Sprinter Will Not Start - Second Battery

[MyRvGoes]

Got ready to take the sprinter out for a spin. Put the key in, dash indicator lights are flickering. Turn the key to start, indicator lights go out and no sounds from the starter.
Took the battery (one year old) to the battery shop and load tested. Battery tested good. Reinstalled, got same result. Took one of the two new batteries from back of sprinter and installed up front. Still sprinter will not start.

Two good batteries and now frustrated.

Took sprinter to Mercedes shop thinking a problem in fuse block area.

Result: Who would have thought the sprinter would have two batteries up front. One under the hood (the one I tested) and one under the floor of the drivers seat.

As I had looked through the forum during this period for "...not starting..." and found discussions of all kinds. But none talked of a second battery.

Just wanted to share so others using this forum may find this and avoid the cost and SURPRISE.

[ITSNO60]

Some, but not all NCV3 vans have the auxiliary battery, if you have a copy of your data card code E2I indicates an auxiliary battery under the seat while E2M indicates it is located in the engine compartment. Neither code means you don't have one at all, like mine.