WFCO WF-8955 amps in absorption mode

[mooky_stinks]

I have a WFCO-8955 (55 amp) that absolutely will not go into bulk mode even though it’s a 3 stage converter. Not sure if it’s inadequate wiring or an inadequate converter. It’s always 13.6-13.8 no matter the state of charge of the batteries. What I’d like to know is how many amps is it putting out in this mode. And don’t tell me 55 because we all know that ain’t possible! ??

[Grit_dog]

^Yup. After a couple PD converters in our old campers I didn’t really understand how bad and useless the other brands were.
Until our newer camper came with a WFCO it was almost useless.

[MEXICOWANDERER]

Just for funsies I drilled out the Whifffco circuit boards and substituted No 6 DLO cable. No change.
And to change the vertically mounted power resistor cooking one of the electrolytic capacitors in the finals would be absurdly complicated.

Did I mention the dollar three ninety eight Chinese components in the Whiffco?

It's like trying to modify a Yugo to become a Baja 1000 off road racer.

[Snowman9000]

Here I found it.

Posted By: Snowman9000 on 11/24/14 01:52pm

Oh, "since my WFCO is 55 amps", turns out to mean nothing in real life. I hooked my WFCO 55 direct with 2' cables to my half-discharged batteries as a test. It did 43 amps for about 3 seconds, was in the 20's in under a minute, and upper teens within a handful of minutes. The WFCO can only supply 55A at volts in the low 13s. So it will supply it for 12v operation, but not for battery charging. The output falls drastically at battery charging voltages. There is an output curve graph in the owners manual.

[Snowman9000]

A few years ago I did a test using super short cables, and posted it here. I’ll see if I can find it. My recollection is that the charger was still lousy.

[ktmrfs]

Bobbo wrote:
When my PD4645 goes into boost mode, I read 14.4 volts AT THE CONVERTER. At the same time, I read 13.(something) AT THE BATTERY. The battery voltage slowly rises to the 14.4v level. When it reaches 14.4v, the PD drops to 13.6v for bulk charging.

So, even if the converter/charger is putting out 14.4v, depending on where you read the voltage, you may or may not read 14.4v. (However, I agree that the WFCO is infamous for never going into boost mode.)

I have a 500AH battery bank and when the PD converters (2) in parallel are stuffing 100A into a 50% charged bank the battery voltage is in the 13 ish range and the 2/0 welding cable to the charger doesn't have much drop, the PD output voltage doesn't get to 14.4 volts, holds at less than 14V till the charging current drops below the combined max 100A. The PD output voltage is determined by the lower of the voltage needed to stuff the rated max current into the battery bank or 14.4V. if it reaches max current before the charger output hits it's 14.4V it will stay at the lower voltage until battery charges enough and internal resistance increases enough that 14.4V is needed at the output to hold current.
The PD output is current limited to rated amps AND voltage limited to a max of 14.4V in boost mode.

[Vintage465]

I replaced the WFCO with Progressive Dynamics Retro-fit. It fit perfectly and was a textbook install. I also installed #2 wire from the converter to the batteries. All is good now.

[wa8yxm]

Oh just not All Electronics dot com has the IOTA 90 amp on sale. Very nice price.
This takes a 20 amp circuit by the way (Do not know if the model they sell is corded) and you really should have at least 300 Amp hours of battery.

[Bobbo]

When my PD4645 goes into boost mode, I read 14.4 volts AT THE CONVERTER. At the same time, I read 13.(something) AT THE BATTERY. The battery voltage slowly rises to the 14.4v level. When it reaches 14.4v, the PD drops to 13.6v for bulk charging.

So, even if the converter/charger is putting out 14.4v, depending on where you read the voltage, you may or may not read 14.4v. (However, I agree that the WFCO is infamous for never going into boost mode.)

[wa8yxm]

13.5 is float not absorption.
WFCO's are well know for not going into boost mode.

NOW: This is relayed info but one forum member says he got into his and it's a singly part. Less than 5.00 (Way less) that burns out.. (A resistor) What I did not "Record" was the value or location of said resistor.
Generally a burned out resistor is obvious.
The value however.. Not so much.

[ktmrfs]

time2roll wrote:

sparkydave wrote:
Strange thing is the manual cryptically says "although the converter is outputting 14.4 VDC, you will not be able to read that on a voltmeter due to the voltage-current relationship".

The best lies have a figment of truth. Yes if the charging system is producing 14.4 volts it may not be seen immediately. Charging at 14.4v & 55+ amps the voltage will rise very soon to 14.4 volts at the converter and maybe a little less direct on the battery terminals.

The WFCO trigger is to get voltage at the converter to sag down lower than 13.0 volts during the first minute of charging. This is virtually impassible without imposing a large load on the battery as stated above. If I hit my system with a 100+ amp load from the inverter for a few seconds the WFCO will go to boost mode every time.

To the OP: The 25 amp portable charger is an excellent solution and should serve you well.

the "quotes" from PD, Iota, WFCO on max current and max voltage are really misleading to say the least. The max voltage and max current spec's are independent. Max current will occur at a lower voltage when the battery is partially discharged, often I see 65A at about 13.5V The 14.4V occurs when the battery is nearing full charge and the current will usually be in the 20A or less.

In fact with both my converters running I see 100A into the battery bank and still the battery voltage is in the mid-high 13V range, a result of the battery low internal resistance when partially discharged.

Other than the WFCO the chargers WILL reach 14.4-14.6V and will reach max current on a discharged enough battery, just not simultaneously. A result of the battery characteristics and charger characteristics. During initial charging the charger is a current limited current source and during final top charging a current limited constant voltage source.

[time2roll]

sparkydave wrote:
Strange thing is the manual cryptically says "although the converter is outputting 14.4 VDC, you will not be able to read that on a voltmeter due to the voltage-current relationship".

The best lies have a figment of truth. Yes if the charging system is producing 14.4 volts it may not be seen immediately. Charging at 14.4v & 55+ amps the voltage will rise very soon to 14.4 volts at the converter and maybe a little less direct on the battery terminals.

The WFCO trigger is to get voltage at the converter to sag down lower than 13.0 volts during the first minute of charging. This is virtually impassible without imposing a large load on the battery as stated above. If I hit my system with a 100+ amp load from the inverter for a few seconds the WFCO will go to boost mode every time.

To the OP: The 25 amp portable charger is an excellent solution and should serve you well.

[sparkydave]

Interesting, our new Wolf Pup has an 8955. So far, I've only seen it stay at 13.6 volts. Haven't left it on long enough to see if it drops to 13.2, but it never goes to 14.4. Strange thing is the manual cryptically says "although the converter is outputting 14.4 VDC, you will not be able to read that on a voltmeter due to the voltage-current relationship". Funny how the WFCO 8712 on my old popup had no problem going to 14.4 volts, and it could be measured. Even my Harbor Freight battery charger went to 14.4 when I used that to top off the battery.

[mooky_stinks]

Thanks! All great responses and pretty much what I thought about undersized wiring. I’d love to replace the wiring and converter but it’s just not practical for a couple times a year that I need it. I’m probably just going to do what was suggested above and bring along my 25 amp charger to help it along. I tried it last night in the driveway and it does boost the voltage up.

[ktmrfs]

mooky stinks wrote:
I have a WFCO-8955 (55 amp) that absolutely will not go into bulk mode even though it’s a 3 stage converter. Not sure if it’s inadequate wiring or an inadequate converter. It’s always 13.6-13.8 no matter the state of charge of the batteries. What I’d like to know is how many amps is it putting out in this mode. And don’t tell me 55 because we all know that ain’t possible! ??

I've measured close to a dozen WFCO's with an output voltage of 13.6V or so, and it's like most any charger hooked to a battery >50% charged that has an output voltage of 13.6V or so.

15A or so is all it's putting out. May be as low as 10A, might be as high as 20A.

Doesn't seem to matter if it is one 12V, a pair of 12V, a pair of GC2's or four GC2's. clip on DC hall device current probe is in the 15A or so range.