Building your own battery bank

[DiscoMick]

One of my workmates was telling me today he has built his own battery bank using discarded batteries from laptops.
He has eight banks of batteries with each bank containing 75 laptop batteries.
He is just experimenting with it in his garage at the moment. He can't connect it to his house solar because it is still on a 50 cent/kilowatt hour rebate, but if he changes the system the rebate will be cancelled.
So, it got me thinking about how this could work.
One of the issues, he said, is you have to test the batteries to make sure they are OK, because if a battery fails it can drain the whole bank.
He said another option is to trawl battery shops looking for discarded batteries from forklifts and similar machinery, since they are much bigger batteries and can often be revived with careful charging.
So, has anyone else done this? What are the traps?
Is it better to go 12 volt, 24 volt, 36 volt or even bigger?
How do you manage the connection to the house and the grid?

[bee utey]

Connecting a home built battery pack to a house wouldn't be something you'd do lightly. Any voltage other than 12V means you need more expensive equipment to use it. A 12V battery can be configured to be entirely independent of the mains and use cheap and common 12V LED and inverter products. If you install a 12V battery bank in your garage and keep it topped up with an automatic charger, you can wire the house yourself with a supplementary set of 12V lighting in every area where it's useful. Kitchen, passageways, stairs, toilets, entrances etc are where I have mine. 12V sensor lights are pretty cheap and can light approaches to the house that still work when the power fails. An inverter at the battery can run small appliances via extension cords. Your battery can be as big or small as you like so long as it doesn't set your house on fire. Charging during power outages can be done with camping solar panels or jumper leads off your car.

As for running an entire house off a battery storage bank connected to your meter box, leave it to the professionals is my advice. Too many pitfalls for the beginner.

[DiscoMick]

Yes, I'll be using professionals for our battery installation next year.

Interestingly, I didn't mention that my workmate has also hooked up a 500 amp wind generator to his battery bank in his garage. he bought the wind generator off ebay for about $250. Says the main benefit is obviously at night when the solar isn't working, but the wind can keep the batteries receiving charge. Interesting.
I've often thought the wind generators used on yachts could be a useful addition to a household battery and solar system.

[goingbush]

if you can put up with the Yanks in this video, (This is what America has evolved into)

EV powered by recycled Laptop batteries

Tesla P100D V.S. DIY Recycled Car - Range Challenge 382+ Miles @ 70MPH! - YouTube

or if you cant stand watching the video Tesla Record Falls Short of The Phoenix - Electric Car Design Consultants, Green Living Expert, Guru

[nick_e]

There is enormous potential in DIY battery packs from reclaimed cells.

Some inspiration

This guy built a EV Kombi
jehugarcia
- YouTube

This guy (aussie) has made a 50kWh grid connect battery system with solar.
HBPowerwall
- YouTube

They go through a lot of info on how to test and bin cells and how to build them into usable battery packs.

It's doable but you need a good source for cheap 18650's, and a lot of time and patience.

You can do it easier with new cells but the cost would be a lot greater.