[mpobor]

hi everybody..

i'm wrapping my head around this modules as they come from factory to re-use them as is for a car conversion..

but there is something i can not figure it out about it.

i don't understand if the OEM bms keep working as stand alone to keep the cell balanced or i should re build completely with aftermarket bms to take them balanced.

second thing is:

why everywhere on the internet they talk about "usable" kwh.. for the first gen is 10 out of 14
and for the second gen 14 out of 18kwh...
i guess for keep the battery long last.. but what control this? the oem bms? or other controllers outside the module?

thank you very much for any suggestion and info!

 

[mpobor]

Battery rated capacity is 16 kwh at 388 v max if you are using the factory bms. 18kwh if you go to 4.15 v per cell.

Useable is: starting voltage x starting amp hours minus stopping voltage x amp hours.

On my pack, it is 196v x 90 ah minus 120v x 90 ah or about 7 kwh. Factory discharges lower than I do.

No bms, been doing this for 6 years so far. 26 mile total commute up & down hills series wound no regen 88 ford ranger.

when you mean if you go "4.15v" i guess you mean running without bms..

so options are, keeping the oem bms who will take everything undercontrol as a proper bms and also don't allow you to use 100% of the battery giving a much more likely longevity to the pack... at the cost to lose 4kwh of spendable energy...
this mean that if i run the oem bms i can just charge the battery up to the "fake" 100% and still stay away from the 100% charging potentially detrimental for the pack.... i undestood right?

for the first gen would be roughly the same but with much less kwh usable...
so 10kwh keeping the oem bms charging up to this "fake" 100% or running without and having 14kwh unbalanced uncontrolled pack...

sounds all right??

 

[mpobor]

Don't know if this helps but I have a first Gen Volt and it is advertised as having a 16Kwh battery. The motor always kicks on after I've used between 9.8-10.2 Kwh. (not sure why it's different because it doesn't seem to count the regenerative braking) I also know that a stock volt will continue for a few more miles beyond this point if it runs out of gas. So using the Stock BMS would be very safe for the batteries since it has a healthy 'buffer' at both the top and bottom of the charge.
Running without a motor, I imagine it would give you a warning after you went below the recommended voltage telling you to "refuel". Sorry, I can't tell you what components control this function. I'm a hands-on kind of guy so my personal strategy would be to try and make the whole system work, outside of any vehicle, and then start unplugging things to see what's what.

this statement add on all the searching i did till now makeing me think that used chevy volt battery are the most well maintained among the others simply because how you manage your battery is completely up to the car not to the owner..

ev with no range extender just advice you to stay away from full and empty battery... the volt does that autonomously..

good to know this... and i would say that the cooling system is extremely efficent...