Xantrex Charger Installation and Wiring Upgrades

[Harold Kroeker]

I replaced the charger/converter in the WFCO (World Friendship Company) Model 8955 power center that came installed in my Escape 19 with a Xantrex Truecharge 2 40A charger/converter. This would seem to be an odd thing to do since they both claim to be 3 stage chargers and the WFCO unit is rated at 55 amps while the Xantrex is only 40 amps, but I assure you that there is method to my madness.

To explain why I replaced the original charger, I have done a comparison of the 3 stage charging systems of the old WFCO charger and the new Xantrex charger. The information is taken from the their manuals.
Bulk Mode
- The WFCO charger in “bulk” mode uses a constant voltage of 14.4V for a maximum of 4 hours. The manual does not say what else besides time could cause it to switch out of bulk mode but I assume that it would be when the battery reaches a certain voltage. I should also mention that constant voltage is the most common way to charge a lead-acid battery and is recommended by most battery manufacturers. This means that the charger output voltage is fixed and the current going to the battery decreases as the battery voltage rises. While this is a very safe way to charge a battery, it can take a long time because the charging current keeps decreasing.
- The Xantrex charger in “bulk” mode uses constant current. This means that it puts 40 amps into the battery until it detects that the battery 80% charged. The result is that the battery charges much more quickly which is important when charging using a generator.

Absorption mode
- The WFCO charger uses a constant voltage of 13.6V. This mode provides the 12 Vdc and current required by the 12 Vdc RV appliances, as well as slow charging the battery. The documentation does not state when it switches to float mode.
- The Xantrex charger uses a constant voltage of 14.4V until a full charge is detected.

Float mode
- The WFCO charger uses a constant voltage of 13.2V. When the converter senses a demand, the converter automatically returns to the “Absorption mode”.
- The Xantrex charger uses a constant voltage of 13.5V and the charger is able to provide current to its full rating to power auxiliary DC loads on the battery.

Standby mode
- The WFCO charger does not claim to offer this.
- The Xantrex charger monitors the battery voltage and will begin a charging cycle 21 days after the last completed cycle, or when the minimum battery terminal voltage drops to below 12.5 V.

As you can see from the above, the two companies have different definitions of what constitutes bulk charging and absorption charging. In my opinion, the WFCO charger doesn’t really have a bulk mode. For most campers, who only go a day or two without plugging in, none of this really matters. The charging algorithm of the WFCO charger is quite conservative and should help the batteries last a long time. It is only for odd people like myself, who almost never have shore power and who charge the trailer batteries from a generator, that will really notice the difference. My charger should bring my dual 6V batteries from 25% charge to 80% in about 1.5 hours.

The other reasons that I replaced the charger are:
- Reliability: The Xantrex charger is simply a better quality unit.
- Onboard Control and Status Display Panel with a Remote Panel option: There is panel right on the charger that shows the charging current and allows the user to change some settings. I installed the remote panel that displays the status of the battery and the charging current and allows me to change a number of variables that are not available on the panel that is on the charger itself. The panel is shown in one of the pictures below.
- Battery type setting: I am using AGM batteries which have slightly different charge characteristics than flooded batteries. I set this once on the charger and it deals with it.
- Temperature compensated using manual setting or a probe: Excessive heat can kill a battery very quickly. The temperature at the battery can be set on the charger or a remote probe can be attached to the negative battery terminal which is what I did.
- Current limiting: I can set the maximum current that I want the charger to put out which limits the current that it draws. This allows me to run my air conditioner and charge my battery at the same time without overloading my generator.

While I was installing the charger, I made a few other changes as well:
- Added a digital voltmeter accurate to 2 decimal places and made a table for my batteries so that I can read the current state of charge.
- Changed the wiring from the charger to the battery from 10 gauge to 6 gauge to reduce the voltage drop. I also installed a ground buss bar and fed it with 6 gauge wire.
- Installed a battery cut-off switch that is capable of handling large currents.
- Installed a 50 amp fuse right at the battery.
- Installed a pair of Lifeline 6V AGM batteries.





I started by removing the WFCO charger from the bottom of the power centre. Then I cut two slots in the back of the charger bay to capture the feet of the new charger.




I wired the charger in exactly the same as the old one but I used 6 gauge wire instead of the original 8 gauge. I slid the two back feet of the charger into the slots that I had made and screwed down the two front feet.




This picture shows the electrical panel after I was done which looks the same as it did before I started. The bright red switch next to the electrical outlet is a high current battery shut-off that I installed. It isolates the battery from the trailer electrical system but still allows the batteries to charge as I drive even if it is turned off. The switch that usually comes with the trailer would not be able to handle the current that the new charger puts out so I chose not to have it installed when my trailer was built.




This is the back of the electrical panel showing the captured charger feet at bottom of the charger bay, the battery switch, the buss bar that I installed for the negative polarity connections, and the 6 gauge wire that I used for all of the high current wiring.




From top to bottom is the input power monitoring display panel that I covered in another post, the Xantrex control and monitoring panel, and the battery voltage display.




This is the table that is posted to the left of the battery voltage display that allows me to see the state of my batteries. I made it specifically for my Lifeline GPL-4CT AGM batteries from the manufacturer’s data. I also have one that I made for the Trojan T-105 batteries that I had in my old trailer. The Xantrex remote panel also displays the current state of charge but only full/half/low which is not enough detail for me. As you can see from the table, the voltage difference between a full battery and a dead battery is very small which is why I had to ensure that the voltmeter that I installed was accurate and would display two decimals. It is not good for the battery to run it too low so I try to charge when it is at 50% and never let it go between 25%. This is indicated on the table by the colours of the different voltages.

[strawbarry]

Harold,

You may be interested in this little device if you want more info on the state of your batteries charge.
http://www.evalbum.com/tech/e-mtrpdf.pdf

[Harold Kroeker]

An excellent suggestion! I was considering getting a similar unit offered by Xantrex http://www.xantrex.com/power-product...y-monitor.aspx but was thinking that I don't use the trailer enough to justify buying it yet. In retrospect, I should have got off my wallet and installed it while I was doing the rest of the wiring. I will probably get one when I add solar panels and an MPPT charge controller when I retire in 4 years. With the advances being made in solar panel design, I figure that it is a good idea to hold off buying them for as long as possible.

[kpitcher]

Have you had a chance to test your charging time yet? Did it go as expected? Does the Xantrex still power the 12v systems (lights etc) in the trailer when plugged into shore power? or does it just charge the battery? I have the same WFCO and have been pondering the change you made. Mine never seems to go into "bulk" mode no matter what the battery voltage is and I don't want to run the genny as long as I seem to have to.

Thanks.

[Harold Kroeker]

I used the new charging system this summer and it performed exactly as expected. The lowest my batteries got was 60% before I ran my generator which was low enough for the bulk mode to kick in. It didn't take long before the batteries were at 80% and then I saw the charging rate decrease as the charger switched to constant voltage charging. The charger still powers the lights etc while charging but the current available to charge the battery is reduced by the amount that you are using for other things. Once the batteries are charged, the full 40A output of the charger is available for the 12V systems in the trailer.

[kpitcher]

Thanks for the reply. Just a couple more questions - I know lots of questions.

Any problems with light bulbs burning out? Especially when the equalization mode is selected? 15.5 Volts seems pretty high and I was wondering if you had any problems with it. Also do you use a temp sensor on the batteries? It sounds like you are charging at 40 amps on 2 X 6v batteries. Do the batteries get very warm? I had heard that you should only charge at 10% the amp hour capacity - you have not had any issues though?

Did you ever consider wiring the true charge in conjunction with the WFCO? Using an amply rated automotive relay to switch beween the two charging stations (WFCO & TC) leaving the WFCO to always power the 12v trailer devices, and the TC to just work on the battery?

BTW your pics are excellent in your installation. Very easy to follow. Nice clean job. Off topic, but one mod I just finished was installing a water expansion or compression tank in the TT. It works awsome, no more cycling of the water pump every time someone turns the tap, and the water comes out under constant pressure - no more waves. My wife thinks I just like spending $, but it is kind of fun "pimping" the trailer.

Kpitcher.

[Harold Kroeker]

- I have no problems with bulbs burning out, perhaps because I have all LEDs which are usually rated for 11 to 30 volts.
- I do not use the equalization mode because I have AGM batteries. Equalization is done so seldom that it should be no problem to leave the lights off while you do it if the higher voltage does present a problem.
- I do have a temperature sensor attached to the negative stud of one of my batteries. I have no idea if the batteries get warm, I have never felt them.
- Xantrex recommends a minimum battery bank size of 80 Ah for the 40 amp charger, I have 220 Ah (2 of Lifeline GPL-4CT, 6V 220 Ah each). According to the Lifeline web site: "The GPL-4CT is designed for charging amperages up to 550 amps or 250% of the rated Amp Hour Capacity due to low battery internal resistance."
- I never even considered leaving the WFCO unit in. The current draw of everything 12V in the trailer is negligible and really doesn't take much away from the battery charging. By going with all LED lights, the biggest current draw for me became running the furnace in cold weather, and that goes on very seldom due to the optional double pane windows and upgraded insulation. There is an excellent post by wcf that lists the current draw of everything in the trailer: http://escapeforum.org/index.php?top...12371#msg12371.

I hope you will post pictures and instructions of your expansion tank install so that we can all learn from your experience. I would like to see where and how you mounted it.

[kpitcher]

I am just starting the switch to LED's. The broader V range would definitely eliminate any potential problem. My 6's are flood type batteries, so that is why I am probably more limited in charging rate. There is a good webpage called "the 12 volt side of life" if you have not come accross it yet. Discusses a lot about everything 12 volt. Thanks for all the info and real life experiece with the TC2.

Regarding the expansion tank, I actually do not own an escape trailer. Just have the WFCO and was looking at the TC and found this forum during a search. So I can not say where it would fit. In my trailer the water pump is under a couch so I had extra room to install this. I purchased the 4.5 gallon tank at Peavy Mart for about $60. Then bought some 5/8 nylon braided hose and used 1/2 barbed connectors with hose clamps to hook everything up (the 1/2 hose was just to tight, 5/8 was perfect). Bought the good connectors from a underground irrigation company not the ones home H Depot (their barbs are way smaller). The expansion tank is piped in after the pump but before the hot water tank. Most tt water pumps kick in at about 25 psi and out at 45 psi. You want the air pressue in the tank to be about 3 psi less than the kick in pressure. Easiest way is plumb everything in, start the pump and let it stop (everything at 45 psi), the tank comes pre-pressured to I think 35 psi, if not then pre-pressure it. Then slowly let the air out of the pressure tank till the pump kicks in, then let just a little more air out and your set. The pressure tank's air valve is the same as what is on your truck tire, or bicycle tire. Basically extends the pressure in your water system without having to run the pump to do it and because it is under a constant pressure like at your house there is no "wave" of water as the pump cycles on and off when you open up a tap. Also gives you a little more water capacity. So the pump only kicks on after running 1-2 gallons. Mind you it will run for 10 seconds or so when it does kick on. I just didn't like it cyling so much all the time and wanted it quiter when the kids get up to use the bathroom in the middle of the night. My water pump was screwed the floor so I also put some of that blue camping foam under it and screwed it back down. Put some of that grey pipe insulation from H Depot around the in and out pipes from the pump to stop any vibration noise and now everything is also way quieter when the pump does run. All in all a very easy mod.

Thanks for all the help on the True Charge, Kpitcher.

[strawbarry]

Herold

Check out this battery monitor. www.bogartengineering.com