35 replies to this topic

[ski3pin]

A couple years back a few members here built their own batteries by assembling lots of little cylinders. What would you use today? I saw this Will Prowse youtube -

 

Are these good ingredients? What are other options?

 

I'm not committed at this point but am curious enough to ask.

 

Thanks.

[Jack]

I built my LiFePO4 battery and have been very happy with it. 280Ah cost about $750. Since my Fleet front dinette has limited battery space, I needed to spend a lot of effort and time making a case for the cells that would fit in the battery compartment and have a reasonable way of maneuvering it. Making the case and mounting the batter management system takes the most time. You want a case that lets you maneuver the battery into and out of your battery compartment. Assembly and wiring and setting parameters takes a few hours. Balancing the cells takes another few hours. But there's no Amazon prime. Figure 30 to 40 days to get your cells and BMS.

 

Assembly is not complicated, but you should be knowledgeable and comfortable working with electricity. The major issue is the energy in the battery (any battery, for that matter). Short it out and and you risk serious fire and injury.

 

https://www.wanderth...embly +required

$280 Ah is much more than we need except for one appliance. We are giving the ZeroBreeze Mark II 2000BTU A/C a try this summer. As our age has increased, our tolerance for temperature has decreased. We lived in St. Louis for 4 years some time ago and tolerated the summer temperatures there - and with a car without A/C. We now like to avoid temperatures that are above 85F for any length of time.

 

If you are looking to build a smaller capacity battery, google search the various RV/expedition forums for LiFePO4 DIYers to find sources for cells. For a modest bump in price and much shorter time, check out https://overkillsolar.com/ I think Will Prowse also has source links for a 100Ah battery.

 

[kmcintyre]

I've built one and posted a lot of info on where I got the "cells" and parts I used.  It's really pretty easy.  The hard part is the terminology and getting the settings right.  

 

I've used mine on about 10 trips so far.  No issues once I got the charging profiles dialed in and the DC-to-DC charger and BMS.

 

That Will Prouse video is still quite old.  His videos, etc. are great.  It's directly mainly for solar but still helps a lot to see his "reviews" and suggestions, tests.

[ski3pin]

I've built one and posted a lot of info on where I got the "cells" and parts I used.  It's really pretty easy.  The hard part is the terminology and getting the settings right.  

 

I've used mine on about 10 trips so far.  No issues once I got the charging profiles dialed in and the DC-to-DC charger and BMS.

 

That Will Prouse video is still quite old.  His videos, etc. are great.  It's directly mainly for solar but still helps a lot to see his "reviews" and suggestions, tests.

 

Searching back through topics here on Wander the West, I believe I've sorted out that this was your source and with two options, one you used for a 120ah battery -

 

3.2v120ah

 

and another option if I decided 100ah -

 

3.2v100ah

 

Am I correct? Thank you.

[rando]

I have been using my 150Ah DIY lithium (with 120 cylindrical cells) for going on 4 years now and it has worked wonderfully.   If I were to do it again, I would use the 120Ah prismatic cells that are currently available at very competitive prices.  These were not cost competitive 4 years ago.

 

Building the battery is very straightforward - but you need to respect the energy that is contained in the batteries.    There are a few caveats:

1. You want to have a way to 'top balance' the batteries you purchase before you install them.  This is usually done by connecting them all in parallel and charging them to 3.5V with an adjustable power supply.    You may be able to get away without doing this,  but omitting this seems to be a leading cause of future problems. 

2. You want to clamp the batteries together, to prevent them swelling. 

3. You should place some sort of insulator (eg 1/8" plastic sheet) between the cells.  The metal cases are also the battery negative, so if you were to damage the blue heat shrink wrap, you risk shorting out the batteries and a fire.  You should also cover the exposed terminals on the cells. 

4. You need to set up your BMS correctly. 

[kmcintyre]

Searching back through topics here on Wander the West, I believe I've sorted out that this was your source and with two options, one you used for a 120ah battery -

 

3.2v120ah

 

and another option if I decided 100ah -

 

3.2v100ah

 

Am I correct? Thank you.

 

Yes, I think that's correct but I used the 120ah version. 

 

I have a write up that I did if you'd like it.  Just PM your email as I don't know how to post the entire thing here.

 

Kevin

[ski3pin]

Jack, kmcintyre, and rando thanks for the information!

[ski3pin]

An update. I put in an order through alibaba for 4 of the 120ah cells that member kmcintyre used. This was my first experience with alibaba. I received only one response from China suppliers. The cost was $43 a piece plus $114 to get it here making a total around $280. Prices are up. Add in a BMS and cost for a DIY is approaching the sale price on the Renogy battery and the SOK that Will Prowse gave favorable reviews. Note, these are both 100ah batteries.

 

I considered the SOK because it can be disassembled and parts replaced.

 

I'm going ahead with a DIY mainly for the learning experience and I like to understand how things work.

 

Thanks all for the information and insights.

[Stokeme]

I posted a thread about this dealer a few days ago. This video (link) also posted may be helpful in construction.

[Stokeme]

Why I love included internal Bluetooth w/BMS. Note ... there are many free Apple apps from other battery dealers. I have found several that work universally with both my batteries from 2 different (now defunct) companies. Some are basic, some are the latest, advanced tech. The graphics/format on some are impressive.

Edited by Stokeme, 14 June 2021 - 04:16 PM.