Do i need a BMS for my lifepo4 battery?

[Gordo]

edit; The little M&M is an ICL, (NOT a capacitor), but we are not interested in it first. The little black battery looking things behind it are the filter caps. We want to know the voltage across those? The little resistor looking things with a silver band on the + end are the diodes, arranged in a bridge. Measure the voltage across those too? Then measure the voltage across the M&M?

[Gordo]

there was no previous owner..... and it obviouslt got unplugged in shipping or something.... and yes i have hat the charger at a electronics shop to try to get it fixed and it dont work at all and he cant fix it....... in the mean time till one gets shipped to me on the slow boat from china i need to find a way to charge my battery some how

Get the charger out of there. The guy knows nothing. Send it to someone close to you. If you post your location, you will get better site specific help.

[UNDERLORD]

the voltage accross the battery lookin things is 167.3 and accross the dieods is the same there is no voltage at all across the little m&m thing

[dnmun]

good

[Gordo]

the voltage accross the battery lookin things is 167.3 and accross the dieods is the same there is no voltage at all across the little m&m thing

dnmun,
Looks like you pegged it several pages back! What is the number of the ICL?

There is a guy in Nanaimo who can fix your charger.

[UNDERLORD]

ok how do i get ahold of this guy in nanaimo?
what is the ICL?

[dnmun]

the ICL is ok, he said the voltage across it is zero so it is functional. he has voltage on the bridge so it is good.

on the heat sink between the transformer that says 48V and the little daughter board is a 3 legged schottky diode. look at the traces and you see that the two outside legs are connected, the center leg goes out to the back end.

measure voltage on the back end by putting the black probe, negative, on the negative output of the charger, where it says - on the pcb. that is ground. put your red voltmeter probe on the traces for that schottky diode and let us know if there is voltage there. on the outer legs and middle leg.

[UNDERLORD]

there is no voltage there.

[dnmun]

the voltage got lost in between.

the current goes from the capacitors in front to the schottky diode in back through that mosfet up in the corner next to the M&M, and from the mosfet to the transformer with 48V on it. the M&M is called an ICL, inrush current limiter, and it has a value of 3 ohms and is 15mm in diameter from reading the label. it is a thermistor, a Negative Temperature Coefficient thermistor which slows the current rushing in when you power up. when it has current flowing through it the temperature rises and it gets really hot so that the resistance drops from 3ohms to almost nothing, so the voltage drop across the ICL is zero when it is still intact. if you had the full 120V there, we would know the ICL had blown open. make sense?

the current goes from the plus side of the caps through that high frequency switching mosfet into the transformer and back to ground on the input. ground in the input section, or front end, is the negative of those capacitors. it should say ground on the pcb right out in the middle. put your negative voltmeter probe on the input ground there, and measure the voltage on the three legs of the mosfet. looking at it from left to right, the legs are gate, drain, and source. the voltage on the source will be high since it is on the plus of the capacitors. the voltage on the gate will be lower by far, and the drain should be higher but less than the source, i would guess. so look for that.

take big pictures of the bottom where the traces are so we can look for open traces.

you need to look carefully at the traces and see if you can find a place where the traces to that transformer or the mosfet are cracked. they can be open with the tiniest of faint lines to indicate they are cracked, look to see if the heat sinks are soldered into the traces and the traces are broken close to that. sometimes the heat sinks hit something or twist the trace and the trace tears open near the soldered spot.

doesn't look like the current is being switched into the 48V transformer, or the leds would light up, imo.

[UNDERLORD]

ok well its broken guess i just wait for the slow boat

[Gordo]

ok well its broken guess i just wait for the slow boat

Good choice. Drop the broken one off when you come south and I'll see what it needs.

[UNDERLORD]

International item arrived in Canada and will be reviewed by Customs

[UNDERLORD]

damnit its not here yet stupid government emploiees not working on weekends now i gota wait another weekend befor i can go for a ride damnit

[UNDERLORD]

got my new charger..... they sent it to me for free.
i just sent the seller an email saying it didnt work and i got a new one.
now to test the hell outa the battery befor my 30 days is up and make shure it performs as it should

[UNDERLORD]

should i charge my battery every time i go for a ride or wait till its dead befor i charge it?

[Gordo]

If you go more than 10km charge it. Look into a CA,

http://ebikes.ca/drainbrain.shtml

Best money you can spend to get an education on ebikes.