LiFePo Batteries: Build or Buy?

[rgleason]

See David Poz
"Save $500/day when you DIY your own batteries!!!"

https://www.youtube.com/watch?v=6Ai5IRQbLcc

Shows how to build a 100 ah LiFePo Battery using a
- Case Battery Box 6.75" x 13.0 x 8.5"
- 3.2v 5000mah cells
- Cell holders
- BMS Battery Management System 4S

at a cost of about $500 ? Battleborn Lifepo 100 ah (12.75" x 6.88" x 9" ) = $949 approximately

("saved me over $500 compared to the big brands"
Built over a period of 4 days.
Resulted in 15% more ah, 34lbs.

[jmc42]

Sourcing the BMS seems to be critical. If it fails, its trouble.

[newhaul]

Or build one like mine for a bit or but still less than 100ah battleborn
https://www.cruisersforum.com/forums...ml#post3063601
250ah for under $700

[Reefmagnet]

Originally Posted by jmc42

Sourcing the BMS seems to be critical. If it fails, its trouble.

I'd agree with that. Finding a BMS with characteristics ideally suited for use on a cruising sailboat is like trying to find unobtanium!

[rgleason]

Hi Newhaul, how is your LiFePo sysem performing?
Where is your thread on your install?
I haven't yet improved my alternator setup.
There are many BMS alternatives.



DIY 12v 100Ah LiFePO4 Solar Battery for $555 - Will Prowse
Good list of equipment under "Show More"
iOS BMS software: https://apps.apple.com/us/app/xiaoxia...

Building a 48-58vdc 3.5kWh DIY Solar Generator for $650 in a Craftsman Toolbox - Lithium Solar
Good List of equipment under "Show More"
Batrium BMS https://www.batrium.com/

https://www.youtube.com/watch?v=PVnQ87Fvsk4

[newhaul]

Originally Posted by rgleason

Hi Newhaul, how is your LiFePo sysem performing?
Where is your thread on your install?
I haven't yet improved my alternator setup.
There are many BMS alternatives.



DIY 12v 100Ah LiFePO4 Solar Battery for $555 - Will Prowse
Good list of equipment under "Show More"
iOS BMS software: https://apps.apple.com/us/app/xiaoxia...

Building a 48-58vdc 3.5kWh DIY Solar Generator for $650 in a Craftsman Toolbox - Lithium Solar
Good List of equipment under "Show More"
Batrium BMS https://www.batrium.com/

Haven't done an install thread yet . I'm running it for a couple years before I post any data on it but eventually I will get around to an install and operation video. I need to get the new westerbeke 10-two installed with its upfitted 50 amp alternator. ( about the biggest that the engine will run without effecting performance at the prop.

[sailing_gal]

Excellent source of information and sources for materials and supplies- the site has a marine use discussion group as well:

www.diysolarforum.com

There is quite a discussion and excellent info on building your own LiFePO4 batteries and comparisons between US/English brands and the Chinese ones.

[Culwatty]

So I've done a lot of research, and decided to go for diy, in the UK cells are difficult to get without pacing for 30 days hoping they arrive and are what they are stated as ( lots of stories of people buying and not receiving or receiving b grade when they paid for A grade. )

So I have settled on either a UK supplier, or a German supplier. You guys are so lucky in the states, will prowses links are almost useless to me 😔 but his videos are spot on.

You do not "need" a bms, if you fit a discharge/ overcharge relay from victron. And have a low temp cutoff capable charge controller. Just passive balancer on each set of cells.

To get a high quality bms, your better off just buying battle or something high end. I cannot get a decent 300a bms that will warranty marine use for under £250

Alternator charging run it though a renolgy 50a b2b mppt controller. £250 (Has low temp cutoff) also added advantage. You can hook a regular shore power 240v charger to the input of the b2b and charge your lifepo4! Oh and the mppt controller 660w but only at 25v

But on a monthly shading is always an issue so just pun all panels in parallel with own cable!

HtH

The only thing I don't know is if you can parallel connect the b2b to increase output say 2x 50a (i have a 150a balmar alternator)

[newhaul]

Originally Posted by Culwatty

So I've done a lot of research, and decided to go for diy, in the UK cells are difficult to get without pacing for 30 days hoping they arrive and are what they are stated as ( lots of stories of people buying and not receiving or receiving b grade when they paid for A grade. )

So I have settled on either a UK supplier, or a German supplier. You guys are so lucky in the states, will prowses links are almost useless to me 😔 but his videos are spot on.

You do not "need" a bms, if you fit a discharge/ overcharge relay from victron. And have a low temp cutoff capable charge controller. Just passive balancer on each set of cells.

To get a high quality bms, your better off just buying battle or something high end. I cannot get a decent 300a bms that will warranty marine use for under £250

Alternator charging run it though a renolgy 50a b2b mppt controller. £250 (Has low temp cutoff) also added advantage. You can hook a regular shore power 240v charger to the input of the b2b and charge your lifepo4! Oh and the mppt controller 660w but only at 25v

But on a monthly shading is always an issue so just pun all panels in parallel with own cable!

HtH

The only thing I don't know is if you can parallel connect the b2b to increase output say 2x 50a (i have a 150a balmar alternator)

A few issues .
1) no need for a bms ? While correct why would you not want to protect a very expensive boat with a simple piece of electronics.
My 200amp bms was 150 USD
A 300 would have cost me 250 but 200 amp is plenty for my needs

You need to really research that renogy 50 amp b2b unit its not as good as you think . It maxes at 25 amps from either source.
Much better off with the 60 amp b2b they make

https://www.renogy.com/12v-60a-dc-to...ttery-charger/

With the balmar I would recommend just get the balmar regulator.

https://balmar.net/balmar-announces-...ium-batteries/

[ABJ87]

We the opted to go with a commercially made battery. (Battleborn)

A few things drove me in that direction,

1) I couldn't find a simple BMS that meet all may requrients ( Hi / lo temp, overcurrent, cell balancing at the time.) I don't have space for a REC BMS and multiple contactors.

2) Difficulty getting high quality cells, it seems to be hit or miss with some sellers coming out of china.

3) Wasn't really looking for a science project.


In the end it was about $1000 more than a DIY setup, but we have a nice self contained unit with a pretty good warranty.

Your mileage may differ.

[LoudMusic]

In a life sustaining setting? You buy that stuff and you thank your lucky stars a knowledgeable engineer designed and built it for you.

In a shed at home? Meh, sounds like a fun project?

[rgleason]

Newhaul, "200amp bms was 150 USD" which one was it? Also what panels are you using with the 200ah batteries? (2) 100watt? How does this system work for your needs?

That westerbeke 2 10 is a good choice. I almost took one home that was just taken out of a boat, purposed as a generator. I thought it would make a good engine, but I did not have a purpose. good luck.

[newhaul]

Originally Posted by rgleason

Newhaul, "200amp bms was 150 USD" which one was it? Also what panels are you using with the 200ah batteries? (2) 100watt? How does this system work for your needs?

That westerbeke 2 10 is a good choice. I almost took one home that was just taken out of a boat, purposed as a generator. I thought it would make a good engine, but I did not have a purpose. good luck.

I have several videos on my YouTube page of the bms the batteries the battery monitor and the westerbeke running . He'll of a deal on it paid 100 USD and she is a good runner.

https://youtu.be/GT00ny_-oR8

Got it direct from efire via Alibaba b2b 148 USD delivered.
I am using 2 100 watt rigid mono panels with another 2 flex that I can put out if I need to . Also eventually will install the 400 watt wind generator.

[Moontide]

Both David Poz and Will Prowse are very good sources / mentors for putting together a DIY battery. Now if I can just learn how to solder better.



In terms of usable AH doing a DIY is getting way closer to being more competitive with FLA.

[Singularity]

Regarding no BMS (I don't have one)...
-In boats I've not seen anyone have a problem with prismatics like Calb/Winston get out of balance
-A ~$100 Victron low voltate cut protects the bottom end (as a BMS would)
-All charging sources are modern with high-voltage cuts

A BMS could be another layer of protection, but to me it's a science project to make sure that the BMS communicates with the alternator regulator should the BMS decide to cut for whatever reason (cue zap-stop no matter what). Otherwise, the BMS just presents another thing to potentially foul, and costs money that could go into something else, like more Ah. If I had a BMS I wouldn't go cheap, and if I remember the 'Balmar equivalent' quality-mainstream BMSs were several hundred dollars...and for what. Meh.

Otherwise the commercial LFP batteries with integrated BMS, as I understand, still have the science project issue with the alternator (what's the workaround with Battleborn?), while putting together a 100ah prismatic set can be done for <$600 in 30 minutes if you have the cribbing material, where one should have a discrete LVC and smart alternator regulator and charger already. No way messing around with a gazillion cells in an off-shore cruising boat.