Planing CanView and BMS+ conversion with lithium

I like your design you should sell them on ebay

 

any you guys have logged info about the cell temp? during driving end charge?

i do a manual log where i have a wireless temp sensor inside the battery pack.
i started at somewhere 24 Celsius ( 75,2 F ) after a short drive and then charged and after that i did a 45km trip and went up to 33,4 Celsius.( 92,12 F )

then after that i charged again and this dropped to 32,6 C ( 90,68 F ) and after that, and at the end of charging it just went down more.
so no small increase during or after stopping charge.

i think 33 C is a bit high .. outside was around 14 C ( 57,2 F ) so what to expect during the summer? i think i need a good Fan attached to the pack.

at what temp of the cells do you guys think its starting to be a risk? 50 C? ( 122 F ) for things like termal runaway.

 

Post moved to

http://priuschat.com/forums/prius-phev-plug-in-modifications/104914-elcon-charger-end-voltage-other-mods.html

 

so you ad a ~3,175 Mohm over R1?

your R1 and R2 are close to mine
i have R1 600Kohm and R2 8,x Kohm and its higher because my endvoltage is 292V so i think that will be ok?

edit
i do think opening a elcon charger mod topic is better then having 3000+ posts in 1 topic about a lot of stuff ..
people need to really dig into the topic to find what they need.

 

R1 - 482300 ohms
R2 - 8680 ohms

Trim Range (Decreasing it only):​

Note I only tried this quickly on my unit, it seemed to work, but tread carefully.
In this case you want to make R1 a bit smaller so you will add a large parallel resistor
between Pin 2 and DC+ (see the following photo).​

1) Measure the upper resistor R1 (between pin DC+ and pin 2). R1 - 482300 ohms​

2)
RatioMax = Vmax/ Vorig = 252v / 256v = 0.984375
RatioMin = Vmin / Vorig = 256v - (256v x 0.10) = 230.4v / 256v = 0.9​

Vmin = 10% reduction of original voltage Vorig​

3) Parallel Resistor total for R1 (in this case)​

RPmax = RatioMax X R1 = 0.984375 x 482300 ohms = 474764.06 ohms
RPMin = RatioMin X R1 = 0.9 x 482300 ohms = 434070 ohms​

4) ​

RAddmax = 1 / ( 1 / RPmax - 1 / R1) = 1 / (1 / 474764.06 - 1 / 482300) = 30384900 ohms
RAddmin = 1 / ( 1 / RPmin - 1 / R1) = 1 / (1 / 434070 - 1 / 482300) = 4340700 ohms​

I think I got that right!!! It should end up a resistor about 10 times R1 for a 10%​

reduction.

Raddmin / R1 = 4340700 / 482300 = 8.6 (not exactly 10 times)

 

I think the control voltage of 5.1v should be 5.0v which gives me more accurate results.

 

here is the pdf again from a guy that did a increase

http://priuschat.com/forums/attachm...n-lithium-how-trim-endpoint-volatge-elcon.pdf

he is talking about a 10% decrease is a 10 x R1

excel sheet cal. just copy past in excel sheet : =SOM(10000/(5/252)) -10000
what is 494Kohm
10000=10kohm R2
5=5 volts control voltage
252= end voltage wanted.

edit
for e better overview i opent a topic for the elcon mods
http://priuschat.com/forums/prius-p...arger-end-voltage-other-mods.html#post1492217

 

He does not show how he derived " a 10% decrease is a 10 x R1 ", he needs to prove it.

 

mm so we have ~786kohm or ~494kohm ( with a 5 volts instead of 5,1 )
what wil it be?

i have 600Kohm and 292volts end now, a 10% decrease would be 262 that i want so 10 x 600 = 6Mohm

 

Using values from FWD's Elcon charger.

R1 - 600000 ohms
R2 - 8500 ohms

Trim Range (Decreasing it only):​

Note I only tried this quickly on my unit, it seemed to work, but tread carefully.
In this case you want to make R1 a bit smaller so you will add a large parallel resistor
between Pin 2 and DC+ (see the following photo).​

1) Measure the upper resistor R1 (between pin DC+ and pin 2). R1 - 600000 ohms​

2)
RatioMax = Vmax/ Vorig = 292v / 292v = 1.0
RatioMin = Vmin / Vorig = 292v - (292v x 0.10) = 262.8v / 292v = 0.9​

Vmin = 10% reduction of original voltage Vorig​

3) Parallel Resistor total for R1 (in this case)​

RPmax = RatioMax X R1 = 1.0 x 600000 ohms = 600000 ohms
RPMin = RatioMin X R1 = 0.9 x 600000 ohms = 540000 ohms​

4) ​

RAddmax = 1 / ( 1 / RPmax - 1 / R1) = 1 / (1 / 600000 - 1 / 600000) = infinity (open circuit) ohms
RAddmin = 1 / ( 1 / RPmin - 1 / R1) = 1 / (1 / 540000 - 1 / 600000) = 5400000ohms​

I think I got that right!!! It should end up a resistor about 10 times R1 for a 10%​

reduction.

Raddmin / R1 = 5400000 / 600000 = 9 (not exactly 10 times)

 

wrong calculationss

 

Too hard to use Excel on my IPad. 504kohm is R1.

 

Please explain

 

(10000/(5/252)) - 10000 = 494
(10000/(5.1/252)) = 484 ( but then with a control of 5,1 volts )

 

problem with my charger is that when i want a 10% decrease using that 10x for 10% decrease example i get 6Mohm ( 600Kohm is my R1 so R1 X 10 = 6000000 ) buth when i use the (8500/(5/262)) - 8500 = 436.9Kohm.

so.. do i need to have a 6Mohm or 439Kohms paralleled over R1

 

If "if" I am building a DIY battery pack with Lifepo4 and I go with 72 cells 40ah 3.2 volt.prismatic battery pack suggestion number (one)
or
"If" I go with 72 cells 60ah 3.8 volt prismatic suggestion number(two) can either work or not?

 

I calculated your Radd = 5.4 Mohms using the calculations given in this PDF

http://priuschat.com/forums/attachm...n-lithium-how-trim-endpoint-volatge-elcon.pdf

Your calculations can be found here ....
http://priuschat.com/forums/prius-phev-plug-in-modifications/99420-planing-canview-bms-conversion-lithium-57.html#post1492224


The value of 436.9Kohm is the Rtotal = Radd//R1 but this depends on whether to use 5.0 volts or 5.1 volts.

Radd = 1 / (1 / Rtotal - 1 / R1) = 1 / ((1/436900)-(1/600000)) = 1607235 ohms

Using 5.1v control voltage instead:

(8500/(5.1/262)) - 8500 = 428167 ohms

Radd = 1 / (1 / Rtotal - 1 / R1) = 1 / ((1/428167)-(1/600000)) = 1495057 ohms

I would go with using a 6Mohm trim pot if they exist. But I would not adjust it to any lower than 1 Mohm. So say a 5 Mohm trim pot in series with a 1Mohm resistor.

 

yes thats confusing haha
so what do you think.. your calculations or the one in the pdf? 1,6Mohm or 1,49Mohm
i think i need a pot meter so i can variable adjust and see.

did you already do your mod? in the pdf there is a picture where you can solder into the DC+ for the decrease voltage.

 

Do you think I am stupid enough to do this mod which has never been tried out to decrease the voltage endpoint. It has only been used and tested to increase the endpoint voltage. I rather just use the current control pot and charge @ 1amp overnight. The calculations are too speculative. It just not worth taking the chance of wrecking my Elcon charger.

 

ok well because you where doing the cal. for you own charger i was under the impression you where going to do that
for what ever reason would you do this then?

increase<>decrease

anyway its been done to increase the voltage and in the pdf he also did t he decrease.
not sure to what point

i want to do this mod anyway i dont like my charger to go to 292 volts end..