Planing CanView and BMS+ conversion with lithium

Undercover is located in the north of the Netherlands, next to Underwater.

 

Today my Prius was sitting partially in the afternoon sun. I found that all my CellLog8s x 10 were all beeping for a low cell (0.20v - 0.30V) for cell 8 which is disconnected. Normally all my CellLogs ignore cell 8 which is disconnected and probably just reads 0.00volts.

I can only put this down to heat. The Prius MFD was showing 30degC outside temperature and I would estimate that inside was around 35degC. The heat was most likely causing cell 8 on all my CellLog8S to read 0.20 - 0.30volts.

This could be a problem for Mr Plug-in. Maybe the Cell 8 connection which I left floating (disconnected) should be connected to 0V but this may cause a short circuit. Does anybody have an answer to this.

This could be a problem if you park in the sun. I have read that LifePO4 cells have the best cycle life at 15degC. The warmer they get the shorter the lifecycle they will have regardless of whether the heat is generated from overcharging or high discharging or just from heat exposure from the sun.

I try to avoid parking in the sun as much as possible depending on availabiltiy. For the last three months I have been using a cardboard sheet to block my rear hatch window from the sun. I use a monitor (connected to a camera on rear) which sits on my rearvision mirror to see behind.

 

wow now i understand wy there is a lot of cooling inside those A123 cell packs
15.. thats way to low i think and degrade at higher temp?
the NIMH oem works best AT 30celsius.
did not now this.. if i would now it then maybe i would not consider buying these.

so i have to take air cooling in to concideration when building the battery pack
because maybe NOW over here its not warm but during summer and not able to part the car in a shade everywhere it would become mager problem i think.

 

The bigger the battery pack mass is the longer it takes to warm up. So the 16KWH battery pack of a Nissan Leaf would take a long time to warm up and it is also located in the floor section where it is cooler. I read somewhere that they place aluminium sheets between pouches to lower the temperature gradient across the cell. Aluminium is a great conductor of heat. This would also connect all cell masses together to keep whole battery pack cooler. The bigger the battery pack the better. This apparently also decreases the delta between cell voltages in a pack. There is very little literature available for the A123 Nanophosphate technology and how much tolerance abuse they can take. I cannot find a graph showing lifecycles/battery temperature for the 20AH A123 pouch cell I purchased.

Despite this A123 pouch cells still leaves NiMH for dead. The NiMH has a high self discharge rate and a higher internal resistance and gets warm quickly. The Electrolyte will boil if SoC >> 80%. It has a much lower power density.

 

lopezjm2001
did you show pitures of your a123 setup in this topic?
can not find them at the moment.. topic is getting big ;-)

alu to have al to mass? you mean al the heat generated? or mass meaning MINUS? like the 12vot battery MIN is connected to mass of car?
i think its the heat but just checking because i did read about the outer silver looking foil of the a123 is connected to MINus of the cell. ( i geuss thats only the case when the foil is damaged )

 

Planetaire has the best battery pack setup at the moment. I just cannot be bothered working on mine lately. Mr Plug-in is good but he is using leggo batteries. Best to look on improving on Planetaire's design. There are photos there if you can find them.

 

yes got those ;-) LEGO

i am going to use ( i think ) some plastic material that i dont now the name of at this moment. i think is called Polystreen
its not that lightweight because the same size MDF is lighter.

 

Definition of "Mass" - a church service you go to to pray to god that your A123 cells stay cool it must be hard for you to comprehend the English language. Obviously it is not your first language. The word mass can have more than one meaning depending in what context it is used. I would have hoped that all those high taxes you have to pay for would have provided you for a better education. Our taxes are low and so is our general education level.

 

alu sheets between batteries inside the larger module..

Exactly, look at pic/vid from A123 and LG Chem (Volt) projects, they even put web of tiny channels on these sheets, could be just pressed or it might be some additional layer of heat conducting material. Simply, picture "function underwear" and these sort of things, grid of channels to help distribute vapor, in our case heat from the batteries. In any event, if you bother weatherizing your pack at all, make it water cooled/heated, air cooling is for kiddies and it (usually) doesn't work (BMW/ACP eMini o. early Tesla o. Leaf, ..) when you need it most. It's not that much more complex or expensive either, lots of OEM/used parts you can utilize from motorbikes and other existing equipment..

 

ok have to keep reminding myself that you life down under
its a shame that with your lower education you can not write or spreak dutch

the prius pack is cooled by air. works good
and there are channels betrween the 7,2 cells.blocks to let air go tru.

i was hoping that compressing the pack would make the heat go to all cells ( colder ones get heat from hotter ones ) and i could just blow air on side and out the other to cool it down a bit.
i can stil do this but i wil think about adding those alu. sheets

but reading comments here these a1234 dont get hot and that i dont need to trouble myself with that i did not think i would come to this poit where i think is most important to cool

EDIT:

a update
just got the tracking number and the cells are on its way.
now lets hope customs does not take to long.
if not i can expect them as early as next week or 2 weeks later.
damm thats fast
dont even got a charger ( stil need to deside .. deside .. deside ) a bms or celllogs
and have to start making the case.. i kinda desides what route i want to go on that....kinda..

 

I am confused. Is'nt Deutch also German? Do you also speak the same language as Germans do? Would this mean that you are of Germanic origin?

 

Deutch is german for german but dutch is dutch for netherlands not german.
and i do speak and write german.. only the math is a bit of a problem EINS TWIE DREI VEIR.. .. i geuss some of that tax money at work

"bitte eine bit ;-)" ( thats german )

 

Thanks for clearing that up. I guess it might be a common misconception.

EDITED: Hitler remark removed - my apologies.

 

My battery pack is made up of five banks. Each bank can be removed and taken away whilst the rest stay in the car. Each bank is made up of 14 A123 cells which leaves me with two vacant positions. In your case if you do not have any vacant connections you should be OK. The CellLog8s are undercover (not to be confused with undercover in The Netherlands).

 

This battery charger could be used instead of the Elcon PFC, it can be customized to any charging voltage or current.

Alloy Shell 4KW LiFePo4/Li-Ion/Lead Acid Battery EV Charger - BMSBATTERY

They even sell A123 20ah pouch cells. It seems you can buy them just about anywhere? They claim they have a max charge and discharge rating of 15C - 300A - not bad.

http://translate.google.com.hk/translate?u=http://shop.lipopower.de/&sl=de&tl=en&hl=de&ie=UTF-8

 

only litle information about that 4kw charger but looking at the picture i would say you can set the amps and voltage to a setting and keep it there.. maybe need to adjust while charging by hand..

this is intressing info for me "SPD: length film about 26mm, width 45mm, thickness 0.3 mm, center distance 79mm "
now i no what the tabs are of size

 

ah look at this

even stuff special for the A123 pouches like terminal blocks!!

Google Ãœbersetzer

 

cells have arived in the EU....

edit:

i have the following that i am thinking about doing for charge and balance

this chargers ( http://shop.lipopower.de/LiFepo-Lad...g-230V&usg=ALkJrhiSUMEFPzDHP5nbw2gONgBGUUxUDg )
have switch to go down to 0,240 amps

i can also get these with a higher voltage like 240 volt

i want to connect a relay to that switch

i use 9 cell logs to monitor the cells and when they get to high ik switch a relay to disconnect the mains power.
but for testing i will have 1 set of cells have 2 cellogs
the second cell log wil be set to a lower END voltage
and wil switch the relay connected to that charger and lower the amps.

at that point with these boards ( http://shop.lipopower.de/Balancer-300mA-fuer-1-Zelle-LiFePo4-LiNANOZ-Lastmodul )
its easy to balance the cells....

then i maybe use 1 more cellog to switchoff the mains again when a pack total voltages gets up to its max voltage.. or maybe better monitor what time it is from almost full to full when balancing and have a timer relay start as soon when the charger is switch into low amps mode.
so after 2 hours or so ( if thats the normal time it will be to balance after almost full charge ) the mains wil be shutoff .