My DIY battery storage system

Solar, wind, hydro and other non-fossil sources of electricity.
User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

My DIY battery storage system

Post by jonescg » Sep 04, 2017 9:30 am

I have converted several lead-sled scooters to LiFePO4 over the years, including these shitty E-max "Sport" scooters.
Emaxsport Pb to Li 001.jpg
Another lead to lithium conversion. Too bad the scooters themselves sucked balls.
Emaxsport Pb to Li 001.jpg (158.93 KiB) Viewed 2152 times
They worked, but they only do 55 km/h, take a calendar month to get there, and they're really badly made. So after years of them not selling, I ended up picking up a couple of them for very little. I recovered the lithium I put into them and will be using them to make a load-shifting system for charging my scooter (which is not shit).
Future powerwall.jpg
Future powerwall.jpg (214.43 KiB) Viewed 2152 times
The scooter to be charged of an evening.
Plates on.jpg
My good scooter - 3 kWh onboard, 60 km range
Plates on.jpg (182.83 KiB) Viewed 2152 times
I hope to rig the solar panels on the shed to charge the 6 kWh LiFePO4 battery, so I can then dump charge from it to the scooter at night.

User avatar
Monstarr
100 W
100 W
Posts: 248
Joined: Apr 12, 2011 4:56 am
Location: The Netherlands

Re: My DIY battery storage system

Post by Monstarr » Sep 14, 2017 7:26 am

You can use a Meanwell ISI-500 MPPT charger & inverter with those LiFePO4 cells. They somewhat have the same charge voltage as lead.

http://www.ebay.com/itm/Mean-Well-350W- ... XQvV9SMITK

There are more on ebay btw.

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Sep 18, 2017 8:23 pm

Thanks for the tip!
I have a couple of ways of doing this, and they cost about the same. But going down the MPPT charge regulator / inverter route might be the best for an 'off-grid' system.

Got two more scooters to rip apart this weekend :D

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Sep 26, 2017 7:53 am

All of the cells ready and willing!
20170926_202906.jpg
20170926_202906.jpg (247.65 KiB) Viewed 1972 times
Next step is to get some busbars cut up. Only needs to be about 1 mm thick, if that.

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Oct 15, 2017 4:42 am

Only a little bit of progress to report - welding up a nuggety little cabinet to house the cells. I want it to be self contained. There's room for another 2 cells in parallel (8 kWh total).
Power cabinet.jpg
Power cabinet.jpg (210.21 KiB) Viewed 1852 times
The aim is to have two lower shelves filled with cells and the upper shelf with the inverter and battery charger. If I had an inverter/charger I'd hook the battery right up to it, but I don't. So for the meantime I'll just charge it off the mains while the sun shines (set a timer from 9 am to 3 pm) and use the inverter to run the scooter charger.

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Oct 28, 2017 5:34 am

Well the shelf part is complete. I'm going to put two sheets of 9 mm plywood down and glue them together for added strength.
There's room for about 8 kWh of these cells (I only have 6 kWh) but with any other chemistry you could probably fit closer to 16 kWh.
Power cabinet 2.jpg
Next step is the busbars.

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Oct 29, 2017 9:12 am

Just going to get these laser cut from 3 mm aluminium since that's what the terminal posts are made of.
Sure, I could drill them myself, but sending a file by email and picking up finished busbars is so much easier...
Power Cabinet Busbars.jpg
Power Cabinet Busbars.jpg (36.4 KiB) Viewed 1693 times

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Nov 18, 2017 7:01 am

I got the aluminium busbars made to suit 9 cells in parallel, since that's what the cabinet can easily fit. I figured at the time I could just leave them there and populate them as I get more cells...

...but then I got greedy :twisted:

So I'm buying another 45 cells. It's not the ideal situation as I didn't want to spend too much on this battery, but what the hell. 9 kWh is more useful anyway.
Busbars going on sml.jpg
Busbars going on sml.jpg (210.73 KiB) Viewed 1546 times

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Dec 29, 2017 5:29 am

Little bit of progress today. I made some trays which I can assemble the battery on before lowering it down onto the shelf and pushing it in. You would need a friend on the other side as there's about 50 kg there.
One shelf nearly ready.jpg
One shelf nearly ready.jpg (238.25 KiB) Viewed 1332 times
Trays made2.jpg
Trays made2.jpg (210.2 KiB) Viewed 1332 times
I'm going to have to run the cables up the left hand side to the upper shelf (fuse, isolation switch, inverter/charger etc). I figure 9 strands of 12 gauge wire would be heaps.

augidog
10 W
10 W
Posts: 84
Joined: Sep 29, 2012 11:49 am

Re: My DIY battery storage system

Post by augidog » Dec 30, 2017 11:51 am

....
Last edited by augidog on Jan 08, 2018 3:44 am, edited 1 time in total.

User avatar
fechter
100 GW
100 GW
Posts: 12414
Joined: Dec 31, 2006 3:23 pm
Location: California Bay Area, USA

Re: My DIY battery storage system

Post by fechter » Dec 30, 2017 1:10 pm

Are you going to compress the cells? Sometimes those will puff if run at high rates.
"One test is worth a thousand opinions"

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Dec 30, 2017 8:23 pm

@Augidog - haha, the scooters were had for a song. I got three 2 kWh scooters for about $2000. The batteries were the best part of them; the scooters themselves were total rubbish. To be honest, increasing the capacity from 6 kWh to 9 kWh was mainly about using the volume available. The cabinet is the size of a small TV cabinet I guess, so I might as well use the space fully. That, and the fact that 9 kWh is a fairly useful amount of storage. 6 kWh might be a little on the small side, especially in an all-electric household.

I picked up a 2.2 kW solar array, complete with 4 kW grid-tie inverter for $1100 off Gumtree (like Craigslist, but shittier). This included most of the rails and mounts, but I had to buy a few extras to make it work. Maybe another $100 in cable etc. But for a battery-buffered 2 kW solar system, it's pretty good going. Longer term I think I will get a hybrid inverter which can use the battery for the afternoon/evening shoulder period and still have grid export capability.

@Fechter - I've build a small timber tray which will hold the base of the cells firm, and the busbars will to a pretty good job of holding the tops in place, but I will also throw a bit of strapping around them too. I will have 180 Ah here, and at absolute worst, I'd be pulling 0.5 C on a really heavy load like the stove. So I think they should be fine. LiFePO4 is one of the more heat-tolerant chemistries too, which suits our climate here.

User avatar
amberwolf
100 GW
100 GW
Posts: 25039
Joined: Aug 17, 2009 6:43 am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: My DIY battery storage system

Post by amberwolf » Dec 31, 2017 2:13 am

FWIW, I have some Thundersky 60Ah cells that swelled right up just recharging them at a low low rate, after only a partial discharge at a low rate. :(

I'd read over and over that they need compression, but hadn't bothered because of the rate I was going to use them at. Now I know better. :/

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Dec 31, 2017 9:32 am

Some of these cells have already swollen a little from their life as a scooter battery, but not so much that I can't terminate them or anything. Plus they were manufactured by GBS about 4 years ago, so they're definitely a better generation of LiFePO4 cell than anything in yellow.

User avatar
amberwolf
100 GW
100 GW
Posts: 25039
Joined: Aug 17, 2009 6:43 am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: My DIY battery storage system

Post by amberwolf » Dec 31, 2017 2:48 pm

I don't doubt that. ;)

FWIW, my swollen ones still work--I just dont' trust them unattended, or enough to use them at any rate higher than a few amps. (they are sometimes used to power my audio amplifier for the music studio, or other "automotive 12v" uses around the house).

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Jan 25, 2018 12:11 am

The last 48 cells have arrived. I'll spread these out amongst the old cells in an effort to sort of 'equalise' their capacities and impedance.
Going to be a fun weekend of making cables and lugs!
20180125_080824.jpg
20180125_080824.jpg (242.38 KiB) Viewed 952 times
And yes, I'll be recycling all those copper links since I don't need them.

User avatar
ridethelightning
1 MW
1 MW
Posts: 1836
Joined: Jul 21, 2013 9:48 pm

Re: My DIY battery storage system

Post by ridethelightning » Jan 25, 2018 3:19 am

following with interest. id like to do something like this one day.

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Jan 27, 2018 3:15 am

I have terminated both trays of cells. Next step is to lower them into the cabinet (with the help of a friend) and wire it up.
9 kWh terminated_sml.jpg
9 kWh terminated_sml.jpg (233.49 KiB) Viewed 900 times

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Jan 28, 2018 12:05 am

Still don't have a strong helper for the shelf-shuffle, but I worked on the main DC isolation board. Switch, fuse, terminal busbars and current shunt. I might make this end the DC distribution board too - if I ever wanted to power stuff on 48 volts I can run several circuits back to a fuse box on this side.
Switch location.jpg
Switch location.jpg (162.55 KiB) Viewed 807 times
The inverter and charger will go to the other side.
Rivnuts in.jpg
Rivnuts in.jpg (190.41 KiB) Viewed 807 times
I put M6 Rivnuts into the steel frame for covers which will keep it clean and tidy. Not sure what material I will use, probably just plywood. I can also power some fans for keeping the cells cool if need be - this way I can put filters on the incoming air.

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Feb 03, 2018 7:41 am

Finally got it together today. I moved the shelves into place on my own - only 46 kg each, and I didn't have to move them very far. I did it while wearing my safety boots! (Truth be told, I was barefoot :lol: )
Battery complete.jpg
Battery complete.jpg (95.83 KiB) Viewed 686 times
The two half packs are joined by 9 x 4 mm2 cables with ring lugs. The final + and - leads have to come from the other side. I didn't have the room to put them up the opposite side - bit of a design fault at the time of construction, but this does work, even if it's messy. The 9 x 4 mm2 leads are terminated inside a single 70 mm2 terminal lug which was crimped using a hydraulic crimper. When you have the right tool for the job, life is easy.
48 V dist board.jpg
48 V dist board.jpg (119.81 KiB) Viewed 686 times
The - side goes through a 125 A fuse first, then to a 200 A max, 50 mV shunt, then a busbar. The + side goes through a manual isolation switch to a busbar where I've fixed a small 6 position fuse box. There is still room for another 50 mm2 cable to bolt onto this to the inverter (which has it's own fuse). The 6 fused circuits can be used for lights, fridges, motors, scooter chargers... whatever. I wanted to make sure this was a complete, 48 volt, 180 Ah off-grid storage unit ready to go. Never forget your fuses!!!

Next step is to fit the charger and do a final balance charge.

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Feb 04, 2018 9:39 am

I bulk charged up until the first cell went over 3.65 V (watching closely while stripping copper wire for recycling) and used the BC168 after that. Took most of the day, but we're sitting pretty with all cells having been taken to 3.65 V each. They're probably going to settle at about 3.5 V each overnight.

I will eventually buy some balance boards which trim the cell voltage down to 3.55 V each. Same as I have on my scooter: https://evparts.com.au/ev-power-bms/bms ... board.html
I will also have to get a dedicated bulk charger but I also don't want to spend too much money since I plan on getting a decent inverter/charger which couples with the solar array. Might get one of these:
https://evparts.com.au/charging/ev-pfc- ... c-25a.html

At least I can take it with me under the seat of the scooter for longer trips. The current charger is the original sealed-lead charger and it goes a little too high I think (59 V max). As a home charger it's not too bad, but I make a habit of turning it off after it's done charging.

Longer term I will probably fit one of these: https://www.outbackmarine.com.au/victro ... x0QAvD_BwE
And find myself a decent inverter for running the house.

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Feb 06, 2018 8:18 pm


KalSteve
1 W
1 W
Posts: 54
Joined: Jun 18, 2014 9:41 pm
Location: Kalgoorlie, Western Australia

Re: My DIY battery storage system

Post by KalSteve » Feb 07, 2018 3:13 am

Legendary stuff. Well done.

Rube
100 W
100 W
Posts: 220
Joined: Jun 25, 2016 10:18 pm
Location: Brisbane, Australia

Re: My DIY battery storage system

Post by Rube » Feb 07, 2018 4:47 am

jonescg wrote:
Feb 06, 2018 8:18 pm
Fame! :lol:
Not as good as your sultury radio voice :D

User avatar
jonescg
1.21 GW
1.21 GW
Posts: 3505
Joined: Aug 07, 2009 9:22 pm
Location: Perth, Western Australia

Re: My DIY battery storage system

Post by jonescg » Feb 07, 2018 8:10 am

Rube wrote:
Feb 07, 2018 4:47 am
jonescg wrote:
Feb 06, 2018 8:18 pm
Fame! :lol:
Not as good as your sultury radio voice :D
Just for you mate :)

http://iview.abc.net.au/programs/abc-ne ... 808W033S00

Starts at 12:27

Post Reply