Planing CanView and BMS+ conversion with lithium

Today, using 8.2 kWh (36.8 Ah) my plug-in prius traveled 81km with only one cells charging.
I used oog mode.
The 140 cells have 9.1 kWh theorical energy.
Voltage was a little over 235v at the begining and more then 220v at the end.

 

Calibrated al the cellogs
Used a true rms meter with zero point button
Some where 30milivolts off now within 3 minivolts ;-)

Also got a max hold function so i can connect on startup and see max amps flow inrush

-Htc Tapatalk ( sorry for auto spell correct )

 

edit
double

 

lopezjm2001
this is after a depleted drive? they are high!?

 

lopez

here is the same with your cellogs data what i did with mine

there is no simelarity betrween mine and yours after a depleted drive....

you only have 1 what we can call maybe a bad cell but al the others look great!

is this pic taken right after the drive with NO load on it or parked after drive with car still in ready mode? or maybe a few min like 10 min after?

 

I think they where not totally depleted..., except one

 

at more then 17ah according to the meter lopez used?
also one cell is just like min already around 2,7xx volts ( that must be a really bad cell then if not depleted and already at 2,7xx )
he got one if them with a not compleet depleted pack? i have several of then at this point
how many more amps do you think would get out of those cells.. i geuss it would be close to 20ah then?!
thats way more then i can pull i have to stop when i have 17ah and you see what my celllogs look like.

 

Thanks

Thanks for doing the graph. I have been too busy to look into this. The cellLog photos were taken at battery pack depletion I pulled over and left the car in park with the battery pack still connected and just drawing standby current whilst taking photos. If you had a EV display unit then you may have better data on your cells. Using the Canview for AH is not accurate as it is also measuring AH discharge of the NIMH. Can you also calculate average of all depleted cells and compare values with mine. If your battery pack is only giving you 17AH I cannot explain why as you would be in the best position as to why. My cells were made in the Korea and yours were made in USA, who knows why.

 

yours are not USA? you got them also from Xuem?

yes the canview even shows the nimh....
and in that case its even worse!!!!
i charge them to full and top balance and as you can see i drive until i have those picture's/celllogs voltages

I have to say that i did recalibrate the cellogs and some where as mutch as 30milivolt off!!

what i did is a used a true RMS voltage meter and i can press a button to ZERO it when its not measuring anything
then i measure the cell and at the same time adjust the cellog readig for that same cell

so i did 70 cells 2 times to be sure
after this i only have seen not more then 3 mv diff between meter and cellogs value.

i have to do a new top charge and full drive to see if maybe its now better?! and i report back.
maybe this Saturday.

 

Why worse ?
Canview only see what is going through the hall sensor. Not the coulomb that your lithium send to the nimh.
Canview will see what your lithium cells receive when you plug them minus what the nimh will loss (in heat).

 

Worst Because if thats the voltages he got when depleted or using 17ah
Then look at mine voltages 37.7 km depleted
Mine are pretty mutch al below 3.1

What are your voltages? You must have some data..
The old pack not your new one ;-)

-Htc Tapatalk ( sorry for auto spell correct )

 

you did not tell us how many km did you drive when your pack as depleted?
cell voltages seem high for a depleted pack?!

 

i got the following test situation yesterday

i drove 112 km about 1 hour and 20/30 min and so the pack was depleted ( several cells below 2,75 volts so it was time to stop )
celllogs started to beep at 214 volts ( supposed to be ! 3,05 per cell ) that cells where dropping below 2,75 during acceleration

a stop with no charging for about 4 hours.

then i drove the same road back
now the cellogs started to beep at 218 volts what is around 3,11
and after a few min and a accelartion again they started to beep at 220 volts

now the thing is i am monitoring the oem battery pack voltage
this is because the canview shows that voltage on the BMS+ control screen

so maybe thats not a good reference

i look at the voltages before i did my drive back and the where al just above 3 and some above 3.1 volts

these A123 can provide a lot of amps several times C but when almost empty its just the same as any battery they drop fast not just because the voltages go's down but then can no longer provide enough amps for a EV to function.

below 3 volts these cell to me seem useless.. so you need to keep them at a higher voltage and when they drop this is a STOP point for me.

i measured the amps from the A123 and it was max 77 amps where i did just a bit more then 100 amps
so 25% is from the OEM battery pack and 75 % from the A123
so when the canview shows me 18ah used this is the A123 and nimh oem combined
75% from the is 13,5ah and at this point the cells drop below 2,75
some cells are still above that so i think i have a few cells that have only ~14ah energy end these are taking t he total usable energy from the pack down what is not good and can i think be pointed to BAD cells.
all cells that are below 3 volts at that point have far less then 17ah in them.

 

I did not record the kilometres. It wouldn't mean much when you compare hilly terrain against the flat lands of the Netherlands.

 

you pulled like 17.2ah out of them
according to my canview i used something like 17 to when i cell started to beep and cells where dropping below 2,75 volts. i could no longer drive because every move i made with t he gas pedal at 20ah amps draw they started to drop below 2,75
but my canview also records power from the oem battery pack... so part of that ~17ah is also nimh energy...
i have only like 6 cells that stay above 3,1 when i park the car in ready mode after a depleting drive.
so dont you think its save to say i have several cells wel below 17ah..

edit

did you go down a hill before stopping the car? maybe charged it up a little again? and did you do this in OOG mode?

i added a pic from 1 of the cellogs that i replaced with a log version so i can see whats happeing
you can see cell8 dropping a lot

 

FWD,
Personally I would give up with the cell logs, and their alarms, and power draw and and and....
MiniBMS is reliable, tested and I feel a lot better. OK, I know 72* cell boards + head end board is about $900, but it does LVC protection, HVC protection, top balancing, temperature compensation, and JUST WORKS. You can set the LVC so that once it sees below 2.5V for a few seconds (which will first appear under heavy draw) you can disconnect the plugin pack.

 

i feel that i spent that amount of money to find out these cells are really low in cap and i have spent XX on cells and XX on bms for nothing....
and with 900dollars that not to far away from a orion bms thats offers a lot more like life graphs on pc etc.
i already spend to many "dollars" on this.

and i also did not say the cellogs do not work
i have them calibrated now and they work.. do what they need to do LVC and HVC
and that imbalance after one night standing with the pin1 disconnect is compensated by just 15 min of low current balance.

 

The fact that you had to calibrate your CellLogs is not good. If they keep going out of calibration they can potentially damage your cells during charging by going too high or at depletion by going too low and reversing the cell's voltage.

Such as the one on your CEllLog8S graph has a lower capacity and could very likely have been damaged as a result of overcharging with a CellLog out of calibration or overdepletion by going too low.

I think that is what Flaninacupboard was trying to point out to you.

 

Here the 70 voltages after 38km, 3918 Wh and 17,9 Ah with the 4,5 kWh plug-in.



This graph is during driving.

 

That is interesting. When did you have 77 amps ? When cells were fully charged or when depleted ?
I suppose that when fully charged this is the lithium that give most of the coulomb.

I think that canview receive amp comming from the nimh ecu. Remember that this amperage have huge values variations and very quick variations. The pid is received 100 times per second. You have to average the values read.

I would not say that because the lithium maximum amperage was 77 A of 100A combined that the coulomb where 77% comming from lithium during the trip. You can have 77% at a moment and 90% at an other.