[ours2012]

depending what sort of obd reader you are using here , will your obd reader read all the van, or just the engine?

 

[ours2012]

Are these Mates
As in not charging, or just a nominal fee

Does it do this all the time, or just first start?

Reason for the question, you could need diagnostics on it as the fault occurs
If ignition is switched off the fault codes you possibly need, because they are not stored in the ECU anymore and vanish
or is that when you have had it diagnosed,

 

[ours2012]

get battery charging circuit checked out..
But try this
Start the van, allow to warm up. then drive it see if its any better
From your last statement it sounds like the battery is strong enough to start the van, but no reserve to cover anything else then alternator puts a charge back in the battery and your problem seems to ease