WOLFBOX MegaVolt24 4000A Jump Starter!

[Tex]

I use a NOCO GB251 24V pack to start my PT6A-34, and it works every bit as well as my old Aero Specialties 4800A GPU that cost several thousand and needed to be wheeled out on its own cart. Voltage levels during startup remain in the same threshold and spool up time is identical with either pack. The NOCO has 1/0ga cables and they get pretty warm after use. I have to use the bypass every time with the pack because it's a relay isolated GPU plug that needs to be powered before it connects to the battery itself. I wouldn't buy a pack without that feature regardless though. I run the smaller GBX75 in my Bronco, it basically stays connected to the rear power point and always stays charged up ready to go. I've used it to start my V8 4runner that had a completely dead battery (was dead for like half a year), and it started up like it was just running five minutes before with a brand new battery installed. It really is surprising what these little packs can do.

The 8ga wire isn't what I'd call ideal, but it's likely adequate for what people would need this pack for. The battery pack could be up to the task, however...modern lithium packs can push up to 120C continuous discharge (often twice as much burst discharge), meaning you'd only need a max size of 33AH battery to get a true 4000A continuous, for maybe 10-15 seconds anyway. Instantaneous, you'd really only need 16AH to get a burst discharge rate of 4000A. All that to say, yes there are jump starters out there, even on amazon of all places, that will push their stated power out of a relatively insignificant looking battery pack. Even this one could push out well over 5000A if they were using a 120C 24AH battery with a 240C burst rating. Most of that rating is insignificant if you're not drawing that much power, but it's available for a very short time if you do. With that in mind, the 8ga wire is probably going to be enough to get a modern vehicle started, but it won't be ideal if it's an older vehicle that needs to be cranked a lot (like a diesel truck that you ran out of fuel and needs time to prime the pump). And just for the record, most lipo batteries have always been rated in mAH until you get up into large packs assembled by a third party seller. Pull any pack apart that you want, whether it's from Bosch or Milwaukee or it's a lithium car battery, if it's labeled in AH on the outside, the individual cells will be labeled in mAH, guaranteed. It's not a marketing tactic, the battery manufacturers label the cells as such, it's just industry standard and they assume people know how to drop zeroes if they care about comparing actual specs.

I'm not saying this particular pack lives up to all of its claims, it's probably slightly exaggerated like any other electronic device outside of a lab, but I'm seeing nothing about it that would prevent it from getting reasonably close to reaching those claims in practice. Maybe it can only put out an honest 3600A burst, who knows, but that won't make a difference in real world use when starting a Bronco that won't need but 1/10th of that current for half a second. The clamps and form factor and bypass features and price and things of that nature will make more of a functional difference in user experience than peak ratings.

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[CalvinT]

I use a NOCO GB251 24V pack to start my PT6A-34, and it works every bit as well as my old Aero Specialties 4800A GPU that cost several thousand and needed to be wheeled out on its own cart. Voltage levels during startup remain in the same threshold and spool up time is identical with either pack. The NOCO has 1/0ga cables and they get pretty warm after use. I have to use the bypass every time with the pack because it's a relay isolated GPU plug that needs to be powered before it connects to the battery itself. I wouldn't buy a pack without that feature regardless though. I run the smaller GBX75 in my Bronco, it basically stays connected to the rear power point and always stays charged up ready to go. I've used it to start my V8 4runner that had a completely dead battery (was dead for like half a year), and it started up like it was just running five minutes before with a brand new battery installed. It really is surprising what these little packs can do.

The 8ga wire isn't what I'd call ideal, but it's likely adequate for what people would need this pack for. The battery pack could be up to the task, however...modern lithium packs can push up to 120C continuous discharge (often twice as much burst discharge), meaning you'd only need a max size of 33AH battery to get a true 4000A continuous, for maybe 10-15 seconds anyway. Instantaneous, you'd really only need 16AH to get a burst discharge rate of 4000A. All that to say, yes there are jump starters out there, even on amazon of all places, that will push their stated power out of a relatively insignificant looking battery pack. Even this one could push out well over 5000A if they were using a 120C 24AH battery with a 240C burst rating. Most of that rating is insignificant if you're not drawing that much power, but it's available for a very short time if you do. With that in mind, the 8ga wire is probably going to be enough to get a modern vehicle started, but it won't be ideal if it's an older vehicle that needs to be cranked a lot (like a diesel truck that you ran out of fuel and needs time to prime the pump). And just for the record, most lipo batteries have always been rated in mAH until you get up into large packs assembled by a third party seller. Pull any pack apart that you want, whether it's from Bosch or Milwaukee or it's a lithium car battery, if it's labeled in AH on the outside, the individual cells will be labeled in mAH, guaranteed. It's not a marketing tactic, the battery manufacturers label the cells as such, it's just industry standard and they assume people know how to drop zeroes if they care about comparing actual specs.

I'm not saying this particular pack lives up to all of its claims, it's probably slightly exaggerated like any other electronic device outside of a lab, but I'm seeing nothing about it that would prevent it from getting reasonably close to reaching those claims in practice. Maybe it can only put out an honest 3600A burst, who knows, but that won't make a difference in real world use when starting a Bronco that won't need but 1/10th of that current for half a second. The clamps and form factor and bypass features and price and things of that nature will make more of a functional difference in user experience than peak ratings.

Ohms law, can't get the burst currents stated.

 

[Tex]

Ohms law, can't get the burst currents stated.

Show me the reason why Ohm's law prevents it, then explain your variables. It won't push the burst current while starting a vehicle, but there's no reason to doubt the claim that it's capable of that when the variables are there to support it. I said as much in my post.

 

[CalvinT]

Show me the reason why Ohm's law prevents it, then explain your variables. It won't push the burst current while starting a vehicle, but there's no reason to doubt the claim that it's capable of that when the variables are there to support it. I said as much in my post.

I'd like to see how the manufacturers derived those current ratings. Did they measure a prototype? Did they measure one from the production line? Is it a calculated theoretical number? And what are the conditions? Shorted terminals? Hooked to a battery in a car? They don't tell you.

I think then number is either calculated from design specifications or are measured when the battery terminals are shorted.

Ohms law is Voltage = Current times resistance. Or...
Current = Voltage divided by resistance.
or
Resistance = Voltage divided by current.

So... Assume a nominal 12volt battery. (The one in your Bronco will measure around 13.5 volts when fully charged.)

So for a battery pack to put out 4000 amps you divide 4000 into 13.5. That equals 0.0033 Ohms.

A good starter motor will measure around 0.1 ohms between the terminals. So using Ohm's law, Current = 13.5 volts divided by 0.1 Ohms or 135 Amps. The only way to get more current through the starter motor is to increase the voltage.

That 0.1 ohms doesn't include the resistance of cables, clamps and the starter solenoid. Since it's a series circuit, you add each of those.

If anyone doubts me, get a multimeter and measure a starter.

 

[CalvinT]

Here's an article that gives a different resistance for a starter motor.
It's more general because it also talks abouit 6V electrical systems.
It gives an excellent description of the starter circuit. It also explains what happens when the starter starts spinning.

https://www.larescorp.com/toolbox/skinned-knuckles-articles/starter-motor/

 

[Tex]

I'd like to see how the manufacturers derived those current ratings. Did they measure a prototype? Did they measure one from the production line? Is it a calculated theoretical number? And what are the conditions? Shorted terminals? Hooked to a battery in a car? They don't tell you.

I think then number is either calculated from design specifications or are measured when the battery terminals are shorted.

Ohms law is Voltage = Current times resistance. Or...
Current = Voltage divided by resistance.
or
Resistance = Voltage divided by current.

So... Assume a nominal 12volt battery. (The one in your Bronco will measure around 13.5 volts when fully charged.)

So for a battery pack to put out 4000 amps you divide 4000 into 13.5. That equals 0.0033 Ohms.

A good starter motor will measure around 0.1 ohms between the terminals. So using Ohm's law, Current = 13.5 volts divided by 0.1 Ohms or 135 Amps. The only way to get more current through the starter motor is to increase the voltage.

That 0.1 ohms doesn't include the resistance of cables, clamps and the starter solenoid. Since it's a series circuit, you add each of those.

If anyone doubts me, get a multimeter and measure a starter.

It's based on testing battery cell performance at the factory. If you're not aware of what C rating is in reference to a lipo pack, then I suggest you read up on lithium chemistry batteries and get up to speed, because there's a lot of info on the subject that you're probably not aware of. It's a manufacturer rating, and most cells do in fact reach and often exceed their claims. The C rating is tested on highly specialized and instrumented load cells that for all intents and purposes have zero resistance. Once they know how many amps the cells are able to push out, the divide that by the rated capacity of the cell and arrive at a C rating (1C=1x capacity, so if you have a 1C 1AH cell it will put out 1A, 10C would be 10A, or a 5C 24AH cell will discharge at 120A, etc.) They can then sell the packs with their advertised C rating alongside the capacity so the consumer will then be able to calculate how many amps the cell is capable of providing. This is absolutely a well established modus operandi in the industry and I'm honestly a little surprised you haven't run across it knowing what you know of electrical theory.

The problem is, you're bringing up how much a starter can effectively use, and that's a meaningless number when you're trying to rate a jump pack that can easily exceed that current by 10-20x. It's not going to tell you what it's capable of when ALL the jump starter packs on the market are able to put out that much. Nobody ever said this pack is going to push 4000A through YOUR STARTER, nobody has. That's something you came up with all on your own. It's like saying Ingersoll-Rand selling a 60KW genset is misleading because there's no way your particular house will ever draw more than 20KW when hooked up to it. Using Ohm's law to justify your position with your particular house doesn't prove that the genset is not capable of 60KW, it just means your particular use case will not see 60KW. Your Bronco is not going to pull 4000A out of this pack unless you inadvertently bolted your starter cable to the frame or something, but if that is in fact the case, I have no doubt that this little pack is going to give you that much...for a few short seconds, anyway.

When you're dealing with lithium packs, that extra C rating on top of what is needed is a good metric to show how much voltage drop you're going to get for a given load. The higher the C rating, the less your voltage will drop when under load. Meaning, if you're only pulling 250A from a 4000A capable lipo pack, voltage drop will be minimal...but if you're pulling 250A from a 300A capable lead acid pack, voltage drop is going to be significant enough to affect reliable use and possibly not even work properly. Similar story when sizing generators...if your peak KW usage is 20KW, you're not going to buy a 20KW genset, you're going to buy a 40KW instead so you're not loading it down and adversely affecting voltage. One other interesting side note about C rating, the higher it goes, the more capacity you generally lose for a given cell size/weight...it's a tradeoff. That's why UPS and solar batteries often use low C batteries, they have more capacity potential. It's generally considered a waste of money to use a high C battery in a power bank application unless it's truly needed.

TL;DR just because your particular starter can't pull 4000A doesn't mean the pack is not capable of discharging at 4000A, and they're not claiming that your starter will pull 4000A either. That high amp rating is just a good way to see if a pack is going to have significant voltage sag in your use case. The higher that amp rating is, the closer the pack will stay at nominal voltage when used. Sorry I'm probably coming off as an ass but I've got the flu or the rona or something, social skills are always the first thing I toss overboard.

 

[Tricky Mike]

I will never ride around with jumper cables again. I've been using NOCO's power boost for years along with the adaptor cables that I attach to the battery and leave on forever. Nothing is easier.

EDIT for clarification: I leave the extension cable on forever, as it has a cap to protect it from water, dirt and mud. I do not leave the Boost plugged in. The cable just makes life easier, especially if you have a car that the battery terminals are hard to get to. It does away with the need for the alligator clamps (unless you are jumping someone else - so I still have those in the case).
I keep the case with the boost inside - usually under the seat but it gets moved around.
End of edit.

The adaptor plugs right into the jump box. That black adaptor plug piece is for a trickle charge that they also make.

I've also created other connectors to make it plug and play with an air compressor so I never have to use the allegator clips, at least on my vehicles, I carry the clips in case I have to jump someone else.

Edit again: By this I mean, I spliced plug connectors to my compressor so I can plug it into the extension cables hanging from the battery terminals, again so I don't have to use the clamps.
End of second edit.


The point is, these things are life saviors and you don't need anyone else to jump you. As far as the Wolfbox, I would think it works, but I've only owned NOCOs and have bought several others for people in my life and will swear by them.
Pics from Amazon.

My wife carries a NOCO because her battery will randomly go stone cold dead without warning. Been through the whole system and can't figure it out, easier just to have the jump box now. I gotta order that adapter.

 

[Techun]

They also need special chemicals to put them out when they catch fire.

And what are these chemicals??

(They don't exist)

 

[Heckler]

I jumped my 6.0 Diesel several times with my cheap $60 lithium jump pack I got at Costco, I still have it today in my Bronco and use it to start the Bronco too no issues.

 

[CalvinT]

And what are these chemicals??

(They don't exist)

They do exist.The following chemicals are a couple that are used for industrial fires. But I do stand corrected. Water is recommended otherwise. But it takes a lot. Teslas are difficult to extinguish once they get started.

https://www.avdfire.com/what-is-aqu...dispersion,aluminium-iron-magnesium silicates.

https://hct-world.com/how-to-put-ou...ecialized,lithium-ion battery fire mitigation.

Here's what the National Fire Protection Association has to say about lithium-ion fires.

Why are lithium-ion batteries flammable?
Lithium-ion batteries store a lot of energy in a small amount of space. When that energy is released in an uncontrolled manner, it generates heat, which can turn certain internal battery components into flammable and toxic gases.

How do fires from lithium-ion batteries start?
Lithium-ion battery fires happen for a variety of reasons, such as physical damage (e.g., the battery is penetrated or crushed or exposed to water), electrical damage (e.g., overcharging or using charging equipment not designed for the battery), exposure to extreme temperatures, and product defects.

What are some unique dangers of lithium-ion battery fires?
Heat, smoke, the release of toxic gases, and the potential for explosions are the dangers associated with lithium-ion battery fires.

Once the batteries catch fire and water is applied to them, does it make the fire worse because lithium in the presence of water creates combustible hydrogen?
Firefighters should use water to fight a lithium-ion battery fire. Water works just fine as a fire extinguishing medium since the lithium inside of these batteries are a lithium salt electrolyte and not pure lithium metal.

Here's the link.

https://www.nfpa.org/education-and-research/home-fire-safety/lithium-ion-batteries

 

[Techun]

They do exist.The following chemicals are a couple that are used for industrial fires. But I do stand corrected. Water is recommended otherwise. But it takes a lot. Teslas are difficult to extinguish once they get started.

https://www.avdfire.com/what-is-aqueous-vermiculite-dispersion/#:~:text=AVD is an aqueous dispersion,aluminium-iron-magnesium silicates.

https://hct-world.com/how-to-put-out-a-lithium-ion-battery-fire/#:~:text=Professionals recommend using a specialized,lithium-ion battery fire mitigation.

Here's what the National Fire Protection Association has to say about lithium-ion fires.

Why are lithium-ion batteries flammable?
Lithium-ion batteries store a lot of energy in a small amount of space. When that energy is released in an uncontrolled manner, it generates heat, which can turn certain internal battery components into flammable and toxic gases.

How do fires from lithium-ion batteries start?
Lithium-ion battery fires happen for a variety of reasons, such as physical damage (e.g., the battery is penetrated or crushed or exposed to water), electrical damage (e.g., overcharging or using charging equipment not designed for the battery), exposure to extreme temperatures, and product defects.

What are some unique dangers of lithium-ion battery fires?
Heat, smoke, the release of toxic gases, and the potential for explosions are the dangers associated with lithium-ion battery fires.

Once the batteries catch fire and water is applied to them, does it make the fire worse because lithium in the presence of water creates combustible hydrogen?
Firefighters should use water to fight a lithium-ion battery fire. Water works just fine as a fire extinguishing medium since the lithium inside of these batteries are a lithium salt electrolyte and not pure lithium metal.

Here's the link.

https://www.nfpa.org/education-and-research/home-fire-safety/lithium-ion-batteries

Thanks for the vermiculite link, had not heard of that. I do doubt what they claim a little bit, since they say it encapsulates and blocks oxygen, but the batteries produce THEIR OWN oxygen so...not sure about that. Maybe it works for small modules/cells.

 

[CalvinT]

Thanks for the vermiculite link, had not heard of that. I do doubt what they claim a little bit, since they say it encapsulates and blocks oxygen, but the batteries produce THEIR OWN oxygen so...not sure about that. Maybe it works for small modules/cells.
[/QUOTE

Once sealed they couldn't produce enough oxygen to support their own combustion. If that were to happen you'd have the makings of a perpetual motion machine. The batteries still need an air supply to burn.

 

[Techun]

It's not perpetual motion...it's burning it's own material.

There are plenty of mixtures that contain their own oxygen to burn and could burn in a sealed box of CO2, or space, etc.

 

[CalvinT]

It's not perpetual motion...it's burning it's own material.

There are plenty of mixtures that contain their own oxygen to burn and could burn in a sealed box of CO2, or space, etc.

Any oxygen produced during a lithium-ion battery fire would have to come from lithium reacting with water. According to the National Fire Protection Association (see link above) that doesn't happen with a lithium-ion battery fire.

 

[CalvinT]

It's based on testing battery cell performance at the factory. If you're not aware of what C rating is in reference to a lipo pack, then I suggest you read up on lithium chemistry batteries and get up to speed, because there's a lot of info on the subject that you're probably not aware of. It's a manufacturer rating, and most cells do in fact reach and often exceed their claims. The C rating is tested on highly specialized and instrumented load cells that for all intents and purposes have zero resistance. Once they know how many amps the cells are able to push out, the divide that by the rated capacity of the cell and arrive at a C rating (1C=1x capacity, so if you have a 1C 1AH cell it will put out 1A, 10C would be 10A, or a 5C 24AH cell will discharge at 120A, etc.) They can then sell the packs with their advertised C rating alongside the capacity so the consumer will then be able to calculate how many amps the cell is capable of providing. This is absolutely a well established modus operandi in the industry and I'm honestly a little surprised you haven't run across it knowing what you know of electrical theory.

The problem is, you're bringing up how much a starter can effectively use, and that's a meaningless number when you're trying to rate a jump pack that can easily exceed that current by 10-20x. It's not going to tell you what it's capable of when ALL the jump starter packs on the market are able to put out that much. Nobody ever said this pack is going to push 4000A through YOUR STARTER, nobody has. That's something you came up with all on your own. It's like saying Ingersoll-Rand selling a 60KW genset is misleading because there's no way your particular house will ever draw more than 20KW when hooked up to it. Using Ohm's law to justify your position with your particular house doesn't prove that the genset is not capable of 60KW, it just means your particular use case will not see 60KW. Your Bronco is not going to pull 4000A out of this pack unless you inadvertently bolted your starter cable to the frame or something, but if that is in fact the case, I have no doubt that this little pack is going to give you that much...for a few short seconds, anyway.

When you're dealing with lithium packs, that extra C rating on top of what is needed is a good metric to show how much voltage drop you're going to get for a given load. The higher the C rating, the less your voltage will drop when under load. Meaning, if you're only pulling 250A from a 4000A capable lipo pack, voltage drop will be minimal...but if you're pulling 250A from a 300A capable lead acid pack, voltage drop is going to be significant enough to affect reliable use and possibly not even work properly. Similar story when sizing generators...if your peak KW usage is 20KW, you're not going to buy a 20KW genset, you're going to buy a 40KW instead so you're not loading it down and adversely affecting voltage. One other interesting side note about C rating, the higher it goes, the more capacity you generally lose for a given cell size/weight...it's a tradeoff. That's why UPS and solar batteries often use low C batteries, they have more capacity potential. It's generally considered a waste of money to use a high C battery in a power bank application unless it's truly needed.

TL;DR just because your particular starter can't pull 4000A doesn't mean the pack is not capable of discharging at 4000A, and they're not claiming that your starter will pull 4000A either. That high amp rating is just a good way to see if a pack is going to have significant voltage sag in your use case. The higher that amp rating is, the closer the pack will stay at nominal voltage when used. Sorry I'm probably coming off as an ass but I've got the flu or the rona or something, social skills are always the first thing I toss overboard.

No offense taken. If I was feeling ill, I probably wouldn't even bother to respond. But we're all different.

To repeat what you stated about C-ratings. C-ratings are used to describe charge and discharge rates.

The C-rate of a battery is the the amount of current a fully charged battery should produce over a given time. Batteries are commonly rated at 1C. A fully charged battery rated at 1Ah should produce 1A for one hour.

A 24,000mAh battery should produce 24A for one hour, or a 1C rate of 24A.

A C-rate of 5C is the amount of current the same battery can put out in 1/5 hour or 12 minutes.

A battery’s measured capacity will decline as you increase you increase the discharge rate. It will increase as you decrease the discharge rate. This is due to internal losses which are dissipated as heat. So the relationship doesn’t remain linear.

Peak discharge is for 10 milliseconds. We can’t use C ratings to calculate peak discharge because the time is too short.

But peak current doesn’t have any relation to battery capacity. It’s just an indication of internal resistance and nothing else. The starter impedance/resistance is the limiting factor. AGM batteries have similar internal resistance but have much higher capacity.

Here are links to two different manufacturers, not retailers, of lithium jump starters.
Both make a range of jump starters. Both say peak current rating doesn't make any difference. I bow to their expertise.

Hulkman sells jump starters rating from 1200A to 4000A
https://support.hulkman.com/hc/en-0...1-What-s-the-Peak-Current-Amps-of-the-product

JF.EGWO sells jump starters with a peak current rating from 2000A to 6000A
https://www.jfegwo.com/blogs/news/what-s-the-peak-current-amps-of-the-product

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