Wipers and batteries

Windscreen wipers

These are driving me around the twist.  Sometimes when we are driving they won't switch on immediately.  I can be driving with very limited visibility for two or three minutes and then they start.

When I put the van in storage I spent an hour or so checking fuses, connections etc, but I could not make them start.  I assumed it was the wiper motor, which is a pig to get out. So I decided to leave it to the garage when he does the MOT. So I went to get the Van this morning:-

• The windscreen wipers started immediately - not sure if this is good news or not as the garage may not be able to find the fault. Intermittent faults are the worst.
• The washers did not work - I tracked it to a defective washer motor/pump.
• The engine would not start - this is bad news.

Starting

During the winter of 2022 I thought the van was struggling a bit to start.  I was not sure it was going to be reliable over the next winter, so in November I fitted a new starter battery.  I decided upon a Yuasa L36-EFB which is recommended for use as both a leisure battery and a starter battery.

But when I went to pick up the van today it would not start.  It seemed to turn OK but it would not fire. After trying quite a few times, I decided to try a jump start from the leisure battery (also a Yuasa L36-EFB).  It's a bitt fiddly, I had to get access to both batteries then use my heavy duty jumper cables.  It started immediately.  

So, what am I doing wrong?

• Have I bought the wrong starter battery?
• The van has been left unattended for three months, and I have been relying on the the solar panel to keep the batteries charged, (this technique has worked for years)  and the voltage was 12.9V this morning before I started. The solar panel controller allows the voltage to rise to 13.8V before it switches out. then it come in again when the battery drops to 13.1.  During the winter I usually disconnect the controller so the battery voltage can get higher during the events when the sun is shining brightly. Maybe I should have disconnected the controller earlier.
  

The Van is in for its MOT just now.  When I get it back I will store it with the controller switched off but be prepared to jump start it again.  If I have to do that, then it will be a new starter battery and I will have a spare leisure battery.  If so I will use the simple timed charger technique to keep it in good nick till I need it.

I will also tweak my controller so it cuts of at 14.4V instead of 13.8. In normal operation this is what the car alternator does. It will not be constant, only when the sun shines.  In the winter, with the fuse disconnected the battery will get a conditioning charge every time the sun is bright enough - 

Changing R2 from 120R to 270R should take the drop out voltage to 14.4 Volts and the pick up voltage to 13.7V.