diy solar

diy solar

Second Life Nissan Leaf Cells - Battery Pack Assembly

That’s a good idea but if any of those cells get out of balance or gets overcharged you would want to have some safety device that is going to cut of the load or charging for you. Just to be safe. You may not be able to get to those meters in time to see what’s going on with each cell.
 
That is a risk, although I'm slight ocd and can meter in my living area. I have very closely monitored the SCC, and it seems rock solid at keeping the upper voltage in spec (Ep Ever I tracer). But true, its slightly risky without a bms. I'm not against the idea, so will probably get one in the future ?
 
I did do the capacity test, although it took me quite a while to finally get the video out.

Thanks for the detailed information.

You mention the batteries were rated by 31.25 Amp Hours, but the Tech Direct Club (aka Big Battery) site shows the batteries as 2.8 kWh which would be considerably more Amp Hours.

The testing I have done with 5 Big Battery Mini Packs showed the kWh capacity ranged from 2.2 kWh on the high end, down to 1.6 kWh on the low end. Strange thing is the Big Battery website shows this same battery to be 2 kWh.

Since Tech Direct Club and Big Battery are the same company, I am curious why the same battery has two very different ratings, and I am also trying to reconcile the significant difference between the best and worst of these batteries.

Can you provide any insight?
 
Thanks for the detailed information.

You mention the batteries were rated by 31.25 Amp Hours, but the Tech Direct Club (aka Big Battery) site shows the batteries as 2.8 kWh which would be considerably more Amp Hours.
............
Can you provide any insight?
The modules I have range from about 31 Ahrs which is 248 Whrs per module, (8 x 31 equals 248) to 45 Ahr. The 48 volt packs may contain 6 or 7 modules. I know Nissan modules but very little about Big Battery 48 v packs.
 
Last edited:
Yikes ?
I have NMC cells 5p14s and have taken them down to below 46v... I'm slightly worried now!
EIG recommended 3.3vpc so I thought I wasn't ragging them excessively, I might have a rethink lol. I charge to 56.5v
Are these cells the LG Chem 3.6v 120A Cells?

Could you post a pic of your setup and how you’ve paralleled them?
 
Hi Calvin, my cells are flat prismatic NMC EIG cells. They charge to 4.2 maximum and working voltage is nominal 3.6v. Each cell is rated at 20ah and has a sustained rate of 5C and can handle 10C for short bursts. I think they were primarily intended for electric vehicle use. They are arranged in 5p14s, so bunches of 5 in a string of 14. The vendor I bought them from had joining bus bars for each 5p group laser cut. It's difficult for me to take a photo as once the pack was assembled, I wrapped the whole lot with gaffer tape including the top. The connections were put together with duralac anti galvanic paste so I could be confident I wouldn't need to disturb anything for quite a while. Each 5p group has a basic voltage meter so I can, in a basic way, monitor for signs of inbalance.
 
Hi Calvin, my cells are flat prismatic NMC EIG cells. They charge to 4.2 maximum and working voltage is nominal 3.6v. Each cell is rated at 20ah and has a sustained rate of 5C and can handle 10C for short bursts. I think they were primarily intended for electric vehicle use. They are arranged in 5p14s, so bunches of 5 in a string of 14. The vendor I bought them from had joining bus bars for each 5p group laser cut. It's difficult for me to take a photo as once the pack was assembled, I wrapped the whole lot with gaffer tape including the top. The connections were put together with duralac anti galvanic paste so I could be confident I wouldn't need to disturb anything for quite a while. Each 5p group has a basic voltage meter so I can, in a basic way, monitor for signs of inbalance.
 

Attachments

  • IMG_20200621_142312.jpg
    IMG_20200621_142312.jpg
    114.5 KB · Views: 22
Thanks for the detailed information.

You mention the batteries were rated by 31.25 Amp Hours, but the Tech Direct Club (aka Big Battery) site shows the batteries as 2.8 kWh which would be considerably more Amp Hours.

The testing I have done with 5 Big Battery Mini Packs showed the kWh capacity ranged from 2.2 kWh on the high end, down to 1.6 kWh on the low end. Strange thing is the Big Battery website shows this same battery to be 2 kWh.

Since Tech Direct Club and Big Battery are the same company, I am curious why the same battery has two very different ratings, and I am also trying to reconcile the significant difference between the best and worst of these batteries.

Can you provide any insight?

From what I understand, BigBattery got a few complaints of these batteries not performing to their rating. Reviewers like Will Prowse and I both capacity tested the packs and got a lower capacity than advertised, so bigbattery did the right thing and adjusted their advertising to be accurate and honest. I think the 2.8 KWH figure is assuming grade A cells, which these packs are not built with. I had talked to Eric at BigBattery at one point and he had informed me that my pack that I made the videos on was a B-grade pack and those were the grade that they had the largest quantity of.

Hopefully this shines some insight.
 
From what I understand, BigBattery got a few complaints of these batteries not performing to their rating. Reviewers like Will Prowse and I both capacity tested the packs and got a lower capacity than advertised, so bigbattery did the right thing and adjusted their advertising to be accurate and honest. I think the 2.8 KWH figure is assuming grade A cells, which these packs are not built with. I had talked to Eric at BigBattery at one point and he had informed me that my pack that I made the videos on was a B-grade pack and those were the grade that they had the largest quantity of.

Hopefully this shines some insight.

Thanks, that helps.

Do you know when BB started showing lower ratings? Seems like it must have been fairly recent. Grade A cells sound like they are new, so it seems hard to understand how any of these batteries have "grade A" if they are made from used Nissan leaf cells.
 
Grade A cells sound like they are new, so it seems hard to understand how any of these batteries have "grade A" if they are made from used Nissan leaf cells.
"Grade A" is not an ISO term so it can mean anything the marketing department defines it to be. Same thing with Recertified or Remanufactured.
The only thing I would imply from Grade A is that they are better than Grade B or Grade Z, whatever those mean.
 
Thanks, that helps.

Do you know when BB started showing lower ratings? Seems like it must have been fairly recent. Grade A cells sound like they are new, so it seems hard to understand how any of these batteries have "grade A" if they are made from used Nissan leaf cells.
From my perspective, it was around when Will and I started to review these batteries in the earlier half of the year. If my memory serves me correctly, Will had brought up the valid point that the batteries were less than the advertising to bigbattery, and in my testing I did the same thing - Except I did this prior to releasing the video.
 
I need help configuring my MPP 5048 inverter to achieve the following:

1.0 I want only solar to charge my 48v Nissan leaf batteries
2.0 I want the inverter to only switch on utility when the battery voltage drops down to 48v
3.0 I want the inverter to switch back to battery when solar has charged battery to 57v
4.0 I want grid to be off during 3.0 above
 
I need help configuring my MPP 5048 inverter to achieve the following:

1.0 I want only solar to charge my 48v Nissan leaf batteries
2.0 I want the inverter to only switch on utility when the battery voltage drops down to 48v
3.0 I want the inverter to switch back to battery when solar has charged battery to 57v
4.0 I want grid to be off during 3.0 above
I just tried googling your inverter, and I'm struggling, MPP Solar's site came up with a controller only, but based on your questions it sounds like it's an all in one unit. Do you know what series your inverter is?
 
I need help configuring my MPP 5048 inverter to achieve the following:

1.0 I want only solar to charge my 48v Nissan leaf batteries
2.0 I want the inverter to only switch on utility when the battery voltage drops down to 48v
3.0 I want the inverter to switch back to battery when solar has charged battery to 57v
4.0 I want grid to be off during 3.0 above
1 - program 16 - OSO
2 - program 12 - 48.0
3 - program 13 - 57.0
4 - program 1 - SBU

With my leaf pack I transition off grid and back to solar+battery at 52 volts
I have my bulk charge set to 57 and my float at 55
 
Just a suggestion for Leaf cell users. Know your BMS balance voltage and set FLOAT little bit above balance start voltage for your BMS. Having played with leaf cells from internet suppliers and cells I have pulled out of brand new cars leaf cells will vary a great amount and should be watched. Avoid gen 1 cells.
 
Back
Top