Have split charger doesn't seem to be working covered some miles as well any ideas appreciated
The simple fact of life is that an alternator is very good at supplying the current the van needs, lights, heater etc,. but not as good at charging batteries.
A leisure battery will only accept a 'trickle' charge, so the most I have every seen my van charging the 110 amp leisure battery is an inital spike of 11 /12 amps that very quickly drops to about 8 amps. My van is a Citroen Relay with a 150amp alternator.
So we have Shurflo pumps that draw about 4 amps on the controller setting we use. If we are working on the glass for 3 'pumping' hours we will expect to use about 12amps of charge from the battery.
If our drive home takes 20 minutes, another 10 minutes moving the van and another 20 minutes driving to work the following day, the most my alternator would have put back into the battery is 6.5amps - fractionally over half what I used the previous day. That is why we have to supplement our charging from time to time.
The other 'problem' is that the fuller the battery gets the lower the amperage of charge it will accept. If I have a fully charged battery and I run the pump for 10 minutes, I will draw just over 1/2 an amp of current. The alternator will return that charge at around an amp. meaning that it will take more than 1/2 of an hour to recharge that battery as the fuller it gets the less charge it accepts.