lithium battery help

[dubob]

I've got a 24v 70# Minnkota Powerdrive. If one of my batteries isn't shot, I think it will be soon. I will be upgrading with lithium when replacing. Question is: 2 12V batteries or 1 24v battery? Which one will give me more run time? Thanks in advance!

Run time is determined by the Amp hour (Ah) rating of the battery setup.  So whichever setup has the highest Ah rating will give you the longest run time.  Two 12 v, 100 Ah batteries in series will give you 24 v, but the Ah is still only 100 Ah.  Two 12 v batteries in parallel will give you 12 v and 200 Ah, but you need them to be in series to give you the needed 24 v.

So, your decision should be based on which setup (1 24 v or 2 12 v in series) will give the highest Ah rating.  Secondary consideration is the dimensions of the storage space that will contain the battery(s).  Right now, you can get a 2-pack of 12 v, 165 Ah smart batteries (connects to your phone for level of charge readings) from Li Time for $690.  The only 24 v smart battery they offer has an Ah rating of 100 and costs $459.  I would definitely go for the 2-pack of 12 v for the increased run time.  The $230 higher cost would be worth it to me.  YMMV.