80% charge after short time with Lipos?

shambolic

Pedelecer
May 19, 2014
111
27
65
Hi all. I know that most Lithium batterys charge up to 80% fairly quickly. Is that the same with Lipos? What sort of time span would it generally take to get to 80%?. It would be really useful to know this. If I go somewhere and plug in for a few hours it would be very useful to know the battery charge life from thereon .
 

mountainsport

Esteemed Pedelecer
Feb 6, 2012
1,419
298
Hi all. I know that most Lithium batterys charge up to 80% fairly quickly. Is that the same with Lipos? What sort of time span would it generally take to get to 80%?. It would be really useful to know this. If I go somewhere and plug in for a few hours it would be very useful to know the battery charge life from thereon .
Firstly, that really depends based on a few factors.

MS.
 

KirstinS

Esteemed Pedelecer
Apr 5, 2011
3,224
899
Brighton
The short answer is Yes to 80% faster than the last 20%

But how fast depends on your chargers capability to pump electricity into your battery (ie what amp rating is it ?)

And how much electricity your battery needs to be 80% full (ie what aH rating it is)

If you have these figures you can make a good estimation
 
  • Like
Reactions: mountainsport

shambolic

Pedelecer
May 19, 2014
111
27
65
ok , I am very electronics illiterate so I will type up what's on the charger.

50/68hz 130w DC output +54.6v ...then there's a line with - - - below it followed by 1.8A. The battery is 48V 14aH
 

KirstinS

Esteemed Pedelecer
Apr 5, 2011
3,224
899
Brighton
Hmm doesn't sound like a lipo battery to me

Sounds like a more standard ebike battery eg liMn

It's a 13 cell series battery at 48v nominal. 54.6v is the charge voltage and pack voltage got off the charger

A 1.8amp charger is pretty low powered/slow. Especially for a fairly big battery like yours at 14ah

A basic calculation would be something like 14/1.8 = 7.75 hours

Add say 15% for inefficiencies of the charger and you get 9hours

80% of that is 7.2

So a rough guide would be 7 hours for a 80% charge from empty

This is back of a fag packet stuff mind !
 

shambolic

Pedelecer
May 19, 2014
111
27
65
Thanks for that
I have a feeling it may be more efficient than it says. it has taken about 7 hours to get from run down to full. Is it possible to get a more efficient charger?

Something puzzling me in the above calculation is the 80% doesn't seem to be any faster rate of charge?
 

KirstinS

Esteemed Pedelecer
Apr 5, 2011
3,224
899
Brighton
Ahh it's nota efficiency thing it's more that the battery won't have 14ah of actually useable power. Once it gets down to about 3.2v per cell the BMS should shut it down

Also I didn't bother with any tapering of charge as I can't guess what that might look like. And the taper wouldn't kick in till after the 80% mark anyway

However If you know from experience it's 7hours to full then I'd guesstimate about 4.5 hours to 80%
 
D

Deleted member 4366

Guest
You shouldn't charge to only 80% except when you have to because there will be no balancing. The balancing happens during the last few percent when the bleed resistors are switched on.

It would be OK to charge to 80% a couple of times, but if you did it every day, the battery would go out of balance.

You can charge any lithium battery at 0.2C, which is 2.8A for a 14ah one. 3A is close enough though.
 
  • Like
Reactions: mountainsport

shambolic

Pedelecer
May 19, 2014
111
27
65
It's only if I go out on , say a 10 mile trip to visit someone, then I have to charge at theirs to ensure I can get back. So are all Lithium chargers the same? If I get one with the same spec but 3A, will that work, and be safe?
 
D

Deleted member 4366

Guest
It will have to be the same voltage: 42.0v for most batteries; around 43.5v for LiFePO4.
 

KirstinS

Esteemed Pedelecer
Apr 5, 2011
3,224
899
Brighton
You shouldn't charge to only 80% except when you have to because there will be no balancing. The balancing happens during the last few percent when the bleed resistors are switched on.

It would be OK to charge to 80% a couple of times, but if you did it every day, the battery would go out of balance.

You can charge any lithium battery at 0.2C, which is 2.8A for a 14ah one. 3A is close enough though.
Good point ! Hadn't thought of that
 

D8ve

Esteemed Pedelecer
Jan 30, 2013
2,142
1,294
Bristol
You have a 48volt 14amp battery and you can't get 20 miles out of it?
What sort of bike do you have?
 
  • Like
Reactions: mountainsport

mountainsport

Esteemed Pedelecer
Feb 6, 2012
1,419
298
You shouldn't charge to only 80% except when you have to because there will be no balancing. The balancing happens during the last few percent when the bleed resistors are switched on.

It would be OK to charge to 80% a couple of times, but if you did it every day, the battery would go out of balance.

You can charge any lithium battery at 0.2C, which is 2.8A for a 14ah one. 3A is close enough though.
Spot on Mr Dave.

MS.
 

shambolic

Pedelecer
May 19, 2014
111
27
65
I can get twenty miles out of it. I just like to be sure. I don't pedal much, I can't.