Where does one put lithium batteries if they won't fit under the stairs?


New member
I'm looking into getting maxed up with solar on the Serenity we're about to order.
AM Solar seems like a trusted installer.
AM solar wrote me an estimate for about $5,000 for a 300w coupled with a 25A MPPT charge controller with built-in battery monitor, traditional lead acid battery set up and $15,200 if we want to go with lithium batteries....
I'll be talking with them today about why the giant cost difference.
But..i'm open to opinion from the forum.

But..i'm mostly hoping to get some opinion from any of you who have tried to max up the solar on your Unity or Serenity's.
We like the idea of boon docking as much as possible.
What works best for you?
Also..they say that lithium batts won't fit under the stairs?
If you've gone the lithium route..where have you had them installed?


Active member
I have four Group 27 AGM batteries. Two are in the original battery compartment under the entry step, and two are in the storage compartment left of the entry door.


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Active member
Yes, the storage bin contains two batteries, inverter/charger, subpanel, and solar charge controller. I have 635 watts of solar panels on the roof.


New member
@jackfish~ Wow!?
Here's AM's suggested setup response.

"We have put together an estimate (see attached) that features 300W of solar installed on the roof of your new Leisure Travel Serenity Van, coupled with a 25A MPPT charge controller with built-in battery monitor, the replacement of your standard house batteries with two (2) Lifeline 6V 220Ah AGM batteries, and an upgrade of your existing converter/charger (if needed).
As of this writing, we do not carry a set of Lithium batteries that will fit in your existing battery compartment. If you're leaning in the Lithium direction, then we would need to inspect your rig for a suitable alternate location, and give you a fair assessment of labor to install. From a budgeting standpoint, it would not be unreasonable to estimate a 180Ah Signature Lithium Battery System at $4,200.00 + $6,000.00 (labor) = $10,200.00. If you were to add solar on top of this, you're looking at a total cost of around $15,200.00 (ballpark).
We understand your Leisure Travel already comes with a 1200W inverter, so it appears you're covered there."

Do you feel they are being conservative towards wattage in their suggested set up?
I've followed your postings for some time and trust that your tech knowledge in solar is much much better than mine ;)
I'm hoping to get the best most useful solar set up right off the bat.


2018 Wonder FTB
And I think $5K for a traditional solar install as they have spelled out is ridiculous! Here is my breakdown using flexible panels:

3 x 100W Flex Panels (Amazon) $200 = $600
1 x Bogart Engineering 30A PWM Charge Controller and Trimetric Monitor = $350
2 x AGM Lifeline GPL-4CT 220AH Batteries $380 = $760
1 x Wiring = $100 (at the most)
6 x Hours of your time = $0

Should be around $2K.

I don't think MPPT is necessary at 300W. Some will squawk that it is but it's like arguing religion: there are no winners.

I'm also thinking that for sort of normal camping this might do it, especially if you move about and run the engine every couple of days. For long periods of boondocking, depending on your electrical use, 300W might struggle to keep up. But with all LED lighting and careful monitoring (something the Trimetric will let you do) you can probably make it work. Is there room for a fourth panel on the roof? I don't know.

P-ass: (I kinda liked abbreviating that) if you want we can take this offline.


New member
On our 2015.5 Unity MB, we installed 300 Amp/hr of lithium batteries under the wardrobe drawers,next to the furnace. The main reason for this location was not space limitations, but the need for the lithium batteries to be in a temperature controlled area. Most lithium systems have restrictions on charging the pack at or below freezing temps.

Peter Tourin

2020 Unity RL, ex 2012 Unity MB
The battery price seems high. Two 100Ah SmartBattery SB100's would be $1300 each, so only $2600, and when I looked last, it was cheaper to build up batteries from cells with a BMS - and when you build from cells, you can certainly fit 200Ah into the compartment. But that means you have to know how to select and install the system yourself.

On the panels - if AM Solar is quoting on 3 SP100 panels, those are expensive panels - but there's a reason - they are very efficient and they're small, so that it's easier to get them on the roof of a small RV. They'll probably be more efficient and last longer than many other panels, including the flexible panels. Those are the panels that have interested me so far - I can fit 3-5 of them on my roof. AM Solar isn't a cheap solution, but they seem to have always tested what they sell, and carried a limited selection of items that they know will work well. It may be that they're a good idea for the solar part, but not quite so much for the lith phosphate part, if you decide to go that way.


New member
Lithium batteries is one option that I would love to see LTV start offering as an option. Pleasureway is offering what is the equivalent of 400AMP Lithium batteries now. If people are willing to pay and LTV can make money why not? I would like to hear more about how difficult it is to switch to a lithium battery system? Maybe I'll start another thread sometime and ask for advice from the knowledgeable folks that have done this.

Thank you


New member
On our 2015.5 Unity MB, we installed 300 Amp/hr of lithium batteries under the wardrobe drawers,next to the furnace. The main reason for this location was not space limitations, but the need for the lithium batteries to be in a temperature controlled area. Most lithium systems have restrictions on charging the pack at or below freezing temps.

That makes sense!
The technomadia couple were talking about that recently in their vlog.
The 'extra chair' between the passenger driving seat and the motor home door.
Any chance you can show a photo of your set up?
Best and thanks,


New member
We upgraded the entire electrical system with: 360 watts solar panels, solar charge controller, upgraded the inverter to 2000 watt, changed out the electrical distribution panel, and swapped out to 300 amp/hr lithium batteries. We can now use all the outlets throughout the RV from the inverter/battery. The battery/inverter can power everything except the air conditioner. Now when we boondock, water storage is the limiting factor.This project started with correspondence with AM Solar. They were booked for more than a year, but recommended Lew Farber as an alternate. His Initial quote for the proposed project:

• 2 GO-160 watt solar panel kits @$400...........................$800
• 3 SF-100 solar panel kits @ $270....................................790
• 1 Signature 25/MPPT/6 Pro controller core.......................800
• 1 roof combiner box........................................................80
• misc sealants, loom, fasteners, hardware, etc..................150
APPROX. SOLAR TOTAL...........$1850

• 1 MAGNUM MS-2012 2000 watt sine wave inverter/charger.............$1725
• 1 Magnum ME-RC remote................................................................185
• 1 Magnum 300 amp inverter fuse kit.................................................170
• 1 AC/DC power center replacement, complete...................................275
• 1 300 amp inverter disconnect switch.................................................75
• required 10/3 marine cable for 120VAC wiring....................................TBD
• required 2/0 class K welding cable for inverter DC wiring.....................TBD

• 1 AM Solar 300 amp/hour lithium battery pack complete........................$2700
• battery restraint system.........................................................................100
• required battery cabling for coach connections........................................TBD
APPROX. BATTERY TOTAL...........$2800 +

• approximate installation required..........38-45 hours @$110.......................$5000*

* Assuming use of existing 8AWG solar pre-wire

This represents a complete and robust solar/battery /inverter system that will provide up to 240 usable amp/hours from the lithium battery. The battery will be well charged each day from the 300/320 watt solar array, leaving generator use strictly for air conditioner use or battery charging during extended periods of inclement weather. One of the benefits of a lithium battery is that they don't need to be at 100% charge each day like lead acid batteries. No damage or ill effects are seen from less than full charging.

With a smooth fiberglass roof, your panels are adhered to your roof with 3M VHB tape and SikaFlex sealant. I use this method exclusively when doing Airstream installations, and have never lost a panel in 10 years of installations.............NO HOLES!!!!!

Lew Farber
RVIA Certified Master Technician
ABYC Certified Master Marine Electrician (pending)
*AM Solar Authorized Installation Center
**Lifeline Batteries***Magnum Inverters
*Member, Aqua-Hot National Rally Service Team
Master Tech Energy Systems Inc.
•278 Capri Blvd.
Naples, FL 34113
•2149 W. Cascade Ave. Suite 106A-214
Hood River, OR 97031
866-490-6801 (fax)
The original plan was to use the factory solar wiring, but Lew discovered that the solar prewire wasn't heavy enough for the distance of the cabling. The other challenge was locating an interior space to relocate the lithium batteries, because they will be damaged if charged at temperatures at or below freezing. We found a spot below the 2 wardrobe drawers.


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New member
Pics always 'say' so much more.
That looks like a good set up!
Plenty of juice.
An I love the labels. I'll need them.

I hadn't even thought about how busy/back logged AM Solar might be.
I like Lew Farbers price better though.
I'll have to give him a holler ;)
I wonder if a Serenity has similar roof space of a Unity?

Our house sale looks like it'll go through.
Took almost two years to sell.

If all is good..we're planning on popping in on the Fretz RV booth at the near to us North East RV Show in Suffern NY this February.
From what I read in this forum..you can get the best deals at RV shows.
Even on factory orders.

Very exciting.


I just finished an installation of 400 Ah of LiFePo4 batteries in 2 banks of 4 cells each, as well as a Victron MPPT charge controller and 2KVA Victron inverter. I used the same GBS batteries that Technomadia has.

Space was a major issue. One of the battery packs fit in the existing understep bay. It was narrower than the lead acid batteries so I was able to mount switchgear behind it on the back wall of the battery bay. The other battery, plus its fuse and controller, went in the 1/2 compartment to the left of the existing inverter space. I was able to mount the new inverter in the same space as the old one but it required modifying the inverter housing and was no fun at all.

I'll be posting some photos and a more detailed writeup when the job is "final final".

Peter Tourin

2020 Unity RL, ex 2012 Unity MB
Sounds interesting - it'd be nice to have those extra batteries! I look forward to seeing your writeup.


2004 T1N Westfalia

I'd recommend John Palmer in northern part of Florida. He's been around solar industry since inception (consultant to manufacturers, used to have mobile installations at RV shows, ran how-to boondocking camps, etc.) and is frank re pros/cons of various parts. While he can do the whole installation, he prefers (requires?) the owner to at least observe him doing the installation so the owner can understand how everything works. You can also assist as well. His rates are very low (his installation is more of a teaching hobby).

Other installers may not permit you to observe.

Of course, don't forget HandyBobSolar.wordpress.com website and JackDanMayer.com


2016 unity tb
Hey pumpkinass!
If I remember right u were trying to get ur house sold? Hope it sold and u get ur serenity soon!

Thought I'd chime in about solar,I've decided to do it in 2 phases, 1st phase is limited to factory heavy guage prewire.. couple of gripes regarding the prewire- 10guage to cabinet and 8guage from cabinet to the battery. The MC4 on the roof is just in front of the shower skylight and the cabinet I'm referring to is the a/v cabinet on the drivers outside wall, and the battery box is back to the passenger side underneath the step. Why they ran wire across the r/v twice when they could have literally went straight down is beyond me, there's a good 12-15 feet of light guage wire. Anyway, this will be the setup till mid/end summer..

(4) am solar sp100 panels wired series parallel
(2) stark 12v125av lithium batteries. Both in factory compartment, should fit, will be tight! https://starkpower.com/shop/stark-deep-cycle-12-volt-125ah/
(1) victron mppt 50
(1) victron mppt control kit
(1) victron bmv 700 battery monitor

I'll program the factory installed magnum controller and inverter to charge the stark batteries.

Late summer phase 2

I'll add 2 more panels and wire all parallel through a combiner box in a much more direct route to the batteries, moving the victron mppt 50.
Add magnum hybrid 3000watt inverter powering full panel, re wire original inverted circuits back to breaker.
We'll definitely add 1 more battery, will have a better idea about if we want/need to add 2, these can go 4 together max. We're not power hogs and don't plan on running the a/c via inverter very often but the option will be there.

The materials will arrive next week and i hope to get started immediately. I'll take photos. :thumbup:

As a side note our composting toilet still works perfectly! :smirk:

Looking for flexible high strand count power wire (1,000's of strands)? Stuff we used in the old car audio days..
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New member
So just how important is all of this modification? All I want is to run the TV and plug in my cPap machine to run all night without the shore or generator power? Will the factory set up with solar and invertor do this for me?

Bone Head

2014 LTV Unity MB
So just how important is all of this modification? All I want is to run the TV and plug in my cPap machine to run all night without the shore or generator power? Will the factory set up with solar and invertor do this for me?

Short answer is yes. Have done so for years. Longer answer: IF you have a CPAP or BIPAP which will run on 12 volts as many of them do. (just look at the transformer brick that you plug into the wall and see if the output is 12VDC) If so, then getting a 12 volt plug adapter will save a lot of amp hours not having to run it through the energy hog inverter.
We have had three CPAP machines over the years and all had a 12 VDC input. I installed a cigarette type plug receptacle near the bed tapping off the power to the slide. One would not NEED to do this as there is a 12 volt outlet somewhere in the Unity depending on the model. It was just a convenience.

I assumed that the slide and the CPAP would not be in use at the same time unless there was a heck of a fight or a walloping big drunk and in that case, a blown fuse was the least of our problems:bounce:


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