Vortech battery backup alternate

[gregzz4]

My little Canuck Tire trickle charger is still going strong, and my original battery purchased back in Dec 2011 is also still good.
Some time back in 2016 I purchased a second battery to double my run time.
This also allows me to overlap the original battery as it ages.
I connected both batteries' positive and negative posts together with 10ga wire, and connected the charger's positive to 1 battery, with the charger's negative connected to the other battery. This ensures both batteries receive a ballanced charge.
I also connected my MP10s to 1 battery's positive and the other battery's negative. This way the pumps draw from both batteries equally.

My run time for 2 pumps should be 72 hours @ 50%, but even if I only get 1 day it's enough.

I think, now that the original battery is 7 years old, I'll replace it soon.