I've not used one of these. They look attractive for size and weight. I think the issue is if you charge a lithium battery to 100% and store it, then it tends to swell and eventually ruin the battery or start a fire if it shorts out. The issue with cold is you have less capacity. I think by 32 degrees F you are down by 20%. Now that by itself wouldn't be a big deal if the capacity is enough. It gets worse as it gets colder and how important that is will depend upon the lowest temps you'll see. It can be as low as 50% of normal full charge at 0 degrees F.
So if you had excess capacity and only charged to 80% of the 0 degree charge capability then you might have something that would work fine. But all your competitors are going to advertise charge amounts and amperage rates at higher temperatures and 100% capacity and no one will buy your device. So it would be possible to make a good device I just don't know if anyone has. Perhaps after a thousand companies make a lousy one someone will make one the right way and get a reputation for being worthwhile.
So the safer approach now is to use the old style larger heavier sealed lead acid jump boxes. Some of those can be opened and the sealed batteries inside are what UPS devices use so they can be replenished every few years.
Interesting, thank you for those insights!
So a full charge of a lithium battery stored over time causes the swelling? I had no idea... There are definitely reviews where people describe them catching fire or exploding which is my major hesitation.
I live in upstate NY and we don't typically go below 0 degrees F but it was 18 yesterday. It's also not uncommon for it to be below 10 frequently. So that would mean a pretty significant reduction in capacity. I would probably want to go for one with larger capacities to offset this then.
I understand why they offer ratings at higher temps but the reality is most people like myself want to leave these in our cars for emergencies so it is very misleading. They all appear to be basically the same, I wouldn't be surprised if they were all made in the same factory just with different outsides and packaging.
Do you know you could test your battery with a multimeter?
I would rather get one of this from ebay and determine when it is time for a new battery.
I am aware, and the batteries in our cars are likely original factory ones so judging by the age of the cars we have I can assume they are nearing the end of their life since car batteries tend to last between 4-6 years depending on the conditions. The real issue is that we live close to work and in general don't drive far when we do drive places. So our modern cars full of electronics don't get a lot of opportunity to charge up. Additionally, the point of these jumpers is for emergencies, since there are many reasons your car battery can go dead on you and you aren't always going to be ready for it.
I bought one of the lithium ones and is junk. When the battery is really dead, it doesn't do anything. It has some boost switch but heaven knows what logic it uses for it to work. Heck, I could not even jump start my mower with it! On top of that the cords were too short to reach the terminals.
This category is like toasters: makers think the cheaper they make them, the better. It is impossible to know which is a quality one. They all seem copycats with the same terminal at the end and junk over-rated specs.
In each instance I have had to get a regular charger and extension cord to get going again.
So if you find a good one, let me know.
I've read of people having that issue actually, it's related to the safety mechanism to ensure the polarity is right. If the battery is fully dead it can't determine the polarity so it doesn't work. Some have a way to override the safety feature.
You are 100% right! They appear all the same, it makes shopping for them impossible. Amazon reviews are largely useless since most people just say "it works!" but under what conditions? Ultimately if it doesn't jump things in the cold it's useless to me. The specs are without a doubt useless and the build quality is bad. The number of reviews I've seen of the alligator clips breaking or wires smoking due to the insufficient gauge of the wire used doesn't fill me with hope for these products.
I'll keep everyone posted if I do get a good one. This one by
Rugged Geek is the one my coworker owns. It seems to work well. The jumpstarter I linked in my original post works great but it's a lead acid one, so big and heavy. If you don't care about the bulk it's a winner! But yeah the hunt continues for the compact ones!