How long will it take to charge.....
 

A 5000mah 4cell at 2.89 ?

Looks like my new quattro charger will only do about 2.9 amps if I'm using all four at once
How long would that take to charge from about 3.7 to 4.2 ?

I'm guessing about an hour and 20 min?

Less than an hour, depends how long charger spends on balancing

Cheers

I'm guessing a little longer, low charge rate, say 1 hour 40 minutes.

What do we win? :)

The latest multi chargers do great on 2S packs, but are still only 50-60 watt chargers (each port)

I keep an Imax B8 (150 watt) on hand to dump juce back into my 4s-5s

I've never timed one coming from 3.7v, but it'll take about 1.67 times as long as it would at 1C.

I have a similar question, How long would it take to charge a 5000mah 2s Pack at 10 Amps?

40 minutes from 3.5v / cell

Cheers

Charge rates used to be simple math and time was easy to predict.

If we really could charge that 5000 mah pack at 10 amps then (and it took 5000 to charge it up) then it is 30 minutes since 10 amps is equal to 10,000 / hr.

The 5000 mah pack at 2.89 amps is 104 minutes since 2.89 amps is equal to 2890 / hr.

In the first example unless the charge rate is held at 10 amps for the full time then it will taper off at 4.2 volts to maintain constant voltage (almost all charge routines use this) and it will slow down the charge. Practically a poor high IR pack with a cheap charger and long skinny leads will take much longer than a high quality new High "C" rated quality smart charger with short fat leads.

In the second example the rate will also not stay constant , but the power will so the 2.89 might be 3.5 at start , but go down to 2.8 or so toward the end. The above problems also exist in this example.

Don't forget that in both cases some chargers stop for brief periods of time and are not accurate for current (both of which slow down the charge) and packs many times are not "empty" (which speeds up the charge)

nice explanation gulio. thank you

Thats ok for calculating charge time as long as its NiMh or NiDc packs.

Lipo or Life, charge time is set by the CC/CV charging sequence and charge rate.