HV Battery Headway 38120HP LiFePo4 70S pack

3.2vdc is between 40% and 80% SOC for an LFP (LiFeP04) cell, 3.4vdc is fully charged rested, 3.45vdc is fully charged maintaining 100% SOC and 3.6vdc is the end of safe charging and really pushing the boundaries trying to keep the cells balanced without a cell voltage run away occurring.
If you use a voltage range between 2.8v and 3.35v, the cells will give a very long service life, holding them at 3.4v or higher isn't good for them long term, but a few hrs each day doesn't do any harm.
What if you build your pack to the 3.2vdc average and once a week plug into power and top them up to 3.5v per cell with a good balancer and monitor every cell voltage so no cell goes over 3.6vdc, the charging stops until the cell drops back below 3.6v mark and stays off for 15 mins to allow some balancing to take place.
This way you will keep the pack top balanced, start the cycle each week with a fully charged battery and monitor it from there, maybe a mid week recharge might give you even better fuel figures.

T1 Terry

 

Purchased these from batteryhookup with the intent of using in my prius c, but I dont trust my spot-welding / soldering. I ended up going with the project lithium batteries. I have 120 of these A123 AHR32113Ultra-B that I would let go at my cost of $6/per. That is less than 1/2 the price of the project lithium batteries, with 20 spares. 80 of them are still in the 10s2p packs yet. They dont have screw ends though, which is why they would either need spot welds or soldering. Screw ends would have been easy to set up, but my loss your gain if anyone is interested.

Specs are:
A123 Systems AHR32113 Ultra-B
Cell Specifications
Cell Dimensions: ø32 x 113mm

Cell Weight: 205g

Discharge Rate: 30C

Cell Capacity (Nominal): 4400mAh

Energy Content (Nominal): 14.6Wh

Peak Power @ 10 Sec: 550W

Voltage (Nominal): 3.3V

Recommended End Of Discharge Cutoff: 2.0V

Recommended Standard Change: 1.5C to 3.6V

Recommended Fast Charge: 4C to 3.5V

Specific Power (Nominal): 2700 W/kg

Specific Energy (Nominal): 71 Wh/kg

Energy Density (Nominal): 161 Wh/L

Temp Range: -30°C to 55°C

Storage temperature range: -40°C to 60°C

 

It's a shame you are in the USA, freight out of there is horrendously expensive from previous experience.
Those cells are the base unit for the ends to be welded to with the special unit the factory uses to attach them.
I'd love to buy them if the freight cost was within reason, any chance of taking say 10 of them to who ever does freight to Australia and getting a price .... if it's not insane then ask them how much to freight all 120 cells .....

T1 Terry

 

Looking at the photos again, there are 20 cells in each module, so if you could find out how much to freight them to Adelaide South Australia would be great.

T1 Terry

 

How much would they weigh, as I found shipping for 30lbs at usd'130'ish, with the price increasing around 20usd for each additional 10lbs; *not including GST, which may not apply if under 1K AUD, though you would know better.

Of course this carrier may not want to haul lithium on an airline, but a slow boat could also be in your future.

Would the average carrier consider these safe to ship?

 

Each 10s2p module is 10lb 12oz, so roughly 65lbs or 30KG for the lot

 

Google helped me find where Decatur TN is, next I need to find a carrier who is interested in transporting lithium battery cells to Australia ....wish me luck :lol:

T1 Terry

 

I just looked to see how much the Aussie $ was against the USD, and it's around 50 cents in the $1 by the time tranfer fees etc are added in .... sadly that puts them out of my price bracket.
Hope you find a buyer in the US that can do the business with these cells, seems too good an opportunity to miss for someone who wants to build a project battery.

T1 Terry

 

Was looking at doing the Headways as well when the A123's popped up I'm in no rush to get rid of them, they will get used for something, but if someone wants a project....

 

Guys, check out the teardown of the NexCell... very minimalist approach... I'm not sure what I searched for and found it. I'm tired of pulling my old pack to replace 2-4 cells a year. After watching this video, I was looking at headway cells, but had some used ones pop the magic button and spray, so those are out. I've used CALB's in the past so i know what LiFeP04 fault tolerance should act like, and that's not it.

enjoy!

 

Hello imgprojts, i find myself in the position you were when you posted on this thread. Could you kindly update if you managed to complete your project. And please share details on how you went about it.

 

Hello OBJUAN - I also haven't been on in a _long_ time but I'm glad I found this thread!
You have put a lot of work into making these Headway cells work & thank you for sharing your adventure.
I purchased 16 of these "used" cells & have made a 12V & a 24V pack with bms for both.
I really only needed 12 cells for the packs but am glad I got the extra 4 cells.
Having extra cells allowed me to pick & choose cells trying to match capacity of each group.
To get a baseline on each cell:
I paralleled all the cells then slowly fully charged them to 3.65V & held there for a couple hours..
For capacity I discharged @ 8A (1C) to 2.5V (using CBAII from West Mountain Radio)
The tested capacity was 6.3-8.1AH for the 16 used cells.
I was able to get a group of 4 cells & another group of 8 cells that closely matched in Ah capacity.
The remaining 4 cells are good, just not closely matched. They are "spares" for now.

OBJUAN, Sep 16, 2021 (post #6)
Batteries had been parallel charged to 3.2v then assembled into the pack.

OBJUAN, Jun 18, 2022 (post #103)
They were used cells and not matched by any means. I did put them all in parallel and charged them to 3.33v.

The Prius OEM nimh batteries were rated @ 6.5Ah.
So even the lowest 6.3Ah cell that I received should have about the same usable capacity as the OEM nimh battery.
Prius battery management only uses the 40-80% range of the batteries.
The <40% range is where your cells are failing due to mismatched Ah capacity.

The parallel charging of all 70 cells to 3.3V would be fine if all the cell Ah capacity were closely matched.
If one or more cells have a lower Ah capacity they will surely die first & that appears to be what you have noted.
With used cells perhaps bottom balancing would be a better idea.
The Headway cells are perfectly happy if they never get above 50-60% charge..

I would consider individually discharging each cell to 2.5V, then recharging a specific amount, say 2-3Ah.
Discharge each cell with the same load & recharge to exactly the same Ah cutoff.
I would suggest a discharge of 0.8A (0.1C) or maybe 1.0A.
But discharge every cell the exact same way.
I would recharge at least 1Ah right after the full discharge as they don't like sitting discharged.
After pack was put together you could use your Meanwell led driver to put in an additional 1-2Ah.
After cell discharge it is important to make sure all the cells are recharged _exactly_ the same.
Ignore any small voltage differences during the recharge.

When reassembled you should have a pack with each cell charged to 2.0 or 3.0AH.
The cell voltages should easily be within the 0.7V error tolerance of the BMS.
Installed in the Prius the battery should be as good as it gets with the used mismatched cells.

Best of luck on the adventure