jauguston
Bellingham, WA
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Joined: 07/03/2005
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There has been mention that the WFCO will work fine "if it is set up right". The issue with proper setup is not exclusive to WFCO but applies to any three stage smart converter. The wire size from the converter to the battery must meet a minimum size for the converter to function properly. The wire size requirements are in the owners manual. To tell if your converter is working right you need to monitor the charge voltage at the battery. If your battery is fairly low the voltage at the battery should slowly rise to 14.3 or 14.4v as it is charging. When it gets there the voltage will drop to some number below 13.6v. It will then slowly climb to around 13.6. When it gets there it will then drop to 13.2v and stay there. When it drops from 14+ to below 13.6 the battery is about 80% charged. when it drops to 13.2v the battery is 100% charged and the converter has gone into maintainance mode. It can take quite a while to go from the 13.6v target to the 13.2v mode. That last 20% of charge takes longer.
If it doesn't go above 13.7v the most likely problem is the wire size to the battery is too small, a fairly common issue.
Jim
Jim, Sharon and Buddy the Yorkie
1999 Gulfstream Sun Voyager 31' ISB Cummins 275
AIMS 2500w inverter 4-6v GC batteries
4-Kyocera 130w solar panels SB3024iL MPPT controller
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ryanallie1
Magalia, Calif
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Joined: 04/12/2005
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Hi All.
Not much info given. Buy a second battery. One group 24 is just about useless. You'll for sure be using that 3500 Genny quite a lot. Manufactors sure are getting cheap. I wouldn't buy an RV with just one battery, espically a group 24 only. Enjoy your trip. Good Luck. Happy Camping. Dan & Jill
1997 Ford F-250, H.D. Extended-Cab, Short Bed, 7.3 PSD, K&N Air Filter, 5000 lbs air bags w/compressor w/guage, SuperChips Tuner/Programer. 1996 Nash 24fter 5er, 15K "Lil" Rocker Hitch w/BedSaver, Twin EU2000i Gen's W/Kit. Nam-Vet, 66-67-68,& 70-71
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Hurricaner
Hurricane Utah
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Joined: 02/17/2007
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Quote:There has been mention that the WFCO will work fine "if it is set up right". The issue with proper setup is not exclusive to WFCO but applies to any three stage smart converter. The wire size from the converter to the battery must meet a minimum size for the converter to function properly. The WFCO has its own issues in addition to wire size. If the converter is sized too large in relationship to the battery size, I don't care how big the wire size is, the WFCO will not go into boost. On a single group 24 the WFCO better not be larger than a 35 amp or it will never go into boost know matter how large the wire size is. The WFCO will only go into boost if it is loaded so severely that the voltage drops below 13.2 and those things do a darn good job at holding that voltage.
Sam
Sam & Kari
Hurricane, Utah
2004 34' Damon Challenger 315
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big_murph_279
Concord, NC
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Thanks for all the advice. I went out to my boat this afternoon and found out that I have a new group 27 deep cycle battery in it. Would it help to hook both the 24 and 27 batteries together? How much longer would it take to charge two of them instead of just one?
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topflite51
In The Desert of Nevada
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Joined: 05/13/2004
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ryanallie1 wrote:Hi All.
Not much info given. Buy a second battery. One group 24 is just about useless. You'll for sure be using that 3500 Genny quite a lot. Manufactors sure are getting cheap. I wouldn't buy an RV with just one battery, espically a group 24 only. Enjoy your trip. Good Luck. Happy Camping. Dan & Jill Have you ever heard of adding a battery? It really isn't difficult.
 David
Just rolling along enjoying life
w/F53 Southwind towing 87 Samurai looking to golf or fish
Simply Despicable 
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pianotuna
Regina, SK, Canada
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Joined: 12/18/2004
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Hi big_murph,
Yes it will, but be sure to wire them correctly. Method 2,3 or 4 on this page will work--method 1 works but does not "balance" them. Because they are different capacities they will not be totally balanced and charging needs to be carefully monitored.
correctly interconnecting multiple batteries
It would be better if both batteries were of the same capacity. It may be wise to provide for a disconnect for the #24 battery, or to use them alternately. That would require a different wiring method with switches to choose A, or B. Another option would be an A, B, or both setting.
big_murph_279 wrote:Thanks for all the advice. I went out to my boat this afternoon and found out that I have a new group 27 deep cycle battery in it. Would it help to hook both the 24 and 27 batteries together? How much longer would it take to charge two of them instead of just one?
Regards, Don
Kustom Koach Class C 28'5" 256 watts solar, 875 amp hours in two battery banks 12 volt batteries 2500 watt inverter.
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smkettner
Southern California
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Joined: 03/21/2005
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big_murph_279 wrote:Thanks for all the advice. I went out to my boat this afternoon and found out that I have a new group 27 deep cycle battery in it. Would it help to hook both the 24 and 27 batteries together? How much longer would it take to charge two of them instead of just one?
This may seem strange but if you have two they will charge almost as fast as one. Just connect with jump cables if you like.
Actual speed will depend on the amp rating of the WFCO and if it moves from normal(13.6) to boost(14.4) voltage while charging.
Two to four hours at 14.4 volts and four to eight hours at 13.6 volts is my best estimate. And this is just 40% to maybe 85%. Getting all the way to 100% will take an additional four to six hours. Most people bounce from 40% to 80% when camped and leave the 100% charge for when you get home.
2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
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Salvo
California
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Hurricaner wrote:Quote:There has been mention that the WFCO will work fine "if it is set up right". The issue with proper setup is not exclusive to WFCO but applies to any three stage smart converter. The wire size from the converter to the battery must meet a minimum size for the converter to function properly. The WFCO has its own issues in addition to wire size. If the converter is sized too large in relationship to the battery size, I don't care how big the wire size is, the WFCO will not go into boost. On a single group 24 the WFCO better not be larger than a 35 amp or it will never go into boost know matter how large the wire size is. The WFCO will only go into boost if it is loaded so severely that the voltage drops below 13.2 and those things do a darn good job at holding that voltage.
This isn't rocket science. There are 3 factors which determine if the 35A WFCO goes into boost: battery voltage, battery resistance, and line resistance.
If the discharged battery voltage is still too high it will not go into boost.
If the combined battery and line resistance is too high it will not go into boost.
This equation must be met to get boost:
V_bat + I_charge * (R_bat + R_line) < 13.2V
If the battery is discharged to 12.0V (~50%), then the combined resistance is:
R_bat * R_line < (13.2V - 12.0V) / 35A = 34 m ohm
The Group 24 battery has about 20 m ohm resistance. That means the line resistance must be less than 14 m ohm.
Sal
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pnichols
Santa Cruz Mountains
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Joined: 04/26/2005
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"V_bat + I_charge * (R_bat + R_line) < 13.2V"
Sal, this is a nice simple form of the equation and should help many in the forums to finally understand the importance of cabling resistance between charging equipment and batteries being made as low as possible.
P.S. #1: Your equation shows clearly that if I use AGM batteries ("R_bat" very low) and use about 8 feet of 2 guage cabling ("R_line" very low), I can probably save ~$200 or more by being able to continue using my stock Parallax 7345 converter for my 200 AH coach battery bank.
P.S. #2: Your equation also shows the importance of completing one's charging equipment's output feedback loop at the batteries (instead of on the equipment's PC board) so as to drive "R_line" to zero!
Phil, 2005 E450 Itasca 324V Spirit
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Salvo
California
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Hey Phil,
Didn't someone once say "An equation is worth a thousand words"? ;-)
For your Parallax 7345 we have a little different equation because it's only a single stage controller. Hence the "much smaller" (<<) sign.
V_bat + 45 A * (R_bat + R_line) << 13.7 V
With battery down 50%, 12.0V we get:
R_bat + R_line << (13.7 - 12.0) / 45 = 37 m ohm
It would be nice to know the internal resistance of AGM batteries. Can you measure them? You'll need a current shunt. My WAG is 4 m ohm for the setup.
That means your line resistance needs to be much smaller than 29 m ohm for the converter to maintain constant current (45A) for any amount of time.
Why not do some line resistance measurements? It's quite simple.
BTW, I'm also using a 7345 converter. But it's almost never used as I rely on solar.
Sal
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