Below is a list of URL's of battery charger and Voltage booster modules that Kiwa and I (Rj Ws) looked at. Our interest was in HO scale, so the lower powered stuff might not be applicable to greater scales......
1 Amp mini-USB charger:
https://www.ebay.com.au/itm/354371665414
2 Amp Adjustable Voltage Booster:
https://www.amazon.com.au/Eiechip-Voltage-Regulator-Converter-Module/dp/B07RNBJK5F/ref=d_pd_di_sccai_cn_sccl_2_3/355-4327533-4100025?pd_rd_w=JCnpG&content-id=amzn1.sym.9311f7e4-4ecc-402d-bb6e-92acdf2c3b19&pf_rd_p=9311f7e4-4ecc-402d-bb6e-92acdf2c3b19&pf_rd_r=589W263QRQ6A8MTHGP9P&pd_rd_wg=gSxyd&pd_rd_r=87311f99-a74d-47c6-b4ff-ab90c6d71b13&pd_rd_i=B07RNBJK5F&psc=1
4 Amp Adjustable Voltage Booster
https://www.amazon.com.au/DZS-Elec-Converter-Adjustable-Regulator/dp/B07L64GJ42/ref=d_pd_di_sccai_cn_sccl_2_6/355-4327533-4100025?pd_rd_w=JCnpG&content-id=amzn1.sym.9311f7e4-4ecc-402d-bb6e-92acdf2c3b19&pf_rd_p=9311f7e4-4ecc-402d-bb6e-92acdf2c3b19&pf_rd_r=589W263QRQ6A8MTHGP9P&pd_rd_wg=gSxyd&pd_rd_r=87311f99-a74d-47c6-b4ff-ab90c6d71b13&pd_rd_i=B07L64GJ42&psc=1
5 Amp Adjustable Voltage Booster:
High Powered USB Charger:
Battery Charger & Voltage Booster?:
Neither of us endorse any of these. They are just for info and reference.
Rj Ws
Thank you for sharing these great finds.
Neither do we endorse any but here's one high current fast charger rated for 3A
https://www.aliexpress.us/item/3256801431696739.html