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Apr 22, 2013, 02:40 AM
Jim in the Desert
Thread OP
Discussion

How do lipo chargers know when to switch from CC to CV?


Do they sense something about the battery as it's getting charged, or do they just go by how many mah have been put in and compare it to what you entered for the battery's mah? I want to charge a battery of unknown mah (label fell off).

I have a Thunderpower 1010C and a Hyperion i610 original version.

Thanks.
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Apr 22, 2013, 05:25 AM
Registered User
Most (all?) LiPo chargers charge up to 4.2v per cell (or your selected maximum voltage) at the selected charge rate, and then reduce the charge rate to hold the voltage at that level, until the charge rate necessary to keep them at that voltage gets down to about 5% or so of the initial charge amps.

Some chargers also have safety functions which will shut them down if the voltage of any cell goes over 4.2v, and if the mAh put in exceeds a certain number.

I would weigh your battery and compare it with others on the internet to get a rough idea of what its capacity is, so that you can set the charger's charge rate appropriately.
Apr 22, 2013, 06:18 AM
Registered User
It's all done by checking the voltage during the charge process.
Apr 22, 2013, 07:13 AM
Registered User
It's all in the names. You have a two stage charge (CC & CV) with a target voltage. It charges via CC till it reaches the target voltage, then it has to switch to CV or it would go over the target voltage.
Apr 22, 2013, 09:06 AM
characters welcome!
Mark Wood's Avatar
Software.

mw
Apr 22, 2013, 09:23 AM
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Quote:
Originally Posted by Mark Wood
Software.

mw
Way to go with the literal Mark
Apr 22, 2013, 09:48 AM
Jim in the Desert
Thread OP
Thanks everyone. So it's using the voltage you input (or number of cells). It's not using the mah of the pack or the charge rate in C. So it doesn't matter how much mah the battery has. As long as I know my pack is 4S, I dont' need to know the mah.

Right?


Jim
Apr 22, 2013, 11:28 AM
Registered User
Quote:
Originally Posted by cloud_9
Thanks everyone. So it's using the voltage you input (or number of cells). It's not using the mah of the pack or the charge rate in C. So it doesn't matter how much mah the battery has. As long as I know my pack is 4S, I dont' need to know the mah.

Right?


Jim
I'd be a bit nervous about any charger that can't figure out the number of cells by looking at the balancing plug. Or any one that doesn't have a built in balance system.

Having the charger guess the cell count from voltage alone, or relying on the user to put it in is probably asking for trouble in the long run.

Now I am talking about a lipo charger here, just to be explicit.
Apr 22, 2013, 11:55 AM
Registered User
Yes the number of cells is the important part. The charger really doesn't care how many mah because you never put in that much unless you run your batteries to 0 in which case they won't last very long. The charge rate is just how fast you are filling it. While not important to the CC/CV transition every charger uses this to determine when to stop the CV stage and declare the battery done. Typically when the current reaches 1/10th the set charge rate it will terminate the CV stage and tell you the battery is full.
Apr 22, 2013, 01:10 PM
Space Coast USA
hoppy's Avatar
Quote:
Originally Posted by Alan Hahn
I'd be a bit nervous about any charger that can't figure out the number of cells by looking at the balancing plug. Or any one that doesn't have a built in balance system.

Having the charger guess the cell count from voltage alone, or relying on the user to put it in is probably asking for trouble in the long run.

Now I am talking about a lipo charger here, just to be explicit.
All the chargers I have (non automatic cell count) compare the users input on cell count (voltage setting) to what the charger sees at the balance plug. If the balance line is connected to the charger, the charger will fault if the counts don't agree.

Without a balancing system or the balance system not used, all bets are off.
Last edited by hoppy; Apr 22, 2013 at 01:47 PM.
Apr 23, 2013, 02:43 AM
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john4565's Avatar
Quote:
Originally Posted by cloud_9
Thanks everyone. So it's using the voltage you input (or number of cells). It's not using the mah of the pack or the charge rate in C. So it doesn't matter how much mah the battery has. As long as I know my pack is 4S, I dont' need to know the mah.

Right?


Jim
If you don't know the mAh capacity of the pack how are you going to determine the maximum current the charger can pump into the LiPo (apart from the small purpose built charger/LiPo systems I've never seen a charger that didn't want you to tell it this bit of info; but I also haven't played with many LiPo chargers)? So, in my opinion, not knowing the mAh capacity of the pack is a bit of a problem and Abenn at post #2 made a good suggestion of weighing the pack and comparing it with similar size packs to estimate the mAh capacity; alternatively you'd have to be very conservative and charge at a low rate to avoid the risk of damaging or destroying the pack.
Apr 23, 2013, 02:56 AM
Jim in the Desert
Thread OP
Quote:
Originally Posted by john4565
If you don't know the mAh capacity of the pack how are you going to determine the maximum current the charger can pump into the LiPo (apart from the small purpose built charger/LiPo systems I've never seen a charger that didn't want you to tell it this bit of info; but I also haven't played with many LiPo chargers)? So, in my opinion, not knowing the mAh capacity of the pack is a bit of a problem and Abenn at post #2 made a good suggestion of weighing the pack and comparing it with similar size packs to estimate the mAh capacity; alternatively you'd have to be very conservative and charge at a low rate to avoid the risk of damaging or destroying the pack.
That's exactly why I asked the question to begin with.
Apr 23, 2013, 07:03 AM
Registered User
I think we all kind of got sidelined. He really asked two questions:
1. How do lipo chargers know when to switch from CC to CV?
2. I want to charge a battery of unknown mah (label fell off).

These two questions are really unrelated since the switch from CC to CV has nothing to do with the mah of the pack.

I would hope you know how many cells it is at least, the balance plug tells you that after all. So do what abenn said and compare the weight to some other batteries out there. Charging is not an exact science, as long as you don't charge at drastically higher rate then the pack is rated for you are fine. Any battery made in the past 5 years will likely take a 2C charge without problem and some people charge at only 0.5C or even less on low power chargers. So say it's a 1300mah pack, that means you've got a safe charging range from 600mah to 2600mah (or more) that nothing bad should happen.

If you weigh the pack and tell us the weight and the cell count, even maybe provide a photo, the collective here can tell you what to charge it at and maybe even identify it.
Apr 24, 2013, 07:01 AM
Southern Pride
everydayflyer's Avatar
Quote:
Originally Posted by john4565
If you don't know the mAh capacity of the pack how are you going to determine the maximum current the charger can pump into the LiPo (apart from the small purpose built charger/LiPo systems I've never seen a charger that didn't want you to tell it this bit of info; but I also haven't played with many LiPo chargers)? So, in my opinion, not knowing the mAh capacity of the pack is a bit of a problem and Abenn at post #2 made a good suggestion of weighing the pack and comparing it with similar size packs to estimate the mAh capacity; alternatively you'd have to be very conservative and charge at a low rate to avoid the risk of damaging or destroying the pack.
FYI There are chargers which you can set to 1C,2c or 3C charge rate and they will automaticly figure out the correct charge rate. Some find this feacture convient as one does not have to remember to change charge rates for different capacity LiPolys.
Apr 24, 2013, 10:35 AM
Jim in the Desert
Thread OP
Here is a pic and the weight of the battery.

However, though I would like to charge this battery, I posted because I want to understand if a lipo charger can detect when to stop charging, regardless of the settings. It has a thunderpower balance connector BTW. I have a TP to Align adapter attached to it.

I bought this used about 7 years ago, have never used it.

Thanks...
Jim


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