When the lithium jumpers first came out a few years back, it was a struggle for me to not click 'place order', but I managed. So much power in such a small package is enticing!
I also do not like hooking my vehicle electrically to somebody elses for jumpstarting them. Even if the clamps are hooked up right and never touch each other, things could go wrong when the jumpee's starter disengages and sends a transient spike though the cables to jump vehicle's cables. I've witnessed more than one modern vehicle being winched up on a flatbed after trying to be good samaratin and trying to jumpstart somebody else. Reports of fried expensive PCM/ECMS are usually what I hear failed.
When I absolutely had to jumpstart someone, I'd pull the ground cable off my battery, not let the other driver touch the cables, even if they provided them, and make them wait a minute or two before allowing the other vehicles starter to engage. None of that rev the engine and let 'er rip for me.
My neighbors all have lithium jumper packs, and I've witnessed them both quickly an easily start a vehicle whose battery was so dead the clicking slowed to a complete stop. I've also seen the same unit later fail to start the same vehicle even though all the lights on it were indicating full charge. That unit is now used only as a portable USB charger by the guy's wife, kept in her purse and she skoffed when i said to not let her purse bake in the hot sun with that battery inside of it.
The JNC-300xl, apparently has a 9 amp hour AGM battery inside of it. That is the smallest lead acid battery I know of inside any lead acid jumper pack.
The replacement battery is some 31$ with shipping on amazon. UNlike other 9Ah AGM batteries of the same dimensions, it has much larger terminals for hooking up cables with a nut and bolt through the ring terminals on the cable clamps.
![[Linked Image]](https://images-na.ssl-images-amazon.com/images/I/71Qz9sg5JqL._SL1500_.jpg "[Linked Image]")
Earlier this year I bought an 18Ah AGM, for 35$, the Ub 12180. It has the same terminals as in the pic above.
My 18Ah battery, by itself, can start my 5.2 liter v8 engine.
https://www.amazon.com/Mighty-Max-B...;qid=1563943823&s=gateway&sr=8-3
I believe it to be no different internally than the Ub12180 battery widely available, despite being marketed ftowards the stereo boom boom crowd.
The OP could disassemble their JNC-300xl, take the clamps from the battery, recycle it, attach those cable clamps easily to a 35$ 18Ah AGM battery and have twice the starting cranking amperage, and amp hour/watt hour capacity to power USB devices, of the JNC 300xl did when it was new.. If the cables are not long enough they could cut up an old set of jumper cables and crimp on new ring terminals
They could also buy one of these panels with a 12v port and 2 USb ports.
![[Linked Image]](https://images-na.ssl-images-amazon.com/images/I/612yXUeGwKL._SL1000_.jpg "[Linked Image]")
The lead acid jumper packs can be made, quite easily, but they do not have the nice carry handle or include a charger. Most of the included chargers are far from ideal for charging the internal battery anyway. Basically well depleted AGMs need higher recharge amperage than the half an amp charger provided. The 18Ah battery linked above wants 'upto' 5.4 amps when deeply discharged. It will appreciate currents up to this level and retain its capacity for longer, as long as it is fully charged regularly, but a part of charging it right is charging it at upto that ~30% charge rate.
upto 5.4 amps for that 18Ah battery when it is deeply discharged.
Ignore the 'trickle charge it overnight' brigade. AGM's can be tickled to a premature death with too little charging current when they are regularly deeply discharged.
I have hit mine when depleted below 50% charged, with a 40 amp power supply set to 14.7v, without issue. (took 36 amps peak to raise battery terminal voltage that high instantly, 5 minutes later was still accepting 25 amps)
The lithium jumper packs are certainly neat, and compact, but I've witnessed 3 of them fail to do their job and be relegated to portable USB power supply duty only. Not sure which brands these were, their owners are not the type to buy the cheapest possible. Two of them were quite large. Once they can no longer worlk as portable USB power supplies, I will be dissecting them and will post pics here. Unlike discarded lead acid jumper packs whose owners do not want to bother with a replacement battery, few/ none of the other components can be easily retasked and prevented from becoming waste in a landfill.
The JNC cables I took from a 660 being tossed, were nice fine strand 4awg with super flexible insulation. It would be a shame if those on teh OP's 300xl, could not be retasked.
I also do not like hooking my vehicle electrically to somebody elses for jumpstarting them. Even if the clamps are hooked up right and never touch each other, things could go wrong when the jumpee's starter disengages and sends a transient spike though the cables to jump vehicle's cables. I've witnessed more than one modern vehicle being winched up on a flatbed after trying to be good samaratin and trying to jumpstart somebody else. Reports of fried expensive PCM/ECMS are usually what I hear failed.
When I absolutely had to jumpstart someone, I'd pull the ground cable off my battery, not let the other driver touch the cables, even if they provided them, and make them wait a minute or two before allowing the other vehicles starter to engage. None of that rev the engine and let 'er rip for me.
My neighbors all have lithium jumper packs, and I've witnessed them both quickly an easily start a vehicle whose battery was so dead the clicking slowed to a complete stop. I've also seen the same unit later fail to start the same vehicle even though all the lights on it were indicating full charge. That unit is now used only as a portable USB charger by the guy's wife, kept in her purse and she skoffed when i said to not let her purse bake in the hot sun with that battery inside of it.
The JNC-300xl, apparently has a 9 amp hour AGM battery inside of it. That is the smallest lead acid battery I know of inside any lead acid jumper pack.
The replacement battery is some 31$ with shipping on amazon. UNlike other 9Ah AGM batteries of the same dimensions, it has much larger terminals for hooking up cables with a nut and bolt through the ring terminals on the cable clamps.
Earlier this year I bought an 18Ah AGM, for 35$, the Ub 12180. It has the same terminals as in the pic above.
My 18Ah battery, by itself, can start my 5.2 liter v8 engine.
https://www.amazon.com/Mighty-Max-B...;qid=1563943823&s=gateway&sr=8-3
I believe it to be no different internally than the Ub12180 battery widely available, despite being marketed ftowards the stereo boom boom crowd.
The OP could disassemble their JNC-300xl, take the clamps from the battery, recycle it, attach those cable clamps easily to a 35$ 18Ah AGM battery and have twice the starting cranking amperage, and amp hour/watt hour capacity to power USB devices, of the JNC 300xl did when it was new.. If the cables are not long enough they could cut up an old set of jumper cables and crimp on new ring terminals
They could also buy one of these panels with a 12v port and 2 USb ports.
The lead acid jumper packs can be made, quite easily, but they do not have the nice carry handle or include a charger. Most of the included chargers are far from ideal for charging the internal battery anyway. Basically well depleted AGMs need higher recharge amperage than the half an amp charger provided. The 18Ah battery linked above wants 'upto' 5.4 amps when deeply discharged. It will appreciate currents up to this level and retain its capacity for longer, as long as it is fully charged regularly, but a part of charging it right is charging it at upto that ~30% charge rate.
upto 5.4 amps for that 18Ah battery when it is deeply discharged.
Ignore the 'trickle charge it overnight' brigade. AGM's can be tickled to a premature death with too little charging current when they are regularly deeply discharged.
I have hit mine when depleted below 50% charged, with a 40 amp power supply set to 14.7v, without issue. (took 36 amps peak to raise battery terminal voltage that high instantly, 5 minutes later was still accepting 25 amps)
The lithium jumper packs are certainly neat, and compact, but I've witnessed 3 of them fail to do their job and be relegated to portable USB power supply duty only. Not sure which brands these were, their owners are not the type to buy the cheapest possible. Two of them were quite large. Once they can no longer worlk as portable USB power supplies, I will be dissecting them and will post pics here. Unlike discarded lead acid jumper packs whose owners do not want to bother with a replacement battery, few/ none of the other components can be easily retasked and prevented from becoming waste in a landfill.
The JNC cables I took from a 660 being tossed, were nice fine strand 4awg with super flexible insulation. It would be a shame if those on teh OP's 300xl, could not be retasked.
