Lithium Battery Upgrade (Storage Bay)

mperra

New Member
Joined
Aug 24, 2021
Messages
1
Location
Edmonton
I have a TMC Fourwinds Super C 33SW (2015). IT has batteries stored under the House Steps.I would like to upgrade my two 100AH Lead Acid Batteries to Two 300AH Lithiums. The storage space will not support this configuration. Has anyone else upgraded like this? DO you have a recomendation of where to place the batteries? What configuration? Also any gotchas I may need to consider (100Amp fuse etc.....) would be appreciated.
 
I have a TMC Fourwinds Super C 33SW (2015). IT has batteries stored under the House Steps.I would like to upgrade my two 100AH Lead Acid Batteries to Two 300AH Lithiums. The storage space will not support this configuration. Has anyone else upgraded like this? DO you have a recomendation of where to place the batteries? What configuration? Also any gotchas I may need to consider (100Amp fuse etc.....) would be appreciated.

Consider moving the batteries to the interior of the RV. Lithium's do not outgas and cannot be charged if they are below freezing. They usually have internal monitoring that will disconnect if the battery is outside a useable temperature.

You can use the same circuit breaker/fuse as the original batteries. Going from 100AH to 300AH only increases the amount of time current can be drawn and does not affect how much current down stream devices use.
 
Bob is correct above. In addition consider installing a DC to DC charger or change out your BIRD for a Precision Circuits Li-BIM 225. The former will limit charging current from the chassis alternator. The latter cuts it in half.

Without one of those, 600 Ah of Li batteries can put quite a load on your chassis alternator and possibly burn it up.

David
 
The mechanics of a lithium conversion are fairly similar from RV to RV. What's different is the constraints of physical layout and space.

When I did my conversion a reference I used heavily is a YouTube channel called Explorist Life.

EXPLORIST life Mobile Marine & Off-Grid Electrical

Although he's primarily van build focused, the same principles apply as far as "electrons math"... cable size calculation, fusing etc.

Spend a few hours browsing and you'll have a lot of questions answered!
 
I'd suggest spending the money on the labor of a professional who does battery stuff(like a solar place).

An involved education in a one time usage subject in a subject you haven't an inkling of an idea about.

The accumulation of tools you may never use again. The chances of you having cash outlay for the needed tools equaling a fair percentage of a pro doing the install is very real.

The time and contortions to do the job...

These do not equal the paltry percentage of your total rv investment it would cost to buy the labor and expertise of a pro.
The pro will know(and explain my math) if you really need the SIX times battery capacity you now have.

Hire a pro.
Support a local business.
 
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Finding a pro that has the skills to plan and execute a Li battery upgrade will be a challenge.

David
 
I replaced 2 Group 125ah AGMs with one Mini Sized 300ah in my battery compartment under the steps. A second would not fit so I did not buy. I figured I could always add a 2nd 300ah later if I ever need. In my case, I basically tripled my usable capacity so I don't need 600ah. If I ever truly need 600ah in the next few years, I will have my Mobile Tech come by to add a 2nd Lithium under a dining bench that is closest to the steps.

It is a gigantic difference between 2 100ah FLA and 1 300ah but no doubt if the 2 mini sized lithiums would have fit, I would have bought 2.
 
I'd suggest spending the money on the labor of a professional who does battery stuff(like a solar place).

An involved education in a one time usage subject in a subject you haven't an inkling of an idea about.

The accumulation of tools you may never use again. The chances of you having cash outlay for the needed tools equaling a fair percentage of a pro doing the install is very real.

The time and contortions to do the job...

These do not equal the paltry percentage of your total rv investment it would cost to buy the labor and expertise of a pro.
The pro will know(and explain my math) if you really need the SIX times battery capacity you now have.

Hire a pro.
Support a local business.

Spoken like a pro! I used to have this conversation with my brother over many topics. It all started when we were kids and he didn't have the patience to put his bicycle chain back on... I always did it for him.

As we got older he preferred to hire work out - even routine lawn tractor maintenance. He could easily afford it. He would rather sit on their back porch looking out over their in-ground pool... which he also hired maintenance for.

I suspect my obsession comes from the downfall of being a perfectionist. Nobody does it the way I want it done. Drives my wife crazy! I will concede defeat on certain things... a deck addition, HVAC replacement, etc. But if I can do it myself, I can't help myself!! :LOL:
 
I wouldn't expect a surgeon to instruct me, by means of a forum, on removing an appendix unless the surgeon had some background information on what was happening on my end.

When all I can construe is the inquirer's lack of knowledge and understanding of the task at hand, I'll call for anyone to use a pro, every time.

I'm not going to tell a life long cube dwelling Junior KeyPunch Operator how to run a bull dozer until I know they have the comprehension and ability. I assume they wouldn't tell me of replacing the carriage return key until they ascertained I had the required hole sharpener and the skill to torque the henway...lest I RUIN everything.

Go to a pro
Is the correct answer on this forum 80% of the time.
The guy who wanted to cut a giant hole in his ceiling so he could see the roof without using the 300 other ways to see the roof comes to mind. Not as good or bad, just comes to mind.

RV BURNED TO THE GROUND! Film at eleven!
Comes directly to my mind.

(I am not a perfectionist. I am an innovator with a knowledge of engineering budget constraints)
 
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A good friend is a very successful home remodeling/building contract locally. He hasn't swung a hammer in years. His crews of employees have done all the grunt work for years. BUT... he knows EXACTLY how things should be done... obviously because he does the financial/billing and customer service.

The easiest sales target is an uneducated consumer. If you DON'T do it yourself, at least educate yourself so you're not taken advantage of.
 
Yes.
The Two reasons to look over the pros shoulder;
Your Verification
and
your education.

Trust but verify.
Verify to learn.
 
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You are basically going to increase your battery capacity by 6X since the lead acid batteries should only be discharged to 50%. Unless you have calculated that you need 600AH from load calculations, I would consider installing the largest capacity that will fit in your existing space which would probably be around 300AH.

If you are handy and comfortable with low voltage DC, you can do the installation yourself. If not then you can hire someone. Unfortunately hiring someone doesn’t guarantee a good job. Try to find some good references.
 
Hey! I don't have the space issues you describe, however, I just got 2 of these (new) Renogy "Mini" Lithium batteries. You may want to check these out... they are a bit expensive, but for me, it's worth the better battery performance, and future scalability: Core Mini - 12.8V 300Ah Lithium Iron Phosphate Battery w/ Low-Temperature Protection (there are other mini options too)
You can get equivalent AH batteries at half that price. DKOldman and I got Newtipower 300 AH "minis" at $387 before Thanksgiving. But their price bounces up and down almost daily so you have to watch them to get the best deal. There are others as well.
 
Side note for LiFePO4 batteries with low temperature cutoff. It's been getting down into single digit temperatures here over the last week. Just checked my batteries... they're disconnected by the BMS low temp circuit. So that works!
 

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