Repurposed Batteries for solar

[Jastevens82]

Hello all,

I was curious if anyone here had repurposed a Tesla, Prius, Nissan Leaf battery as a bank for solar storage and if so, what type of work did you have to get into to make it viable.

Thanks
John

[john61ct]

LFP and maybe LTO are IMO the only LI chemistries safe enough for that use case.

The sophisticated monitoring, control and protection systems, aka "safety electronics" are not inside the packs, but are part of the overall EV systems' design, and are no longer present once the cells are removed.

And the thermal management systems / TMS , temperature controls are especially critical, circulating fluid to keep the packs in the right Goldilocks range, millions invested in just engineering those.

These have not been reverse-engineered yet, and personally if someone claimed to sell such I'd be **very** skeptical.

One day maybe open-source engineers will reverse-engineer standalone infrastructure to make these packs safe enough to use inside our dwellings, but for now people plugging these ideas are IMO the height of irresponsibility

Tesla will come out with "powerwall" type banks designed for mobile use one day I bet.

But an inherently safe chemistry internally will to me always be worth sacrificing even half the energy density.

Risk of thermal runaway, i.e. fire, boom bad, is just too high for use in a small mobile living space.

Stick to lead or LFP.

[neversayneverbus]

There are youtube videos about this subject. However, it seems you would have to get extremely lucky to find one of these batteries to convert for a reasonable price. Individual modules sell for a lot of money, and to buy new, it's 6 grand or more minimum.

I love the idea of using these type of batteries, because they are light weight and very energy dense. And even at full price, brand new, are a better deal than any of the other lithium style batteries, such as battle born or others. If you were to try to purchase the same energy density of a tesla pack in battle born it would cost tens of thousands.

There are also youtube videos that walk you through making a battery management system for the packs. This can be done, and safely. But it's still a expensive.

[john61ct]

Anything "can" be done with crazy engineering skills.

People build up DIY EV cars from scratch, but just watching youtubes is not the most effective education on how to do it.

High energy density is only important in that sort of context.

LFP is half the weight / size of lead, as good as you're going to get, safely.

But yes it costs 7x as much, plus the extensive knowledge needed to get the longevity payback on that investment.

Most should just stick to lead, tried & true at $1 per Ah.