For those with Ecoflow and Bluetti units, they have their own proprietary DC-DC charging units. The Ecoflow dc-dc unit looks pretty impressive and they go on sale quite often.
us.ecoflow.com
www.bluettipower.com

EcoFlow 800W Alternator Charger
Charge while you drive, and stay powered up on the road. 800W turbo alternator, 8× faster than traditional in-vehicle auxiliary power outlets. Top up 1kWh in only 1.3 hours. A 3-in-1 fast charger, maintainer, and jump starter keeps your battery in mint condition. Easy installation Suitable for a...


BLUETTI D40 DC-DC Battery Charger
- Compatible Models: BLUETTI AC200L- 12V / 30A, 400W Max. DC Output- Compatible with LiFePO₄, AGM / Gel, Lead-acid, and Calcium Batteries- Charge RV House Battery via AC200L / Solar Panels / Starter Batteries- House / Starter Battery Protection- Charge up 12V RV Appliances
