Originally Posted by rbreding
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The factory WF-8735 Converter is on the small side amps wise and only has 3 stage (of which I have only seen it do 2 stages).
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Progressive dynamics PD4135. The complication I see with this unit is it is only rated at 40amps DC. It does however state it has 4 stage "Charge Wizard" technology that will charge in 3-6 hrs @ 90%. Specs are limited and I haven't heard back yet from PD regarding what size bank they are assuming for this 3-6 hrs.
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Progressive Dynamics PD4060 . . . The DC Amps of this unit is rated at 60 which should be enough for the proposed battery banks . . .
WFCO converters (WF-8xxx) are notorious for rarely going into bulk (14.4v) charge mode. They typically remain in absorption mode (13.6v), even when the batteries are significantly discharged. Charge times are significantly higher in absorption mode (vs. bulk mode).
A Progressive Dynamic converter (and/or power center) is a good choice. They're good about going into bulk mode automatically when appropriate, or they can be placed in float/absorption/bulk modes manually using the "Charge Wizard".
As for charge times, we have a PD-4060 Inteli-Power power center with a 60-amp converter. It will typically charge two GC2, 6-volt batteries (discharged to 50%) to 90% in approx. 2.5 hours in bulk mode. I'd guess-estimate a 40-amp converter (charging these same two batteries in bulk mode from 50 to 90%) would take approx. 4.0 hrs.