Adding a "helper" charger

[xrated]

Hopefully, I can clear this issue up just a bit. Second Chance is spot on telling you that the integrated converter can be upgraded for LFP batteries, but as he also mentioned, there will likely be space limitations for the integrated one. The simplest solution is to buy a "deck mount" converter of the brand/model/amperage that you prefer. Then, by accessing the back of the combination breaker panel/fuse panel, you remove the DC pos. and neg wires from the built in converter, where they attach to the DC buss in the combo breaker/fuse panel. You will also need to remove the 120VAC that feeds the existing converter. Once that is done, you then install the new deck mount unit wherever it is convenient or where it can fit. Most of the combo breaker/fuse panels will have a built in 120VAC recept. on the back side of them and you should be able to plug the new converter into that. If it isn't back there, you may have to provide your own 120VAC recept. and feed it from the 120V breaker that feeds the existing converter that you are taking out of service. Then, depending on the Amp rating of the new converter, you may or may not have to put new wire in for the Pos. and Neg leads that go to the battery circuit. That might be the hardest part of the job, depending on the routing of the existing wire.....could be fairly straight forward, could be that you have to hire a midget contortionist. If your new converter in a typical 55A unit...AND the wiring going to the battery or batteries is at LEAST 6AWG, it wouldn't be necessary to run new wire to the battery. Having said that though, you probably would need to check and see what the voltage drop is AT THE Battery itself, when it is charging. Small AWG wire and distance and current tend to make for voltage drops at the end of the circuit (the battery). Bad connections, battery disconnect switches, corroded wire.....they all can cause voltage drop also. That enough for now, let me know if you have questions.

[docque]

Hopefully, I can clear this issue up just a bit. Second Chance is spot on telling you that the integrated converter can be upgraded for LFP batteries, but as he also mentioned, there will likely be space limitations for the integrated one. The simplest solution is to buy a "deck mount" converter of the brand/model/amperage that you prefer. Then, by accessing the back of the combination breaker panel/fuse panel, you remove the DC pos. and neg wires from the built in converter, where they attach to the DC buss in the combo breaker/fuse panel. You will also need to remove the 120VAC that feeds the existing converter. Once that is done, you then install the new deck mount unit wherever it is convenient or where it can fit. Most of the combo breaker/fuse panels will have a built in 120VAC recept. on the back side of them and you should be able to plug the new converter into that. If it isn't back there, you may have to provide your own 120VAC recept. and feed it from the 120V breaker that feeds the existing converter that you are taking out of service. Then, depending on the Amp rating of the new converter, you may or may not have to put new wire in for the Pos. and Neg leads that go to the battery circuit. That might be the hardest part of the job, depending on the routing of the existing wire.....could be fairly straight forward, could be that you have to hire a midget contortionist. If your new converter in a typical 55A unit...AND the wiring going to the battery or batteries is at LEAST 6AWG, it wouldn't be necessary to run new wire to the battery. Having said that though, you probably would need to check and see what the voltage drop is AT THE Battery itself, when it is charging. Small AWG wire and distance and current tend to make for voltage drops at the end of the circuit (the battery). Bad connections, battery disconnect switches, corroded wire.....they all can cause voltage drop also. That enough for now, let me know if you have questions.

Thanks for that info. I didn't even think of the gauge of wire going to the battery. I was looking at two options. Swap the current WFCO with the newer version that can handle the different battery types. This would be the easiest since it is a direct replacement. I looked at the Powermax PM3. This is a cheaper alternative but would be a little more complicated due to it not being a direct replacement.

Not sure really on this because I am sure each is a bad choice depending on who you ask. My thought is since I am going to have a single battery that the WFCO would be the better option.

[Donpworks]

My 22mle has an 8735 WFCO power center. It’s my understanding that on that unit the converter is integrated but not removable. I assume those who install a full Victron type system simply disable the charger and wire up the inverter/charger bypassing the existing charger. I already have an inverter and SOK 206 AH battery installed under the dinette but would like to be able to top off the lithium battery. I have 400 watts of solar which usually covers me but it would be better to start a trip fully charged. I have covered storage.

[docque]

My 22mle has an 8735 WFCO power center. It’s my understanding that on that unit the converter is integrated but not removable. I assume those who install a full Victron type system simply disable the charger and wire up the inverter/charger bypassing the existing charger. I already have an inverter and SOK 206 AH battery installed under the dinette but would like to be able to top off the lithium battery. I have 400 watts of solar which usually covers me but it would be better to start a trip fully charged. I have covered storage.

That is kind why I asked my original question. Seems to be less work if there was another charger you could use. I guess you could always disconnect the battery, fully charge it and reconnect.

[xrated]

Thanks for that info. I didn't even think of the gauge of wire going to the battery. I was looking at two options. Swap the current WFCO with the newer version that can handle the different battery types. This would be the easiest since it is a direct replacement. I looked at the Powermax PM3. This is a cheaper alternative but would be a little more complicated due to it not being a direct replacement.

Not sure really on this because I am sure each is a bad choice depending on who you ask. My thought is since I am going to have a single battery that the WFCO would be the better option.

I am on DIY Solar Forum and there was a very long discussion thread involving the Powermax PM3. I can't remember all the details of the discussion, but the guy that started that 40+ page thread ended up very unhappy with it and sold it on marketplace or somewhere.

When I ditched my OEM converter, I went with a MeanWell NPB-750-12. It has a 43A output and there are DIP switches on it to set it for FLA, AGM, LiFePO, or you can even make your own settings if you buy the programming panel....which I didn't. You can also set it for two stage or three stage charging, and for my LFP battery, I chose the FLA setting and 3 stage charging. The FLA profile, which seems counter intuitive to charging LFP batteries, puts out 14.2V in bulk mode (Constant Current), then when it switches to float, it is 13.4V Then, it stays there and acts as a converter, supplying power to the trailer.

Here is my reasoning for the FLA setting instead of LFP. 14.2V will fully charge a LFP battery to 100% SOC. It will just take a little longer than if it is set for 14.6V.....but the bonus for me is that 14.2V to charge the battery is a lot less stress on the battery health. The float voltage of 13.4V is less voltage than what it takes to fully charge a LFP battery, and that is what I wanted....because keeping a LFP battery sitting at full charge is not good for them, according to most of the info that you will find out there. The MeanWell isn't for everyone, but I've make it work perfectly for my application and what I want to accomplish.

Any Yes, always keep in mind the current that will or could be flowing through a wire and make sure that the AWG size is adequate for the amount of current flowing through it. Plus, the larger the wire, the better the connections (all of them), the less voltage drop you will have when the charger is putting out full charging amps. I ended up with a voltage drop of about .1 to .15 volts between the output of the charger and measured at the battery terminals. I used 2ga welding cable and also changed out a battery disconnect switch that was dropping voltage across it contacts, and relocated the charger closer to the battery....along with excellent connections on every single connection point.

[docque]

I am on DIY Solar Forum and there was a very long discussion thread involving the Powermax PM3. I can't remember all the details of the discussion, but the guy that started that 40+ page thread ended up very unhappy with it and sold it on marketplace or somewhere.

When I ditched my OEM converter, I went with a MeanWell NPB-750-12. It has a 43A output and there are DIP switches on it to set it for FLA, AGM, LiFePO, or you can even make your own settings if you buy the programming panel....which I didn't. You can also set it for two stage or three stage charging, and for my LFP battery, I chose the FLA setting and 3 stage charging. The FLA profile, which seems counter intuitive to charging LFP batteries, puts out 14.2V in bulk mode (Constant Current), then when it switches to float, it is 13.4V Then, it stays there and acts as a converter, supplying power to the trailer.

Here is my reasoning for the FLA setting instead of LFP. 14.2V will fully charge a LFP battery to 100% SOC. It will just take a little longer than if it is set for 14.6V.....but the bonus for me is that 14.2V to charge the battery is a lot less stress on the battery health. The float voltage of 13.4V is less voltage than what it takes to fully charge a LFP battery, and that is what I wanted....because keeping a LFP battery sitting at full charge is not good for them, according to most of the info that you will find out there. The MeanWell isn't for everyone, but I've make it work perfectly for my application and what I want to accomplish.

Any Yes, always keep in mind the current that will or could be flowing through a wire and make sure that the AWG size is adequate for the amount of current flowing through it. Plus, the larger the wire, the better the connections (all of them), the less voltage drop you will have when the charger is putting out full charging amps. I ended up with a voltage drop of about .1 to .15 volts between the output of the charger and measured at the battery terminals. I used 2ga welding cable and also changed out a battery disconnect switch that was dropping voltage across it contacts, and relocated the charger closer to the battery....along with excellent connections on every single connection point.

Life was so much easier when I was working on my Jeep. Want lift? Well, here are your options that are pretty straight forward.

Change a battery in a TT? Ok, well, your converter doesn't work well with that type of battery. So, swap the converter. Now you have to deal with adjusting voltages, having proper wires, monitor. This brand is good but it has a tendency to shut down. This one over heats. Oh, you need to drain your battery so it can figure out what a full charge is.

Well, I have all Winter to figure this out.

[xrated]

Life was so much easier when I was working on my Jeep. Want lift? Well, here are your options that are pretty straight forward.

Change a battery in a TT? Ok, well, your converter doesn't work well with that type of battery. So, swap the converter. Now you have to deal with adjusting voltages, having proper wires, monitor. This brand is good but it has a tendency to shut down. This one over heats. Oh, you need to drain your battery so it can figure out what a full charge is.

Well, I have all Winter to figure this out.

Well, if it's any consolation for you, when I decided that I was going to go LFP for the trailer, because I was going to have the JC Refrigeration mod done to mine (twin 12VDC compressors), on a scale of 1 to 10, my knowledge about LFP batteries was about .5 This was last fall after we got back from our 1 month trip out west. I figured that I had the entire winter to research, learn, purchase and build my new battery, and I followed that time line pretty well. I even had an unexpected family situation come up....(wife had open heart surgery for a Mitral Valve repair and a Afib procedure done that was out of state, but I made it happen when she got back on her feet so to speak. The battery was built, tested, and working when we went to Shipshewana in May for the Fridge conversion. Take the winter to learn about them as much or as little as you want to go into it, and by springtime, you'll be an expert! LOL! Good luck, I'm sure you can do it.

[Butcher]

I would agree with xrated. There is so much information out there and you will find information that is conflicting. The more you understand how it works, the better you can take that conflicting information, and find out what works for you. The more you know, the more you will change your mind on what you want to do.

One thing that I find misleading is how much you can charge a LifePo4 battery and how much you should charge the battery. It was difficult or me to grasp the voltage thing. You could fully charge the battery and fully drain the battery but the amount of extra amps on the top and bottom end is very very low. What I found is that fully charging/discharging a LifePo4 battery is not that much of a gain.

There are plenty of passionate people when it comes to charging batteries and the voltages you need to charge them at.

[xrated]

I would agree with xrated. There is so much information out there and you will find information that is conflicting. The more you understand how it works, the better you can take that conflicting information, and find out what works for you. The more you know, the more you will change your mind on what you want to do.

One thing that I find misleading is how much you can charge a LifePo4 battery and how much you should charge the battery. It was difficult or me to grasp the voltage thing. You could fully charge the battery and fully drain the battery but the amount of extra amps on the top and bottom end is very very low. What I found is that fully charging/discharging a LifePo4 battery is not that much of a gain.

There are plenty of passionate people when it comes to charging batteries and the voltages you need to charge them at.

Absolutely....I'm going for long life for the battery instead of every single AH I can get out of it. If I NEED every single AH, I've sized my battery too small in the first place.

[Redapple63]

I am also going to agree with xrated and Butcher. I have been slowly purchasing materials for my electric upgrade while educating myself. There is definitely contradictory information out there and it does take time to sort through it. I also agree in “over sizing” the battery bank to a point. You want enough capacity to do more than what you want but not oversized to the point of not being able to charge and use it in a conventional way.

I also feel there is advantage in larger batteries rather than the conventional 100ah.

I am installing two 300ah batteries. Again, based on system use. For many a single 100ah is sufficient.

Bill