Multiple Subpack Balancer

[boelle]

started to mod peters BMS slave program but got stuck.. any that can help out?

http://tina-og-bo.dk/v1stickbalancer.TXT

i get this:

symbol PreviousAmperage  = w7
                           ^

Error: Unknown symbol - w7

basic what i want to do for starters is to messure the voltage and amps.. if the voltage is less than max voltage then it should charge if above max then do nothing.. later i want to expand so that i cycles between charge and discharge

[boelle]

my latest code "fart":

http://tina-og-bo.dk/v2stickbalancer.TXT

ignore 20m in schematic.. figured i needed the x variant

[retepsnikrep]

Bo

Read the PICAXE basic manual from cover to cover first. That's what I did.

w7 is not allowed in the 20M variables only go upto w6.

Also make sure picaxe software is set to correct chip

Originally Posted by boelle

started to mod peters BMS slave program but got stuck.. any that can help out?

http://tina-og-bo.dk/v1stickbalancer.TXT

i get this:

symbol PreviousAmperage  = w7
                           ^

Error: Unknown symbol - w7

basic what i want to do for starters is to messure the voltage and amps.. if the voltage is less than max voltage then it should charge if above max then do nothing.. later i want to expand so that i cycles between charge and discharge

[boelle]

i did change it to a 20x2... but i guess i will be reading again... I just hope that i will unerstand it

i for sure know what i want it to do

also i have not added the opto's yet

[boelle]

wow....

for the 08m i managed to have a LED flash when pin3 was high...

read all of section 1 but did not catch how to use inputs on the 20x2

guess it's on with section 2 then

[boelle]

section 2 did not help me much and the same for section 3.... so i will look for a "picaxe for extreme dummies" guide

[boelle]

just did some updates to the design:

the schematic: http://tina-og-bo.dk/stickbalancer.pdf
vsm design file: http://tina-og-bo.dk/stickbalancer.DSN

doing thoughts on what could be left out without loosing the intended functions.. i guess flashing the leds in sequence over and over could be used to indicate a bad stick so there is no need for extra leds

is the 20x2 a bit "overkill" for these tasks:

charging while messuring volt and amps and send that to master module

discharging while messuring volt and amps and send that to master module

figure out when a stick is bad (ah not within range after 6 cycles of charge/discharge)

doing trickle charge after 6 cycles and the stick is marked ok


should the number of cycles still be 6 if the stick is ok after 1 cycle? could reduce the time to do the balance

for the charge part a stick could also be marked bad if it tops before it should... if top voltage is not within range

for discharge similar way could be used.. if the stick hits knee point faster than it should...

[boelle]

have been monkeing around a bit and so far i have modified the slave code to start charging and then when the cells peaks it will discharge if the cells then go under a set voltage it will start all over again

is it possible to figure out the ah number if the charge/discharge current is fixed?

i plan to add another pic to disconnect the stick after 6 cycles

[boelle]

been thinking and fooling around a bit... came up with a total different idea

a charger based on National Semiconductor LM3647, what it will be able to do is:

when a stick is connected it will first discharge to the minimum level, as i have not build it or tested it i can not tell what it will do if the voltage is lower than that

next phase is a charge at 0.2C (0,65 A) for about 5 min if the temp is within -5 C and +50 C. it will abort if the voltage goes above 3.017 Volts or stays below 1.2 Volts

next phase is a charge at 1C (6,5A) until neg delta is detected (17mV/cell). the Charger can optional be fitted with temp messure probe to terminate if the stick get to hot

next phase is topping charge at 0.2C at a setable time

last phase is maintence charge at 0,1C (0,325A)

to recondition a pic that repeats this 6 times (by disconnect the stick at last phase and reconnect) should give most features needed.. only missing option is to count AH

but is it of much use? i figure the unit could be used to rent out to those who have trouble with their pack.. but please comment

[Hybrid-Battery-Repair]

Originally Posted by boelle

when a stick is connected it will first discharge to the minimum level,

One of the big problems with all the chargers out there is that they are designed for a couple of cells or at least a set of matched cells.

The very real problem here is that these subpacks are not in good shape. Let me give you a very real scenario. Here's the voltages of the cells of a hypothetical pack (like dozens on my shelves):

1.1V
1.2V (high IR)
1.1V
1.1V
0.2V (low IR)
1.1V

Total subpack voltage: 5.8V

What happens when you start your initial discharge and take it down to 5.4V?

What we need is a charger that will sense a low-charge condition and start an initial CHARGE not discharge.