Jump starter not starting newer AGM equipped cars

[avacado11]

In my line of work I jump start cars all day long.

Employer supplied me with a Clore JNC660(425amp crank/1700 peak) which would start just about anything except maybe a completely dead AGM. with these cold snaps I come across dead AGMs a lot more, even some lead acids that I can’t start with the JNC660. My current solution is to run the pack alongside jumper leads from my work truck to get these vehicles started. It works, but a major hassle and sometimes isn’t possible as the truck is too tall to fit into parking garages.

Anyways I’m planning on picking up a second jump pack to make my life easier. Considering I don’t ever see anything over 850CCA could I get away with a cheaper 330 crank/630 peak jump pack in addition with my JNC 660? This would put total at 755 cranking amps and 2230 peak.

I have no clue how cranking amps and peak amps come into play with jump starting completely dead batteries. Electrical has never been my forte. Trying to decide if I should fork the extra money over for a matching capacity jump pack so I have 2x the power instead of 1.5x. HF is selling 500/1700 peak jump pack for $170 where as the 330/630 pack is $70.

 

[Jetronic]

I think the issue is the residual voltage left in the battery. get a small battery to hook up to trick the system in thinking there's adequate voltage. it's to do with short circuit protection. Or if you can have the starter pack supply a fixed voltage do that for a few minutes to get a surface charge in the dead battery.

 

[Wheel]

If its that they don't even try to crank, it may be because some of the 'smart' jump start packs check the voltage present as a reversed lead check. If there's no voltage, it keeps the jump pack out of the circuit to prevent damage. You hooking up jumper leads may be what gives a detectable 'safe' polarity/voltage to allow the jump pack to engage. Most have a process to bypass this safety.

 

[Oil Changer]

I say this in the nicest, meaningful, and respectful way. If your line of work is to jump start vehicles all day, electrical is not your forte, and have no clue how batteries are rated, why not take it upon yourself to spend 15 minutes a day to educate yourself? Enroll in a community college? It will be safer for you, the people's cars you jump, and the vehicles themselves. It will make you a better employee and may lead to advancement. You can take pride in being the most knowledgeable person in the room on the subject matter.

I've had two batteries blow up in my face. Not fun.

 

[oil pan 4]

I play with a lot of agm batteries charging them that is. They can pull a lot of amps when drained. A group 34/78 optima can pull up to 80 amps even when it's cold. They may pull more than that, I only have 4 battery chargers that put out 20 amps a few times I have put all 4 chargers on one battery just to see what would happen.

 

[mk378]

Yes the issue is probably the protective circuitry inside the lithium jump starters refusing to engage on a fully dead battery.

Almost all of the handheld lead acid jump packs have the same 18 AH battery inside. The amp ratings are hype. You might do better carrying a fully charged full size AGM and a good set of jumper cables. Also if this is a garage full of cars that the same company owns, consider hoping that the car next to the dead one can start and be used to supply a jump start.

 

[zzyzzx]

Is using a corded battery charger with jump start capability (and old school type) and option here?

 

[oil pan 4]

Is using a corded battery charger with jump start capability (and old school type) and option here?

Never use those plug in jump starters, they will hit the vehicles electrical system with over 20 volts which fries stuff.

 

[zzyzzx]

Never use those plug in jump starters, they will hit the vehicles electrical system with over 20 volts which fries stuff.

Source? I've never seen anywhere near that much on mine.

 

[oil pan 4]

Yes the issue is probably the protective circuitry inside the lithium jump starters refusing to engage on a fully dead battery.

Almost all of the handheld lead acid jump packs have the same 18 AH battery inside. The amp ratings are hype. You might do better carrying a fully charged full size AGM and a good set of jumper cables. Also if this is a garage full of cars that the same company owns, consider hoping that the car next to the dead one can start and be used to supply a jump start.

The biggest agm battery that will fit in the support truck and get some real 2 gauge jumper cables. None of that aluminum clad junk.

 

[oil pan 4]

Source? I've never seen anywhere near that much on mine.

I fried a computer with one that I had. When I put the meter on it was making just over 20v.

 

[Davejam]

The Clore product you mention seems to indicate whether a battery can be jumped or not. Is that feature working?
The alternative is carry a cheap voltmeter and check battery before even attempting to jump it.
Bottom line these products aren't meant to bring a dead battery back to life.

 

[Astro14]

The biggest agm battery that will fit in the support truck and get some real 2 gauge jumper cables. None of that aluminum clad junk.

Awfully heavy to tote into the garage where the truck won’t fit. He’s got the truck’s battery, which he’s using when he can get the truck to the car in need. So, his question is more about what to do when he can’t get the truck to the car.

I like the big battery idea, it just is too heavy to carry.

I think I would shop for a second jump pack, one with a sealed lead acid that can be “forced” to connect, even with zero voltage. Hook that up first, let it get a bit of charge on the dead battery, then, disconnect it, and hook up the Clore - which looks to be a big SLA as well.

I’ve got an SLA jump pack. After a couple of years, the battery croaked. When I took it apart to find the size of the battery, I saw that the battery was held in placed by a couple of big spacers, so I measured the external dimension, the spacers, and it was pretty clear that in the manufacturing process, they built one case, and then sold different models with different size, and capacity sealed lead acid batteries. so I ordered up the biggest sealed acid battery that would fit in the existing case volume left by removal of the spacers, for about 50 bucks, and I still have the same case, with the same electronics, but a great deal more capacity.

It may be that your jump pack battery is running down in capacity. Any chance of testing it? Or of replacing it?

 

[wag123]

The Clore JNC660 uses a Gel Cell lead/acid battery.

Avacado, are you leaving the jump box outside in the cold? If so, that might be your problem.
Additionally, don't trust the specs/numbers given on any product coming from China. They lie like crazy on everything... like these jump boxes, audio amplifiers, portable generators, air compressors, light bulbs, batteries, etc, etc. PF did a test on Li-Ion jump boxes and found that every one of them had exaggerated their claimed output substantially.

 

[zzyzzx]

I fried a computer with one that I had. When I put the meter on it was making just over 20v.

Was that 20V open circuit or 20V while connected to a car battery?

 

[oil pan 4]

Was that 20V open circuit or 20V while connected to a car battery

It was effectively open as the battery was completely dead, wouldn't take a charge wouldn't hold a charge. It's something that can be easily avoided.

 

[avacado11]

The Clore JNC660 uses a Gel Cell lead/acid battery.
View attachment 200990
Avacado, are you leaving the jump box outside in the cold? If so, that might be your problem.
Additionally, don't trust the specs/numbers given on any product coming from China. They lie like crazy on everything... like these jump boxes, audio amplifiers, portable generators, air compressors, light bulbs, batteries, etc, etc. PF did a test on Li-Ion jump boxes and found that every one of them had exaggerated their claimed output substantially.

Jump pack is kept in a heated cab and always plugged in to charge when not in use. The pack is maybe 2-3 years old. I’ve gone though 3 in the last month. Boss just swaps one out for another

 

[SHOZ]

Completely dead AGMs take a long time before they really start taking a charge. Sometimes days if it's been like that awhile.

 

[avacado11]

I think the issue is the residual voltage left in the battery. get a small battery to hook up to trick the system in thinking there's adequate voltage. it's to do with short circuit protection. Or if you can have the starter pack supply a fixed voltage do that for a few minutes to get a surface charge in the dead battery.

Ok that makes sense. If that’s the case then I can probably get away with a cheaper battery pack just for the sake of tricking the JNC.

Sometimes I’ll pull the terminals and set the jump pack directly to the post to give it a surface charge before I attempt a jump, but with some of these cars that have distribution boxes on the positive terminal it’s simply too much disassembly. I’ve had a few instances that it didn’t work so I’m looking for a more time efficient way to do it.

 

[avacado11]

Yes the issue is probably the protective circuitry inside the lithium jump starters refusing to engage on a fully dead battery.

Almost all of the handheld lead acid jump packs have the same 18 AH battery inside. The amp ratings are hype. You might do better carrying a fully charged full size AGM and a good set of jumper cables. Also if this is a garage full of cars that the same company owns, consider hoping that the car next to the dead one can start and be used to supply a jump start.

My truck has a built-in inverter(not sure of spec) that is specifically made for jump starting. I’m usually jumping cars in peoples driveways. Most of the time I can get my truck right up to it, but sometimes I can’t.

Just yesterday I worked on a Cadillac XTS with a 680CCA lead acid. Thing had been parked for a while. Tester read 3.2V. Hook my JNC660 up and it’s reading 12.2-3V. Thing could barely cycle the starter once. I jump with my truck and same thing. Ended up having to use truck and jump pack to get it fired up.