How to use pass through charging

I am a new EB70s owner and want to know how I can charge external AGM Batteries while charging the EB70s.

Plug an AC (agm) powered battery charger into the EB70 AC outlet and connect the charger to your AGM batteries. The charger output needs to be less than your charging input to the EB70 or you will deplete the EB70 battery while doing this.

Thanks Scott.
I should have made myself clearer. I want to go from the EB70s, without a charger brick, directly to the batteries with alligator clips.

The only 12 volt DC outlet is the cig socket. But…if you rig up a cig plug to alligator clips cord you are not going to be satisfied. You need around 13.5 to 14 volts to charge your AGM batteries and the DC output of the bluetti is nowhere near that under load. That is the reason I stated to plug in an AC powered battery (Car battery charger) charger. It will supply the correct voltage and taper off the amount of charging when your batteries get full.

Hi Scott,
Thanks for the info.
Are these AC battery chargers specific to charging batteries? I don’t think I have ever seen one.

Almost all automotive battery chargers are AC that you would plug into a wall outlet. This would be the same type of battery charger you would use to charge your car or RV battery. I would find one around 10 amps of capacity.

Below is an example of a good one and a cheap one and a middle of the road one