UKH

What options are there for backing up SD cards when you don't have a laptop?

I use a RAVPower FileHub, and it also offers much more features than simply backing up SD cards:

https://www.ravpower.com/products/rp-wd009-filehub

I pair it with a 1TB Samsung T5 SSD. The two devices are very compact and easily portable.

https://www.samsung.com/uk/memory-storage/portable-ssd-t5/MU-PA1T0BEU/ 

I shall look into that.

Cheers

There is also a fully dedicated solution. WD wireless (pro?) has or has that option. Then there is something like rughedbox SSD. Both offer the SSD (or HDD) and SD reader in one package. 
 

considerably more dough than the one linked above (especially as I already have them T5 SSDs I use as scratch Fiskars for editing).

Does this allow you to transfer photos to the backup without access to WiFi/internet simply by plugging the SD card into the gadget.

Also, if you backup daily, does it recognise which files have already been backed up and does not duplicate them?

Yes. You connect your storage device to the FileHub; insert your SD card into the FileHub; press a little SD > USB button and away it goes. A flashing light monitors progress and stops when the transfer completes.

... There's also an app available, that allows you to kick the process off from there and monitor things from within the app.

Yes, I'm fairly sure that it supports incremental backups... I'll check it out and get back to you.

Thanks. Could be just what I'm after!

What sort of run time do you get on the power hub, between charges?

What read write speeds do you get sd card to SSD card please?

CORRECTION: It seems to do a full backup each time. It creates a timestamped directory on the storage device, in the following format, and copies the contents of the SD card to it:

YYYY-MM-DD-HH-MI-SS e.g. 2020-02-28-16-00-31

... I've had a tinker and taken a look through the docs, but can't see any way in which to change the default backup behaviour.

That's difficult to quantify, because it's dependent on how you're using the device and how intensively you're using it... It offers a decent runtime for my own demands.

It has an internal 6700 mAh Li-ion battery that it uses both to support its own operations and also to potentially be used for recharging other devices.

Ok. Thanks.

It uses USB 2.0 to connect to the storage device, and theoretically transfers data at 300 Mbps.

The specifications state that it offers an SD card backup rate of 12-18 Mbps.

My work here is done... RAVPower aren't paying me to provide technical support, and I've got a day job to get on with

... Take a look at the manuals for any other queries:

https://www.ravpower.com/products/rp-wd009-filehub

Cheers buddy