This is the charger we use for our RV, it works great. 
 
compact PWM Solar Charger
can be used with the TM-2030 battery monitor
unparalleled control over the charging proces, extending the life of your expensive batteries.
low-temperature charging cut-off at a user-specified temperature (10C to -5C)
compatible for lead-acid, lithium LFP, Nickel-Iron, and other battery chemistries
connects to your smartphone, tablet, or laptop using Trimetric WF 2030
uses Amp-hrs returned in addition to voltage and trailing current criteria to ensure a fully charged condition, preventing sulfation and extending the life of your batteries
built-in shunt for measuring solar current