Hi guys, I saw this in Banggood: http://www.banggood.com/20000mAh-Car-Jump-Starters-Pack-Boos…
It is basically a powerbank that can be used to jump start car's battery. Do you think this works? I am interested to buy … would be handy to have it in the car. Thanks.
That should be plenty to start a car several times, it doesn't take a lot of mAh to start a car less than 1000mAh. It should work for most 4 cylinder engines for larger engines would want one with higher than 200 amp start current rating.
Fair enough. Google fu has helped my understanding, dosn't help that they are talking mAh, which is what you use in phones when compared with a car requiring 200A starting current.
Perhaps if there were better advertising standards we could expect that a 1Ah battery with a 200A discharge would suit, but the marketers love putting bigger figures out there, hence the 20,000mAh (20Ah) reference despite the actual only being 8Ah.
They have something similar - which does work - at your local car shop. I think it may be about the same price, too, so I'm not sure it's worth betting on banggood's version.
Keep in mind that an NRMA membership, that'll cover a lot more than just flat batteries, is only about $100.
Why not get the more expensive kit for $81.67? http://www.banggood.com/68800mAh-4USB-Multi-Function-12V-Car…
I am not convince about the smaller charge kits. The heavier duty kits would work.
Still don't get it. How can the advertise capacity as:
Capacity:68800mAh
Actual Capacity:12000mAh
Maybe a duty cycle or peak load? I am not sure, but it might be that it is capable of 68000mAh draw for 10% duty cycle. So enough to jump start a car, but not enough to run a 20kW motor for an hour.
There is so much maths with batteries and electrical loads. There is a difference between amps and amp-hour. That's why some car batteries are quoted in CCA and some in Ah. CCA is basically an amp rating, or how much punch the battery has over a short burst. Ah is how much work that battery is capable of in one hour.
Amp is more like torque, amp-hour is more like horsepower.
For example, a phone battery might be 4.4aH or 4400mAh. Meaning it will last about 1 hour with a load of 4.4amps constantly applied. Because it has a time component, h, it is a measure of potential work that can be done.
A car battery may be 700CCA (cold cranking amps) but it would not sustain that 700 amps being dragged out of it for 1hour. So the max is 700, but if you wanted to use it as storage to run some lights, you might find that it only has a really low Ah rating, like say, 10Ah.
These batteries are like that. If you want to use them to jump your car, they would peak at 200 amps for maybe 15 seconds at a time up to 5 or 6 tries before it would be flat. High output, low storage. Peaks at 68Ah 5% duty cycle. If you wanted to use it to charge your phone, you could drag 8amps from it, and it would last 1hour…
I know the numbers are not right, but this is just an example on why there is two Ah figures quoted for these batteries. Peak load vs. cycle load.
Clear as custard, yeah? :)
They advertise something similar on the informercials. For that reason alone, I'm less likely to trust the reliability of a similarly marketed product.
Thank you for your comments guys. Myself is a member of RACQ so I guess having that in the car is just more about convenient (don't need to wait). But as the reliability might be doubtful I would keep my US25. Thanks again.
When it says stuff like:
Capacity:20000mAh
Actually Capacity: 8000mAh
I'd run away. I can't see how this is enough power to start a car if the battery is flat. It might work if the battery is a little low though.