How to carry a 2nd / extra battery ...

[egroover]

Brilliant thank you, exactly what I was looking for, I take it it just velro's to the rear rack? is it sturdy?

Yes, there's 2 wide velcro straps underneath and one at the front. I tend not to put too much heavy stuff in the side pockets, but to be honest once a battery is in the lower compartment it doesn't move about. I have a bungee I put across the bag onto the rack if I'm filling it up

 

[Trod]

Sorry to hijack your thread but I have searched for days looking for a bag for the rear rack to fit a Woosh Gran Camino battery with no look. I don't know if the OP is looking how to use two batteries at once or if he is like me, just wants to transport another battery safely on a rack?

It’s the 2nd option ... transporting a spare battery so I can remove the 1st exhausted battery during a ride and slide in the 2nd so I can continue, with renewed range. So far, I have started to use an old laptop bag to bring one / both batteries from the house/flat to the bike so that they are protected from bashes and risk of dropping. Next I’m favouring the idea of doing the same with a rack mounted bag, so I can pre prepare, snacks spares and tools too.

 

[peterjd]

It’s the 2nd option ... transporting a spare battery so I can remove the 1st exhausted battery during a ride and slide in the 2nd so I can continue, with renewed range. So far, I have started to use an old laptop bag to bring one / both batteries from the house/flat to the bike so that they are protected from bashes and risk of dropping. Next I’m favouring the idea of doing the same with a rack mounted bag, so I can pre prepare, snacks spares and tools too.

On my Swytch converted bike, I modified the system (really for weight distribution reasons) so that the main battery is in a rear pannier bag (in a Jiffy type padded bag!), connected to the original front bag with low resistance leads. The spare (a much smaller and lighter 36V battery)can be put in the original front battery/controller pack (if I think I need a spare). For safety, it is physically impossible to have both batteries connected at the same time. Simple but seems to work well.

 

[Flycaster]

This was suggested to me by egroover.

https://www.amazon.de/Prophete-Gep%C3%A4cktr%C3%A4gertasche-Bike-schwarz-0604/dp/B018KLD58O/ref=sr_1_4?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=prophete+rack+bag&qid=1633038077&sr=8-4

In the end I decided to go for this one due to being a hard case and fits the battery on my Gran Camino fine:

XLC Unisex Ba-b02 Cargo Box BA B02, Schwarz, 40 x 25 cm EU : Amazon.de: Sport & Freizeit

XLC Unisex Ba-b02 Cargo Box BA B02, Schwarz, 40 x 25 cm EU : Amazon.de: Sport & Freizeit

www.amazon.de

They are both from the German big river.

 

[Energizer Bunny]

Cairn Cycles sell a specific case:-

Cairn Range Extension Pack (FAZUA Battery Case)

Overview The Purpose There will come a time when you just need to carry a spare battery. Maybe you want to go touring or bikepacking and charging facilities are few and far between, or you just know you want to ride further than you know one battery can manage. Thanks to the fact that the FAZUA...

www.cairncycles.com

I'm always chasing a bargain so went down a different path with 2 bottle holders, you could just use the larger one using bubble wrap around the battery. These are in a rucksack, but you could adapt for frame or handlebar mount. Just use a cloth to prevent contact pins touching aluminium insulation (unlikely but may cause arching)

Small bag (battery fits perfectly, material is thin):-
https://www.amazon.co.uk/gp/product/B09KRWHJ8G/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Larger bag (material is robust but battery is loose, either use in combination with small bag or with bubble wrap)

https://www.amazon.co.uk/gp/product/B08LZLX5X3/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1