I have been using the factory installed Strobel solar system on my 29 with K2 batteries for the past 4 years without issue. The Strobel controller was designed for Lead-acid chemistry and the K2's "can" be charged by lead-acid chargers due to their lower output voltage. That being said, the 13,75 Volt output of lead-acid systems won't charge the LiFePo to it's full capacity that needs 14.6 V.