What can a standard WF 8735 PB Converter do with lithium batteries?

[DonBr]

There have been a lot of answers to this question, including percentages thrown out like 80%, 85%, etc. Other answers say it would work but take a long time. Other answers are a combination of the two.

Today I was swapping out my PWM controller for a Renogy MPPT, so I thought it would a perfect time to test with solar disconnected. I started with AC service off by discharging the batteries to 75% by running the microwave with a bowl of water. I did it for 25 minutes in 5 minute increments (to keep the bowl from getting too hot to empty) starting each increment with cool water.

Figure 1 below is the power monitor about halfway. I was losing about 1% per minute, or 2AH on my 200AH battery combo. As an aside, the inverter fans only kicked on about a minute before I stopped, but it is cool here, ambient about 68.

Figure 2 is at the end of the run, and Figure 3 is with the inverter off and the converter on. Clearly I didn't go low enough to kick the converter into bulk mode, but it was charging at almost 10 amps. At 4 hours, with the batteries at 89%, it was down to 5.75%. Over the next hour it gained only 2%, and I discontinued the experiment because I was impatient about getting the controller hooked up. Figure 6 is with both controller and solar operating; single 190W panel late in the day.

So, I can't say definitely that the controller is capable of hitting 100% with lithiums, but given enough time it will come close, and it does act as a helper to the solar when shore power is available. Certainly will keep me from springing for an AD model.

[TaftCoach]

Thank you

[ARoamer]

Thank you for some real world data. I have lithium, a PB only progressive dynamics converter, and solar but I never tried a full lithium charge with the converter only. I have read to expect about a 80% charge. 5er has been sitting at dealership for warranty the last 2 months but when I get it back I may try a converter only charge to see what I actually get.

[DonBr]

It would be good to get another data point. Maybe you can be more patient than I was and give it 24 hours to see if it will ever reach 100%! Not many are going to try this, since the solar has to be disconnected, and I suspect a controller with a shutoff is unusual, so physical disconnection. I wouldn't have bothered except I was cutting it off anyway.

[Lasttruck]

I have disconnects on either side of my solar controller, so would be fairly easy to do.

Thanks for the info.

[DonBr]

It was pointed out to me elsewhere that the charging profile of the PB unit will, except for an early boost when voltage is low, pump just 13.6V and only for 48 hours, then drop to 13.2. My experiment stopped at 13.4V, so it would likely have gone a few percent higher, possibly close to 100%, but after a couple of days any draw on the batteries would have to bring them down quite a ways before the converter kicked back in. It could be "tricked" by cycling power to the converter to have it go back into 13.6V for another 2 days.


Still, for anybody with much solar it shouldn't make a lot of difference.

[Noblewk]

The WF 8735 PB Converter only has a 2 Stage Charge profile with lithium. Bulk is 14.4 Volts and Absorption is only 13.6 volts. The best the WF 8735 PB Converter will charge a LIFEPO4 Battery is 90% of the capacity. To get 100% you are going to need about 14.6 Volts.

[DonBr]

As you can see above, I stopped the experiment at 91%, and it had not yet reached 13.6 volts, so 90% is not the limit.



The WF 8735 PB is a THREE stage converter, 14.4/13.6/13.2 although obviously the 13.2 trickle wouldn't do much for us lithium owners.

[Noblewk]

Originally Posted by DonBr

As you can see above, I stopped the experiment at 91%, and it had not yet reached 13.6 volts, so 90% is not the limit.



The WF 8735 PB is a THREE stage converter, 14.4/13.6/13.2 although obviously the 13.2 trickle wouldn't do much for us lithium owners.

DonBr Your Battery Monitor is using a Flood Acid Profile not the Lithium Profile.

See the following

https://renogy.com/blog/expectations...e-percentages/.

And

https://www.solacity.com/how-to-keep...tteries-happy/

[DonBr]

Noblewk ??? I think you are confusing the monitor with the controller. You made me look to make sure, but the monitor does not have a "profile." It works identically with LA and Li. In fact it has no idea what is there, just the capacity (which you set) the voltage, and the amp flow in/out. Time to full and wattage are calculated from those three.

[TomC_AZ]

I will chime in on this as well, I have not yet replaced my 8735PB with the LIS or AD models. However I do have 400ah of LiFePO4 battery. I also have 600w of solar on the roof of the 166fbs.

The 8735 will, at times, charge to 90-100%. I have seen it do it, however, and there is always this side of the story. It will NOT do this consistently or consecutively. It usually does between 70-80 on the more regular basis.

We just completed a 2month long 10,000 mile trip and that is what I regularly saw, I didnt document it so you will just have to experience it on your own :-)

With that being said, 200w or more will easily recharge 100ah and our 600w recharged/topped off our 400ah of batteries without issues when needed within a couple hours with good sun.

[DonBr]

Soon after I did the experiment I turned off the breaker to the charger and haven't turned it on since. The 12V refrigerator is running, and I turn on the inverter as needed at rest stops, etc. In the morning I'm down to 85-90% on my pair of 100AH lithiums, and it is back to 100% in just a few hours. We'll see what it does in the winter in northern climes, but at this point I don't care what the converter can or can't do.

[Charles in WV]

Interested in this as I have a 200W Renogy system not installed yet. I have been watching battery pricing to decide on which to go with, 100ah or 200ah. An 8735 23 stage in a 2014 184bh. Have replaced fridge with 45 watts running fridge and we use mwave and some small electric appliances. Have a generator to run AC if we are gonna need it when boondocking.
Charles

[mtjag7]

Originally Posted by TomC_AZ

I will chime in on this as well, I have not yet replaced my 8735PB with the LIS or AD models. However I do have 400ah of LiFePO4 battery. I also have 600w of solar on the roof of the 166fbs.

The 8735 will, at times, charge to 90-100%. I have seen it do it, however, and there is always this side of the story. It will NOT do this consistently or consecutively. It usually does between 70-80 on the more regular basis.

We just completed a 2month long 10,000 mile trip and that is what I regularly saw, I didnt document it so you will just have to experience it on your own :-)

With that being said, 200w or more will easily recharge 100ah and our 600w recharged/topped off our 400ah of batteries without issues when needed within a couple hours with good sun.

Originally Posted by DonBr

Soon after I did the experiment I turned off the breaker to the charger and haven't turned it on since. The 12V refrigerator is running, and I turn on the inverter as needed at rest stops, etc. In the morning I'm down to 85-90% on my pair of 100AH lithiums, and it is back to 100% in just a few hours. We'll see what it does in the winter in northern climes, but at this point I don't care what the converter can or can't do.

Changing out the charger then sounds like a "nothing burger" if you are using lithium batteries. I was about to press hard on changing the WF-8735P for the WF-8735AD because I am using lithium batteries, but the difference is not worth the effort after all. Since the dealer was going to charge me for the WF-8735AD and for install labor and also told me Jayco would not warranty the new WF-8735AD because it was not part of the original assembly, it just doesn't seem like it's worth the effort or expense. I was thinking of just asking them to install a new inverter/charger and tie it in (since that also would not be covered under warranty) and just by pass the original charger in lieu of using the lithium capable charger of the inverter, but even that doesn't seem to be needed. You guys may have saved me a bundle and a lot of anxiety!

[TomC_AZ]

MTJag, I will ask, what do you want the inverter to do? For me I wanted to run everything including the AC, which I do on a Xantrex Freedom 2000w (no charger). Had I not found this inverter for $300 (total price) I would have purchased either the 3000w FreedomPro or a Victron Multiplus just so I would have their chargers as well. A 100amp or higher charger would do quick work on the batteries when plugged in.

Knowing that any mod like this void's the warranty I wanted to keep it as simple as I could. In about 1hr I could take everything out that I did and put it back to default mode and no one would know any different, including the panels on the roof and removing all wire I added.

Yes the 2000w inverter runs the AC and will do it all day long as long as there is battery enough to do it (which I dont have). It will run the AC, fridge, and water heater at the same time without issue. But do not try the microwave or hairdryer with it, thats too much wattage.

BTW if you have never done any of this, 30amps (shore power) is also NOT enough to run the AC and the fridge, and water heater and a hairdryer (or microwave). My watchdog EMS pops each time as it draws too much amperage. So even with shore power you cannot run everything like you would in a house. This is why I felt very comfortable going with a 2000w inverter.

The Freedom inverter also has a passthrough that is 30amp so all shore power goes through it first then into the power center (8735). The converter inside the power center I have on a separate leg of power directly off the shore connection with its own breaker (out side of the power center). This ensures that I never create any electrical loop (that is very bad).

Anyway determine why you want an inverter and what you want it to do. I am happy with what I have and it serves us well as we like to boondock a lot. Its nice to take a shower and have the ability to use a hairdryer and toaster etc.. without having to worry about a generator. While we can run the AC for about 4hrs straight, we would only ever run it for 2hrs or so just to cool things down a bit at night. If we have actual shore power we can and will run the AC all day.

[mtjag7]

Originally Posted by TomC_AZ

MTJag, I will ask, what do you want the inverter to do? For me I wanted to run everything including the AC, which I do on a Xantrex Freedom 2000w (no charger). Had I not found this inverter for $300 (total price) I would have purchased either the 3000w FreedomPro or a Victron Multiplus just so I would have their chargers as well. A 100amp or higher charger would do quick work on the batteries when plugged in.

Knowing that any mod like this void's the warranty I wanted to keep it as simple as I could. In about 1hr I could take everything out that I did and put it back to default mode and no one would know any different, including the panels on the roof and removing all wire I added.

Yes the 2000w inverter runs the AC and will do it all day long as long as there is battery enough to do it (which I dont have). It will run the AC, fridge, and water heater at the same time without issue. But do not try the microwave or hairdryer with it, thats too much wattage.

BTW if you have never done any of this, 30amps (shore power) is also NOT enough to run the AC and the fridge, and water heater and a hairdryer (or microwave). My watchdog EMS pops each time as it draws too much amperage. So even with shore power you cannot run everything like you would in a house. This is why I felt very comfortable going with a 2000w inverter.

The Freedom inverter also has a passthrough that is 30amp so all shore power goes through it first then into the power center (8735). The converter inside the power center I have on a separate leg of power directly off the shore connection with its own breaker (out side of the power center). This ensures that I never create any electrical loop (that is very bad).

Anyway determine why you want an inverter and what you want it to do. I am happy with what I have and it serves us well as we like to boondock a lot. Its nice to take a shower and have the ability to use a hairdryer and toaster etc.. without having to worry about a generator. While we can run the AC for about 4hrs straight, we would only ever run it for 2hrs or so just to cool things down a bit at night. If we have actual shore power we can and will run the AC all day.

Tom, what you have just outlined here is what I want to do. I was thinking it would take way more inverter than 2000 watt. So, if I can just figure out how to install this it would be great. You said you did all this in an hour? I'll have to re-read this a couple of times. So you don't think I need to buy an inverter with a charger?

[TomC_AZ]

Sorry, that was not clear! It took a few days to inspect the trailer and plan out routes, run wires, install and then many days to plan out equipment and how it will be hooked up. My main goal was to have minimal changes or holes/screws into walls etc.. I didnt have to drill or screw into the roof for more solar due to the rack thats up there, I used it and the rails. I then used all the natural and existing wire runs that the MFG used. I had to drill two small holes to allow for some wire as existing holes were not big enough.

Now that its installed if I wanted to take it all out it would only take me 1hr or so to remove and I can easily put back in the GoPower PWM solar controller. I would have to reconnect the power center etc. but it would all be using the existing stock wire including the battery wires up front (never removed or disconnected those).

One key component to this is the use of a soft start for the AC. Without this the AC will not run on 2000w or a 2200w generator. Everything else, including the microwave, will and is fine. Again, if you can get 3000w get it. For me I took a chance as a 3000w was an additional $1200 at the time and well I figured if it ran on my 2200w generator it should run off this inverter so why not try for only $300... and it works fine. Make sure to get a good inverter though and that it has enough headroom and you know its constant running wattage. There is a difference between say Xantrex, Victron and pretty much everything else. There are some other brands that are bigger use in marine applications and those will also work, but there is a reason why these two are the main names. Again, cant stress this enough, know what the inverter is RALLY rated for ie. constant wattage and boost. The 2000w Xantrex is rated to actually run at 2000w for extended periods. It also can boost to like 4000w and I believe the 3000w version will boost to 6000w for a few seconds. This is important for motor startups (microwave/AC etc).

[Bob K]

Originally Posted by TomC_AZ

I will chime in on this as well, I have not yet replaced my 8735PB with the LIS or AD models. However I do have 400ah of LiFePO4 battery. I also have 600w of solar on the roof of the 166fbs.

The 8735 will, at times, charge to 90-100%. I have seen it do it, however, and there is always this side of the story. It will NOT do this consistently or consecutively. It usually does between 70-80 on the more regular basis.

We just completed a 2month long 10,000 mile trip and that is what I regularly saw, I didnt document it so you will just have to experience it on your own :-)

With that being said, 200w or more will easily recharge 100ah and our 600w recharged/topped off our 400ah of batteries without issues when needed within a couple hours with good sun.

That's my experience as well. Charging level is inconsistent depending on lithium battery's voltage when the 8735 starts its charging cycle.

https://www.jaycoowners.com/forums/f...tml#post979939

https://www.jaycoowners.com/forums/f...tml#post990250