help with controller upgrade please!

[m303625]

Hi guys
ok I have read previous posts about ecrazyman controller mods
I have a ebike with geared brushless motor like bafang I think, 36v10ah lion pack and standard controller.Want to use 48v battery, opened up controller(pic below) main filter caps rated 470uf 50v and Fets are p65NF06 (rated to 60v)
So I assume I will need to upgrade these components! I understand that 48v lion pack will actually be closer to 55v when charged, so can I get away with main filter caps at 63v?? and does anybody know what fet I can use with a higher rating and preferabley easy to obtain at local tandy (jaycar here in Australia)
And finally have I missed anything is there anything else I should worry about??
onboard regulator appears to be LM317 I assume if i increase total input voltage this may mess up the micro positive rail (I am assuming that is mainly what this regulator is for??)
hoping to get away with filter cap upgrade only, 36 to 48v increase of 12v
What do you think??
thanks in advance

 

[wrobinson0413]

.

 

[Mark_A_W]

I fitted 470uf 63v caps from Jaycar to my 48v controller....it came with 50v caps fitted..

It uses:

P75NF75 6off 75v Fets
TIP122 1off voltage regulator (I think)

 

[rkosiorek]

lm317 come in 2 different flavors. one the plain old LM317T has a maximum 40V input and the other LM317HVT has a maximum 60V input. the HV in the part number stands for High Voltage. sice the HV parts are like 3X the price of the regular parts most manufactures would opt for a cheap resistor in series with the regulator. these regulators are programed by 2 external resistors. one of them will be either 120 ohm or 240 ohm and will connect from the middle terminal to one of the ends. this sets the current flowing through the resistor that actually sets the voltage. so increasing the voltage in will not increase the voltage out because it would not affect the current..

i suspect that if you trace out the circuit you will find that there is a power resistor of some kind in series with the input of the regulator. this would drop the voltage down a bit. it may be easier to just increase the size of the resistor. you can more or less judge the size of this resistor. if the original is 1.5K ohm increase it by 1/3rd. so you would make it 2.0K ohm. how did i get that number? simple 48 is 1/3rd bigger than 36.

for FETs there are many choices. P75NF75 are common but have ha very high on resistance. IRFB4110 are the premium part. and IRFB4310 would be the middle of the road. both of these have a lower on resistance than even your original parts and would improve efficency.

63V would be enough for the caps.

rick

 

[m303625]

Hey thanks for the advice guys
have ordered a 48v ecrazyman controller as a backup incase I damage the original,
after I test the new controller I will attempt the mods to the original controller
will post the result

 

[fechter]

60v rated FETs should be OK for a 48v system.
There are a few good 75v rated ones also that may be less expensive than IRFB4110s.

Not all controllers will be happy with a simple FET substitution. The gate drive requirements are higher for something like a 4310 or 4110. It's best if you have an oscilloscope to check the gate drive after making the change. If the drive is not enough, the new FETs may get hotter than the original ones. If you don't have access to a scope, at least try to trace the gate drive on the board and see what value of resistors are in series with the gate.

The other comments about the voltage regulator are correct. Most cheaper controllers will require a resistor in series with the input to the voltage regulator to keep it below it's rated voltage.

 

[Mark_A_W]

Fechter, what about 75v fets at nominal 60v (66v fully charged)?