BFL13 wrote:
Let's not confuse charger voltage with battery voltage. You start off at battery voltage of say 12.1. It spikes to 13.x, then slowly rises until eventually hours later it (almost) reaches charger voltage and so there is no spread between them and so no more amps.
But at first, the charger is at its rated voltage such as 14.8 while the batt has spiked to 13.x. So you get lots of amps with that much spread.
(You can see during bulk stage with the battery still at 13.x that the charger is going full blast, by using a Kill-A -Watt. This shows the charger is pulling full rated watts as VA from the gen or other supply. Do not think the charger is also at 13.x but just a little higher.)
The charger is current limited, so the amps are clipped to that so you get constant amps at that limit until the battery voltage rises close enough to the charger's voltage, that the spread is too small to make that many amps, so amps taper.
The absorption constant voltage stage is mis-named because the charger is still at its 14.8 but now the amps are tapering but the battery voltage is still slowly rising--or no amps would flow.
Amps stop at the very end when battery voltage gets (almost) the same as charger voltage. Actually absorption can go to infinity, so you just have to cut it off and let the rest happen on Float.
The big thing is that the charger needs to be at 14.8 vs 13.8 right from the start, so there is lots of spread between it and the battery's voltage, AND to get the battery above "gassing voltage" for the absorption stage.
BTW, I have had my single stage 13.8v Parallax 7355 doing 56 amps at its 13.8v. I had it backing up the batts which were being drawn down by the inverter sucking 98 amps. Short fat wires so no issues about voltage sag and all that.
The converter was acting as a power supply and was able to do its rated amps no sweat. That is a completely different thing from using it as a battery charger, facing huge resistance and only able to do less than rated amps at first and tapering from there too.
So, don't get all confused.
OK. Its just I dont want to waste $200 bucks on a new charger lower end unit if what I have perfors the same.
As I said the wfco and my truck idling for 2 hours took the batts from 12.2 volts to a 1265 hydrometer reading. Starting at 50 amps and working its way to about 10 amps when it reached 13.6 volts at the batts..
I can do more testing of the wfco but I need to know what to look for when testing..
Id also like to compare readings of someone with a PD under similar conditions.. Wire size, length, amp readings, voltages, etc..
I know, I have too much time on my hands....LOL... Im a little OCD....LOL
