55 Amp Converter Charge Times

smkettner wrote:
The difference is that if you see boost mode (14.4v) the 9 amps into the converter will hold for 60 to 90+ minutes instead of 30 before it starts tapering.

You can check around all you want to check the system and with great effort you may or may not ever see boost mode.

The real measurement is the voltage right off the WFCO converter during the first 2 minutes of charging. This voltage right at the converter needs to be somewhat below 13.2 volts to trigger boost mode and is actually fairly difficult to achive. Been through this years ago. Far better to just get a new converter that works as expected.

X3. Got a PD 9245 and a pendant, along with a short run of some fat wiring, and I am good to go, getting that 14.4 volts bulk mode charge for 4 hours, manually. Good enough for either a Trojan 150AH T1275 12V or group 24's or 27's, when boondocking.

Well good to hear WFCO finally understands that thier converters just do not work as the consumer expects. I wish they would take that "3 stage charging" off the sticker.

And yes I could flip on my inverter and pull 160 amps to run the microwave 15 seconds and WFCO-55 would be in boost every time.

Powermax has a direct bolt in replacement for the WFCO board when you are interested. With a single group 24 I recommend the 35 amp.

Again, thanks to everybody for being patient with my questions!

First, for now I'm satisfied with the WFCO's charge rate. At some point and time, if I start boondocking, I'll probably seriously consider swapping out the WFCO for a PD or Iota. My post was more of an exercise in understanding the charge process and all the electrical relationships than anything else. Definitely accomplished that, thanks!

Secondly, I called WFCO tech support this morning and told them about this very common complaint about the WFCO converters not being able to go into the 14.4 bulk mode. Of course, I probably didn't completely understand his somewhat technical response, but I did get an answer that made some sense to me. He said the WFCO (8955??) has to see approx. a 60-61 amp load or a voltage drop to roughly 12.5 vdc before it will go into bulk mode. He said you could do this artificially (or as I would say, by brute force--lol!) by turning on 60-61 amps worth of 12 vdc lights and appliances. When I asked him why a typically discharged battery would not place the WFCO into bulk mode, he kinda hesitated and said the WFCO was not designed to be an "automotive type of charger" . . . interesting.

RoyB wrote:
If your 55AMP converter/charger is the WFCO WF-8955 then just note not many folks can get those to go into the BOOST 14.4VDC charge mode. I never could get my WFCO WF-8945 to do it so I replaced it with the PD9260C 60AMP converter/charger. It works everytime now...

...

EXACTLY!

I couldnt get my WFCO 8955 to go into bulk mode, ended up going to a PD9280 to charge my Trojans, works very well.

To add to what SM says if you replace the converter get one that you can set the boost voltage to 14.8v.

Jim

smkettner wrote:
Been through this years ago. Far better to just get a new converter that works as expected.

X2

Some converters are rated at their 13.6v level in their specs. This means they give the watts at 13.6 x 55 = 748w Now add on for the 0.7 PF and you draw 1068w (VA actually) Now throw in what might happen at 14.4v and 55a. Some converters (PD) can't do their 55a at the higher voltage stage because there isn't enough power because they are rated at 13.6.

In other words, it can get complicated. Yes you can get high amps at first at the 13.6v level, but it tapers very soon because the battery voltage rises into the low 13s and the converter is only at the mid 13s. Not enough "spread" (voltage diff) to make many amps.

The 14.4 level is used because now there is more "spread" between the battery voltage and the converter voltage, so you get more amps. (Until the "battery acceptance rate" gets to where it can't take that many amps anymore at that voltage, so amps taper (like under battery control for that due to its chemistry etc.)

Look again at my ugly graph above and the drooping curves to the right side. That is the amps tapering due to battery acceptance rate falling as SOC rises.

All I am going to say is I have been through this with these guys before. I had a WFCO 55 amp converter. I would never see the boost mode and would spend hours charging. I got a Iota 55 amp converter it help. Then, I increased the wire size for the converter to the batteries and everything works great.

The difference is that if you see boost mode (14.4v) the 9 amps into the converter will hold for 60 to 90+ minutes instead of 30 before it starts tapering.

You can check around all you want to check the system and with great effort you may or may not ever see boost mode.

The real measurement is the voltage right off the WFCO converter during the first 2 minutes of charging. This voltage right at the converter needs to be somewhat below 13.2 volts to trigger boost mode and is actually fairly difficult to achive. Been through this years ago. Far better to just get a new converter that works as expected.

Some GREAT info here! Thanks to RoyB, mena661, and smkettner, and everyone else.

Ok, if I understand everything correctly, there's basically three charge modes: 14.4 volt bulk, 13.6 volt absorption, and 13.2 volt float. Everyone keeps telling me the converter never went into bulk mode because I never read 14.4 volts at the battery. I guess we can can reasonably assume it was in 13.6 absorption mode.

Question(s):

The 120 VOLT INPUT side of the converter was drawing 9-10 amps (maximum rated current for this converter) for almost 30 minutes when I first turned it on and started the charge cycle with the battery discharged to 11.90 volts. I'm NOT, repeat, NOT referring to 12 vdc charge current here. My question, if my converter was always in the 13.6 volt absorption mode, which supposedly takes 40 hours to charge to 90%, where in the heck was all that current (9-10 amps at 120 volts) going? That easily converts to 20-40 amps 12 vdc even assuming terrible efficiency. That's way, way more current then what's needed for the 13.6 absorption mode to charge a battery in 40 hours isn't it? Isn't that the kind of current you'd expect to see in the 14.4 bulk mode? Should I be checking for connection/cable loses in the 5 ft #4 cable that runs from my battery to the converter? FWIW, I pulled ALL the 12 vdc fuses before charging to prevent any inadvertent 12 vdc loading.

Again, thanks!