T-Pain Is On A Boat: Re: Re: [Electric Boats] RE: testing used Thundersky 90AH LFP90 Lithium Iron Phosphate Batteries

Thursday, November 21, 2013

Re: Re: [Electric Boats] RE: testing used Thundersky 90AH LFP90 Lithium Iron Phosphate Batteries

The battery seems to be taking a charge.
I guess if I only give it .5 or less of an amp on a 90Ahr battery It will take over 7 days to completely charge.
with my charger only putting out or battery only taking .25 of an amp, it would take 14 days to charge.

Here is what I have found this far.

LIFePo4
constant voltage 3.5V
time        amps/volts        Volts
08:00            0                    0.0
8:30           1.49 A             .97
9:00            1.14A            1.52
9:30            1.02A            1.72
10:00        .91A            1.91
10:30        .78                2.13
11:00        .67                2.32
11:30        .59                2.45
12:15        .56                2.50
13:00        .53                2.54
13:30        .52                2.56
14:00        .51                2.59
14:30        .50                2.60
15:30        .48                2.64
16:00        .47                2.66
16:30        .46                2.67
17:30        .44                2.70
18:15        .44                2.74
tuesday
08:00         .28                3.00
09:00        .28                3.00
19:00
Wed
08:00        .18                3.15
16:00         .17                3.15

changed charger to 3.7 Volts from 3.4
1700        .32                3.16
20:00        .31                3.18
Thursday
08:00        .25                3.24

I am hoping to get 4 batteries charged to 3.5Volts and then connect them to an inverter and run a few light bulbs(load) to see my AH(at a reasonably light load)

I have done this with my NIMH batteries to see if they are all close in performance.
I connect the inverter and on the A/C side I connect a string of lights and also an old school analog clock that is powered by A/C.
When the inverter brings the batteries down to 10.5 Volts it shuts off. The clock stops and I can see my Ah.

I hope the LiFePo4's are good down to 2.625 Volts.

If this works well, I may have these batteries ready for my boat by spring:)

Mark

From: Mark F <mark.internet@yahoo.ca>
To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
Sent: Monday, November 18, 2013 9:37:16 AM
Subject: Re: Re: [Electric Boats] RE: testing used Thundersky 90AH LFP90 Lithium Iron Phosphate Batteries

After removing more batteries, I found one that was actually installed as a single with the expansion plates on it.

I have connected it to my bench power supply 60Volt 5 amp adjustable CC or CV.
I have set it at CV with 3.5 V as the ref.
I connected a meter at the battery to check voltage at the battery.

start 0.0 Volts
1/2 hr   charger sending 1.49A   voltage at cell .97
1 hr    charger sending 1.14A   voltage at cell 1.52
1.5                                 1.02                            1.72

cross my fingers and hope for the best.

I suspect they will be dead, but its worth trying to bring them back to life.
If they come back with reduced AH, I would be happy.

Mark

From: "boat_works@yahoo.com" <boat_works@yahoo.com>
To: electricboats@yahoogroups.com
Sent: Sunday, November 17, 2013 8:53:40 PM
Subject: RE: Re: [Electric Boats] RE: testing used Thundersky 90AH LFP90 Lithium Iron Phosphate Batteries

I charge my prismatics at about C/9 (21A). They don't swell at all, but then I am careful not to overcharge them.

-Tom

---In electricboats@yahoogroups.com, <mark.internet@...> wrote:

I purchased the bike with these batteries.
I suspect there was a drain on the system as a whole as all the batteries are 0 Volts.
I have taken one and tried charging it slowly with about 1 amp and it has climbed to a .5 volt after 1.5 hrs.
When the batteries were in the bike, they had aluminum brackets on the sides of the strings.
Is it ok for me to charge these slowly without the brackets, or do I risk the batteries expanding or worse?

Thanks for everyones help.

From: "boat_works@..." <boat_works@...>
To: electricboats@yahoogroups.com
Sent: Tuesday, November 12, 2013 9:42:22 PM
Subject: [Electric Boats] RE: testing used Thundersky 90AH LFP90 Lithium Iron Phosphate Batteries

Testing is easy:

Check individual resting voltage.

If near 0V they are probably toast, but you can try to gently charge them (a couple amps), and see if the voltage rises during charge. If not, they're goners.

If they are 2V or more you can charge them to about 3.5V per cell. This is almost a full charge. Resting voltage should be around 3.35V

Once charged, either:

1. Time the discharge into a constant load (lights, heater), measure the current, stop the clock when cell measures at 2.5V under load (or maybe 2.8V or bit more if you want to be conservative), so you can calculate the Ah capacity of the cell.

2. Apply a load, and monitor the Ahs consumed with an Ah counter (LinkPRO, JLD404, etc.). Keep an eye on the voltage., stop test at 2.5V or so.

I'll bet that if the sellers of the car say the cells are bad, they are bad.

-Tom

---In electricboats@yahoogroups.com, <mark.internet@...> wrote:

I am thinking of purchasing a vehicle with these batteries.

They say their pack is dead.

Any suggestions on how to test the pack or cells and what to worry about if they are used batteries.

Or should I just consider the pack bad and recycle them?

Thanks