Planing CanView and BMS+ conversion with lithium

If you are good at carpentry you could have used dovetail joints to join your enclosure pieces.

 

nice that picture where they fit in the spare tire ....
can you make close up pictures if the boxes? i can blow these up but then the resolution is so low.

so you got them from ebay? the A123 cells..

what time did it take for you to get them in france? any customs you needed to cleare?

 

One pack close up:



Buying A123 cells on ebay:
Lopezjim2001 gave a really good information.

About 2 weeks to get them. Custom is depending country.

 

Xueming is now selling them with full size tabs.

http://www.ebay.com/itm/8P-A123-20a...s=63&clkid=5325935805799135976#ht_9149wt_1026

Or

http://www.ebay.com/itm/70P-A123-20..._Batteries&hash=item3a6e2fbfeb#ht_9043wt_1026

Send him an email asking for a price including delivery. You may find a better price if you email Xueming.

I recommend buying the full tab A123 cells although the tabless A123 cells are cheaper but you run the risk of puncturing the cells as they have to be modified to make connections amongst other problems such as they are rejects and only hold about 18ah. Delivery time cannot be guaranteed as mine took about four weeks as he had problems with DHL accepting them.

 

Thanks for the close up. You have inspired me to start building each 14 cell bank enclosure out of Perspex as I have a plentiful supply at work. One at a time so I can still use the kit.

Could you show us a close up photo of your cell connections? Thanks.

I see that you have machined out a section of the Perspex to keep the red Anderson plug straight. Good idea.

 

Here they are:


On this pic there are only bms wires. Power wires are also soldered but on two brass pieces, one on each side of the cell tab.



Three flat parts: aluminium, brass (for soldering purpose) and aluminium.
Screws are 4x10mm size.

Isolation between two cells (6v6) is a wood piece that is hold on the 2 screw heads.

 

thx nice photos and info!!!
from the larger pictures to me it looked like the Perspex was really tihck but i see its really thin..sheets

something else

a charger is not cheap so wy not buy 70 small 2 amps chargers so you can charge every cell and do not need a balancer..
the charger wil be bigger ( lots of small adapters ) and a bit more money but you dont need to spend the money and space for the bms...
ofcourse in that case you alwats charge to full... maybe not that great idear.
you can shuutoff based on total voltages ( 240? ) but then some cells maybe not charge to the point you want them...mmm thinking out loud ;-) maybe bms is better haha

edit
just for the fun of it i looked-up a old picture ~2008 where you can see my oem nimh add packs.
not fully installed but just to show

 

You might want to send off this design to Jack Rickard at EVTV if you haven't all ready. He is looking for a good design for these now cheap "A123" cells. I know he would not like the BMS and possible the anderson connector but the cell box he might like.

Also you might want to use nord-lock washers. A little more expensive but a must have in a car and battery environment.

 

do you need a diferent BMS for the a123 cells becasue of the 3,3 nom voltage instead of 3,2

also what chargers do you use to charge the seperated packs?

i dont want to solder those boards ( i dont like to solder haha ) so i hope i can find a cheap compleet set of boards.
maybe this can do it
CBM1 - Balancing Module - GWL/Power - Your Complete Power Solutions - EV-Power.eu

its simple bleeding of exess watss with heat i guess.....

 

Good find but too late for me. Cheap as chips!! Should be a good cheap option for Mr Plug-in.

 

3,3v or 3,2v is not a problem. But end-voltage 3,6v is over the 3,5 that I use, so you will have more inrush current when connecting lithium on nimh. And they say 3,5+-0,05 to 3,6 +-0,05. So after balancing you can have cells from 3,45v to 3,65v. Not a very good balancing.

There bms don't manage the charger. But you could add an optocoupler with a resistor (330-560ohms) paralleled with each cell-shunt. After what you connect 70 on a relay via some pic or transistor..
That relay will manage the charger.

Bleeding is Ok. No need to use capacitive or inductive bms. Simple is better. There is not a lot or energy to evacuate.

I use a 48v(+-10%) 500w power supply. I will use a high voltage. 48v need to connect/disconnect several anderson plugs.

@Theforce. I use grower washers. Didn't know nord-lock.

 

not sure i like them
its just dispensing heat up to 80celcius if a cell gets overcharged and only 1,7 amps max so if you put in more than that you need to paralel them
its a lot of heat.
i would prefer a cell by trickel cell charger after a bigger charger is used to bring the pack back up to around the max voltage.
but ofcourse then your talking about a lot more money for the bms/charger

a 2 amps charger for me would be OK
it wil take about the night to charge and that if i do a dod of 80% for me thats fine.
i onnly wil charge at night.

its not really a BMS its just bleeding off energy thats i think a shame.. lost energy.
after al cells will be the same with these "Bms" then the total voltage will be what i want it to be and that wil be my cutoff point for the charger. dont relly need a bms to tell me that.
maybe a cell logger would be nice there are some cheap option out there to
that only LOG but can also direct a relay based on the logged voltage so i can use that to cshutoff the charger.
still i am not that happpy about using contactors.... the OEM nimh or dc-dc plugin route is more of my liking.. but looking at the cost of this A123 setup and the fact that i have 2 OEM packs as backup for my own if anything would go wrong i am not that afraid of anything going wrong to the point that i can not drive my car.

i need it for almost every day..

what abuot this balancer? http://www.ebay.de/itm/RC-2s-6s-Lipo-battery-Voltage-Balancer-LCD-discharger-/270787190542?_trksid=p4340.m185&_trkparms=algo%3DDLSL%252BSIC.NPJS%26its%3DI%26itu%3DUCI%252BUA%26otn%3D10%26pmod%3D320744258648%252B320744258648%26po%3D%26ps%3D63%26clkid%3D5333615938357637159

 

Hi Planetaire,

Could you show us a photo of your lithium//NiMH contactor and HRC fuse, where they are located. Thanks.

 

Here are 2 pictures:

My car without lithium cells. On left orange wires are HV. Green is 12v coil contactor. The white with a db9 plug is the bluetooth for data transfer to/from my Pc. You can also see bms+ box.
There is just enough place in order to open the service plug.



Inside the small metallic box the contactor and hrc fuse. The box cover have isolated tape inside.



Because there is only one contactor (please install two in your car), one wire is allways connected to one nimh pole. So I have to be careful, even after waiting few minutes after power off.

 

ok great
i have 2 prius fuses so will use those.
i also have 2 of those contactors because back in 2007-2008 i wanted to do the callcars build but i did not like the contactors base system and found the hybrid interfaces system.

i am stil nog sure what to do.....

planitair your max voltage is 3,5.. what was your lowist voltage and what DOD range are you using to get thet 40km range?

i made a drawing for a battery case that i wil build if i deside to go with the A123.
it will have a compressed setup just like the OEM prius battery got but i build it first out of wood. ( MDF i think )
with see tru perplex sheets so i can see the cells and bms.

3,6 volts is indeed a lot higher 7 votls or so to 252 volts. abd i guess it wil drop to 240 underr load... so maybe thats not to bad. just the instand current to the OEM battery us maybe a wurry...
what if i use the same setup as prius with a risitor first contact and then the bigger contactor.
i also have 2 prius contactors with the 3e resistor contactor.

this is because i have 2 compleet OEM batterys and housing from back in 2008 where i got those from a junk yard.

edit

what if i buy a charger that charges to max 3,5 volt so 245 ( 70 x 3,5 ) and use the cheap nice person boards to bleed off energy if some cells get above 3,6..

planitaire did you see any reason to use a bms after you monitort the voltages during charging
or did you not monitor them?
do the voltages go up almost the same to 3,5 volt but start to diff when charging higher?
or some cells 3,4 and some 3,5 so no need for balancing. of do you think you stilll need to balance a 3,4 cell to 3,5?

 

Max voltage is between 3,50 and 3,54v. My bms connect each shunt when voltage is 3,54v and stop connecting when it fall to 3,50v

My two last trip where : 110km each, 4100Wh and 18,6Ah (and of course some gazoline). Cells are given for 4550Wh and 20Ah. So Dod was near 90% !!
This without precharging the nimh cells.
After driving cells where, in this exemple, between 3,16v and 3v.

For shorter trips say 40km 3,2v +-0,05v, 3800 Wh, 17Ah.

Cells voltage is very close in the range 3,3-3,1v. Differences appear over 3,3 and under 3,1v (due to capacity and internal resistances).
I use top balancing. During end charging voltage increase quickly on some cells. You can have 3,54v for the highter cell and 3,42v for the lower
This depend upon the Dod. The more it was the more the pack is unbalanced. But for A123 you must have all cells over 3,38v with 2A charging current.

If you don't balance cells, range will be reduced slowly.

At the end of charge you have two solutions:
-one cell is over some max voltage then you unplug the charger.
-if you want to balance cells, using just bleeding is not enough. You must disconnect the charger if one cell is over the max voltage then wait and when under an other voltage re-connect the charger. Then repeat this cycle.


Monitoring is interesting because you can see if a cell is becomming bad before it be bad.
I have a look sometimes in the log file to control if it is always the same cell that is first depleted. I can also know if the others are close or far from this one.
It is also interesting, when driving, if you want to use the maximum electric energy. You will know before "the end" if you can use some more electricity or avoid this and use engine. If you can use a lot of amperage or not.

With monitoring you can even saw if some bolt between two cells is well tight. If not the two adjacents voltages will be lower then the others, when amperage increase.

 

ok dont understand the following
i need to charge the A123 with 2 ampere after the celvoltage gets to 3,38volts? but can i use more or less? and wy only 2 amps?

dont you think 90% dod is a lot? for battery life?

the guy from ebay selling those A123 told me that the cells ar always 19ah of 20ah but no less.. do you agree? because urlier in this topic i read 18ah etc.

do you also charge the oem battery? sometimes or not at all?

i would prefer to go nowhere higher then 80% dod so 16ah at most.
so i can expect somewhere like 36kms max.

25km is what i need
i would use somewhere like 11ah used i geuss...

but when discharging 11ah what voltage i would get.?
i mean if the its higher then the oem pack it would keep discharging itself into the oem pack .. and maybe overcharge.. then again the ice would run to prevent that./.. or is that not working with the bms+ connected

 

You are transferring data via a bluetooth device to your computer to isolate noise or induced EMF and to keep isolation of 230Vdc floating above ground. Does your Bluetooth device get affected or freeze due to noise or induced EMF?

What data from ypur BMS do you look at on your computer? Does your computer ever freeze up from noise? My notebook computer normally freezes up after a minute or so but my Canview never does. What do you recommend you can do to avoid computer freezing up? In my case I have added DC Converter noise. I am thinking of putting a metal screen over the lithium pack HV cables and connect metal screen to ground. Then place heat-shrink tubing over the metal screen.

 

Along as none of the cells do not go over 3.8v is good enough for me. It does not have to be perfectly top balanced. At the HVC end of the charging curve the difference in cell voltage is equivalent to very little difference in charge (SoC). At that price it is good. Although it could do with a red LED for each resistor to indicate when it is burning excess charge. I also like the idea of adding more in parallel to increase shunt current. If you use a low current charger you can put enough balancers in parallel so that it would still keep burning all excess charge (total charge current) and still keep cell voltage below 3.8v should the HVC relay become faulty or not operate. This would be a good backup high voltage protection should the high voltage relay fail.I do not think that inrush current is a big deal as the lithium//NiMH HRC 100A fuse should be able to take 150A for a few seconds. It depends on the HRC fuse data sheet as to how much current it can take over how much time without blowing. If you are really worried you can use a motor rated slow blow HRC fuse which can handle very high motor starting currents.

 

You can charge with more or less then 2A. This was just the amperage you gived and this is the one I use. During driving you could have more then 100A with boost-converter pulses (I suppose 4khz or 8khz)

Probably, that's the maximum possible. I don't use so much every day. The A123 life is very long, more then my Prius life.

I don't have the exact capacity.
Because I can use 18,6Ah my 70 cells must be over 19Ah. Capacity is given with 2v end-voltage, low amperage and a good temperature.

I do this sometimes. I charge the lithium, connect to nimh, wait half an hour, disconnect, charge the lithium. Second charge is only about 125Wh.

For example, if you use 2/3 capacity all cells stay at the same voltage, even when using 70-100A. Without amperage voltage must be at this moment near 3,20-3,25v. Total voltage stay above 220v I think.
Nimh has the same voltage then lithium. The contactor is on during all the travel.
You cannot have overcharge except if you go down a high hill just after grid charging. I think when total voltage raise over 245v bms+ cancel ccl (charging current limit) so the prius don't send any more energy. But I have not tested with lithium. I saw this when using only oem nimh with bms+.
If your cells stay well balanced, it's ok: 3,5v. If not you have to open the contactor.