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Old 06-11-2021, 10:38 AM   #1
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Battery Charging, Solar vs WFCO Conv/Chrgr

. We just returned from camping to test the boondocking capabilities of our
2021 E-Pro 19FBS equipped with:
- Go Power 190w Solar thru GP-PWM-30-UL Solar Chrg Cont, FR install
- WFCO 8740P Power Center/Charger/Converter, NO LiFePO4 setting
- Go Power GP-LiFePO4-250AH Lithium Battery, w/BMS, dealer installed
- Renogy RBM500 Battery Monitor, w/ 500A shunt at NEG battery

Our 12 V Power Loads are mostly all intermittent:
Magic Chef 4.4 cf 12V ONLY Comp’r Refidg, Water Pump, LP Water Heat, LP Furnace (night only), LED lights, USB ports, Radio/Audio, Slide, Awning, parasitic draws

. We arrived at an NFS CG at 8,000 ft in the Colo rocky mtns, with 30A-120V AC shore power available. The battery was at 99% SoC (248AH). The site and solar panel was partially shaded, with full sun from 12-2 PM. I logged the SoC and System Voltage each day at 8AM & 8PM for 7 days, and stayed unplugged for 4 days, followed by 3 days plugged into AC shore power. System stayed at 13.0-13.2V at all times.
The SoC dropped 20-24% (50-60AH) each day on Solar only,


The charging log:

190W Solar charging ONLY 13.0 - 13.2V
6/1, 8 AM SoC 99% Partly Cloudy,
-33 AH to 8 PM SoC 86 % -17 AH overnight
6/2, 8 AM SoC 79% Partly Cloudy,
-17 AH to 8 PM SoC 72% -40 AHovernight
6/3, 8 AM SoC 56% Mostly Sunny,
-25 AH to 8 PM SoC 46% -35 AH overnight
6/4, 8 AM SoC 32% Full Sun 8.9A -28 AH to 8 PM SoC 21% -25 AH overnight



START WFCO Conv/Charging Start 8 PM ~13.1 V @ ~1.1 A
6/5, 8 AM SoC 20% Cloudy/Rain, +1 AH to 8 PM SoC 21% 0 AH overnight
6/6, 8 AM SoC 21% Pt Cldy/Rain, +3 AH to 8 Pm SoC 24%

. WFCO Charge: 13.2 V @ ~0.6 A
. Turn OFF WFCO 8 PM SoC 24% -3 AH in 1 hr.
. Turn ON WFCO 9 PM SoC 21%

. WFCO Charge: 13.2 V @ ~8.5 A
6/7, 8 AM SoC 60% Overnight Charge +98 AH
. 11 AM SoC 67% Unplug AC Power/WFCO OFF +17 AH in 3 hrs

190W Solar charging ONLY 13.0 - 13.2V
6/7, Decamp/Drive home 11 AM to 5 PM SoC 75 % +20 AH in 6 hr
6/8, 8 AM SoC 71% Refrigerator OFF, Parked, NO AC Power -10 AH overnight

My Questions:
1) Why won't the WFCO Conv/Chrg provide the spec'ed output of 40A @ 13.2-14.4V?

2) Why the variation in Day to Day AH Net in/out and Night to Night AH OUT on Solar only (daytime) charging?

3) Why was the Converter/Charger only putting out a trickle charge (1.1A) for the first two days while the battery was below 25% SoC?

4) Why did the the Converter/Charger ramp up to 8.5A after turning it off (at AC breaker) for one hour? Why not higher A?

5) Do I need to change out the Converter/Charger for one compatible with a LiFePO4 battery?

6) What changes can anyone suggest? (I do plan to add a 200w Portable Solar Suitcase to my system)

7) What advice can anyone offer to extend my boondocking time, or improve my system?

. On longer trips I would like to be able to boondock for a week, go to an RV Camp/Park for a night to refill fresh tank, dump gray/black tanks, recharge battery if needed, buy some groceries, and return to boondocking.
. Thanks for any info anyone can add as this is my first TT and I am new to Solar. Sorry for the lengthy post, but I thought it best to include all available info to you guys.

Rod
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Old 06-11-2021, 11:09 AM   #2
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Many reports of WFO converters not going into bulk mode.
I picked up a progressive dynamic with the charge wizard. I can put it into bulk mode anytime.
Variations in ah due to sun, shade, fridge coming on.
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Old 06-11-2021, 11:09 AM   #3
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Well I had a similar set up (the go-power items) when I first started out. So if it were me. and others may have a different view or advice

If you want to boondock longer off power, you might need to add some solar and another lithium battery to match. (you mention a 200W solar suitcase, that is good)

Change out the Converter Charger for a Lithium Compatible one Progressive Dynamics 12V Lithium Ion Battery Converter/Charger

You only have (mounted) 190 Watt Panel id invest in 1 or 2 more 190W, if you plan to add more in addition to the solar suitcase get a MPPT Controller. (more efficient)

Id also pick up a small portable generator for those times you dont get solar and need to recharge. (as a back up) because you may not always have sun when boondocking.

These simple items should extend your boondocking experience.
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Old 06-11-2021, 12:18 PM   #4
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Quote:
Originally Posted by robo44 View Post
Well I had a similar set up (the go-power items) when I first started out. So if it were me. and others may have a different view or advice

If you want to boondock longer off power, you might need to add some solar and another lithium battery to match. (you mention a 200W solar suitcase, that is good)

Change out the Converter Charger for a Lithium Compatible one Progressive Dynamics 12V Lithium Ion Battery Converter/Charger

You only have (mounted) 190 Watt Panel id invest in 1 or 2 more 190W, if you plan to add more in addition to the solar suitcase get a MPPT Controller. (more efficient)

Id also pick up a small portable generator for those times you dont get solar and need to recharge. (as a back up) because you may not always have sun when boondocking.

These simple items should extend your boondocking experience.
I agree, except for the generator part-too noisy for me.

The heart of a solar system is the battery bank. You have to be able to store power on the good days. Your system is relatively small for extended dry camping unless you cut back on your usage.

The OP mentioned that the site was partially shaded. Partial shading can kill solar output. I posted a video by Amy at Alt-E a while back that demonstrated the effects of partial shading on a solar panel. Even shading of a small portion of the panel can stop most of the output wattage. It is imperative that the whole panel be in the sun. This is why non-mounted solar panels like suitcase systems are so popular in wooded areas of the country. You can place them away from the shaded areas where you would park the TT.

As per the WFCO converter, every source I have read, indicates that you should be able charge your LIFEPO4 battery to about 80% or 13.2-13.3V with a LA converter like the WFCO. I never measured my output when I had the LA WFCO. I now have a drop in WFCO lithium charger and have measured a flow of 50 amps.
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Old 06-11-2021, 12:30 PM   #5
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Your stock WFCO converter will never go into bulk charge mode with an LFP battery. The nominal voltage remains relatively constant with respect to state of charge so the voltage difference is insufficient to switch the converter into bulk mode.

I have a similar setup to yours and I've made a few changes that have been helpful. I added a second 190W solar panel opposite the dealer installed panel. This allows me more flexibility to orient my trailer within a site. If oriented along a N/S axis, I have at least one panel in the sun all day. If oriented along an E/W axis, I have one of the two panels in the sun all day. I also have a 200W solar suitcase that is particularly useful in shady sites where I need to chase the sun around during the day.
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Old 06-11-2021, 12:38 PM   #6
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I forgot to mention that, in addition to being slow, an LFP battery will never reach full charge with a non-lithium compatible converter. You'll only get to ~80% charge. This will prevent the passive balancing that occurs at top-of-charge. I should note that I have *not* replaced my converter and just mostly rely on solar charging. This works for me, but your mileage may vary. An external charger is also an option.
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Old 06-11-2021, 12:44 PM   #7
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WFCO LA converter will only charge in bulk mode for a max of 4 hours before it will shut itself off. From their site:

1. NORMAL MODE (Absorption) powers all DC loads, and keeps the battery charged.

2. TRICKLE MODE (Float) is initiated when there is no significant change in current draw for 44 continuous hours, keeping the battery charged while prolonging its life.

3. FAST CHARGE MODE (Bulk) kicks in to charge the battery if its significantly discharged due to improper maintenance, long term storage, or significantly heavy system overloads. Bulk mode is maintained for 4 hours (max.) to prevent possible battery damage.

Normal and Trickle Modes are the only charging modes your battery should ever require when you properly maintain your battery. The WFCO Normal Mode is a powerhouse, capable of charging a fully-discharged battery in under 3 hours. Trickle Mode will keep the battery safely charged when your RV is not in use.

Some RV and battery manufacturers believe high-voltage charging can potentially damage the battery if not absolutely required. The WFCO Fast Charge (Bulk) Mode is provided for the rare times a battery needs extra power for charging.
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Old 06-11-2021, 01:36 PM   #8
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Battery Charging, Solar vs WFCO Conv/Chrgr

. Thanks for all the useful and very informative help.

. I still don't understand why the WFCO Conv/Chrg won't go into the Absorption or Bulk modes to fully top off my LFP battery. It seems to stay in Float mode (trickle charging) unless I turn it off, wait a hr, and turn it back on, even then it won't go into the higher Bulk mode at 14.4V which would allow my LFP battery to re-balance it's cells.
. As I mentioned originally my battery seems to stay at about 13.0-13.2 V most of the time. Is this voltage too high to allow the WFCO to switch modes?
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Old 06-11-2021, 01:49 PM   #9
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Because it can't. LFP require 14.1volts to fully charge. WFCO you have can't do that.
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Old 06-11-2021, 01:55 PM   #10
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Originally Posted by Old Coyote View Post
As I mentioned originally my battery seems to stay at about 13.0-13.2 V most of the time. Is this voltage too high to allow the WFCO to switch modes?
My understanding is that these WFCO converters need to hit full output current to switch to Bulk mode. The voltage of an LFP battery stays relatively constant across its discharge curve (see below from Battleborn's website). Thus, you won't get sufficient voltage difference to drive max current. LA battery voltage drops more quickly as a charge drops.

It *may* be possible to get this converter into bulk if your battery is at a very low state of charge, but even then, it will not stay in bulk long enough to fully charge your batteries.

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Old 06-11-2021, 02:30 PM   #11
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Battery Charging, Solar vs WFCO Conv/Chrgr

Quote:
Originally Posted by mbbutler View Post
Because it can't. LFP require 14.1volts to fully charge. WFCO you have can't do that.

mbbutler, You may have found the problem, the specs on my
GP LFP 250AH battery are:

. Nominal Voltage = 12.8V
. Charge Voltage = 14.6V

. Maximum Charge Current = 100A
. Charge Cut-off Voltage = 14.6V


The Specs on my WFCO 8740P Conv/Chrgr are:
. Absorption Charge Voltage = 13.6V
. Bulk Charge Voltage (4hrs) = 14.4V
. Storage Charge Voltage = 13.2V
. Rated DC Current = 40A


[QUOTE=NullPtr;2576563]My understanding is that these WFCO converters need to hit full output current to switch to Bulk mode. The voltage of an LFP battery stays relatively constant across its discharge curve (see below from Battleborn's website). Thus, you won't get sufficient voltage difference to drive max current. LA battery voltage drops more quickly as a charge drops.


NullPtr, Considering the specs for my equipment above, would you suspect that the WFCO would need to reach 40A output BEFORE it would go into Bulk mode at 14.4 V? Would that be high enough Voltage for the LFP which says it charges at 14.6V? I would hope that the LFP would charge at anything above 12.8V, but during my week long test the battery voltage always stayed in the 13.0-13.2V range. Any thoughts?
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Old 06-11-2021, 02:57 PM   #12
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NullPtr, Considering the specs for my equipment above, would you suspect that the WFCO would need to reach 40A output BEFORE it would go into Bulk mode at 14.4 V? Would that be high enough Voltage for the LFP which says it charges at 14.6V? I would hope that the LFP would charge at anything above 12.8V, but during my week long test the battery voltage always stayed in the 13.0-13.2V range. Any thoughts?
Yes - that is my understanding based on this paragraph from the manual:

If the output current reaches its maximum (normally caused by a discharged battery), this will cause the converter to go into Bulk Mode, which means the target output voltage will change to 14.4 VDC and a timer will start. 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. From the paragraph above, as load current increases, output voltage decreases. The actual output voltage will not rise until the load current is reduced, which happens naturally as the battery charges or if 12 VDC appliances are turned off.

Bulk Mode will be maintained until the current draw drops to approximately five Amps, or until the timer reaches four hours (whichever happens first). Then the target output voltage is changed back to 13.6 VDC for Absorption Mode. Lights that are powered from the output may change brightness slightly at that time.
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Old 06-11-2021, 03:10 PM   #13
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I would hope that the LFP would charge at anything above 12.8V, but during my week long test the battery voltage always stayed in the 13.0-13.2V range. Any thoughts?
Your battery will charge anytime the converter outputs a voltage greater than the battery voltage (assuming your BMS has not hit high-voltage cutoff). The charge current will increase as the voltage difference increases. The problem is that, the higher voltage of an LFP battery limits the voltage difference and thus the charge current. This why it's difficult to get to the current required for bulk mode. It *may* be possible if your battery is deeply discharged to get the voltage low enough, but I can't say for sure.
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Old 06-11-2021, 03:15 PM   #14
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Don't forget that the solar voltage input is on the same circuit as the converter (the 12V side) so that is contributing to the converter not knowing the actual SoC based on voltage so during the day as the panel(s) provide juice the converter sees that at the battery and adjusts accordingly
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Old 06-11-2021, 03:32 PM   #15
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Don't forget that the solar voltage input is on the same circuit as the converter (the 12V side) so that is contributing to the converter not knowing the actual SoC based on voltage so during the day as the panel(s) provide juice the converter sees that at the battery and adjusts accordingly

jbflag,
. Would you expect the Solar charge to be reduced if the Converter is also trying to charge the battery on any day with less than full sun, or full sun? Do you see any way to hide the Solar Charge from the Converter? Or hide the Converter charge from the Solar Charge Controller?
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Old 06-11-2021, 03:37 PM   #16
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Your battery will charge anytime the converter outputs a voltage greater than the battery voltage (assuming your BMS has not hit high-voltage cutoff). The charge current will increase as the voltage difference increases. The problem is that, the higher voltage of an LFP battery limits the voltage difference and thus the charge current. This why it's difficult to get to the current required for bulk mode. It *may* be possible if your battery is deeply discharged to get the voltage low enough, but I can't say for sure.
NullPtr,
. Given what you suggest above, it seem to me my only option is to add another Portable Solar panel (200w) that can be placed in the sun to get a full charge on my LFP battery. Would I need to also turn off the WFCO Converter (at AC breaker) to allow the Solar Charger(s) to develope maximum voltage to the LFP?
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Old 06-11-2021, 03:46 PM   #17
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jbflag,
. Would you expect the Solar charge to be reduced if the Converter is also trying to charge the battery on any day with less than full sun, or full sun? Do you see any way to hide the Solar Charge from the Converter? Or hide the Converter charge from the Solar Charge Controller?
The solar controller outputs at fixed voltage and adjusts amperage based on the available watts from the panels. There is no way to separate them since the voltage at the battery terminals is what the converter sees. Even then, that is surface voltage and not "at rest" voltage.
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Old 06-11-2021, 03:48 PM   #18
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NullPtr,
. Given what you suggest above, it seem to me my only option is to add another Portable Solar panel (200w) that can be placed in the sun to get a full charge on my LFP battery. Would I need to also turn off the WFCO Converter (at AC breaker) to allow the Solar Charger(s) to develope maximum voltage to the LFP?
There is no need to turn off the converter. Because your converter will not go into bulk mode it will stay at 13.6 or 13.2V which is below the solar controller's absorption threshold.
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Old 06-12-2021, 11:14 AM   #19
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Since I do not have battle born batteries either, I would not call them, but I use their FAQ stuff off their site. Basically, they report that the factory WFCO will never charge their batteries past about 50%.

The simple problem is they read lifepo voltage as being fully ornear fully charged so WORTHLESS. Before your NEW CONVERTER INSTALL, TRY THE AGM SETTING, IF IT EVEN HAS THAT.

ADD SOLAR is the best idea. And for sure upgrade your charge controller.

Also a Renogy DC to DC with heavy wiring will let the lithium batteries ale charge from the truck. In my motorhome a 40 amp Renogy DC to DC will feed my 600 amp bank at 40-41 amps with engine running.
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Old 06-12-2021, 04:23 PM   #20
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Others also make replacement converters but Progressive Dynamics does not make a lithium-compatible converter you can swap out directly for the one in your WF8740. Theirs will replace only the 8900 series from WFCO. If you call them, I'm sure they can provide useful advice.

The higher-rated power centers supply more amps and can accommodate more AC circuits. The important difference to you is physical size. I believe the dimensions of the 8900 (and similar) series are larger. That may be a limiting factor.
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