One of my 4s batterys has a cell that wont balance so the last few times Iv just charge it (with out balance) & hoped for the best. So far so good.
What could go wrong if I keep using it ???

Does your charger have a readout for each cell while it's balance charging? If so what's the one cell that won't balance read?

C1, 2 & 3 usually ready 4.19v or 4.20v but C4 is anywhere inbetween 4.14v & 4.16v maximum
I dont bother to balance it anymore & it takes about 40 - 50 minutes at 10amps for a normal charge.
Iv only got two batterys & I carnt afford to buy more just yet.

Cheers

Try balance charging at 1amp and let it go until it's done.

I'll give it a shot

cheers

Sounds like a bad cell. I'd recommend to balance charge it in a firesafe location. If the one cell won't get up to the other cells voltage is OK. What you don't want is to overcharge the other three cells and a balance charge won't let that happen.
If you don't balance charge than the cells that are good will be over charged and a fire is very possible, and you don't want that.
If the packs aren't that old I'd look to get it replaced.

How long does the charge take when you balance charge the pack?

I've had packs go to time out (aprox 90 minutes) on the balance charge because the bad cell just can get to 4.2 volts.

It times out at 120 minutes, Hence why I dont bother to balance it anymore.
I always charge it in a fire proof lipo bag too

Im more worryed about it catching on fire while its in the buggy

cheers