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Charger Converter size??

mcarney402

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Jan 27, 2021
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Hello!

I'm ordering all of the components for my system that will be installed in my RV. I've never done any of this before, really excited to learn and get this thing put in!

I'm putting a transfer switch in with my system and I'm trying to figure out what size converter charger I need for my batteries. My system is as follows:

3 x 370 watt mono panels (1110 watts total)
60A Ep Ever charge controller
3000 watt pure sine inverter
130 AH Valence LifePo4 x2

My RV is a 30A shore power. Please let me know if there is additional information needed, thanks in advance!
 
Have you already ordered an inverter? If not, consider buying an inverter/charger instead of a separate inverter and charger and transfer switch. It may be cheaper and simpler, or at least simpler.
 
Your RV should already have a converter - what is it?
I'm running a single Valence very successfully with the stock WFCO 8955. It sounds like the converter will be a minimal part of your system.
 
Have you already ordered an inverter? If not, consider buying an inverter/charger instead of a separate inverter and charger and transfer switch. It may be cheaper and simpler, or at least simpler.
I already bought the inverter. Depending what size the inverter charger is I think it will be cheaper this way. I'd like to go inverter charger but I'm already at the top of my budget. Any idea what AMP inverter charger I would need?
 
Your RV should already have a converter - what is it?
I'm running a single Valence very successfully with the stock WFCO 8955. It sounds like the converter will be a minimal part of your system.
I heard on a video that the standard inverter charger in an rv is not compatible with LifePo4. Im not sure what is stock in my rv, its a 2005 Jayco Jayflight 28.5. Can you confirm a new inverter charger isn't necessary? Thanks!
 
I heard on a video that the standard inverter charger in an rv is not compatible with LifePo4.
The issue is the voltage settings. Its best to use an inverter (or inverter/charger) with a proper LiFePO4 profile, or customizable settings. That said, often times, you can find another profile such as AGM or GEL sometimes that will work okay. The main parameters to pay attention to are low voltage disconnect of the inverter and and the float and absorption voltage of the charger.

A float voltage below 13.6V, an absorption below 14.6V, and a low voltage disconnect around ~12V is the ballpark you want to be in.

There are resources and threads that cover the above in more detail.

What inverter did you buy? Or are you saying you are using the inverter that came with your trailer?
 
I heard on a video that the standard inverter charger in an rv is not compatible with LifePo4. Im not sure what is stock in my rv, its a 2005 Jayco Jayflight 28.5. Can you confirm a new inverter charger isn't necessary? Thanks!
So I'll state the following very carefully - there are lots of strong opinions on the camper forums I frequent - I'll say it depends on your style of camping including the time the camper is in storage and how you store it. Plus, I'm talking about just the converter and not a combo unit with inverter. I did not go combo as I prefer to hand pick the components. My path picking a converter seems to fit our use case.

We have two campers, a newer Lance with the 8955 (this one has the Valence) and an older JayCo with a 8935 running the original Interstate FLA battery. But speaking for the LiFePO4 in the Lance, we'll camp in almost every scenario except full-time either on or off shore power. It might go a month or two in storage, then a couple nights in a full hookup campground, finally ending up at a week of dry camping. My original plan based on reading many, many posts about Li installs, I needed to upgrade to a Li compatible converter. But once I chose the Valance, I started looking at how I was going to use it in practice and how to get the longest life all while not having to fuss too much with its care. Being that the Valence was not a "drop-in" FLA replacement and allows for a lot of internal monitoring, I could see more of what was going on inside the battery.

Number one was that the converter doesn't perform an equalization charge at any point. I'd like a lower "top of the knee" charge rate to 100% staying away from any potential over voltage even if it requires a bit more charge time. I'd also like for the battery not to sit at 100% during storage and didn't want to manage discharging the battery followed by disconnecting at some lower charge point. I keep the camper plugged in during storage for several reasons.

After looking at the WFCO published profiles (and that I already owned it vs. the $250 Li compatible upgrade), I installed the Valance in the Lance, setup a mini PC for monitoring and logging, and started testing.

I found that after whatever state the battery was in after camping, it would charge 13.7V at a <45A rate tapering within 2.5 hours to near zero amps and 100% SOC. During this time the Valence will balance periodically. Without any heavy draws and after ~40 hours (the camper is in storage now), the WFCO would reduce it's output to 13.2V. The Valence will now be running the parasitic loads such as CO detector, radio memory, a couple automation controllers, and the Valence management PC. It takes a long time for the Valence to draw down to the "float" ( I call it storage) level of the WFCO. At this point the Valance is reporting a ~30% SOC and it stays right there during camper storage. It will not balance at this level however I'm consistently within 2mV. The day before the next excursion, I'll go by to turn the fridge on and unplug shore power briefly (if I really need a full charge for this leg of the trip) causing the converter to begin topping off the battery towards 100% and now we're ready to go.

I do have solar but my storage is covered (otherwise I'd disconnect the panels) so they have no impact of storage levels.

I am logging 24/7, remotely monitoring, and am performing periodic capacity testing to judge impact. I keep up with published papers regarding LiFePO4 variants and believe two things: There is no one size fits all and that the designers are still figuring out how to properly maintain these for the long term. Oh, and all my thinking could be just plain wrong.
 
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