L5 USB Car Chargers

Has anybody tested those cigarette lighter USB 2.0 chargers with their L5? I know it would require a USB-C to USB 2.0

it should work, with a limited current at 500ma (USB 2.0 specs), so it will be charging slower than with the provided USB-PD charger

Yes it works. But it barely suffice to keep the charge, L5 isn’t getting charged so much probably because of the limited current mentioned by fralb5.

For myself aluminum body and proper shape/stability comes at first place. Secondly without 2.4A pro USB2.0 charging port someone is just throwing their money away (simple approach). 500mA approach from @fralb5 I cannot follow as adequate for car charger selection, let me pretend I disagree, as Librem 5 will take what it needs (500mA or more) but if charger is weaker than 5V/2.4A pro … old man (although this is my main point here). I have several car chargers (my favorite one even includes BC1.2, but it’s not for everyone’s need, as provides 100W in total) but car chargers like this one and this one (AliExpress links) are from reliable manufacturers (if someone don’t want to spend hours in searching, without knowing for what to pay up front). And, for example, this one confirms BC1.2 charging protocol (might turn out it is just fine car charger for Librem 5, but no need to test it myself).


That might be right.

Ignoring inefficiencies, if the 4500 mAh battery is flat in 9 hours with the phone doing nothing then the phone, while doing nothing, is drawing about 500 mA i.e. the charging of the battery is “running on the spot” if the charger can only deliver 500 mA.

I don’t know whether it is possible to charge the phone (battery) while the phone is powered off. If you shut down the phone and then plug it in to charge (using the supplied charger) then the phone immediately boots, which isn’t really what I want.


The USB 2.0 specs limit to 500ma, but if your charger can do more, the Librem 5 internal charger can go up to a 3.25A limit

But you will have to set up manually, with the following command line

But be extra careful with this command, you can break your stuff with it, here some recommandations

I suggest you to go check this thread, there some others interesting stuff about it

Also remember that the optimization of power consumption is a work in progress, it will get better with time (and updates)

I’m by no means an expert, but TI’s bq25895 includes support for “non-standard” adapter 1A, 2A, 2.1A and 2.4A:

Besides USB500 and DCP, the device can also detect three types of non-standard adapters as shown in Table 5-1.

“When DCD 0.5 sec timer expires, the non-standard adapter detection is used to distinguish three different divider bias conditions on D+/D- pins. When non-standard adapter is detected, the input current limit (REG0[2:0]) is set based on Table 5-2 and REG08[7:6] is set to 10 (Adapter port). If non-standard adapter is not detected, REG08[7:6] is set to 00 (Unknown) and the input current limit is set in REG0[2:0] to 500mA by default.”

If you insist, but: “Most HVDCP adapters that use the QC3.0 protocol are rated to 1.5A instead of the 3.25A of a DCP. … At the present time, there are no adapters that include the MaxCharge™ algorithm.

Just FYI (or orientation) above post info (as linked) TI published on Dec. 30, 2020! And, @Torrone already linked another (quite) related issue:

Take a look here: https://source.puri.sm/Librem5/librem5-base/-/merge_requests/190.

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Injoinic Technology IP6505 eSOP8 is a Synchronous-Rectified Buck Converter and support 10 fast charge output standards (to include DCP / with BC1.2 support in particular). Therefore I think (after some research) that this car charger with two IP6505 power converters (one pro USB-A 24W port) might be worth of trying it out (order it before sold out and try it out with Librem 5). @brandonrosano, please let us know if this car charger worked out well for you (once in use).

And, if anyone looks for the IP6538 power converter based solution, link is here.

Edit: In exchange, once I get my Librem 5, I’ll test YZ826 (using Zhirong SW3518S charging chip) module with it.

I think you missed my point, I’m not insisting on anything, I’m just giving specs here, with a way to set manually the input power, and warnings about it
You are talking about handshake protocols to auto-determine input power

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Yes. And as a slow motion learning person I might even speculate on Librem 5 using brand new TI’s bq25790* battery charger ICs that is able to detect USB BC1.2, SDP, CDP, DCP, HVDCP and non-standard adapters, meaning negotiate (handshake) preferred current with the Librem 5 original charger (or some adequate car charger), as I’m trying to understand this (as example here).

Either way, and even if bq25980 eventually in use I’d recommend I’m aware of only several options for Librem 5 that may count, and those are 500mA, 700mA, 1.1A, 1.3A, 1.6A, 1.8A, 2.1A and 2.4A as described here and here:
#define BQ25890_TREG_TBL_SIZE ARRAY_SIZE(bq25890_treg_tbl)

*“When the adapter is unplugged, the sources to power the system and accessories can switch from the adapter to the battery seamlessly, making it possible to eliminate the DC/DC converter for OTG mode and FRS from the block diagram.” This might be found (just my nonexpert opinion) as big advantage of bq25790, but only few people here, to include @guido.gunther, know exactly if applicable (and how to) or not.

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@Quarnero as you say bq25895 is capable of charging at higher currents we currently basically only enable this for pd charging (up to 5V/3A with pd contract) not for e.g. USB-3, BC1.2 or similar.

We’ve verified we can trigger higher charging currents for ‘usb-3, bc1.2, …’ too but that’s not enabled at the moment since that needs some additional signalling in the USB stack we’re currently missing.

So for car usage a PD charger is likely the safest bet at the moment (and which is what i’m using).


Thanks a lot @guido.gunther, helping me to understand proper approach!

And, to me now looks like that something like DUX DUCIS® PD3.0 (including PD PPS) car charger (over USB-C to USB-C cable) should be compatible with the Librem 5 battery expectations from its PD port. Same product (relatively cheap) Aliexpress links are here and here.

Note: This car charger isn’t tested from my side (no promise it will work as it should).

@Quarnero something like these should work. I’m using a similar one from varta and added it to the list of the ones i tested here: https://source.puri.sm/Librem5/firmware-tps6598x-nonfree/-/merge_requests/24/diffs (not a buying recommendation, just something that works for me)