Battery pack - max charge current?

[SirJMD]

Im just wondering.. Whats the recommended charge current for a 14.4V 5Ah pack?


Ive always used a general rule, that says "1/10th the capacity" - but if anyone reommends otherwise, id like to know.

 

[BVH]

What cell chemistry is being used in your pack?

 

[Marduke]

And what termination method?

 

[SirJMD]

BVH --> NiMh.

Marduke --> Large tamiya connector. The cells er soldered together with a copper plate, instead of the standard thin alu/other. Its not home made

 

[Marduke]

I don't mean the connectors, I mean the method of charge termination detection (if any).

Trickle charge on timer?
-dV?

Etc.

 

[SirJMD]

I don't mean the connectors, I mean the method of charge termination detection (if any).

Trickle charge on timer?
-dV?

Etc.

ahh, misunderstod that one.

Im using a Multiplex MultiCharger LN-5014. Im not sure which method it uses for charging, but im guessing its dV.

 

[Marduke]

ahh, misunderstod that one.

Im using a Multiplex MultiCharger LN-5014. Im not sure which method it uses for charging, but im guessing its dV.

It seems to terminate by 0dV, so charging at 0.5-1C seems to be the ideal rate.

In your case, that would be 2.5-5A.

 

[SirJMD]

It seems to terminate by 0dV, so charging at 0.5-1C seems to be the ideal rate.

In your case, that would be 2.5-5A.

Thats quite alot!

I just fear that the battery will get VERY hot, when its inside a search light.

 

[dano]

http://www.candlepowerforums.com/vb/forumdisplay.php?f=9

This may be more helpful.

 

[BVH]

I tend to do my Nimh's at about .7C. They get warm, not hot and have not had any issues with missed termination on a Schulze. But I know different chargers are better than others at termination detection.

 

[SirJMD]

dano --> Ill give it a look !

I tend to do my Nimh's at about .7C. They get warm, not hot and have not had any issues with missed termination on a Schulze. But I know different chargers are better than others at termination detection.

I think im gonna go with the 0.5C - should take max 10 hours to recharge then.

After all, its inside the search light, so the heat got nowhere to go. Gonna play it safe

I ended up paying $80 for a 14.4V 5Ah pack, made with copper plates between the cells, and a 12AWG wire on the connector.

 

[DM51]

Moving this to the Batteries section where it belongs...

 

[SirJMD]

Moving this to the Batteries section where it belongs...

I was looking for that board, but couldnt find it - thanks!

 

[Mr Happy]

I think im gonna go with the 0.5C - should take max 10 hours to recharge then.

After all, its inside the search light, so the heat got nowhere to go. Gonna play it safe

I ended up paying $80 for a 14.4V 5Ah pack, made with copper plates between the cells, and a 12AWG wire on the connector.

Note that 0.5C by definition means "2 hour charge rate" (1/0.5 = 2).

A 0.5C charge on a 5Ah pack would equal 0.5 x 5 = 2.5 amps.

Paradoxically, lower is not always better. A long slow charge at 0.1C (0.1 x 5 = 0.5 amps) for 12 to 16 hours will be fine -- this is called a balancing or conditioning charge. But if you want the charger to automatically stop the charge at the right time (this is what "termination" means), then you need to use a substantially larger charging current like 2 - 5 amps. This will generate a stronger end of charge signal for the charger to detect. The batteries won't get too hot as long as the charger stops when it is supposed to.

On the other hand if you go with a current that is too low, like 1 amp say, then the charger may not get a good indication of when to stop charging, and might overcharge your batteries. This is when they can overheat and get damaged.

 

[SirJMD]

Note that 0.5C by definition means "2 hour charge rate" (1/0.5 = 2).

A 0.5C charge on a 5Ah pack would equal 0.5 x 5 = 2.5 amps.

Paradoxically, lower is not always better. A long slow charge at 0.1C (0.1 x 5 = 0.5 amps) for 12 to 16 hours will be fine -- this is called a balancing or conditioning charge. But if you want the charger to automatically stop the charge at the right time (this is what "termination" means), then you need to use a substantially larger charging current like 2 - 5 amps. This will generate a stronger end of charge signal for the charger to detect. The batteries won't get too hot as long as the charger stops when it is supposed to.

On the other hand if you go with a current that is too low, like 1 amp say, then the charger may not get a good indication of when to stop charging, and might overcharge your batteries. This is when they can overheat and get damaged.

Yea, i misstyped there - i ment 0.1

I gave the flashlight a run today.. quite impressed! Got a nice hotspot, and a big spill - excellent for what i need.

 

[KiwiMark]

Im just wondering.. Whats the recommended charge current for a 14.4V 5Ah pack?

I would go with 3 to 4 amps. I like to charge in less than 2 hours and the batteries should take it just fine. My normal charging is around this level and I use a hobby charger with a thermal sensor on the battery - the temperature doesn't even go up 1 degree until near the end of the charge so I don't think the charge rate causes much heat. Once the cell is nearly full the temperature does rise, but shouldn't go above 45 degrees Celsius before the charge ends.

 

[SirJMD]

I would go with 3 to 4 amps. I like to charge in less than 2 hours and the batteries should take it just fine. My normal charging is around this level and I use a hobby charger with a thermal sensor on the battery - the temperature doesn't even go up 1 degree until near the end of the charge so I don't think the charge rate causes much heat. Once the cell is nearly full the temperature does rise, but shouldn't go above 45 degrees Celsius before the charge ends.

Super, thanks