I do on average 35 miles a day on average when cleaning, is it worth getting a split charge relay?
Would my battery get enough charge doing that amount of miles?
I would say yes although you will still have to supplementary charge it which I would do on a weekend.
But the most important thing isn't the distance you travel but rather the time it takes to travel that distance. My van charges the leisure battery at exactly the same rate (amps) whether is engine is idling or 'revving' down the motorway. So if you are stuck in a traffic jam or very slow moving traffic your battery is benefiting from the extra charge even if you are 'pulling your hair out' with frustration.
We travel about 10 miles a day tops or about 20 minutes driving time. With a 2 man system and a 110 amph leisure battery, I usually supplementary charge the battery every couple of days.
The one time that SCR really paid for itself is when my first leisure battery failed on a job miles from home. We were able to continue and finish the job off with the van's engine running so we didn't have to go back the following day, or scratch around for a replacement battery in an unfamiliar city. Not all motor factors keep leisure batteries in stock. Caravan sales outlets, who do stock leisure batteries are few and far between.