Battery pack with 12v socket plug in?

[Sunny]

I get it BUT you are charging the power bank whilst using its power!!!!!
I WILL not do this, it's unsafe!!!!!!!!!!!!!!!!!!!!!!!

You didn't get it.
I tried but read my last post few times.
Anyways, my suggestion was to simply the use of battery pack.
If you are not confident that it's safe, don't do it.

 

[DavidUK]

No, you were charging the battery pack too. Read your post again.

Without the 2nd cable to charge the battery pack your idea is fine.

 

[Sunny]

No, you were charging the battery pack too. Read your post again.

Without the 2nd cable to charge the battery pack your idea is fine.

I'm not sure if I want to laugh or be sad.
I didn't come up with this device.
That's how the product works.
I was just explaining it how to use it for dashcam and I'll stop now as it's not going anywhere.

Anyways, forget it. Don't do it if you are uncomfortable.

 

[DavidUK]

I have replied to Nextbase asking why they allow the Amazon ad to mislead, and also to advise why two answers there say they use the pack whilst charging it.

Will report back...

Reply today from Nextbase Shop:

"Hi
Nextbase have actually confirmed that the unit can be used whilst being charged.
Regards,
Nextbase Shop"

 

[DavidUK]

@Dashmellow what do you make of my online chat with Nextbase, below, about their battery pack (see post #1).

WELCOME TO LIVECHAT
RYAN
2:56 pmHello. How may I help you?

DAVID CHAPMAN
Hi,

I had an email today about the Nextbase External Battery Pack.

Do you have a technical expert to hand?

1st email yesterday: "The battery will not work whilst being charged and the warranty period is 6 months.
Kind Regards
Karen"

Then today: "Nextbase have actually confirmed that the unit can be used whilst being charged"

So, is it safe to charge the pack whilst also using it to power a dash cam?

This is so that when I park up and leave the vehicle I can just leave the cam running on battery power.

RYAN
Hello

Yes I can confirm that you can power your camera and charge the powerbank at the same time

I have just tested it

DAVID CHAPMAN
Isn't in dangerous to do this?

I thought it an unwise idea to charge a lithium-ion power bank at the same time it is being discharged because it puts a great deal of stress on the battery cells.

RYAN
This is the first I have heard of there being any stress caused on the battery while it's being charged, same as you probably use your mobile device while the battery is charging

DAVID CHAPMAN
Ryan, what is your position at Nextbase and what experience do you have of these battery packs? No disrespect intended, just like to know by what authority you speak.

RYAN
Hello David, I have just spoken to the gentleman who designed the powerbank and he has explained to me that...

When the DC out is plugged in while the unit is being charged that the circuit is designed in parallel meaning that the DC out takes priority while any left over current gets redirected to the battery to charge it.

Therefore the unit isn't being drained while it's being charged

DAVID CHAPMAN
There's a debate going on over at Dashcamtalk about whether this pack can be used to safely power a cam AND charge at the same time. The general consensus about similar packs is that it's dangerous.

However, your one seems to have been designed with a dash cam in mind, whereas others charge iPads, phones, etc.

So, could you ask the designer to confirm that this pack was consciously designed with the idea a user could charge it, and power a cam, simultaneously? And that this would be both safe and not cause any damage or loss of lifespan to the battery's cells? Thanks.

RYAN
Yes I can confirm that the pack was consciously designed to charge it's internal battery and power a camera (or DVD player) simultaneously... although the power bank will charge slower than usual while another device is being powered

hope this helps

DAVID CHAPMAN
...and that it's safe to do so and won't cause premature failure of the cells?

RYAN
Correct

I hope that I've answered all of your questions David

DAVID CHAPMAN
Yes, so far! Many thanks!

 

[Dashmellow]

Reply today from Nextbase Shop:

"Hi
Nextbase have actually confirmed that the unit can be used whilst being charged.
Regards,
Nextbase Shop"

Again, most power banks "can" be used while charging. The question is "should" they be?
So far, I've primarily seen manufacturers make this claim knowing that if the product lasts only a year or so instead of two or three years like it should, the customer is none the wiser.
Anker used to claim that their power banks could do "pass-through-charging" but to their credit they eventually withdrew that claim for their products and advised against it.
Without a full explanation from Nextbase regarding the approach they take to achieve their claim I suggest we remain skeptical.

 

[Dashmellow]

"When the DC out is plugged in while the unit is being charged that the circuit is designed in parallel meaning that the DC out takes priority while any left over current gets redirected to the battery to charge it."

Everything I've read on this subject suggests that this is not how "pass-through-charging" is achieved.

 

[DavidUK]

So is this explanation something new to you? Or is it Bul***it?

 

[Dashmellow]

According to Isidor Buchmann, the man behind the web site Battery University, owner of Cadex Systems (battery analyzer manufacturer ) and author of
Batteries in a Portable World: A Handbook on Rechargeable Batteries for Non-Engineers it is not good to simultaneously charge and discharge a lithium-ion battery for several reasons.

If you are discharging a battery at the same time you are charging it and the battery is hovering at the "threshold voltage" where it is very nearly but not quite fully charged (saturation point), this confuses the charging circuitry and puts it and the battery under stress.

Charging Lithium-ion:

"A portable device should be turned off during charge. This allows the battery to reach the set voltage threshold and current saturation point unhindered. A parasitic load confuses the charger by depressing the battery voltage and preventing the current in the saturation stage to drop low enough by drawing a leakage current. A battery may be fully charged, but the prevailing conditions will prompt a continued charge, causing stress."

One of the primary reasons lithium-ion battery banks should not be charged while power is simultaneously being drawn from them is because it violates the electro-chemisty of how batteries function.

In a lithium-ion rechargeable battery as used in these types of power banks both the positive electrode (cathode) and the negative electrode (anode) bind lithium ions from lithium oxide in the electrolyte that migrate back and forth between the cathode and anode during the charging and discharging process. When the battery is discharging, the lithium ions moving back to the cathode release energy (electrons) in the process and this is how the battery powers your device. When the battery is being charged, the lithium ions migrate back through the electrolyte in the other direction towards the anode.

So, if you charge the battery while it is simultaneously discharging, then you are trying to force the lithium ions to move in opposite directions through the electrolyte at the same time which will cause a lot of stress to the cells and this will eventually lead to lithium metal plating which is the dangerous process that can ultimately cause a thermal runaway (chemical combustion) - (as with the recent Samsung Galaxy Note 7 fires & explosions), but for the most part will most likely just shorten the lifespan of the bank's cells and prematurely reduce its charging capacity.

All Apple products and many other brand computers, smartphones and tablets have special circuitry that allow them to be plugged in while being used. Power banks generally do not.

Not too long ago, Apple was under attack from consumers because the products would display 100% charge even if they were not quite fully charged. This turned out to be simply because Apple keeps the battery management process hidden when plugged in to avoid confusion to the consumer. When an Apple device is nearly 100% charged while plugged in, it stops charging and lets the battery drain down slightly before allowing the charging process to resume. That way it is not charging and discharging simultaneously.

AllThingsD article:

"Apple does, in fact, display as 100 percent charged just before a device reaches a completely charged state. At that point, it will continue charging to 100 percent, then discharge a bit and charge back up to 100 percent, repeating that process until the device is unplugged. Doing so allows devices to maintain an optimum charge, Apple VP Michael Tchao told AllThingsD today. “That circuitry is designed so you can keep your device plugged in as long as you would like,” Tchao said. “It’s a great feature that’s always been in iOS.”

You can read the full article HERE.

If the Nextbase power bank has circuitry that actually does what Apple describes above and that addresses what Isador Buchmann is cautioning against it should be fine but the explanation from Nextbase: "When the DC out is plugged in while the unit is being charged that the circuit is designed in parallel meaning that the DC out takes priority while any left over current gets redirected to the battery to charge it.", sounds nebulous and suspect.

"Left over current?"

 

[DavidUK]

But the Nextbase one, if discharging a bit then charging, would cut off the cam's power when deciding to go into charge mode and stopping discharge?

 

[Dashmellow]

But the Nextbase one, if discharging a bit then charging, would cut off the cam's power when deciding to go into charge mode and stopping discharge?

No, with the proper circuitry the power bank should continue powering the camera but should temporarily stop charging its own cells.
This would be the same as continuing to talk on a smartphone or use your laptop when it is plugged in. These devices won't shut down while the battery management circuitry is doing its job.

 

[DavidUK]

I could research this for ever, but found this little test: http://www.theoutpost.org/6-techy/raspberry-pi-usb-power-bank-ups-pass-through/

Following the link of the last device, RS Pro 5000mAh Lithium Polymer PB-A5200 which passed both tests, the user guide is here: http://docs-europe.electrocomponents.com/webdocs/12e3/0900766b812e31a0.pdf

It says...



But, once again, can this be trusted?

 

[Dashmellow]

I could research this for ever, but found this little test: http://www.theoutpost.org/6-techy/raspberry-pi-usb-power-bank-ups-pass-through/

Following the link of the last device, RS Pro 5000mAh Lithium Polymer PB-A5200 which passed both tests, the user guide is here: http://docs-europe.electrocomponents.com/webdocs/12e3/0900766b812e31a0.pdf

It says...

View attachment 26802

But, once again, can this be trusted?

You know, David, you've been at this for three days now ever since you started this thread. I've tried my best to provide helpful feedback and answer your questions but you are still hammering away at it regardless. Accordingly, I have nothing else to add to the discussion but do wish you good luck with this endeavor.

 

[Dashmellow]

I could research this for ever, but found this little test: http://www.theoutpost.org/6-techy/raspberry-pi-usb-power-bank-ups-pass-through/

Following the link of the last device, RS Pro 5000mAh Lithium Polymer PB-A5200 which passed both tests, the user guide is here: http://docs-europe.electrocomponents.com/webdocs/12e3/0900766b812e31a0.pdf

It says...

View attachment 26802

But, once again, can this be trusted?

FWIW, I'd like to add a little addendum here in reply to your last query.

The so called "testing" that was done in the link you provided engages in the same sort of wishful thinking about whether an inexpensive power bank "supports" (tester's terminology) pass-through-charging or not that you seem to be engaged in in your quest for this feature.

As mentioned several times here in this thread there is a critical difference between whether a device like this will "let" you charge it and discharge it simultaneously and whether it is a wise thing to do.

As also mentioned previously, it is quite common for manufacturers of generic Chinese power banks to claim their products "allow" pass-through-charging whether it has the appropriate circuitry to actually "support" it or not.

There is a reason the claim is worded vaguely enough for you to be asking, "But, once again, can this be trusted?"

The chances that the £16.80 5000mAh power bank you cite making this questionable claim can really have this sophisticated feature otherwise usually only seen in £500 smartphones and tablets at that price is highly unlikely.

The reason most power banks don't commonly have the circuitry for "pass-through-charging" is that this is not a design goal for the product as most consumers do not use the product this way.

 

[Rajagra]

Sigh.

You cannot charge and discharge a battery at exactly the same time. There are wires leading to the battery. Current can only flow through wire one direction at a time. (OK, there are things called eddy currents, they are not relevant here though.)
When a battery is "charging and discharging at the same time" what do people imagine is happening in the wire to the battery?
Seriously, at some point someone is going to have to demonstrate this by getting three olde worlde analog ammeters and hooking them into key places in a circuit.

If you have a battery pack on charge from an external source while it is also powering a device (where allowed), then one of three things is happening:

1) The external power source is supplying more current than the device needs. In this case the device takes what it needs and the rest goes to charging the battery.
Status: The battery is just charging, no reason to be alarmed.

2) The external power source is supplying less current than the device needs. In this case the device takes everything from the external source plus some from the battery to make up its needs.
Status: The battery is just discharging, no reason to be alarmed.

3) The external power source is supplying exactly what the device needs. In this case the device takes it all, the battery is left alone.
Status: The battery is doing nothing, no reason to be alarmed.

So whatever the case is, no reason to be alarmed.

The only conceivable problem is when the device is fluctuating wildly between high and low current draw. This could be enough to keep swapping between states 1 and 2. But even then, the battery is not charging and discharging at the same time, it is merely alternating. Not great for battery life, but in normal use of a dashcam this isn't going to happen unless for example you keep turning the screen on and off and are extremely unlucky in how the numbers pan out.

P.S. If you are uncomfortable about that, consider the idea I put forward in another thread: Use a simple relay to sort out the problem.
When accessory power is off, the dashcam runs off of the battery pack through the normally closed pin of the relay.
When accessory power is on, it charges the battery pack and toggles the relay, which disconnects the dashcam from the power pack, and connects it to accessory power instead through the normally open pin of the relay.

 

[DavidUK]

@Dashmellow - I do get like a dog with a bone when I find there's a problem with something I'd like to work but maybe doesn't. This thread isn't somehow aimed at you. You've been very helpful. So please don't feel you have to keep up with my sometimes inane ramblings!

 

[DavidUK]

@Rajagra - so you're saying there's no internal conflict of electrons fighting against each other across the sea of electrolyte, firing off cannon shots at each other as they meet?

Did you ever finalise your relay idea? I did come across it the other day (it's all a blur!) but didn't take it all in.

 

[Rajagra]

@Rajagra Did you ever finalise your relay idea? I did come across it the other day (it's all a blur!) but didn't take it all in.

I stopped having a need for it, so put it on hold. But I will most definitely get around to it.
The only difficulty is making it tidy. Would be nice to put the project in a box with the appropriate USB sockets, but much easier to have flying leads (from chopped up USB cables.)

 

[Dashmellow]

Sigh.

You cannot charge and discharge a battery at exactly the same time. There are wires leading to the battery. Current can only flow through wire one direction at a time. (OK, there are things called eddy currents, they are not relevant here though.)
When a battery is "charging and discharging at the same time" what do people imagine is happening in the wire to the battery?
Seriously, at some point someone is going to have to demonstrate this by getting three olde worlde analog ammeters and hooking them into key places in a circuit.

If you have a battery pack on charge from an external source while it is also powering a device (where allowed), then one of three things is happening:

1) The external power source is supplying more current than the device needs. In this case the device takes what it needs and the rest goes to charging the battery.
Status: The battery is just charging, no reason to be alarmed.

2) The external power source is supplying less current than the device needs. In this case the device takes everything from the external source plus some from the battery to make up its needs.
Status: The battery is just discharging, no reason to be alarmed.

3) The external power source is supplying exactly what the device needs. In this case the device takes it all, the battery is left alone.
Status: The battery is doing nothing, no reason to be alarmed.

So whatever the case is, no reason to be alarmed.

The only conceivable problem is when the device is fluctuating wildly between high and low current draw. This could be enough to keep swapping between states 1 and 2. But even then, the battery is not charging and discharging at the same time, it is merely alternating. Not great for battery life, but in normal use of a dashcam this isn't going to happen unless for example you keep turning the screen on and off and are extremely unlucky in how the numbers pan out.

P.S. If you are uncomfortable about that, consider the idea I put forward in another thread: Use a simple relay to sort out the problem.
When accessory power is off, the dashcam runs off of the battery pack through the normally closed pin of the relay.
When accessory power is on, it charges the battery pack and toggles the relay, which disconnects the dashcam from the power pack, and connects it to accessory power instead through the normally open pin of the relay.

Batteries should not have a parasitic load on them of any kind when they are charging. Period! Otherwise you are causing it and the charging circuitry stress regardless of the load.

 

[Dashmellow]

@Dashmellow - I do get like a dog with a bone when I find there's a problem with something I'd like to work but maybe doesn't. This thread isn't somehow aimed at you. You've been very helpful. So please don't feel you have to keep up with my sometimes inane ramblings!

I know the feeling! Been there myself all too many times. Don't sweat it!