+) and the negative cable to either battery neg(-).