Update: We’ve written an article about how pass-through charging enables power banks to be used in creative ways. Check it out.
Power banks are fantastic inventions, letting you charge your devices while on the go. But, as rechargeable batteries themselves, power banks will sometimes need to take a reprieve from their work to build their energy back up through a wall outlet. This brings about a question that continues to be the cornerstone of ongoing debate: can you charge your device while your power bank itself is charging, without causing any damage? Let’s take a look at the evidence and why pass through charging is needed.
What Is Pass Through Charging?
In very simple terms, pass through is an integrated technology in power banks that allows a device, say a cellphone, to be plugged and charged while the power bank itself is connected to a wall outlet. Today, most devices are embedded with chips that speak to a charge source, like your power bank. These chips indicate to the power source how much power it needs to charge quickly, as well as when its batteries are topped up. The intention here is to make sure that a battery doesn’t get overcharged, which could ultimately shorten its lifespan over time. The use of the chip is why we’ve been able to dismiss, once and for all, the myth that leaving your phone plugged in overnight is poor practice.
Pass through technology itself is in essence a series of power regulating circuits inside a power back that helps match the draw of energy needed by an output device to the amps being pulled from a wall outlet. If done right, pass through will move power directly from the wall outlet to the connected device, via the power bank. This is called prioritization. Depending on load balancing performance in the power bank, the latter should charge at either a regular or slower speed than normal when working with an output device.
How are Batteries Damaged?
We know from research that the most significant source of damage to a battery comes from excess heat, especially for lithium-ion batteries. It impacts maximum storage capacity, charge transfer speeds, and overall effectiveness. In order to deal with this issue, cellphones and other modern electronics will use that handy battery chip to throttle power transfers, slowing energy reaching the device to minimize potential heat creation. The longer the charge takes, the more opportunity there is to build heat, and the greater the potential to damage a battery.
So is Pass Through Potentially Dangerous to Power Banks and Batteries?
The answer, annoyingly, is maybe. If your power bank is able to effectively use designated internal circuitry to match input and output power levels, then you may not see a noticeable difference in charge capacity over time. That said, there doesn’t exist yet a purely efficient pass through system, meaning that it will almost inevitably take longer to charge your power bank if its output is connected to another device. More charge time will likely mean more heat build-up. And more heat could lead to sped-up degradation in a lithium ion battery.
The above also depends on build quality. Reputable companies working with pass through will often build their power bank out of more robust materials, helping to prevent battery degradation. The advice here is if you want to use a pass-through feature, don’t buy a knockoff. If your power bank doesn’t have any pass through tech built in, then you can bet there will likely be damage when attempting a conga-line charge.
In the end, to avoid damaging your device or power bank, follow two simple rules. First, make sure your power bank is equipped with the right circuitry to support pass through. Second, if you need to use it, don’t do it for very long – think emergency rations situations. By limiting pass through to a few hours at most, you should be able to reduce heat and the potential for battery damage.
67 Replies to “Is Pass Through Tech Dangerous to Your Power Bank’s Health?”
Can power banks with pass through technology keep the output power while I plug and then unplug input power?
Can I charge the Ravpower via the micro-USB inlet ?
Yes you can.
Can I use this to continously power a 5v DAC using pass thriugh. The dac draws less than 2.5 mA.
You can but don’t do it for too long.
So what is ‘too long’. If I use it to power my 3A DAC for intermittent listening sessions (12 hrs max per day) with there being minimal power draw (the DAC is not processing any music) for the other 12 hours then would this be acceptable. And, should I get the 10000 or 16750 RAV power bank?
No set amount of time. Go with the 16750mAh – more power in case you need it.
I am concerned that my device requires 3A power surge at startup and probably 2.4A ongoing charge whereas your device is rated at 2A charge input and output. I notice you also supply items with a USB c port that can process 2.4A. Since I only have one device but I do require 2.4A output (when the music is playing) then which device do you suggest I get. I would need to get a wall charger and a USB-c cable to 5v barrel power cable adapter.
From memory, only our 10000mAh mode has USB-C capabilities.
is it better to charge a powerbank with a 29W usb-c PD wall charger or with a microusb QC3.0 wall charger? i am particularly interested in the RP-PB059 model.
thank you in advance!
Choosing a right USB charger for power bank depends on the input requirement of the power bank. So the first thing you need to do is to check the input of your power bank. If the max input that the power bank supports is 5V/2.4A, a normal USB charger with a 5V/2.4A output will provide a sufficient charging speed. A Quick Charge 3.0 charger with 5V/3A is good too. However, remember that the max input the power bank can take is 5V/2.4A.
For the RP-PC059 charger, the max output of each iSmart USB Port is 5V/2.4A, the max output of the Type C port is 45W with 5 voltage levels (5V/2.4A, 5V/3A, 9V/3A, 15V/3A, 20V/2.25A max).
If your power bank has a USB-C port, you can use the USB-C port to charge the power bank. But remember, the max output will be restricted by the power bank’s input current and voltage.
I hope that’s clear.
Is it allright to charge the powerbank using both usb-c and micro-usb ports at the same time (using both charging inputs)?
I’ve never heard of that before. I guess it’s not fine otherwise it would be common charging advice.
Doubin dual input charging with usb-c and micro-usb is being done with at least one power bank on the market. Google it.
I am a little confused previous advice seems to contradict your above comment, which answer is correct?
Under your page:
RAVPower Q&A: We Answered Your Most Common Questions
28th November 2018 3am “Team Ravpower” made the below reply to a similar question.
Actually you can charge the power bank with the micro-USB input and USB-C input at the same time. However, but the micro-USB will not Quick Charge and can only charge at 5V. I hope this answers your question.
I think this explains why (somewhat annoyingly) I can’t use my RAVPower 24W Solar Panel and my 10050mAh Power Bank, even though the Power Bank has Pass Through?
I bought them for long distance (several months) bike touring with the idea that I would use the Power Bank to power the tech (GoPro, Cycle Computer & iPhone) while trickle charging from the Solar Panel. I worked out that, although the Solar Power wouldn’t be enough to power all that gadgetry, it would certainly slow the discharge of the Power Bank with a little power in to balance the lot of power out.
However, the reality is that if I try to connect it all, the Power Bank just rapidly flashes its lights and doesn’t work as I need it to.
Am I right in thinking that the internal Pass Through protection is now inhibiting this or am I doing something wrong here?
That is correct, Mark. It’s also likely that the sunlight is affecting performance.
Thanks for the confirmation and I get the point about the sunshine.
I’m about to go on a world cycle tour for 2-5 years and the perfect solution for me would be pretty much as described, a power bank that I could leave in the handlebar bag to power the GoPro and a couple of other GPS gadgets, but that would also receive a variable charge, dependent on amount of sunshine, from the 24W solar panel.
Are there any devices specifically designed that could be wired up like this?
This charger has a decently-sized battery and supports pass-through charging. It might be an option for you. What do you think?
Can a RAVPower pass-through power bank be used as battery back up for 5V devices?
I mean, can I use it to protect a 5V router from loss of mains (typical load <2W)?
In that case the power bank, fully charged, will be permanently connected to both a 5V wall charger and to the load (the 5V router): does your pass-through technology support such a setup?
I spoke to a product technician who confirmed that it is okay for the power bank to power up a 5V router while the power bank itself is recharging via a 5V wall charger.
Thanks for your answer, Sir.
May you kindly ask to your product technicians whether they’re able to say in how much time the power bank cells will degrade (up to the point they will not be able to power up the router in case of loss of mains) in such a setup?
Said differently, in UPS devices the batteries need to be replaced every 36-48 months or so: can your technicians say when in such a proposed setup the power bank should be replaced, in order to always have it fully functional?
Thanks in advance for your understanding in the matter.
Normally, the power bank could be used for 18 months as an UPS device. Therefore there is no need to replace it within those 18 months. Please note that it isn’t recommended you constantly use pass-through charging. As this blog article indicates, a purely efficient pass through system doesn’t yet exist so battery performance may be harmed with long-term use. Apologies for not mentioning that in my first reply to you.
Thanks for your further words, Sirs.
So, summarizing, despite your first advice, RAVPower pass-through power banks SHOULD NOT be used as a UPS device because they do not supply DC power directly from the wall charger to the connected output devices, even when the power bank is fully charged, given that those power banks will constantly feed the connected load through the cells and not through the charger: is that RAVPower official, final advice?
Last question, if I can take the liberty to ask: could your Model RP-PB066, even if it isn’t adviced as pass-through power bank, be used as a continuous UPS device for 5V output devices, given that it is both a wall charger AND a power bank, or won’t it ever behave/act as a battery back up in case of loss of mains?
Thanks in advance for your understandings.
We wouldn’t say official. It’s just something that one of our technicians advised when asked. You would need to contact firstname.lastname@example.org for an official response from the product team. Now in response to your other question, the same technician answered that when the power bank is fully recharged, the power bank will constantly power up the connected device through the cell or through the charger – it depends on which model you use. Case in point, the RP-PB066, once fully recharged, would directly deliver the current through the charger. On the other hand, other models would charge up through the cell inside the power bank. We hope that helps.
Do I understand correctly that models that directly deliver the current through the charger when the power bank is fully charged, can safely be used as permanently connected UPS’s for devices that are constantly drawing power?
Could you please post a list of models that have this feature?
(In particular, do the 6700mAh models RP-PB17 and RP-PB060 support this feature? These models may be tiny, but they can power Wyze USB cameras for several hours.)
In this case, PB17 and PB060 capacities are too small to support this feature. We can suggest RP-PB058 or RP-PB159!
Thanks for the straight answer, Sirs, I will ask to your support team.
To leave an informative note to other readers interested in such an application, charger / power bank combos from well known competitors, similar to the quoted RP-PB066, are not suitable for such a use because there’s a brief loss of power in the transition from mains to cells feed.
Just a follow up for people interested into this power bank application: I contacted email@example.com right before posting my answer here: well, up to now (almost five days later), they never answered, nor I got any bounce/ack for my email (so I cannot say if they didn’t get my request for some reason, or if they chose not to answer at all).
Summarizing, nothing official, just try if you wanna be brave.
Best regards and thanks to the blog team for all the kind help.
Thanks for letting us know Mark. Your email appears on our backend so I will pass it on to our customer support team. Sorry for the delay!
Would it be possible to have the power cell connected to the cigarette lighter in my car, and also to a dash cam? I.e Install and forget about- style? Or is it necessary to be unplugging it every so often? I’m not worried about running the power cell down when the car is off, I just don’t really want to be hardwiring an an alternative dash cam power source and switcher.
If you do this, the temperature would be higher than average as it is being recharged via the cigarette lighter while being connected to the dash cam. A higher temperature can cut the battery’s lifespan down. By the way, do you have a photo of this set up?
thanks for your reply. since posting I’ve read a lot about this and you are correct. I think what we need is the ability to leave a power bank permanently or semi-permanently connected to the car (either hardwire, or USB), and then that cell has the ability to pass through (or actually pass around) the power when the car is on, so it is not charging itself up, just a bypass, while being used as a conduit to supply power from the car to the dash cam. then when the car switches off, the bank senses that, and automatically starts powering the camera by itself. And of course, when the car switches off, it must not draw any more current from the car battery. I can think of a few solutions to this, a couple of relays would do it quite well (I’m making one this week actually), but I wonder, if this has been made commercially yet? surely THIS is the function that everyone needs? or maybe it is already out there, and called something different?
Currently purchasing a RP-PB043, so far my i got a QC cig charger, cable to powerbank, usb- cig( female adapter) connected to powerbank and then my dashcam connected to it. So far i have tried a few Zendure and misread one that said it supports QC but it was output only. My method works great but slow charging, bank will ran out of power in 2 days if i don’t drive it, and my daily driving time around 2 hours won’t be enough to charge it enough so hope Ravpower one will be a better solution for me.
Let us know how it goes and be sure to include a photo of your setup!
Hi, I have been wanting to do exactly the same, or quite close actually. 2 methods that I have been thinking of:
1) Hardwire power bank to car ACC only (red wire) – only powered after igniting the car.
2) Hardwire power bank to car CONSTANT (yellow wire) – always on
Either hardwiring will be using a 12v to 5v adapter (much like a cig socket charger) and WITH battery discharge protection – meaning it cuts off the supply if car goes below 11.6v.
The power bank(s) that I am getting will then be connected to my dash cams for overnight recording in case of unforeseen and unlucky accidents – I was looking at 2 x RAVPower 32000mAh to do the job.
With all that theory above, I guess the outcome for each method would be:
1) Slow charging of power banks, in the end will need to bring them home to charge properly every other day, but has dash video downtime at some point.
2) Will never run out of power supply and dash video capture, however run risk of car battery going flat if the hardwiring adapters are not so good.
The commercial solutions out there are pretty expensive i.e. BlackVue CellLink + Power Magic Pro or iRoad Power Pack. So if anyone wants a cheaper alternative, these DIY suggestions might just work, with similar concept.
Is RAVPower interested in creating something solid for car/dash cams/security support like this? Say like a 50,000mAh bank with hardwiring cables/tools and battery discharge protection technology.
Sounds like a great idea and we wish RAVPower could be part of it. Sadly we have no plan for the rest of the year to release a power bank of that size or with those tools. If you do try it with two of our 32000mAh power banks, then please let us know.
Thanks for the response and consideration. I think the capacity need not be huge but it all boils down to:
a) Super fast charging in 45mins (high voltage and ampere input),
b) Car-battery discharge protection.
Such banks are in good demand so RAVPower can probably capitalize on that 🙂
I have just bought rp-pb055 27000maH, can it charge pass through via ismart usb?
For the AC output, no. But for the DC output, the answer is yes.
I’m using Macbook Pro 2016. Sometimes when I charge my macbook pass through via usb-C, the macbook says “Battery is not charge” but it still use the power source as the adapter, not using the battery. Sometimes the battery will charge at very slow rate (around 6-7 hours). Is it any problem?
Try and hold the power button down for 5-8 seconds to reverse the flow of charging. Which product are you using? Which charger are you using? Are you recharging via the USB-C? Tell us so we can advise you.
I’m using rp-pb055 27000maH
My mistake. So the RP-PB055 doesn’t have a power delivery function, therefore it will charge a MacBook slowly.
Can I keep my ravpower charged via solar panel and an external device connected at the same time?
It’s not advisable. The external charger powering from the sun won’t be faster than the battery being drawn from it via the connected device.
Some RAv power model have input =15W (5V@3A) that a solar panel can easily supply. It means that a 74Wh battery (20000mAh) will be fully charged in about 5 h! If my raspberry zero consumption is about 3W, I can theorically power it for a very (very) long time
Heat shrink tubing is what we like to use to fix/reinforce things like that in my house. I hadn’t thought of some of the others you suggested – very inventive. Thanks for sharing!
You are welcome!
Do you have an updated list of the devices that support passthough?
As i wanted to check if the devices below were supported.
Solar 15k RP-PB130
Solar 10k RP-PB082
Both have pass-through charging. No updated list but we will make one soon.
I have an energizer power pack when I plug the wiring to charge it up when it’s fully charged it keeps putting out a voltage out of the charger socket even though it’s charged thank you
I have a energizer power bank I plug the wire into the charging socket and it charges up when it’s finished charging it starts putting an output out of the charging socket even though it indicates fully charged thank you for replying to my comments
Can your jump starter products ( https://smile.amazon.com/dp/B0743BFD5H/ for example) support pass through charging? I’d like to use a power bank to power my dash camera in standby bump detection mode but also have the battery serve the dual use of being a jump starter if necessary.
We don’t recommend that you use jump starter products for pass through charging. In this case, the jump starter may damage the Dash Cam.
Hi Thom. I have two different brands of power banks. I have used them both for my dash cam and they both work great because they has pass through charging. I have a Viofo A119 V3 that runs into my console and it is plugged into a USB port but shuts off when the key is turned off. The new dash cam has parking mode so I wanted to keep it simple so I plugged the dash cam into the Power bank and the power bank into the USB plug to keep it charged when I’m driving. The 20000mah and up will keep filming for 5-6 days without starting the truck. I like the fact that it will drain the power bank and not the battery. Here is the down side of doing this if you do. Most of the better quality dash cams use Capacitors and not lithium batteries due to heat and cold. A power bank uses lithium so make sure it is not left in the heat or cold or it will not work. I keep mine in the console and it works great in there but will not in freezing temp. I find this better then hard wiring it and maybe draining my battery
I am going on a cycle tour and have been reading the posts above. I have a dynamo hub 6V 3 Watt, so 0.5 amp and I would like to run the charge feature of the dynamo in to the RavPower RP-PB41. And then connect my smart phone (LG G4), to the pwerbank for GPS.
Would this work with the pass-through feature, i.e. charge the powerbank whilst the powerbank provides power to the phone?
Thanks for getting in touch! Unfortunately the RP-PB41 won’t support a dynamo hub, so this wouldn’t be possible. Enjoy your cycle tour!
Hi, I’m interested in using a power bank such as a RAVPower device as a battery backup for my Wyze home security cameras, which are powered by microUSB and draw about 600mA. The idea is that I would power the RAVPower device via a MicroUSB charger in the wall socket and then plug my camera into the RAVPower device. If the wall power was on, the camera would be provided power from the wall while the RAVPower device slowly trickle-charged itself. If the wall power was interrupted, RAVPower would switch to providing power from the battery. Is that a safe use of existing RAVPower devices? Is there anything you could recommend?
Hi, thanks for getting in contact!
In this situation, your RAVPower devices can be used normally. We recommend useing RP-PB058 or RP-PB159; other models are also supported, but when the camera is charged and disconnected the power bank output will also be disconnected and automatically connected after 5S, affecting your experience.
When you say “camera is charged and disconnected”, are you referring to interruption of the wall power?
If so, could you please post a list of models that do not interrupt output when input is disconnected?
We can suggest RP-PB058/RP-PB059/RP-PB159. Hope this helps!
My tesla model 3 does not support qc charging. Can I connect the power bank to car USB for charging and then connect the qc output to charge my phones?
So when there is no phone to charge, the power bank charges.
Would this be a safe permanent soluton?
Hi, if the devices are not QC3.0 compatible, then it will be charged at the standard speed.
When I trickle charge my power banks everything I plug into my power bank also trickle charge.
I want a power bank that charge 1,4A while delivering 2A.
Is there such a bank?
Hi Anton, we have many RAVPower banks that support this function. We suggest the RP-PB186, you can find it here: https://www.ravpower.com/products/rp-pb186-10000mah-power-bank