diy solar

diy solar

Cannot afford Lithionics Batteries for large scale RV Battery Bank; What is a cheaper quality alternative?

Dellberts

New Member
Joined
Aug 6, 2022
Messages
9
What is a cheaper quality battery bank to use on a large scale RV battery bank (approximately 20KW so I can run two 13,500 watt air conditioners)?
 
What is a cheaper quality battery bank to use on a large scale RV battery bank (approximately 20KW so I can run two 13,500 watt air conditioners)?
What voltage is your system and where do you live?
 
Low cost is building your own battery.

How do you plan to recharge the battery? That is a lot of solar.
 
You need to put in some specifics here so we can help you.
What are the current HVAC units you have installed, have you tested to see how much power they draw?
What inverter and battery system is currently in your RV and how is it configured? (12v, 24v, etc)
How will you charge the batteries?
How long do you expect to go on a single charge?
 
Low cost is building your own battery.

How do you plan to recharge the battery? That is a lot of solar.
The RV came with a "small" solar system, 2X 100W PV panels and a PWM controller. I would have to change all of that to an MPPT inverter and dual DC-DC chargers. There are two alternators on the vehicle for charging the house batteries (presently AGM's which as you know, don't last long and are only good for 50% draw). I believe the alternators are 180 amps each running at 12V. Some people use a different alternator running at 52V for faster charging and smaller wires (see Advanced-RV.com). The idea is to be able to boondock for a time while running the residential refrigerator and two air conditioners. I saw the video on the SOK 12V, 206Ah and the BigBattery 170Ah along with the recommendation to use "Fortune Cells" for a DIY build because of being better for high vibration. In a motorhome, you definitely have to consider vibration and jarring.
 
You need to put in some specifics here so we can help you.
What are the current HVAC units you have installed, have you tested to see how much power they draw?
What inverter and battery system is currently in your RV and how is it configured? (12v, 24v, etc)
How will you charge the batteries?
How long do you expect to go on a single charge?
The RV has one 13,500 Btu and one 15,000 Btu air conditioner which are pretty standard. Starting amperage is about 13A @ 120VAC, less while running. I know that I am limited to the number of solar panels that I can physically put on the roof and I really dislike a noisy generator running so I prefer an alternator that would charge the system while driving. Advanced RV has a beautiful system using a 52VDC alternator for charging the batteries and I may try to copy their system. What I really wanted to know was "would a Chinese Battery Bank like the server types work in a motorhome or would I be better to use a combination of drop-in automotive/marine type batteries like the SOK 206Ah to get the 20KWh bank like James of thefitrv.com put in his Winnebago EKKO. He used five 320Ah Lithionic batteries, 4KWh each for a total of 19.2KWh of DC power. Lithionic batteries are wonderful, but very expensive. What is a good Chinese substitute that will hold up in RV usage...?
 
Sorry that I wasn't more clear in what I was looking for. I built a system for my house using 36X 385W PV panels, a SOL-ARK 12K Inverter, and 6X EG4 5.12KWh server batteries for a 30KWh battery bank. The EG4's work great for the house, but maybe not for an RV. Will Prowse was talking about SOK and Trophy LifePO4 batteries that might be better than the EG4's for a rugged environment. Just wanted to get everyone's input on which of the cheaper batteries was best for an RV environment.
 
Just some quick estimates. To charge 20kw of batteries will take about 10 hours with an 180A alternator. Or, it will take about 7000W of solar to charge via solar. If it were me, I would not consider either of those viable, and would look at how to reduce my consumption.
Take a look at Kilovault batteries for a battery similar to Lithionics in quality at a much lower price. Much better quality than SOK etc.
 
The actual starting current needed for those HVAC units will be well in excess of the running requirements, and I bet you will find the running amperage to be above 13 when on full blast. I'd recommend you really put a meter on the HVAC and watch how much it's actually using, it will probably surprise you.

Before you go all in on batteries, think about conservation first and battery/inverter second. You mentioned having limited space for solar, so cutting down on consumption makes it easier to support with solar.
You need to pay careful attention to the number of batteries you can place in a string, a lot of them are limited to (4) 12v packs, so think about that too.

It will probably be cheaper and more effective to replace the HVAC units with more efficient models (Look at houghton on the recpro website), than to try and build a system to support what is currently installed.
This will let you lower the startup and running amperage, and result in longer run times on a smaller system.

Here's my experience, hopefully it's helpful.
I've got a large bus with 3 HVAC units and (2) 12V inverters. The AGM battery bank was failing, so I replaced the AGM's with (3) of the EG4 12V rack packs for a total of 15kWh. I can charge from the genset, shore power or the 300amp alternator.
Since my entire bus is 12V, it didn't make sense for me to move to 24v or 48v.

My next step will be to start replacing the HVAC units with more efficient and quieter units. This will give me a much quieter system as my main goal, but will probably double or even triple the battery run time since the new units are more efficient.
 
Look into replacing or supplanting AC with at least one mini-split or window unit. RV air units have to be the most inefficient power hogs on the planet.
Or drive to where it's cooler. :giggle:
 
The actual starting current needed for those HVAC units will be well in excess of the running requirements, and I bet you will find the running amperage to be above 13 when on full blast. I'd recommend you really put a meter on the HVAC and watch how much it's actually using, it will probably surprise you.
My 15000 btu ac unit can theoretically draw over 60 amps on startup. At the very least you will want soft starts for the ac. I have a 38’ travel trailer that I rebuilt and insulated with polyiso insulation. I was able to swap out the 15000 btu unit with a 9000 btu mini split. The result was less than half the use of electricity and better cooling. I would have preferred a 12,500 btu but alas not enough room for the inside unit. The functionality of a mini split is superior in every way to a rooftop unit. The mini split gradually increases power consumption when it is started so starting amps are not an issue.
Because I eliminated the roof top ac I was able to raise the solar panels 8” off the roof. This way I was able to put 3240 watts of solar on my 35’ long roof and at still have space for a walk way to sweep off the slide out roofs. The roof vents exhaust underneath the panels. I am aware of at least 2 5th wheels that have installed over 5000 watts of solar using variations of this same method.
There’s obviously challenges installing mini splits in an rv as well as sizing them but the reality is that 20 k of battery will barely take you through a hot night with 2 rooftop units running steady. Where as mini splits could potentially do the same thing with 10k. The overnight power consumption of my mini split is less than one quarter of my old rooftop unit this advantage is much less in the daytime as my windows are not tinted and I have not taken measures to insulate them. In sunny weather I successfully power my ac 24/7 on 3240 watts of solar combined with a 5k battery and a 3500 watt inverter.
 
The actual starting current needed for those HVAC units will be well in excess of the running requirements, and I bet you will find the running amperage to be above 13 when on full blast. I'd recommend you really put a meter on the HVAC and watch how much it's actually using, it will probably surprise you.

Before you go all in on batteries, think about conservation first and battery/inverter second. You mentioned having limited space for solar, so cutting down on consumption makes it easier to support with solar.
You need to pay careful attention to the number of batteries you can place in a string, a lot of them are limited to (4) 12v packs, so think about that too.

It will probably be cheaper and more effective to replace the HVAC units with more efficient models (Look at houghton on the recpro website), than to try and build a system to support what is currently installed.
This will let you lower the startup and running amperage, and result in longer run times on a smaller system.

Here's my experience, hopefully it's helpful.
I've got a large bus with 3 HVAC units and (2) 12V inverters. The AGM battery bank was failing, so I replaced the AGM's with (3) of the EG4 12V rack packs for a total of 15kWh. I can charge from the genset, shore power or the 300amp alternator.
Since my entire bus is 12V, it didn't make sense for me to move to 24v or 48v.

My next step will be to start replacing the HVAC units with more efficient and quieter units. This will give me a much quieter system as my main goal, but will probably double or even triple the battery run time since the new units are more efficient.
Sounds wise; thank you. Hope the EG4s hold up.
 
Look into replacing or supplanting AC with at least one mini-split or window unit. RV air units have to be the most inefficient power hogs on the planet.
Or drive to where it's cooler. :giggle:
Some mini-splits are very efficient; I'm running Hotspot Energy's 48VDC units in my house. For my older RV, I installed "SoftStart" units (basically it changed the size of the starting capacitor). I was able to run two 13,500 Btu units on a 30A circuit. Thanks for your input.
 
My 15000 btu ac unit can theoretically draw over 60 amps on startup. At the very least you will want soft starts for the ac. I have a 38’ travel trailer that I rebuilt and insulated with polyiso insulation. I was able to swap out the 15000 btu unit with a 9000 btu mini split. The result was less than half the use of electricity and better cooling. I would have preferred a 12,500 btu but alas not enough room for the inside unit. The functionality of a mini split is superior in every way to a rooftop unit. The mini split gradually increases power consumption when it is started so starting amps are not an issue.
Because I eliminated the roof top ac I was able to raise the solar panels 8” off the roof. This way I was able to put 3240 watts of solar on my 35’ long roof and at still have space for a walk way to sweep off the slide out roofs. The roof vents exhaust underneath the panels. I am aware of at least 2 5th wheels that have installed over 5000 watts of solar using variations of this same method.
There’s obviously challenges installing mini splits in an rv as well as sizing them but the reality is that 20 k of battery will barely take you through a hot night with 2 rooftop units running steady. Where as mini splits could potentially do the same thing with 10k. The overnight power consumption of my mini split is less than one quarter of my old rooftop unit this advantage is much less in the daytime as my windows are not tinted and I have not taken measures to insulate them. In sunny weather I successfully power my ac 24/7 on 3240 watts of solar combined with a 5k battery and a 3500 watt inverter.
What you say makes great sense, especially with an older RV where you can change things at will and not worry about resale. I've studied several factory-installed systems using OEM air conditioners and like you say, they are weak at best and expensive to duplicate. Thanks much for your input.
 
Back
Top