Ping Jim Wilkins - Lithium Ion Jump Starter and Power Pack at Harbor Freight

Read the negative reviews on it.
The local store told me they were out and not expecting more in the next shipment, so I called around for price and local availability (returnability) and bought a LiPo Whistler WJS-3500 in WalMort.
The HF one has a 6A limit on the skimpy-looking coax output port. The laptop power bricks I intended to use with it surge to 9A. The WJS-3500 has no separate output so I bought an EC5 connector and made one, with a 30A fuse and Powerpoles to fit all my other cables. It supplied 22A for a quick test. The controller in the jumpstarting cable needs to see external battery voltage and limits cranking time.
Then I stopped at HF while shopping for something else, and saw one on the shelf. I don't really need two expensive Li jumpstarters. Hopefully I won't need one, but I had just measured the capacity of a 5 year old "18 Amp-Hr" AGM jumpstarter that I top up monthly at 4.5 A-H. Maybe this LiPo battery will hold up longer. I can squeeze long life from flooded lead batteries but not sealed ones.
--jsw

They changed their website code awhile back and the reviews don't show anymore. I can still get to them but not with my default browser settings. If I'm serious about buying something I'll go through the trouble to read'em...
I suspected you already knew of it and had checked it out...
I've got around 1600 CCA under the hood of my old truck, if the batteries are up to snuff (pretty sure one is kaput right now). Makes me smile to think they would advertise these as "jump starters". Might work for my motorcycle if the battery was just borderline :)

Mine is not from Harbor Fright, but it is basically the same thing - Volt Reactor JP08, suitable for starting engines 5.4 liters and up - from AvtekElectronics. Paid $99 Canadian for it a year or 2 ago - so very close to the HF price. (at a $0.74 canadian dollar)

How well do these and supercapacitors work for starting cars? May the forces of evil become confused on the way to your house. --George Carlin

Have you used it enough to review it?
My experience is with high-end industrial battery packs with sophisticated supervisory circuits which kept the cells balanced. We've seen what happens with the low-end batteries in hoverboards. This is my interest: "For reference, the average person uses 30 kWh of power a day."
For comparison I've been using 4 to 5 KWH per day for decades and paid about $200 for 2 KWH of lead-acids. My inverter is an APC1400 pure sine UPS that was free (broken?) at a flea market. I wrote a program to monitor it on this laptop.
-jsw

I don't know yet and am not about to drain a good battery to find out.
The test I'm planning is to connect it to a battery through some resistance to convince it that it's connected to a weak battery, then load it to its 200A rating with the HF carbon pile. I have to figure out what I have that can rapidly measure and record that much DC current since the manual implies that it may shut off after 3 seconds.
If not connected to a battery it lights a Fault LED and outputs about 6V. They don't want you to use it as the only vehicle battery. Unlike Lead-acids, Lithiums can't tolerate an overcharge from the alternator. --jsw

Mine cranks the Corvair engine quite briskly as the only battery. Don't know how long though.

No? Why _ever_ not?
That long? (Wow, that's brief.)
Hence the BMS for those. Close maintenance on each cell.
- May the forces of evil become confused on the way to your house. --George Carlin

"Looks like you're using an ad blocker." Yes, and I'll continue. I use an average of 10kWh/day, and that's with electric water heating and air conditioner. I'd love a used Tesla battery and BMS, if anyone wants to get rid of the shabby old thing. (A GM, Ford, Toyota, or Nissan battery pack would be OK, too.)
That's a great low usage. Congrats. I should cut my electric bill in half once I get the solar up and running. It's a $2k investment, but it's also off-gridable.
- May the forces of evil become confused on the way to your house. --George Carlin

AFAIK, the Corvair is the -only- GM engine which cranks easily.
- May the forces of evil become confused on the way to your house. --George Carlin

They are NOT to be left connected to the charging system through the "booster" connection, there is a "charging" connector to charge them through that connects to the BMS

This CorvAir engine has a Ford planetary permanent magnet starter and a 64 inch prop on it.

"SLI batteries are not designed for repeated deep discharge, and their life is considerably reduced when subjected to this."
SLI means Starting/Lighting/Ignition, the normal car battery, as opposed to Deep Discharge. I think I damaged a battery with -one- deep discharge using an ATV winch.
-jsw

I use the solar system only for backup when the grid fails, most recently two days ago. The panels keep the batteries topped up. If we have an extended outage I'll use my reasonably quiet (stealthy) HF inverter generator and that 25A welder transformer power supply to recharge during the day and run the fridge on the batteries overnight. Thursday night it consumed 0.18 KWH.
If I get a very optimistic 400 cycles from the $200 batteries that's $0.50 per 2 KWH discharge, or $0.25 per KWH. Grid power costs me $0.166 per KWH.
-jsw

Literal much? The facetiousity factor on that query was 100%.
Ouch! That's something I've never seen. Were you winching it and yourself out of a 100' gorge after an Evel Knievel moment?
- May the forces of evil become confused on the way to your house. --George Carlin

Have you figured the cost of the generator-fueled power yet? I have two deep-cycles for the KW array and 1 standard car battery + 1 deep-cycle for the vast HF 45w array. I'm eyeing 4pc sets of Trojan T105-RE (225Ah) and L16RE-B (370Ah) at $934 and $1,535, but that upgrade isn't budgeted. HF is for backup lights. Murphy has respected it and the power has remained on here.
Only 400 cycles? Ouch! Are they out in the cold? What's your DOD? Sounds deep. The Bi-Mart group 27 deep-cycles cost me $70 apiece. For the HF set, I doubt they'll die any time soon, but the run time on those would be light. 76w at full burn of the lights, or 226w with the 12v heater in a tent. I sure hope it never comes to that. If it did, I could always move to the other system, rerouting the water heater power to the 2kw HF modified sine wave inverter and run the milkhouse heater, on low if it remained cloudy. I'm also eyeing a Taiwanese controller inverter @ $500 delivered. 2.2kw pure sine wave 240v, MTTP controller, 60A. What to do for step-down, though? Even used variacs are spendy.
$0.117/kwh here. I just refigured and I'm at 16kwh per day annually. I must have figured a Spring month for the 11kwh figure. It breaks down to $41/mo until I replace the grid water heater with the solar.
- May the forces of evil become confused on the way to your house. --George Carlin

The prop doesn't matter at cranking speeds, but I didn't know Ford ever made a geared starter. I don't recall seeing or hearing of them back when I wrenched. Chrysler and Toyota, yes. And GMs only had the harsh gear noise when the shims weren't correct. Heh, heh, heh.
I'll bet that plane is quiet. Corvairs are so much better engines than VW, in every aspect. (/proud ex-Corvair owner)
- May the forces of evil become confused on the way to your house. --George Carlin

Some readers may not know that.
I was happy to watch and cheer on my friends' aerial vehicular antics, and let them think they could do at least some things I couldn't (wouldn't). If I want to blunder through the air I can rent a Cessna.
In that case a large oak tree on the steep hill behind my neighbor's house broke at the rotted base and wedged into another one, instead of crushing his shed just beyond.
The only way to (relatively) safely free it was to winch the lower end uphill after cautiously lifting it off the ground and trimming the ragged end square.
It was entangled by multiple branches so I couldn't know that the trunk wouldn't jerk sideways toward me as it slid down if I cut short lengths off the bottom, as I might with a simpler tree hung up in one fork.
I had a tension gauge in line to warn if I was close to overloading my gear. It took up to 3500 lbs (in addition to its own weight) to pull the tree loose, even with the lower end lifted off the ground.
-jsw

My HF 2500W inverter generator is claimed to run 5.5 hours at half load on its 1.35 gallon tank, pretty much 1 quart or ~$0.60 per hour. But really availability counts more than price for a backup generator, so two 5-gallon cans should last over a week if I recharge the batteries morning and evening. I've put 9-1/4 hours on it so far, mostly unloaded to get past the break-in period, and don't think the total adds up to one full tank but I didn't go through the fuss and risk of measuring each time I topped it off.
I saw 400 on some manufacturer's website, but also that some people get only around 40 cycles.