WFCO WF-8950L2-MBA and Wire Gauge Question

[jsmathers]

Hi, I recently received a 2022 1800bh Micro Minnie. I am planning to add a WFCO WF-8950L2-MBA board to my existing converter as mentioned by Ken in the post in this thread, as the installation seems very simple. I plan on getting a 206Ah SOK LiFePo4 since Will Prowse and others give them good reviews. I will probably get the marine (plastic) version of the battery just to make initial installation easier (on the tongue), but plan to move it into the front storage bay at some point. Not sure if I would need an additional outdoor battery box for the marine battery.

From what I understand, the wiring is only 6 gauge from the converter to the battery, and there is a manual 30A fuse located on the tongue. I am only expecting about 20-25A charge current given the 6g wiring based on others posts I have seen. Is this assumption correct? Should I worry about too much current being driven from the converter and overheating the wiring or tripping the 30A breaker? If I were to guess there is probably 15-20ft of wire between the converter and the battery, which will result in a greater than 3% voltage drop even at 30A with the 6g wire, so I am also worried that proper charge voltage will reach the battery.

I see the WF-8950L2-MBA outputs 50A (max?). The SOK battery can handle 50A max with a recommended charge current up to 40A. Does the MBA board regulate the current output in any way? I'm just hoping I don't need to replace all of the 6g wiring as I assume this would not be an easy task.

Thanks for any input!
- Jason

[Fred 2106DS]

Originally Posted by jsmathers

Hi, I recently received a 2022 1800bh Micro Minnie. I am planning to add a WFCO WF-8950L2-MBA board to my existing converter as mentioned by Ken in the post in this thread, as the installation seems very simple. I plan on getting a 206Ah SOK LiFePo4 since Will Prowse and others give them good reviews. I will probably get the marine (plastic) version of the battery just to make initial installation easier (on the tongue), but plan to move it into the front storage bay at some point. Not sure if I would need an additional outdoor battery box for the marine battery.

From what I understand, the wiring is only 6 gauge from the converter to the battery, and there is a manual 30A fuse located on the tongue. I am only expecting about 20-25A charge current given the 6g wiring based on others posts I have seen. Is this assumption correct? Should I worry about too much current being driven from the converter and overheating the wiring or tripping the 30A breaker? If I were to guess there is probably 15-20ft of wire between the converter and the battery, which will result in a greater than 3% voltage drop even at 30A with the 6g wire, so I am also worried that proper charge voltage will reach the battery.

I see the WF-8950L2-MBA outputs 50A (max?). The SOK battery can handle 50A max with a recommended charge current up to 40A. Does the MBA board regulate the current output in any way? I'm just hoping I don't need to replace all of the 6g wiring as I assume this would not be an easy task.

Thanks for any input!
- Jason

Hi Jason,

A couple things you didn’t mention that would help in answering your questions. What is the model of your current Power Center (WF-8955?) and how do you plan on using your Micro Minnie? Will you be off-grid or be hooked up to shore power most of the time?

Our 2016 2106DS has 6 AWG wire between the OEM converter/charger and the battery, I can’t speak to other years or models, but I assume they are the same.

If you have the WF-8955 Power Center, in my opinion, I wouldn’t worry about the 6 AWG wiring or 30 amp fuse on the tongue. The converter/charger for the WF-8955 ([email protected]/13.6V/13.2V) and the WF-8950L2-MBA ([email protected]/13.6V) have similar charging specs for absorption and bulk charging.

I don’t know what the charging current at the battery will be after installing the WF-8950L2-MBA, but using a voltage drop calculator based on the WF-8950L2-MBA specs and 6 AWG wire, you should expect to see about 14.0V-13.8V at the battery based on your estimated 15’-20’ wire run. As for reaching full charge at these voltages, probably not in a reasonable amount of time, the resting voltage for a fully charged 12V LiFePo4 battery is 13.6V. The recommended charging voltage at the battery, for a 12V LiFePo4 battery, is 14.4V-14.6V. Personally, we use short runs of 6 AWG (2’-2.5’) to our batteries from our PD9145ALV converter/chargers and our SC-2030 solar controller and have disconnected the OEM converter/charger in the Power Center.

As for the WF-8950L2-MBA and the way it regulates charging current, its spec sheet states: “Charging control” is “automatically controlled by micro-processor” and it uses “intelligent charge mode” for “absorption and bulk mode”. If you are looking for specifics, I would suggest contacting WFCO.

In my opinion, the replacement converter/chargers mentioned in my earlier post are a good option for anyone that wants a simple and straight forward solution to get the proper charging parameters for 12V LiFePo4 batteries when hooked up to shore power most of the time. If your off-grid most of the time and are looking for the most efficient way to fully charge 12V LiFePo4 batteries using a charger/converter, then you are going to need to place a converter/charger much closer to your battery or run much heavier wiring between your Power Center and battery. The battery lugs on the WF-8950L2-MBA will accept up to 2 AWG wire which should give you about 14.3V at the battery for a 20' run.

Fred

[jsmathers]

Originally Posted by Fred 2106DS

Hi Jason,

A couple things you didn’t mention that would help in answering your questions. What is the model of your current Power Center (WF-8955?) and how do you plan on using your Micro Minnie? Will you be off-grid or be hooked up to shore power most of the time?

Our 2016 2106DS has 6 AWG wire between the OEM converter/charger and the battery, I can’t speak to other years or models, but I assume they are the same.

If you have the WF-8955 Power Center, in my opinion, I wouldn’t worry about the 6 AWG wiring or 30 amp fuse on the tongue. The converter/charger for the WF-8955 ([email protected]/13.6V/13.2V) and the WF-8950L2-MBA ([email protected]/13.6V) have similar charging specs for absorption and bulk charging.

I don’t know what the charging current at the battery will be after installing the WF-8950L2-MBA, but using a voltage drop calculator based on the WF-8950L2-MBA specs and 6 AWG wire, you should expect to see about 14.0V-13.8V at the battery based on your estimated 15’-20’ wire run. As for reaching full charge at these voltages, probably not in a reasonable amount of time, the resting voltage for a fully charged 12V LiFePo4 battery is 13.6V. The recommended charging voltage at the battery, for a 12V LiFePo4 battery, is 14.4V-14.6V. Personally, we use short runs of 6 AWG (2’-2.5’) to our batteries from our PD9145ALV converter/chargers and our SC-2030 solar controller and have disconnected the OEM converter/charger in the Power Center.

As for the WF-8950L2-MBA and the way it regulates charging current, its spec sheet states: “Charging control” is “automatically controlled by micro-processor” and it uses “intelligent charge mode” for “absorption and bulk mode”. If you are looking for specifics, I would suggest contacting WFCO.

In my opinion, the replacement converter/chargers mentioned in my earlier post are a good option for anyone that wants a simple and straight forward solution to get the proper charging parameters for 12V LiFePo4 batteries when hooked up to shore power most of the time. If your off-grid most of the time and are looking for the most efficient way to fully charge 12V LiFePo4 batteries using a charger/converter, then you are going to need to place a converter/charger much closer to your battery or run much heavier wiring between your Power Center and battery. The battery lugs on the WF-8950L2-MBA will accept up to 2 AWG wire which should give you about 14.3V at the battery for a 20' run.

Fred

Fred,

Thank your for your detailed response! To answer some of your questions, yes my wfco is an 8955 series. I plan to do a mix of on and off grid trips. For example, I would like to be off grid for 3 or 4 days or more in some cases and then head to a campground for a day or 2 to recharge. Will also have many trips when I am entirely on shore power. I am considering adding a DC-DC charger at some point to allow charging at 20A while driving.. and maybe also add MPPT charging for solar. I currently have the factory 190w solar panel and the factory PWM solar charge controller, which I believe has a setting for lithium. While in storage (not in use) I am always connected to shore power. I do not plan to use a generator or inverter at all. I installed an olympian wave 6 propane heater and can run a small LG led tv and boundless breeze fan off of 12v. We have an absorption/propane fridge. A 100Ah LiFePO4 would probably be enough for 3 days or more off grid for me given previous experience with a similar setup.. not even factoring in solar.

I called WFCO tech support, but it didn't help much. They just said it will work, but that charging speed will be reduced with the voltage drop. I'm still concerned about not being able to get the lithium battery into the absorption phase to balance the cells... I think a charge voltage of 14.2 (or maybe down to 14.0v?) is required. I'm thinking the solar controller may help boost the voltage, but would rather not rely on that. Worst case I will replace 6g wiring with 2g, and I should be able to get the one-way wire distance down to maybe 12ft if I install the battery in the storage bay. All estimates, I need to measure.

How exactly do you bypass the factory power center for your setup? I assume you still have the original 6g wiring running back to the fuse box, but it is disconnected from the converter? Did you run romex to the new charger?

Thanks,
Jason

[creativepart]

Originally Posted by jsmathers

I'm thinking the solar controller may help boost the voltage, but would rather not rely on that.

Solar charge controllers are smart chargers. They don’t just dump current into the battery if it’s already charged up. The Zamp PWM controller is basically an on and off switch. When your battery voltage is low it turns on for longer periods to charge your battery. But when the battery shows full voltage the controller is off much more than it is on.

When your converter or alternator is charging your battery at 14+ volts your solar charge controller senses this as a fully charged battery and virtually stops providing current to the battery.

So, no, it’s not going to add additional voltage in concert with your converter.

But, when nothing is charging your battery and the battery is being drawn down by a load, then the solar charge controller jumps into action.

By the way, an MPPT controller also reduces charging current when your battery is fully charged. Think of it as a smart DC-DC charger, not an off and on switch. But it is also different than a PWM controller in that it operates at full solar panel voltage (18+v) and a PWM controller operates on battery voltage (12+v). In essence the PWM controller can’t use all of the voltage your panels generate. This is what makes a MPPT controller more efficient.

For a small one panel, one battery system you’ll probably find the PWM works just fine. If you plan to expand the system then look at a MPPT controller

[Fred 2106DS]

Originally Posted by jsmathers

How exactly do you bypass the factory power center for your setup? I assume you still have the original 6g wiring running back to the fuse box, but it is disconnected from the converter? Did you run romex to the new charger?

Hi Jason,

To bypass/disconnect the converter in our Power Center, I disconnected the 120VAC Hot and Neutral wires for the converter. Below is a picture of the disconnected wires capped with wire nuts, prior to finishing with electrical tape.

As for powering the PD9145ALV converter/chargers in the pass-thru, I added an outlet in the pass-thru and power it using the factory installed outlet on the wall behind the bed. Below is a picture of the outlet in the pass-thru. It is to the left of the battery boxes. With both PD9145ALV converter/chargers on, combined they pull 12A@120V. The converter/chargers are mounted to the lid of the first battery box.

You also mentioned about possibly adding a 20A DC-DC charger. If you look at the first post of my blog, you will find a PDF with links to all of the Mods, Add-ons and Upgrades we've done to our Micro Minnie. On page 4 of the PDF is the link to our Renogy 20A DC-DC charger install.

Fred

[jsmathers]

Fred,

Thanks for the details about bypassing the factory converter. As for adding an outlet in the passthrough storage to power a new charger, I also have an outlet on the front wall above the bed. How did you access this outlet for adding a new outlet? Was it necessary to run wiring on the outside of the camper, or were you able to access on the interior wall? I haven't had a chance to remove the outlet to see what it looks like in there yet.

I am considering the approach of using a PD9145ALV or similar charger/converter as it appears the models manufactured late last year now support two stage charging, so they appropriately drop the voltage from 14.6V to 13.6V when not charging (idle).

https://www.progressivedyn.com/wp-co...ge-lithium.pdf

I'm trying to determine what wiring would be involved with this install. I have included a wiring diagram from the forums below that looks like it matches my 2022 model pretty closely. Note, I do not have a slide on my camper and I have replaced the power tongue jack with a manual (I disconnected the wiring for the power tongue jack). I'm wondering if the battery can be connected before the 30A manual breaker to avoid extra runs of wire. I haven't thought through this much yet, but here is what I am thinking initially.

1. Disconnect and cap off 120V Hot and Neutral wires at power center.

2. Plug charger into new 120V outlet in passthrough storage.

3. Connect charger positive to "on" side of battery disconnect (same place where 6ga red wire from the Fuse Panel connects). The charger will still supply voltage to the Fuse panel (DC distribution) when the battery disconnect is switched to "off".

4. Connect wire from "common" pole of battery disconnect to battery positive terminal.

5. Connect 6ga white wire from Fuse panel to battery negative terminal. (Need to cut 6ga white wire near the battery disconnect)

6. Connect charger negative to battery negative terminal.

7. Connect charger "chassis ground lug" to trailer chassis ground using separate wire.


https://www.winnieowners.com/forums/...am-360528.html

https://www.winnieowners.com/forums/...8&d=1616280073

Thanks for any input!

Regards,
Jason

[thataway4]

I suggest that one monitor the LiFePO4 batteries, to be sure that the battery is adequately charged and cared for.

The Victron 712 meter works with a smart phone to give more information than just the instrument (702 monitor). For less money there is a smart shunt for half the price, and your phone will be the readout device. This requires a shunt in the negative circuit, and should read current in and out, voltage and state of charge. There are a number of other meters which will give the same information.

[gurroz]

I went down the LiFePO4 rabbit hole in our Minnie Winnie 25B. Some will say it is a drop-in replacement. It was to some degree. For the first season, we installed the LiFePO4 battery and the Victron 712 battery monitor. It worked with some issues. The WF 8955 would charge the battery once we were below 50% SOC. When it did charge the battery it did not charge to 100% SOC. I had to pull out my Renogy 200W solar panels to fully charge the battery. I always kept the battery at a high SOC to protect the alternator from overheating. Last year we installed the WF-8950L2-MBA and it will recharge the battery even if we are at 97% SOC. We recently installed the Renogy DC to DC charger to protect the alternator. So in my opinion you are on the right track.

[Bobn1957]

#6 AWG wire is good for 60 amps so you won't have to worry about overheating because the 30 amp fuse will blow long before an overload could damage the wiring.

[joppo]

Originally Posted by Fred 2106DS

Hi Jason,

As for powering the PD9145ALV converter/chargers in the pass-thru, I added an outlet in the pass-thru and power it using the factory installed outlet on the wall behind the bed.

Thanks, Fred - that's a creative way to solve this problem! I'm doing a similar swap out of the WF-8955-PEC with a WF-8955-AD-MBA (should be available in the next 60 days, so it might be worth waiting for, Jason). I was initially planning on running #4 AWG from the passthrough bay to the converter to limit the voltage drop for my new lithium battery bank, but I like the idea of keeping the converter closer to the batteries.

Showing my ignorance here, if you tap into the existing bed receptacle to power the converter, where do you connect the converter ground to since the receptacles are wired with 14/2? Can the AC and DC share a ground or is that bad/dangerous? I was also thinking I could run conduit back to the sink area like you did for your inverter install, with an added benefit of keeping the converter and receptacles on separate breakers in the panel.

-Joe

[Fred 2106DS]

Originally Posted by joppo

Thanks, Fred - that's a creative way to solve this problem! I'm doing a similar swap out of the WF-8955-PEC with a WF-8955-AD-MBA (should be available in the next 60 days, so it might be worth waiting for, Jason). I was initially planning on running #4 AWG from the passthrough bay to the converter to limit the voltage drop for my new lithium battery bank, but I like the idea of keeping the converter closer to the batteries.

Showing my ignorance here, if you tap into the existing bed receptacle to power the converter, where do you connect the converter ground to since the receptacles are wired with 14/2? Can the AC and DC share a ground or is that bad/dangerous? I was also thinking I could run conduit back to the sink area like you did for your inverter install, with an added benefit of keeping the converter and receptacles on separate breakers in the panel.

-Joe

Hi Joe,

The 14/2 Romex wiring running to the outlets has three wires, a Hot, Neutral and Ground, so no problem with grounding the AC side of the converter. If you do tie the new converter into the receptacle wiring, you will need to keep an eye on your receptacle loads when running the converter. I don't plug my converters in unless I want to charge my batteries, which is usually once a day, for a couple of hours on the generator when camping. When not camping, our solar panels keep our batteries charged.

Also, I would recommend using a stand-a-lone converter/charger if you plan to mount it in the pass-thru. The WF-8955-AD-MBA does not come with a case to protect it.

Your second option of running a dedicated circuit is the way to go if you don't want to play the load game with the receptacles.

This year, as an experiment, I'm thinking about changing the pass-thru receptacle to a remote controlled one, allowing us to turn the receptacle on and off as needed.

One other thing to consider is how you plan on camping, if you plan to be on shore power most of the time, then I would opt for the dedicated circuit.

We are setup the way we are because we are rarely on shore power, we use a generator to charge our batteries the majority of time when camping and use the inverter when we need AC. I believe in the past 5 years we've only been on shore power a dozen times.

Fred

[joppo]

Fred, thanks once again! I didn't realize (but it makes sense) that the outlets have a ground wire too, so that's perfect. And I never even considered that the converter/charger didn't have a case, so you save me there. I really appreciate the help.

Joe