I got this unit to explore it as an option for providing a high current 12V power supply for short term use. It's a car jump starter and USB power bank. The 12V output is direct from the lithium battery pack with no protection, so care would need to be taken not to over discharge the pack when using it as a 12V supply.
The connector is a standard EC5 high current battery connector, which is handy. The USB connector has floating data pins, so it may not be recognised by some devices.
It's a very modular design. A microcontroller that displays charge level and controls the buck regulator for the 5V output that is also used for the LED, and a current regulator for charging the lithium pack that has a three cell protection chip and matching charge/discharge control MOSFETs. One oddity is the use of the microcontroller to directly drive the charging buck regulator's MOSFET.
The Battery pack has a four pin connector for charging and monitoring individual cell voltage. There's no balancing, just a shut-off when one of the cells reaches about 4.25V. It also has the high current connector tapped directly across the pack that then feeds a plug-in jump start module that contains the anti-reverse charging diodes and the MOSFETs used to switch the output to the beefy alligator clips when a separate microcontroller detects that suitable conditions have been met.
The lithium cells used in these are usually the high current type that have a different internal construction from normal cells. Instead of the electrode foils being long spiral-wound strips, the high current cells often have a stack of alternate layers of electrode foils and dielectric separators with a cluster of parallel tabs brought out the end of the cell. This allows discharge at very high currents, in brief bursts of hundreds of amps.
It looks a fairly sensible design, but as with most of these jump starters it's only really suited to an occasional quick jump start as opposed to endless cranking of an engine with issues that caused the car's battery to go flat in the first place.
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The connector is a standard EC5 high current battery connector, which is handy. The USB connector has floating data pins, so it may not be recognised by some devices.
It's a very modular design. A microcontroller that displays charge level and controls the buck regulator for the 5V output that is also used for the LED, and a current regulator for charging the lithium pack that has a three cell protection chip and matching charge/discharge control MOSFETs. One oddity is the use of the microcontroller to directly drive the charging buck regulator's MOSFET.
The Battery pack has a four pin connector for charging and monitoring individual cell voltage. There's no balancing, just a shut-off when one of the cells reaches about 4.25V. It also has the high current connector tapped directly across the pack that then feeds a plug-in jump start module that contains the anti-reverse charging diodes and the MOSFETs used to switch the output to the beefy alligator clips when a separate microcontroller detects that suitable conditions have been met.
The lithium cells used in these are usually the high current type that have a different internal construction from normal cells. Instead of the electrode foils being long spiral-wound strips, the high current cells often have a stack of alternate layers of electrode foils and dielectric separators with a cluster of parallel tabs brought out the end of the cell. This allows discharge at very high currents, in brief bursts of hundreds of amps.
It looks a fairly sensible design, but as with most of these jump starters it's only really suited to an occasional quick jump start as opposed to endless cranking of an engine with issues that caused the car's battery to go flat in the first place.
I specifically avoid using intrusive mid-run video adverts, which means I don't earn as much from my content as other YouTubers.
If you enjoy these videos you can help support the channel with a dollar or two for coffee, cookies and random gadgets for disassembly at:-
https://www.patreon.com/bigclive
Patreon supporters get early access to advert-free videos as they are made, and also regular live streams.
This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.
Other contribution options are available at:-
http://www.bigclive.com/coffee.htm
#ElectronicsCreators
it jumpstarted my sunday
Really unfortunate they didn't include balancing in the internal PCB, as it had all the needed connections.
Sounds a lot like the DeWalt flexvolt batteries (can be used in 60v and 20v tools), where they advertise them as being 60 volt, 9 amp hour. But in the fine print, they mention is 60 volt, 3 amp hour, or 20 volt, 9 amp hour. Its 3 banks of 20v 3 amp batteries, and the controller on the battery either runs them in series or parallel depending on the tool youre using.
I’ve had a few of these when they used SLA batteries, they required a handle due to the weight. Now I’ve got one of these types now and it’s amazing the size engine it can start.
The phones BigClive mentions are the Samsung Galaxy Note 7. The issue with those was actually slightly different from what BigClive describes — no real fault of his, it's hard to find out what actually happened. I no longer remember my source (perils of ADD-associated and other memory issues) but it was extremely trustworthy.
Basically what happened was, lithium cells, especially pouch cells, need a very tiny amount of extra space allocated to them when charging, because charging makes them swell very slightly. During the design phase of the phone in question, this space was not allocated, as a management directive over the protests of the engineers. Thus, when charging is attempted, the battery kind of swells into itself, if that makes sense, and shorts out internally… which, because it's a lithium battery, means that extraordinary energy density kind of lets loose all at once.
For the less-technical amongst us: an internal short in a battery is the equivalent of connecting the two battery terminals directly together with a bit of wire, but INSIDE the battery. If you've ever done that thing where you test a car battery by twiddling a wrench between the terminals to get sparks, you kinda know what you're in for here. If not… well, the spectacular shows the Note 7 put on are pretty well documented at this point… other videos on YT will help. Basically imagine one of those cheap home fireworks sets you get at Wal*Mart going off inside your phone — the entire set, all at once! (In the famous word of Wile E. Coyote: YIPE.)
The kicker here is that the space required for the battery to properly function was a mere one-tenth of one millimeter. That distance is imperceptible to the human eye. If you want to try and conceptualize it… go to an office supply store, they sell 0.5mm (half-millimeter diameter) pencil lead for mechanical pencils. Look at the pencil lead in that size and imagine something 1/5 as thin… or go to Wal*Mart and look at the 0.7mm lead and divide by seven instead of five. (or divide by eight, it's easier — divide in half, then in fourths — and there's essentially no difference at that point lol.)
Management people do dumb stuff sometimes.
As a former automotive tech, the choice to omit a low voltage shut off for the 12V is a mistake. The most common response from people when their car won’t start is to run the starter and crank the engine continuously either until the engine starts or it stops cranking. Quite frequently I’ve seen cars come in with dead batteries, melted starters and even melted battery cables due to engine not starting for some other reason (like a bad fuel pump, failed engine sensor, or my personal favorite, it’s out of gas). I’d imagine that more than a few of these jump starters have hit the dump because the owner strapped it on their battery and just repeatedly cranked the engine until the jump starter died.
A very good Sunday morning to you all from Wellington Somerset
Can't wait until batteries have more power to where you basically have a mini nuke in your pocket.
Morning Clive me old mate!
Golly you do work around the clock, I am ill so up at all sorts of time, what’s your excuse? Lol
You are still the only channel I can click ‘thumbs up’ before I even watch because your work is so reliable. And once again I enjoyed this video it explains a lot.
Kindest
Bob
England
Clive, do you have any thoughts why these LiPO packs performed so poorly on Project Farm and most wouldn't crank his low-compression 2.9 V6? I routinely jumped my 2012 Mustang with a 3.7 liter, high-compression V6 with one of these with a 11.1v, 4000 mAh pack inside when my battery would die nearly instantly after being shut off.
I know he basically directly shorted them using a big load tester when in reality the 'peak' current of hundreds of amps is only needed for less than a second to get the starter up to speed, after which much draw only about 150 amps while cranking. He then tried jumping his small truck with a battery that had like 5 volts, which I'm guessing took the current instead of it going to the starter while cranking? I know these can provide the current to crank an engine at least briefly unassisted, and they basically all use the same batteries.
Smart that they went with a 15V charging voltage, as that means you can easily charge it from you vehicle after its stated…. since a running vehicle (with a good alternator) outputs anywhere from 14V to 14.8V.
A word of warning on these type jump starters. If left in your glove compartment too long, two months in my case, the batteries can dip below acceptable levels, and then when you attempt to recharge it, it will not take a charge! Keep them topped off is all I can say, and yes, I attempted to force charge it in a last ditch effort by bypassing the charge circuitry, to no avail… As Clive would say, it's time to take it to bits…
The mosfets on the 12 volt side look like the legs of them are all soldered together won't that short them out
We used the Ablic IC for secondary OVP for an ASIL-D 12V automotive pack. It’s definitely shouldn’t be used as a substitute for charging. There are standalone true BMS IC’s but I understand why most manufacturers don’t use them, they can be quite complex little systems. But this is the safest approach.
Speaking of automotive applications… Sometimes we will put redundant parts in series or parallel parts to take more current but specify different part numbers to get a better FIT rate and also to ensure during mass production if a batch of parts has an issue, it’s not effecting the second part. In this product it might be they were available but yeah it’s a common practice in safety critical systems.
Am I having deja vu I thought you did a video about one of these a while back
Ahhhh 3am and the smoothing educational voice of BigClive… thanks
You do realise the mismatched diodes will conduct differently and when it's under a big load they will let the smoke out as one will take too much currant and pop then the other two will amd the whole thing will end up open or short also could burn you if your holding it or go to touch it after said event