If you’re anything like me, you’ve been having a cold winter. It’s been brutal up here in the North Woods. Well, one of the days I got up and it had been minus 17 outside, and my poor old 2008 Element was sitting there in the driveway. I had to go somewhere. I had an appointment. So I go into the back of the car, and I have two jumper cable boxes back there.
We’re going to talk about what these devices are and how you can buy them. But I put the first one on—my go-to, very nice jump starter. Nothing happened. Car wouldn’t turn over. Nothing at all. It didn’t even cry.
Okay, well, I got another one. Got the other one out. This one had been sitting in my house. Maybe, you know, maybe this other one was just too cold. Hooked it up. It gave me an error at first when I was looking at it. Car wouldn’t start again.
Two jumper cable boxes failed.
Trying a Brand-New Jump Starter
But here’s the nice thing. In my other car, I had bought, over Christmastime, a brand new jumper cable box. And I thought, well, let’s just give this a try. I needed to leave.
And what I bought and what I tried was the AstroAI S8 Ultra Jump Starter. It has 4,000 amps. It is a battery box that has a flashlight on it, a USB-C port, and a USB Type-A port on it. And then you also have the jumper cables on it.
All right, let’s give this one a try.
So I connected it up. It gave me the green light. Okay, started the car. First thing—cranked up the car and it worked.
Actually, the hilarious thing was, I turned the key in the car to start it, thinking it was going to fail once again. And it started, and I immediately turned the key back, and I went, wait, the car—it started. Oh no. Turned the key again. The car started right up the second time. Everything was working.
But the question is, why? Why did these other jump starters fail while this one did a great job?
Why Cold Weather Kills Batteries
So first of all, you know, when you’re in a cold area, it kills the battery’s ability in a car—or anything that’s outside—to start. You lose chemical efficiency. The voltage drops. Thicker oil. I read about a million different reasons why this happened.
Starting a motor requires a great deal of torque. And when it’s this cold outside, you need a bunch of force in there too. We’re going to explain what all that means.
The jump starter isn’t just about charging the battery. That car had been on a trickle charger all night long. The battery was charged. It just was too cold. And it couldn’t get enough energy because batteries, when they’re cold, lose their capacity until they warm up again.
So what made all the difference here?
What Made the S8 Ultra Different
The S8 Ultra isn’t just bigger. It is bigger and it is bulkier, for sure. But the 4,000 amps of peak current means that it can deliver an enormous surge of power.
And then it has something that is called a 45C discharge rate. That means the battery is designed to release energy very fast without collapsing. Not physically collapsing, but electrically collapsing. Good thing we have engineers on this podcast that can explain this better than I can. I’m not a car nerd.
And that means that with the lower internal resistance, the voltage stays stable and the current flows.
So essentially, if we look at it, when you’re trying to start a motor, you need torque. And you need to have it before the voltage falls below a failure threshold. See, I’m totally reading their explanation of why it worked better.
Voltage is how hard electricity is being pushed. Amps determine how much electricity is actually moving. So between the voltage and the amps, I need a lot of power to this car that does not want to start.
I was able to provide both the amps and the voltage through the battery and get my car started.
Cheaper starters may list a high peak amp, but they often can’t sustain that level of energy for even a fraction of a second, especially during cold conditions.
When you have that discharge rate that I mentioned before—the 45C rate—that shows you how fast a battery can safely release its stored energy. And the battery can deliver 45 times its capacity in current very rapidly without putting anything in danger. That means that it has everything it needs to start an incredibly dead battery.
So in this particular case, it worked just great for me.
Understanding Car Battery Voltage
Now, this design with the battery means that it can go through all the thresholds that are critical to starting a car.
Smart batteries in general—if you take a look at batteries—are 12-volt batteries when you have them in cars. Generally, that’s the safety performance rate that you have with it. But cars can get below 9 volts. Does that mean it’s like a 9-volt battery? But anyway, it can get below that when it gets either completely drained or very, very cold outside.
So when you’re adding these jump starters to it, essentially, you’re going to try to get that battery to kick over and start up.
So what’s nice about this particular model is while this new AstroAI battery started the car on the first try, it also has something that is called a boost mode.
And what the boost mode will do is it temporarily ignores the battery’s condition—the very conservative safety guidelines—and just ups that amount of energy a little bit more. It says that essentially, to the battery, I’m going to just give a little more juice to all of this.
And because the cold had made my battery worse, it suddenly got the car running without boost mode. It would have also started my car too, safely and without any sort of danger.
Why I Love Portable Jump Starters
I want to talk a little bit about why I like having these battery jump starters to begin with.
First of all, if you remember the old days, someone would ask you, hey, could you jump start my car? And you’d go digging around in your trunk, maybe moving all the stuff you put in your trunk, get a big, greasy cable out of your car, and you had to remember where the cables went. Was it red to black or red to ground? I don’t even remember.
And if you got it wrong, it could actually endanger your car.
Plus, it’s very cold outside. And so you also have to then move your car—which is running—or the running car in a position where the two hoods are closer together so this maybe five-foot cable can reach between the two batteries to jump-start the car.
A lot of complexity goes here.
In my particular case, this car was in the driveway, and there was no way I was going to get a car anywhere near the front of the hood. I would have needed someone with very long cables or someone to drive on my lawn—which you can’t, because it was full of snow—to come jump-start my car.
When you have these jump starter boxes, you have everything you need. It is a battery. It has jumper cable clips that you plug into it. It has USB ports to charge your phone. It has a 12-volt port in it, so that if you have some sort of device you’re trying to run, it’ll run that as well.
But you don’t need another car.
So I could stand there right between my garage door and the front of the car, put the clamps on—red to red, black to black. It gives you an indicator to tell you you did it successfully, and then it just works. No need for that second car.
Being a Good Samaritan
The nice thing about it is that it helps you to be a good Samaritan, too.
Think about the situation where someone comes to you and needs help. It’s really cold outside, and I need to be somewhere. Oh no, you know, now I have to stay here, go find my jumper cables, and spend maybe the next 20 minutes in severely cold weather helping this person out—which, of course, you want to do.
Now it is so easy.
You’re able to take this little box with the jumper cables on it and hand it to someone, and they can start their car and give you the box back. That way, you’re leaving your trunk intact, you’re helping the other person in a very dangerous situation, and you’re still clean, free of grease, and feeling good that you were able to help someone as you did.
So I love even owning this device.
A Real-Life Story
There was a situation a couple of years ago where I worked in an office that was right below an oncology clinic, and I was leaving for the day at work. And this couple came to me, and they said, my husband just got done with his treatment and our truck will not start. Can you help us out?
So there I go. Got my handy little box out of the car, handed it to them. I helped them, and they were able to start the car when I hooked it all up.
And then she comes back out of the car and says, thank you. We cannot afford a new car battery. And this happens to us all the time.
Well, you can’t have people having just the worst days of their lives being stuck because they can’t afford a battery for their car.
So I handed them the whole box. I said, you just keep this. You need to know that wherever you go, you will have a way to start your car.
Cost and Value
They run, in general, somewhere around $50. This AstroAI S8 cost me $75, although I noticed this week it went on sale for $69. I think at the lowest point during Black Friday sales, it goes on sale for $59.
You can get cheaper ones, but like I said, in this particular case, this was the best car battery jump starter I could buy.
It normally lists for $139. I would even say it’s worth that. To have the kind of peace of mind that no matter where you go, you will be able to start your car—or you will be able to help someone start their car.
When it’s particularly dangerous conditions out there, having that kind of peace of mind is invaluable.
And I was so glad that I was able to help that couple. I was so glad that I was able to start my own car. And I liked that AstroAI box so much, I went and bought myself a second one for the other car.
So now both of my cars have that exact same model in them.
Final Thoughts
The clamps are easy to grip. I found that one of the cheaper ones I had had very stiff clamps, and my hands could barely squeeze the clamps to get them on the battery. And it’s cold outside. Your hands are cold outside. So having clamps that you can actually use made all the difference.
So I hope you enjoy this review of the AstroAI S8 Jump Starter.
I have owned other products from AstroAI. They make a cooler that is electric that you could take camping so that you don’t need ice, and it is fantastic too. So far, everything I’ve owned by them is really great.
If you’re looking for a jump starter, I highly recommend it.
The other brand that I also really liked—and thought that they thought of everything as well—was Anker. Anker was the second-best battery I bought. But I’m so happy with the new AstroAI.
And, as I said, I bought another one just so that both my cars could each have one.
All right. Well, I hope that helps you stay safer in the wintertime. Or even in the summertime, when maybe your car battery goes dead, and you’re in some remote place that you wouldn’t want to get stuck in.