Cell log 8S and A123

[orpheedulogis]

Hi everybody

Actually, I use Cell log for my motorcycle conversion ( www.motoelectrique.unblog.fr )
I just want to know the voltage setting for A123 so cell log alarm playing for a good reason :wink:
Thanks for answering

 

[scoot]

Assuming you can hear the alarm :? I have trouble with that myself

I set my LV for 2.5 volts just for a little extra safety... 2.5 volts is at the steep portion of the discharge curve. I've seen some BMSs set go as low as 2.0 volts for LiFePO4 cells. With a motorcycle I am guessing you use a high discharge current, so once you hit your LV and stop the voltage will jump back up a bunch anyway. If you want your alarm to sound off when you hit the 80% discahrge point (recomended for cell life), you might consider a higher LV point like around 2.9 or 3.0 volts (just a guess though)

EDIT: I can't read French, but looks like a very nice conversion... and I see you have some louder buzzers for the alarm?... very nice 8)

 

[orpheedulogis]

Scoot

Oups !! I forgot something important , due to my bad english of course :wink:

The alarm sound I was speaking about is in charge, not in discharge ! A123 cell lower value doesn't "exceed" 3V3 in my application.
Thats why I was asking for limit value for A123.

Sorry for my french page ( www.motoelectrique.unblog.fr ) I will traduce it in a few time but you have some pages in english.

 

[Doctorbass]

Salut,

Ce que tu as besoin c'est de seter l'alarme a 3.7V pour la recharge.. donc si ce que tu desire c'est de savoir a quel moment les cells atteignent leur voltage max durant la charge, c'est effectivement 3.7V

En Cc CV ( Constant voltage constant current), le CV sur des A123 doit etre de 3.7V... certain prefairent 3.6V mais cela ne change pas grand chose puisque ces cells tout dependant de leur temperature peuvent prender jusqu'a 4.2V lors de très basses temperatures. Donc on suppose que 3.6V ce serait si elle sont très chaudes et 3.7V a T ambiant....

Si tu utilise le desing de BMS de Gary, c'est 3.7V le voltage de shunt plus ou moins 20mV je dirais par experience...


En Passant ce fut un veritable plaisir de te rencontrer à Kingsey Falls! Quand vas tu presenter ton desing de display OELD pour Cycle analyst ?

Doc

 

[orpheedulogis]

scoot: I tried to write in english on my blog last post ( http://www.motoelectrique.unblog.fr/ ). You will have a short explanation of the actual project.

Merci à toi Doctorbass et j'espère qu'on se reverra ! 8)

Je crois que d'origine l'alarme est réglée à 3V65. Je vais donc peut être la laisser là, c'est juste un peu génant quand les accus sont pas encore tous rendus au même niveau mais pas vraiment non plus.
4DGL m'a contacté pour me dire qu'ils s'étaient ré-approvisionnés ( http://www.4dsystems.com.au/products.php ) donc ça peut effectivement intéresser les bricoleurs de mon genre. Au fait, t'as peut être lu sur mon blog, les deux pneus étaient à niveau de pression frisant le zéro !!!
Pour ce qui est de donner des infos sur ce que j'ai fait je peux mais, comme je te l'ai dit, c'est quand même très spécifique. Je pense plus que des astuces du genre: comment l'alarme fonctionne (blocage de l'alimentation en marche par Mosfet), comment couper le CellLog8S ... seraient éventuellement intéressantes. Ou alors, pour ce qui est du langage, comment faire dire des valeurs...

 

[scoot]

I just finshed up reading it and I could understand well enough :wink: . Awesome build/conversion 8) . Looks like you have put a tremendous amount of work and thought into it. That's a lot of A123 cells I see you are using a BMS from ECity. Does it seem to be working well for you? I am considering one from them for my baby scooter build.

 

[orpheedulogis]

"I see you are using a BMS from ECity. Does it seem to be working well for you? I am considering one from them for my baby scooter build."

Until now, it works correctly. I putted this BMS instead TPpacks one's because resistor heating (-> problems for me) , capacity BMS are best for this.
The problem is that this BMS take a lot of place and you will probably have to make a specific box for this. I did mine with copper PCB (and fiber).
For A123, I think it's best to find biggest battery package.

 

[orpheedulogis]

updated pictures/text at www.motoelectrique.unblog.fr

 

[Doctorbass]

I really think that if you post something like that here on E-S.. ALOT of people could be interested in making similar re copy that for themself!:

( I must specify that this cute OLED is communicating with the Cycle analyst and display TTL data with an original display art!!)

Please.. provide us more details or schematics!!! it'S a very good display desing!!

Doc

 

[orpheedulogis]

The schematics (too large for here !):

http://rapidshare.com/files/400383363/YSR15.jpg.html

Proteus schematics:
http://rapidshare.com/files/400377396/YSR15.DSN.html

Actually I'm changing (as usual 8) ) some parts.

 

[orpheedulogis]

Une petite vidéo qui te rappellera quelque chose Doctorbass :wink:

http://www.youtube.com/watch?v=Jx6b83NuxOs

J'en ferai d'autres bientôt.