diy solar

diy solar

New RV, need advice

Norm01

New Member
Joined
Feb 9, 2021
Messages
28
Hi all, I purchased a new RV yet to be received. It’s a class B+. I ordered the 400w solar panels and 3600w LP generator. The upgrade from AGM to Lithium was approx $5,000 which I felt completely crazy. I did my research and my 2000w inverter, dc-dc charger and solar controller can all be set from AGM to lithium so a LifePo4 battery should be plug and play with a couple of configuration changes on the onboard hardware. I could buy an LifePo4 or build my own. I would like 280A and need a BMS with low temp charge cut out(I’m in Canada). This industry is moving fast and would like recommendations from those who follow this all the time. Assumption will be 4 x 280A batteries in series plus a BMS. Do I need anything else. Please recommend parts and how you would set this up.
 
Hi all, I purchased a new RV yet to be received. It’s a class B+. I ordered the 400w solar panels and 3600w LP generator. The upgrade from AGM to Lithium was approx $5,000 which I felt completely crazy. I did my research and my 2000w inverter, dc-dc charger and solar controller can all be set from AGM to lithium so a LifePo4 battery should be plug and play with a couple of configuration changes on the onboard hardware. I could buy an LifePo4 or build my own. I would like 280A and need a BMS with low temp charge cut out(I’m in Canada). This industry is moving fast and would like recommendations from those who follow this all the time. Assumption will be 4 x 280A batteries in series plus a BMS. Do I need anything else. Please recommend parts and how you would set this up.
I'm confused.
Did you already buy lithium batteries for +$5000.00?
 
Sounds like the OP wants to buy his own batteries instead of getting the $5,000 dealer package, First decision is do you want to buy some drop in batteries or do you want to build your own?
 
Hi all, I purchased a new RV yet to be received. It’s a class B+. I ordered the 400w solar panels and 3600w LP generator. The upgrade from AGM to Lithium was approx $5,000 which I felt completely crazy. I did my research and my 2000w inverter, dc-dc charger and solar controller can all be set from AGM to lithium so a LifePo4 battery should be plug and play with a couple of configuration changes on the onboard hardware. I could buy an LifePo4 or build my own. I would like 280A and need a BMS with low temp charge cut out(I’m in Canada). This industry is moving fast and would like recommendations from those who follow this all the time. Assumption will be 4 x 280A batteries in series plus a BMS. Do I need anything else. Please recommend parts and how you would set this up.
If it's just "drop in" replacement, it should be as simple as that. You will need to make sure the BMS will support the loads the RV was designed to handle, and you'll need the hardware/tools for building and testing your batteries.
 
What do you need 4 x 280A for? Are your trying to run an AC through the night? If not, I'll call this overkill. You won't have enough room for solar panels on a class B to feed those 4 x 280A LifePo4 batteries, let alone in Canada. Keep in mind that 4 x 280A LifePo4 batteries are the equivalent of almost 20 lead acid car batteries, because lead acid only has a usable capacity of roughly 50%.

You need to start over by providing more info:

1.) What brand / model RV are we talking about?
2.) How many AGM batteries does it comes with per default?
3.) List all electronics build into the RV.
4.) List all electronics you want to add.
5.) Will you travel full time or vacation only? How long if vacations only?
6.) Where will you travel, Canada only or further South?
7.) Planning to use the AC from batteries / solar power?
8.) Does the RV come with a DC to DC charger?
 
Last edited:
Hi guys. Still waiting for my LTV Unity 24TB. It will have 400w solar and as said a 3600 lp generator. Batteries as ordered are AGM, I believe 2x 6v. These are what I want to replace. I’m an electro technician by trade and have all the tools, looking more for what you guys feel and recommend today. 280A + with BMS or other
 
Hi guys. Still waiting for my LTV Unity 24TB. It will have 400w solar and as said a 3600 lp generator. Batteries as ordered are AGM, I believe 2x 6v. These are what I want to replace. I’m an electro technician by trade and have all the tools, looking more for what you guys feel and recommend today. 280A + with BMS or other
No one can recommend anything without knowing the loads the RV was designed to handle. The best I could guess is slap a 100a bms on a 280ah battery and call it done.

But rather than guessing, follow the energy audit link in my signature.
 
What do you need 4 x 280A for? Are your trying to run an AC through the night? If not, I'll call this overkill. You won't have enough room for solar panels on a class B to feed those 4 x 280A LifePo4 batteries, let alone in Canada. Keep in mind that 4 x 280A LifePo4 batteries are the equivalent of almost 20 lead acid car batteries, because lead acid only has a usable capacity of roughly 50%.
I think OP was planning to install 4x280ah cells and you are probably talking about 4x280Ah 12 volt batteries. 16 cells would indeed sound more likely overkill but one 280Ah battery sounds quite reaaonable.

cant help with the bms choices, JBD?
 
I would probably use the unit a few times to see where it is deficient before making changes. You may find the setup completely adequate as is, or you might find nothing works the way you want to use it.

If you must make changes before you know what your new system can or can't do, ask the manufacturer how much battery capacity they install when they add LiFePo4 and start with that.

edit: to fix a couple of sleepy-eyed typos
 
Last edited:
I may of made this more complicated than it needs to be. The RV is an LTV Unity 24TB. It comes with 400w of solar and a 2000w inverter. Batteries are 2 x 100A AGM, no matter what power needed will only be 2000w to the inverter, not sure the brand but it is high end. I do not expect to run my AC on this, just looking to replace the AGM’s. I have all the tools and ability to build my own rather than buy. My questions was more for those in the knowledge, what batteries would you buy and what BMS. Looked at all of Will’s videos and it would seem 4 x 280A lifepo4 are a good drop in, but which ones and what BMS with low temperature charge protection. Thanks all, hope this answers the questions.
 
I may of made this more complicated than it needs to be. The RV is an LTV Unity 24TB. It comes with 400w of solar and a 2000w inverter. Batteries are 2 x 100A AGM, no matter what power needed will only be 2000w to the inverter, not sure the brand but it is high end. I do not expect to run my AC on this, just looking to replace the AGM’s. I have all the tools and ability to build my own rather than buy. My questions was more for those in the knowledge, what batteries would you buy and what BMS. Looked at all of Will’s videos and it would seem 4 x 280A lifepo4 are a good drop in, but which ones and what BMS with low temperature charge protection. Thanks all, hope this answers the questions.
Is it an inverter/charger with automatic transfer switch or just a discrete inverter?
 
It’s full transfer to shore power or generator or alternator as needed. its a Xantrex 2000w. I do not want to replace any of the factory equipment, just want to build my own lifepo4 batterie bank to replace the 2x 100A AGM because the $5000 upgrade was ridiculous
 
I may of made this more complicated than it needs to be. The RV is an LTV Unity 24TB. It comes with 400w of solar and a 2000w inverter. Batteries are 2 x 100A AGM, no matter what power needed will only be 2000w to the inverter, not sure the brand but it is high end. I do not expect to run my AC on this, just looking to replace the AGM’s. I have all the tools and ability to build my own rather than buy. My questions was more for those in the knowledge, what batteries would you buy and what BMS. Looked at all of Will’s videos and it would seem 4 x 280A lifepo4 are a good drop in, but which ones and what BMS with low temperature charge protection. Thanks all, hope this answers the questions.
confirm inverter is 12v or 24v.
 
It’s full transfer to shore power or generator or alternator as needed. its a Xantrex 2000w. I do not want to replace any of the factory equipment, just want to build my own lifepo4 batterie bank to replace the 2x 100A AGM because the $5000 upgrade was ridiculous
Sorry I can't map your answer to my question.
 
It’s full transfer to shore power or generator or alternator as needed. its a Xantrex 2000w. I do not want to replace any of the factory equipment, just want to build my own lifepo4 batterie bank to replace the 2x 100A AGM because the $5000 upgrade was ridiculous
LFP cost stateside is absurd. If they were going to install battleborns, then that expense is no surprise.


check this out:

 
Since you have indicated top of the line and 12 volts I will assume this model https://www.xantrex.com/power-products/inverter-chargers/freedom-sw-12v_newgen.aspx

It's surge capability is 2x continuous for only 5 seconds which will not significantly influence the math.
2000 ac watts / .85 conversion efficiency / 10 volts low cutoff = 235.294117647 service amps.
You need a battery bank and BMS that can handle ~240 continuous amps.
The overkill solar BMS has low temperature protection and is rated for 120amps continuous.
You could either put 2 of them on the same 4s battery or you could make 2x batteries each with its own bms.

That would pair well with the EVE 280ah lifepo4 cells that are popular here.

@Amy Wan (Luyuan) should be able to hook you up.
I've not dealt with her personally but she has a good reputation here on the forum.
 
I really like the link to the Solar Blue Prints on the top right. Helps choose a system for the size of RV you will have.

The bad thing about lithium cells is they take months to show up. Perhaps four months. Certainly gives you time to plan the build.

I am also finding because I need to “Tool Up” and also purchase other accessories like hardware (Screws, nuts, bolts) and build Battery cases and fuses, that I’m not building my pack for 1/5th the price like some claim. I will end up saving money, but not as much as I Thought at first.
 
i have a small 24' Class C - 200W solar on roof
came with 1 FLA 120Ah battery
i added Xantrex 2000W inverter - could run uwave for ~5 min if fully charged

switched to 4x280Ah LFP with Chargery BMS (300A relays)
now i can run the uwave for as long as i want (within reason)
use single induction plate for all cooking (saving propane)

i put in a relay so the absorption fridge does not run from inverter - too inefficient on AC - 300W
maybe you have 3-way fridge, so maybe not a problem
the difference with LFP is hard to describe - never going back

this trip i melted the AC connecter on the Xantrex - hard to get a good connection with the spring clips & 10ga wire
maybe you have a newer one with levers

mark

adding active balancer - Chargery has passive balance - just not enough sometimes
cells would intermittently get out of balance >14.0V (only going to 14.2V)
if i was doing it again, 280Ah @24V

if you just bought a new LTW, then $$$ isn't your main concern
DIY will save you some over the $5000 LTW wanted, but the convenience every day going forward is hard to quantify
 
Back
Top