Hi Dale
Question 1: Assuming I will be using only lights and vent fan from my 12V battery for a few hours each day, say 24 amps per day total. On a three day weekend with shore power to the converter, what is the down side to having a single stage charger putting out constant 13.4 volts? Even if it outputs 2 amps per hour, it should (I think) bring my battery back to full charge.
Answer 1: Ok if you are using 24 Amps per day and that is being supplied by the convertor, in this situation the battery is merely a capacitor to aid smoothing and if this is the case do you need a battery at all?
But if you require to have a battery that will be supplying the lights off grid, then you want that battery fully charged, A convertor wont do it, I have tested UK convertor's that output 13.8 Volts and after 4 Weeks of constant charging with NO loads they still do not get the battery charged at much over 90%, the 13.4 Volts on US convertors would be worse.
Question 2: I found a good explanation of the stages of a multi-stage charger: My second question is, regarding the WFCO converter with the 3-stage charger. Their specs states “Output: Nominal13.6 VDC (Includes charging and load) Boost 14.4 VDC; Sleep 13.2 VDC” . How do their 3 stages compare with the 4 stages explained below (What does the 3-stage charger NOT do that the 4-stage does): Etc etc see original post.
Answer 2: Some 3 stage chargers are not intended to be used as power supplies, their program would revert to charging if say you switched a light on it would drop the ternminal voltage and thus kick in another full charging cycle(even if the battery were full), thats why I always tell people to avoid using bench chargers as plumbed in systems, this could lead to thermal runaway and a battery explosion (and a battery explodes with same force as a stick of dynomite) The WFCO is intended for hooked up use, its also low voltage enough for use with Gel and AGM batteries, its not the best charger due to these voltage levels being made idiot proof for the American market (To aviod muppet litigation)
Comparisons of 3 Stage for one manufacturer with the 3 or 4 stages of another manufacturer are dificult and would be hard to explain or even meaningless to a non techy person. Consider this though some three stage chargers work on a set time for each stage, this means that if the bank is larger it will not be charged and will re cycle, the Sterling UK and Pro Marine (USA) descern the bank size and alter the cycle accordingly, I have an 1100 Ah battery bank (yes that right 10X110 Ah batteries) and the sterling charges them fully in one single(4 stage) cycle and supplies the motorhome's power while charging too.
This link will explain a lot though its the sterling brochure but its very informative too
http://www.downloads.sterling-power.com ... nglish.pdf
Question 3: Is there any great (i.e. really important) disadvantage of having a 3-stage vs. a 4-stage charging system when the power usage is light (24-30 amps per day max). I plan on fully charging my battery once I get home and putting a float charger on it, unless the 3-stage charger will suffice as a float charger.
Answer 3: yes you get less useful ah out of the same battery, The battery will not last as long (in years)
Say a 100 amp hour battery is poorly charged lets say it gets 90% in (and NEVER gets connected to the alternator) thats 40 Amps per battery available to use. 30 Amps a day (for three days) is more than the capacity of a single 100 Ah battery that as been poorly charged (ie any method that isnt a GOOD 3-4 stage charger) so you would require 3 X 100 ah batteries to supply your three days At 30 Amps per Day. Charged properly with a Good 4 stage charger gives you 50 Amps available per battery therefore 3 days would be OK from 2 100 Ah batteries. Your batteries will last longer (life as in years) I always hook mine up when I get home, that means I always have Fully charged batteries.
Float chargers may get the battery up into the 90's percentage wise, but even after trying junk charger's for a month at a time NONE as ever got close to 100% charging a battery, I define Junk as any charger that's not a 3-4 Stage charger.
