OnTheFlyPDX
New Member
- Joined
- Jun 27, 2021
- Messages
- 18
Hi all. I’m sorry if these questions have already been answered before. I searched the threads as best I could (where I found tons of great advice) but couldn’t find a thread that’s entirely on point as to what I’m thinking about doing for my build. Also, sorry in advance for the length of this post, I tend to over explain.
I am awaiting shipment on 8x 3.2v 200ah lifepo4 cells from AliExpress. I haven’t purchased anything else, so if someone who actually knows what they’re talking about thinks I should adjust my plans (e.g., 12v system instead of 24v) I have some flexibility. My plan is to build in series for a 24v 200ah bank. We have an 18’ travel trailer (ORV Creekside 18ck), so space is a little limited. There’s a bunk over the main bed that we converted to storage space where I’d like to put the battery bank and system. To make things simple and so I can easily remove my build to install in a tool shed after our upcoming year on the road, I don’t want to fully integrate the battery into the trailer’s electrical system. I’m also being a little lazy and want to avoid fishing wire. But I still want to keep the convenience of using the trailer’s 12v and 120v systems as if it was plugged into shore power. Our goal is to be able to boondock for a week at a time. We will need to keep a couple laptops and a 5G hotpot powered, occasional microwave use, and run a hair dryer every couple of days. No illusions about running the A/C with this small of a build. With all that in mind, here’s my plan so far with a few questions:
Build a 8s 24v Lifepo4 with an overkill bms connected to a MPP 2724LV-MR all-in-one. I’ve read fan noise on the MPP LV2424 can be pretty annoying, whereas the 12v version of the MPP does a better job of turning the fans off when there’s no/low load. Anyone have experience with fan noise on the 2724?
I plan to wire a 30a receptacle from the MPP’s output and install it on the back of the trailer. Then I can plug the trailer’s shore power cord into the receptacle and run the entire trailer off the MPP’s inverter. I’m going to keep the 200ah 12v AGM that’s currently on the trailer tongue and powering the 12v system separate from the lifepo4 build. This way I don’t have to run the MPP’s inverter when all I need to power is the rear camera and fridge (on propane) when we’re driving to our next destination.
If I run it this way, do I need to turn off the circuit breaker for the trailer’s battery charger when plugged into the MPP? I’ve read that you have to turn off the breaker to avoid a power drain loop if the battery running the inverter is also tied into the rv’s 12v system. However, I don’t think that would be an issue with my idea of separate battery banks because the trailer’s charger will only be charging the 12v AGM.
I think I might just turn the charger breaker off most of the time anyway (and probably install an inline switch to disconnect the AGM battery entirely). Still seems odd to use one battery to charge another. I think I should be able to get by with just using the trucks’s alternator to charge the AGM battery while on the move. My understanding is that even if the tongue battery is disconnected, the trailer’s 12v system will run off the trailer’s 12v converter when on shore power (i.e., the MPP’s inverter in my case)?
Assuming my idea isn’t crazy so far, where I’m struggling the most right now is solar panels. At first, I was leaning towards 400-600w in briefcase panels (200w Renogy), but those are pretty expensive and I don’t know if I want to deal with setting up and storing them each time we move spots. The really thin foldable (think Dokio) or flexible panels (the one’s Will says to avoid at all cost) would be ideal, but everything I’ve read says they’re all junk. There’s almost always someone in my area selling lightly used residential panels for cheap, so now I’m thinking it best to install 600w solar (the MPP’s capacity) on the roof. Any thoughts on the best setup for that? Should I run 3x 200w panels in series? 4x 150w panels in series and parallel? 2x 300w in series?
If you’ve made it this far, thanks for your patience. Really looking forward to reading y’all’s answers and any/all ideas you might have about what I’m trying to accomplish here. Thanks!
I am awaiting shipment on 8x 3.2v 200ah lifepo4 cells from AliExpress. I haven’t purchased anything else, so if someone who actually knows what they’re talking about thinks I should adjust my plans (e.g., 12v system instead of 24v) I have some flexibility. My plan is to build in series for a 24v 200ah bank. We have an 18’ travel trailer (ORV Creekside 18ck), so space is a little limited. There’s a bunk over the main bed that we converted to storage space where I’d like to put the battery bank and system. To make things simple and so I can easily remove my build to install in a tool shed after our upcoming year on the road, I don’t want to fully integrate the battery into the trailer’s electrical system. I’m also being a little lazy and want to avoid fishing wire. But I still want to keep the convenience of using the trailer’s 12v and 120v systems as if it was plugged into shore power. Our goal is to be able to boondock for a week at a time. We will need to keep a couple laptops and a 5G hotpot powered, occasional microwave use, and run a hair dryer every couple of days. No illusions about running the A/C with this small of a build. With all that in mind, here’s my plan so far with a few questions:
Build a 8s 24v Lifepo4 with an overkill bms connected to a MPP 2724LV-MR all-in-one. I’ve read fan noise on the MPP LV2424 can be pretty annoying, whereas the 12v version of the MPP does a better job of turning the fans off when there’s no/low load. Anyone have experience with fan noise on the 2724?
I plan to wire a 30a receptacle from the MPP’s output and install it on the back of the trailer. Then I can plug the trailer’s shore power cord into the receptacle and run the entire trailer off the MPP’s inverter. I’m going to keep the 200ah 12v AGM that’s currently on the trailer tongue and powering the 12v system separate from the lifepo4 build. This way I don’t have to run the MPP’s inverter when all I need to power is the rear camera and fridge (on propane) when we’re driving to our next destination.
If I run it this way, do I need to turn off the circuit breaker for the trailer’s battery charger when plugged into the MPP? I’ve read that you have to turn off the breaker to avoid a power drain loop if the battery running the inverter is also tied into the rv’s 12v system. However, I don’t think that would be an issue with my idea of separate battery banks because the trailer’s charger will only be charging the 12v AGM.
I think I might just turn the charger breaker off most of the time anyway (and probably install an inline switch to disconnect the AGM battery entirely). Still seems odd to use one battery to charge another. I think I should be able to get by with just using the trucks’s alternator to charge the AGM battery while on the move. My understanding is that even if the tongue battery is disconnected, the trailer’s 12v system will run off the trailer’s 12v converter when on shore power (i.e., the MPP’s inverter in my case)?
Assuming my idea isn’t crazy so far, where I’m struggling the most right now is solar panels. At first, I was leaning towards 400-600w in briefcase panels (200w Renogy), but those are pretty expensive and I don’t know if I want to deal with setting up and storing them each time we move spots. The really thin foldable (think Dokio) or flexible panels (the one’s Will says to avoid at all cost) would be ideal, but everything I’ve read says they’re all junk. There’s almost always someone in my area selling lightly used residential panels for cheap, so now I’m thinking it best to install 600w solar (the MPP’s capacity) on the roof. Any thoughts on the best setup for that? Should I run 3x 200w panels in series? 4x 150w panels in series and parallel? 2x 300w in series?
If you’ve made it this far, thanks for your patience. Really looking forward to reading y’all’s answers and any/all ideas you might have about what I’m trying to accomplish here. Thanks!