As I said in an earlier post, removing the battery as an option would depend on the age of the vehicle, and the circuitry used. If the van is not computerised, then remove the battery. If the van as computerised coding or other devices reliant on a constant voltage feed, then seek further advice.

When you used jump leads, did you use another battery, or was the leads connected via another vehicle, with its engine running, so as not to drain that battery and provide a constant charge flow?.

The charger that you are attempting to use, appears to be a DIY 6amp 'trickle' charger, which is not made to 'revive' a 'dying or dead' battery in a quick charging time.

Would mention at this point, that there are jump-starter with compressor units available (Aldi are selling these, this week). but I have found that these not all that reliable, compared to the commercial units available at a far higher price.

My wife has a very low milage (8000miles) X reg Honda (bad back restricts driving) I regularly charged the battery but had to get a new one this year as I am told that age does in the end mean that even a low use does not mean that it does not die of old age. Protyre locally fitted it for free.