That said the OP is one of the very very few that I've know that was able to get the WFCO into the constant current mode. most I've seen almost immediately drop into the 13.6 constant voltage mode. wrote:

Can you explain this better?

So the comments I have read above even the PD's show a low voltage when initially plugged in with higher amps .. As theory goes high amps lower voltage.

Even though I do not see said 14.4 at the converter terminals it may be in that 14.4 mode right? Because of said amps. This may just be the algorithm of the wfco.

And the wfco will hold said amps until it drops out... Im thinking when batts reach 13.4? volts, hench why you dont see the batts reach 14.4..

Now when talking to the wfco tech I brought up the same point to him. I tried to compare it to my solar..

Mu solar will charge ar bulk 14.7 until the batts reach 14.7. The amps will stay maxed at what the solar can produce with the controller. With mine its 20 amps max. Common I see is 17 amps. Then the solar will go to absorp stage and amps then taper.

Tech stated the wfco's dont work like that

And I understand the 14.7 thing will charge faster.

But is it true say the wfco charging at 30 amps 13.6 vs the PD at 14.4 20 amps ( lower volts = more amps) it would be a wash?

Mike L ... N.J.

2006 Silverado ext cab long bed. 3:42 rear. LM7 5.3 motor. 300 hp 350 ft lbs torgue @ 4000 rpms
2018 coachmen Catalina sbx 261bh

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.

2003 Chev 2500HD Gas, 2003 Komfort 26FS 5er,
1981 Frontier 11ft Truck Camper
See Profile for Equipment Lists

there is always this from PD, fast means high current to 14+v, hold 14+v

14.4v boost, 13.6 'normal', 13.2 float

WFCO theroy of operation:
"If the converter observes no significant variations in current draw for approximately 44 continuous hours, it will drop the output of the converter from 13.6V to 13.2V."

Ask why 44 hrs before float.

east penn states c/20 --- 20%... The 30% is for a monoblock design.

Those charts above , wfco vs 20 amp charger, mean nothing IMO as anyone can make a chart.. I would need testing data to prove anything...

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

But is it true say the wfco charging at 30 amps 13.6 vs the PD at 14.4 20 amps ( lower volts = more amps) it would be a wash?

Depends on the rating but no PD-55 will be sagging to 20 amps if the batteries need the charge. WFCO at 13.6 will taper off the charge faster every time. Once in absorption mode it is not about the converter but the voltage and the battery. If the same rated WFCO puts out more amps it will only be for a few minutes.

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.

do some voltage measuring AT the converter, in bulk mode, voltage will be the battery voltage plus line drop. the converter is in constant CURRENT mode. It supplies the current regardless of what the voltage is. (up to 14.xV) converter output voltage may be in the 13V range even with 60+A. with a single battery it may be that converter output voltage is near 14.x v due to battery internal resistance. But that is not necessarily the case with a large battery bank.

the problem with the WFCO is it often goes out of constant current mode very quickly into the constant voltage 13.6V mode which will not deliver much current.

now as the battery charges you want the current to remain constant till the battery is near 14.5V or so, then go into a constant VOLTAGE mode, and hold that voltage till the current drops to a few % of rated AH.

then drop down to the 13.6ish volts

2011 Keystone Outback 295RE
2004 14' bikehauler with full living quarters
2015.5 Denali 4x4 CC/SB Duramax/Allison
2004.5 Silverado 4x4 CC/SB Duramax/Allison passed on to our Son!

That said the OP is one of the very very few that I've know that was able to get the WFCO into the constant current mode. most I've seen almost immediately drop into the 13.6 constant voltage mode. wrote:

Can you explain this better?

So the comments I have read above even the PD's show a low voltage when initially plugged in with higher amps .. As theory goes high amps lower voltage.

Even though I do not see said 14.4 at the converter terminals it may be in that 14.4 mode right? Because of said amps. This may just be the algorithm of the wfco.

And the wfco will hold said amps until it drops out... Im thinking when batts reach 13.4? volts, hench why you dont see the batts reach 14.4..

Now when talking to the wfco tech I brought up the same point to him. I tried to compare it to my solar..

Mu solar will charge ar bulk 14.7 until the batts reach 14.7. The amps will stay maxed at what the solar can produce with the controller. With mine its 20 amps max. Common I see is 17 amps. Then the solar will go to absorp stage and amps then taper.

Tech stated the wfco's dont work like that

And I understand the 14.7 thing will charge faster.

But is it true say the wfco charging at 30 amps 13.6 vs the PD at 14.4 20 amps ( lower volts = more amps) it would be a wash?

In your case it appears the WFCO is acting like a PD or similar. when the batteries are discharged it starts in a constant current mode giving 30 amps to the battery and then holds it till the battery voltage rises to near 14.X V and the goes to constant voltage to finish charging. then hopefully will drop back to 13.6V to keep the battery charged.

Now a PD 40, 50, 60 etc A unit would do similar. you'd see the PD rate current or near it initially, dropping some as it gets near 14.6V.

Now, many with the WFCO have found it NEVER goes into the constant current mode as it should or they drop out pretty quick and goes to the 13.6V constant voltage mode with low current. It immediately thinks the battery is fully charged and goes to the 13.6 constant voltage mode. in that case it can't supply much currrent to the battery, especially if the run between the battery and converter is very long with the typical #6 wire. what I have seen is 10-15A or so.

as an example one camper friend's 4 GC batteries were way down, around 40 percent SOC, and the WFCO would immediately go in the 13.6V constant voltage mode giving a whopping 15A charging current. I pulled my 60A PD out of the pass through and we hooked it up to the battery bank and it immediately started stuffing 60A into the bank and continued for several hours. Initial voltage was still only arou 13.4V with the 60A, it's constant current mode. gradually as expected battery voltage rose, current started to drop and when current was around 25A it finally reached 14.6 volts and went into constant voltage mode to finish the charge.

* This post was
edited 10/10/17 09:51pm by ktmrfs *

Yes, the voltage on each end of the wires between charger and battery is the same except for voltage drop. However, the charger is at 14.8 and the battery is just getting up from that 12.1 it was at the start.

The battery voltage appears to "spike" to 13.x, but that is just the voltage "middle-ing" between the two voltages. The charger is still at full power.

Here is what happens again:

55 amp charger not on battery, start charger, set it to 14.8v, and meter shows 14.8v at the charger's terminals. Battery is at 12.2, say.

Connect charger to battery--Kill-A-Watt between charger and 120v power supply. (Honda gen 127v no load--less with charger as load)

124.7v, 11.06 amps ( both AC) 980 watts, 1383VA PF 0.70 Charger DC amps 56.8a (what the battery is taking in as seen by Trimetric), battery voltage (and charger terminals too) showing 13.7v

So the 55 amper is doing full power at its 14.8v setting as seen by the VA it requires. If it were at a lower voltage it would not be sucking anywhere near that much power from the gen. That is why guys with Honda 1000s have to dial down their converters to 13.8 at first so it will not conk out the gen, until the battery comes up to the point where they can hit the Charge Wizard to go 14.4. By then the battery doesn't accept so many amps at 14.4 so it can now run on the 1000.

If you immediately disconnect the charger from the battery you will get 14.8v at the charger and still 12.2 at the battery (if you kill off the surface charge)

I have a gen, 2400 watt, and a kilowatt meter.Id like to do a test to see when this comes out of constant current and into constant voltage.. How would I know.. The wfco wants 980 watts AFAIK...

And as stated my wfco may be in a constant current mode, but at no time do I see 14.4 volts anywhere. As in my first post I show voltages at batts and converter..

Its clearly dropping out of 14.4 constant current mode at some point... but when?

As far as the pd,s the few you tube vids I see show the higher voltage at the converter, but I believe in those cases the batts are pretty much fully charged..

So its vids like this that I have trouble with..

7:45 mark.

This guy states his 4 6 volt batts were down 12.2. He says he used his old converter as a test ( wfco) and was getting 11 amps. Converter 20 ft away.

Then he states he plugged in the new PD converter and was getting 27 amps... ( LOL converter is 2 ft from batterys)

Then he states he pushed the wizard button and got 40 amps..

Trouble is these PD's would go in boost without pushing the button ( with 12.2 batts) so his video is flawed..

Time is money when using a generator to recharge a battery. If a charger does not have a correct voltage profile you pay for it in wasted fuel. With a manual Megawatt, a 36 amp model I guarantee I can fully recharge a battery in One - Third the time it takes your WFCO. With my big manual charger I slice twenty minutes more. No brand of automatic charger can do this but trying to make a WFCO into an optimum charger is like hiring a one-armed brick-layer. Or buying Lucas electrical parts to gain reliability. An oxymoron with oak-leaf-clusters and diamonds.