SF3 Charging from 24v DC

[CRMS]

I am using my SF3 on a boat and want to charge from 24v DC. I can get a DC-DC 5A converter and adjust the output to 15v DC and adapt a standard 5A USB C cable to connect to SF3. Basically chopping off the USB A plug and connecting the + and - wires to the converter output.
Will this work??

 

[sharpuser]

A bit dangerous. You may be taking some of the regulation safeguards away by doing that.
For my boat (Westsail 32) I use a 12v source using this step down converter, this socket, and this cable at the parlor table.

 

[CRMS]

I’ve been charging with a Lidl Silvercrest Qualcomm QC 3.0 car charger on a boat. It is plugged into a 24v car type socket. (Red outlet 3.6-6.5V @3A, 6.5-9V @2A, 9-12v @1.5A and White outlet 5V 2.4A)
Then USB A lead with Ailun micro A to USB C converter tip. Plugged into the laptop and it doesn’t work.
So I plug into a USB C hub that supports 100w power delivery:

USB C Hub, Type C Hub Adapter, 3 USB 3.0 Ports, TF: Amazon.co.uk: Electronics

Free delivery and returns on eligible orders. Buy USB C Hub, Type C Hub Adapter, 3 USB 3.0 Ports, TF/SD Card Reader, 4K HDMI port, USB-C Power Delivery, 7 in 1 Aluminum Adapter Compatible with New MacBook/MacBook Pro 2017/2018 (Space Grey) at Amazon UK.

www.amazon.co.uk

And it charges well. I have a USB in line power meter, A, V, mah and it shows charging at 5.2V and 1.96A. Just about 10W. So 0-100% in about 5 hours, which is fine.
When at 100%, the A drops to 0.06. Shame the SL3 doesn’t have a simple red/orange/green charging LED. It is crazy to switch on laptop just to check state of charge!!
With further thought, these batteries last best when kept between 20 – 80%.
So a red/orange/green laptop LED that can be configured in power settings to change. Say Red at 20% and Green at 80%, would be brilliant.

I prefer USB C charging to the mains charger. It is much better to slow charge for longer battery life. Just as with an electric car – slow overnight is way better than a rapid charger.

 

[CRMS]

An update. I bought an expensive BatPower CCS, £50, that advertises a 12-24v capability. It only charges from 12v and nothing from the 19v supply, for my current laptop and the 24v DC supply. In fact I've bought 2 and both useless. Luckily returned to Amazon.
I don't believe the charger/converters are anything else than just that and just do the dumb task of producing a stable 12v for the MSSL3. Any BMS is in the laptop.
What I really need is just the fancy magnetic cable and I can hook it up to a stable 15v DC, same as the mains charger.
USB C charging is fine, but too slow if using the machine.

 

[CRMS]

Solved it. Surface laptop connector and an adjustable DC-DC converter. Set to 15v DC and just works. As I suspected BMS in laptop. I have battery limit set in UEFI to 50%, and charging just stops at 50%.