More economic than alkaline battery.
eBay
54.6V 4A Lithium Battery Smart Charger 13S 48V 4A Charger Li-ion Battery Pack Charger DC-XLR-GX16-GX12-XT60-XT90
Aliexpress UK
(A /c Mains adapter 3A 14.6V DC output for Lifepo4 Battery System. (Lifepo4 cells are 3.2v - 3.65volt each, you need 4 of these cells in series connected for proper charging.). Avoid this mistake). It can also be used to WAKE up a DEAD LIFEPO4 battery.
eBay
58.8V 2A Lithium Battery Charger 14S 52V 2A Li-ion Battery pack Charger Fast Chargeing XT60-XT90 Power Tool Charger
Aliexpress UK
Clear split between Lithium and lead-acid charging modes. Upgraded algorithm for both Lithium and lead-acid modes. Protected against reverse polarity, overcharging, overheating and short-circuits.
eBay
KENTLI AA 1.5V 3500mWh lithium li-ion rechargeable battery +4 Channel polymer lithium li-ion battery batteries charger
Aliexpress UK
This is possibly the best upgrade to any existing electric trolley and you may never have to buy a battery again as it will last 10 x longer than a standard lead-acid or Gel battery and is the top grade Lithium.
eBay
54.6V 2A Lithium Battery Charger 48V 13S Kugoo G1 Charger High quality Li-ion Battery pack Charger With Fan
Aliexpress UK
Maintain any type of 12V lead-acid battery, STD (filler cap), AGM and GEL and 12.8V/13.2V lithium (LiFePO4) batteries without overcharging. For all 12V powersport battery types including STD, AGM and GEL and Li-on made with LiFePO4 / LFP technology.
eBay
54.6V 2A Lithium Battery Charger 54.6V2A Electric Bike Charger for 13S 48V Li-ion Battery Pack EU/US Plug Charger High Quality
Aliexpress UK
Designed for Lifepo4 Battery. More information.
eBay
54.6V 3A Lithium Battery Charger 48V 13S Kugoo G1 Charger High quality Li-ion Battery pack Charger With Connectors 100-240V
Aliexpress UK
Output : 42V 2A. Model Number :42V 2A. When charging, first connector to the battery, then connect to AC; after full, cut off AC, then pull the battery plug. Output Power :37.5-50(include50). Use :Standard Battery.
eBay
54.6V 3A Lithium Battery Charger 48V 13S Kugoo G1 Charger High quality Li-ion Battery pack Charger With Connectors
Aliexpress UK
Internal resistance: 30 m Ω. POOVER 1 2V INR Li-ion Battery Pac k. Scope of application: backup power battery. Hard, strong resistance to solubility. Super long cycle life more than 2000 cycles. 12V LED lamp with light bar.
eBay
KENTLI AA 1.5V 3500mWh lithium li-ion rechargeable battery +4 slots polymer lithium li-ion battery batteries charger
Aliexpress UK