DIY Lithium Guide

[tek-noid]

Originally Posted by zboss

I'm still looking for a reliable source of lithium cells by CALB or Sinopoly inside the USA so I don't have to deal with duties or anything.

What about http://www.calbusainc.com/?

[Davidhoy]

Does anyone have thoughts on creating your own LiFePO4 battery bank using individual cells? There are some pretty good deals on cells that you can then bundle together into appropriately sized packs. I've seen YouTube videos of guys creating homemade "Powerwall" type battery banks using salvaged 18650 type cells. Not sure I'd go with salvaged cells, as these cells are fairly readily available. Basically, you can create a bank of whatever voltage and Ah capacity you need by connecting the requisite number of cells in a serial/parallel matrix. Add a battery monitoring system, and you should be all set, right? How safe would such a battery bank be in a marine environment? Am I out of my mind for even considering this?

[GTom]

Originally Posted by Davidhoy

Does anyone have thoughts on creating your own LiFePO4 battery bank using individual cells? There are some pretty good deals on cells that you can then bundle together into appropriately sized packs. I've seen YouTube videos of guys creating homemade "Powerwall" type battery banks using salvaged 18650 type cells. Not sure I'd go with salvaged cells, as these cells are fairly readily available. Basically, you can create a bank of whatever voltage and Ah capacity you need by connecting the requisite number of cells in a serial/parallel matrix. Add a battery monitoring system, and you should be all set, right? How safe would such a battery bank be in a marine environment? Am I out of my mind for even considering this?

Of course it can be done. However, properly done using quality cells to get your expected capacity, balancing them properly, I highly doubt that you come out cheaper. Safety is another issue, decent banks are well sealed. I'd just pick a Winston or something similar.

90Ah@12V needs about 120pcs of 18650, quality cells (Panasonic & Co) will cost you the same as a 90Ah tested Winston under warranty (700€).

If you give up on quality, then your bank will suffer, especially under higher loads.

[john61ct]

Originally Posted by zboss

Who makes the best programmable BMS? I wish Mastervolt made a BMS since that is what we have on the boat.

MasterVolt lithium systems include their BMS of course.

[john61ct]

Originally Posted by Davidhoy

Does anyone have thoughts on creating your own LiFePO4 battery bank using individual cells? There are some pretty good deals on cells that you can then bundle together into appropriately sized packs. I've seen YouTube videos of guys creating homemade "Powerwall" type battery banks using salvaged 18650 type cells.

Too much trouble, I think wouldn't pass for insurance.

ABYC regs coming soon will likely require prismatic cell based LFP "systems", I suspect will not include DIY BMS

[zboss]

Originally Posted by john61ct

MasterVolt lithium systems include their BMS of course.

Yes, it would be nice if they made a discreet one.

[Davidhoy]

Originally Posted by john61ct

Too much trouble, I think wouldn't pass for insurance.

ABYC regs coming soon will likely require prismatic cell based LFP "systems", I suspect will not include DIY BMS

What does "prismatic" mean in regards LiFePO4 batteries? From what I've read it mainly refers to flat, rectangular cells, as opposed to cylindrical cells. Clearly the flat rectangular cells can take up less space than cylinders, but is there something that makes them inherently safer than other cells?

Also, when you refer to "DIY BMS", do you mean any add-on BMS that is not integral to the battery pack itself?

Regards,
David.

[zboss]

Who is making the programmable discrete BMS's favored by professional installers now?

What about the preferred cut off relays?

[Maine Sail]

Originally Posted by john61ct

Too much trouble, I think wouldn't pass for insurance.

ABYC regs coming soon will likely require prismatic cell based LFP "systems", I suspect will not include DIY BMS

You've made similar shot in the dark statements here and elsewhere and all I know is that you seem to have more info on this than I do, and I'm actually on the committee that is developing this standard....

Suffice it to say the process & standard still has a ways to go despite over three years of hard work & research. I can't say any more than that at this point.

[john61ct]

Yes on prismatic, totally different construction.

LFP system sellers have a proprietary BMS built in.

Users buying bare cells then fitting "open hardware" OVD / LVD protection is what I call DIY BMS.

Active balancing is not needed IMO

[Davidhoy]

Originally Posted by Maine Sail

You've made similar shot in the dark statements here and elsewhere and all I know is that you seem to have more info on this than I do, and I'm actually on the committee that is developing this standard....

Suffice it to say the process & standard still has a ways to go despite over three years of hard work & research. I can't say any more than that at this point.

Thanks, Maine Sail! Anything you can share on how to proceed in the interim?

BTW, I've read many of your invaluable articles, they really are a goldmine. I think I learned everything I know about rebedding deck fittings from you :-)

[TheThunderbird]

https://www.ev-power.eu/en/By-Brand-...hparam=winston

GWL has good reputation among electricians

I think a US based customer can ask the system w/o cells

The cost of system integration comes at a high price with the likes of Victron and Mastervolt...

GWL is serious, and some steps beyond a pure DIY approach.

On top, I would never install a no-name Lithium based battery onboard. GWL sells only CALB, WINSTON, SINOPOLY

YTTRIUM? Due to its basic voltage, you come up with 5x batteries for a 12V system, and again there is some mismatch...

[TheThunderbird]

In setting a 3-Phase charger for Lithium, what's better? FLA, GEL, OR...??

[GTom]

Originally Posted by TheThunderbird

YTTRIUM? Due to its basic voltage, you come up with 5x batteries for a 12V system, and again there is some mismatch...

?? What's wrog with that? A lead cell is just 2.x Volts. Yttrium AFAIK expands the temperature range and (also AFAIK) further decreases flammability of the internals.

The LiFeYPO4 Winstons/etc are not bad when it comes to capacity/weight...

[john61ct]

A BMS sold as compatible with whatever-mfg prismatic cells, I would call an "open hardware" BMS.

User-adjustable setpoints, ideally off-the shelf parts as much as possible, scalable from a small 50AH portable powerpak, up to 1000 and higher House banks.

Maybe even open-source software running on Arduino or Raspberry Pi.

Anything like this out there? Or with even some of these attributes, please let me know.