Is this correct for a max discharge with a 7s4p pack?

[silviasol]

controllers are cheap... if you're replacing the battery, just replace the controller too, then you can go with whatever voltage you like

The scooter has a stock battery indicator throttle I would like to keep using.

check the throttle, most of the time they just need a +ve and -ve and work out which/how many leds to light on there own

The throttle and power indicator would work? It is a combined unit which has a connector plug(6-10 pins I think). I have this picture of the inside I took awhile ago after I cleaned it out.

 

[silviasol]

if you can find the voltage regulator we can see what it has for a power resistor so you could add some input resistance in front of the regulator.

there are 35V caps on the power so those could be upgraded to 63V caps so if you go lipo then you could get 15S under the caps, and the mosfets would be stressed. so maybe 13S would be the max with lipo. maybe 14S. but i bet you could use those mosfets with 16S lifepo4 and the 63V caps. or 4 of the 12V SLA. or you could combine packs with diodes.

I opened the scooter today and took a look at the other components. The only part number of the 4 multipin chips I am finding with a search online is the 16 pin uln2003a. The pdf file for it says it is a HIGH-VOLTAGE, HIGH-CURRENT DARLINGTON TRANSISTOR ARRAYS and says it handles 50v. This is the chip directly below the black tyco boxes.

ULN2003A
http://www.ti.com/lit/ds/symlink/uln2003a.pdf

 

[dnmun]

the mosfets are under the heat sink. the two 35V caps are on each side. the two black boxes are relays.

 

[silviasol]

the mosfets are under the heat sink. the two 35V caps are on each side. the two black boxes are relays.

So do I need to change the 35v caps to say 50v? Then I would be good to go for 8 series? I removed the heatsink shown in the previous post and they are all 50v mosfets.

 

[dnmun]

irfb 3205 is 55V BVds so that is 13S of lipo and you would use the 63V caps. make sure the leg spacing for the caps will work on the pcb. i suspect it is the same but verify before you order it.

you can find a lot of 13S BMS so you can bulk charge the pack using a 36V lifepo4 charger adjusted up to 54V DC. some are cheaper than others and some are made for up to 13S and some are hacked from 16S down to 13S. but some of these cheaper ones have low continuous current ratings:

http://www.bestekpower.com/481v13spcmbmspcbforli-ionli-polymerbatterypack/

 

[wesnewell]

8s is only 33.6V fully charged so you don't need to change anything other than the HVC if it truly has one. If you could find the LVC circuit I'd change that to 28V or at elast monitor voltage and recharge once you hit 28V under normal load or 29V under no load.

 

[scoot]

wesenell... A while back I was occasionally running a 9s life pack with the ESR controller. When all of the cells were topped off, the controller would not respond or turn on. After draining off the so called "surface charge", the controller turned on and worked fine. I don't remember the precise voltage where that happened, but I think it was around 31 volts. It may be an adjustable setting with a GoPrammer, but I really can't say. Hope that gives you some additional insight of how it functions.

 

[dnmun]

if it actually has a HVC signal it would be a resistor bridge off the input voltage, with the middle going to a spot on the processor and it will have a capacitor beside it going to ground with the bottom leg of the bridge. you can spoof it by changing the equivalent resistance of the bottom leg by added another SMT resistor on top of that one to drop the voltage it would see on the pin.

 

[silviasol]

irfb 3205 is 55V BVds so that is 13S of lipo and you would use the 63V caps. make sure the leg spacing for the caps will work on the pcb. i suspect it is the same but verify before you order it.

you can find a lot of 13S BMS so you can bulk charge the pack using a 36V lifepo4 charger adjusted up to 54V DC. some are cheaper than others and some are made for up to 13S and some are hacked from 16S down to 13S. but some of these cheaper ones have low continuous current ratings:

http://www.bestekpower.com/481v13spcmbmspcbforli-ionli-polymerbatterypack/

Sounds good. For now I will be using 8s only, like wesnewell says that should work fine. Later when I add a higher voltage motor I will swap the caps. I assume I should replace all the 35v caps, there are two larger and 4 smaller.

Thanks for the link, looks like a good store. I will order when I purchase the cells. Will I need one per pack or just one total?

8s is only 33.6V fully charged so you don't need to change anything other than the HVC if it truly has one. If you could find the LVC circuit I'd change that to 28V or at elast monitor voltage and recharge once you hit 28V under normal load or 29V under no load.

I think I found them. One is fr9024n and the other ksh127. I made a picture showing how the power is sent thru the HVC. Is it possible to just remove the HVC chip or would it need to be replaced? I assume a BMS will take care of any over/undervoltage.

Will there be any issues with the motor running 8s?

LVC?
http://www.datasheet4u.net/datasheet/F/R/9/FR9024N_InternationalRectifier.pdf.html
HVC?
http://www.datasheet4u.net/datasheet/K/S/H/KSH127_FairchildSemiconductor.pdf.html

if it actually has a HVC signal it would be a resistor bridge off the input voltage, with the middle going to a spot on the processor and it will have a capacitor beside it going to ground with the bottom leg of the bridge. you can spoof it by changing the equivalent resistance of the bottom leg by added another SMT resistor on top of that one to drop the voltage it would see on the pin.

That would be an easy solution! Looks like are three resistors it runs thru. Basically the middle pin goes to a 35v cap then to a 4 pin chip, 1 pin to a resistor(red), middle pin to a 35v cap then the red resistor, then top pin to a fuse then two other resistors

 

[dnmun]

Q1 and Q2 are mosfets.

 

[silviasol]

Q1 and Q2 are mosfets.

I have links to each of those chips specifications in the post.


LVC fr9024n
http://www.datasheet4u.net/datasheet/F/R/9/FR9024N_InternationalRectifier.pdf.html
HVC ksh127
http://www.datasheet4u.net/datasheet/K/S/H/KSH127_FairchildSemiconductor.pdf.html

 

[MrDude_1]

silviasol, did you ever successfully modify the HVC to accept 8s lipo?

 

[silviasol]

No I gave up on it. Just search ebay for brushed motor controller and there are tons of controllers for under $50. You just need to wire the throttle to it.