Batteries Discharge and Recharge time.

[Moha99]

A bit unfortunate that the data sheet doesn't give recommended charging info
But I will tell you now, if you intend to continuously fast charge and discharge
Don't expect the batteries to have a long life till they fail

That's from experience, using fast chargers out in the field to charge same type of battery when doing storm chasing filming/ photography

Dave

Dave

Well Dave battery life is not a priority to me right now... I want to balance the discharge and re-charge rate thats really what I want to active and i think the only way to do so is to give more power while recharging the batteries.

Does this generally apply to all type and kinds of batteries or only this type?

 

[(*steve*)]

If I were you, I would use protected LiFePO4 cells and charge them from a current limited voltage source. Set the voltage to just under the recommended end point for charging (say by 0.1V to 0.2V).

Leaving them to float charge at this voltage isn't the best for them, but the reduced float voltage will be somewhat kinder.

Using protected cells means there's less chance of disaster if you do it wrong.

Using LiFePO4 cells means that disaster generally means a bit of black smoke rather than a potentially pyrotechnic explosion.

Even easier, you can get 1 chip solutions for charging lithium cells but you may need to be very explicit when ordering to get the one which matches your cell type.

 

[(*steve*)]

Does this generally apply to all type and kinds of batteries or only this type?

Yes, and (obviously) no.

Read this.

Especially read the first sentence (which I will repeat below for your benefit)

"NiCad and NiMH batteries are amongst the hardest batteries to charge."

 

[Moha99]

Yes, and (obviously) no.

Read this.

Especially read the first sentence (which I will repeat below for your benefit)

"NiCad and NiMH batteries are amongst the hardest batteries to charge."

checking out the best types of " LiFePO4" batteries that would fit for my circuit! And i hope their more safer than what i have now i got a bit worried there...

Yea I'll check for good voltages that will work for my circuit!

But I need to buy a regulator or a convertor to charge it a very low voltage...

 

[Moha99]

I'm currently check out the best type of "LiFePO4" batteries on ebay!

Steve do you recommend a certain brand?

 

[(*steve*)]

Not particularly. In any case [on Ebay], can you even ensure the brand names are real?

Buy from a reputable source, or take your chances.

The voltage will be about 3V when dead flat, up to a little over 4V when fully charged. If you can live with a single cell you can get away with cheap cells because there is no issues with "balancing" cells.

When considering a charger, remember that the end of charge voltage for various types of batteries differs slightly. So whether you need 4.1, or 4.2 volts is an issue. Picking the wrong value can be bad for your battery. So make sure you know the correct value for your battery. This is another reason to buy from someone who can supply data.

 

[Moha99]

Not particularly. In any case [on Ebay], can you even ensure the brand names are real?

Buy from a reputable source, or take your chances.

The voltage will be about 3V when dead flat, up to a little over 4V when fully charged. If you can live with a single cell you can get away with cheap cells because there is no issues with "balancing" cells.

When considering a charger, remember that the end of charge voltage for various types of batteries differs slightly. So whether you need 4.1, or 4.2 volts is an issue. Picking the wrong value can be bad for your battery. So make sure you know the correct value for your battery. This is another reason to buy from someone who can supply data.

Then where do you think i should buy it from? Im not really sure what brand is the best... I would like to buy it online so if i can buy it directly from a brand would be perfect.

I will probably need about 3 to 4 volts in which is perfect and i'll recharge it with more energy which is why i need to contact the supplier and that would be good with a good brand name.

 

[Moha99]

Yea on eBay there were a few that were perfect for my requirements so thanks everyone!

 

[Moha99]

Alright I found a good Lifepo4 battery that is rated at 3.3V and 2.3AH

So now i was thinking about the batteries discharge and re-charge process...
If im using 3.3V at 2.3AH for one hour 7.59Watts/Hour... I'll drain it dead.

If I re-charge it with 3.6 at 3Amps wich is 10.8Watts/Hour I'll recharge the battery in 45Mins good deal for me

Here's the link if anyones interested:

http://www.ebay.com/itm/1-PCS-NEW-A...s=63&clkid=7467869482327333899#ht_3423wt_1216

 

[(*steve*)]

7.59Watts/Hour...
10.8Watts/Hour

It's actually watts * hour, otherwise known as Wh.

Because if you are drawing the same power in watts for 2 hours instead of 1, the total amount of energy is greater

A 26650 cell is a good size. A battery holder for it may be a bit of a challenge though.

Note the internal resistance. It gives you a theoretical short circuit current of over 400A

 

[Moha99]

It's actually watts * hour, otherwise known as Wh.

Because if you are drawing the same power in watts for 2 hours instead of 1, the total amount of energy is greater

A 26650 cell is a good size. A battery holder for it may be a bit of a challenge though.

Note the internal resistance. It gives you a theoretical short circuit current of over 400A

"A battery holder for it may be a bit of a challenge though." What do you mean by that?

"Note the internal resistance. It gives you a theoretical short circuit current of over 400A" Should I be worried about that?

And one last thing is that... Can I successfully charge it faster then it discharging as I stated earlier?

 

[(*steve*)]

"A battery holder for it may be a bit of a challenge though." What do you mean by that?

I assume you're not going to employ someone to hold the wires onto the end of each cell.

In that case you'll need to attach wires and secure the battery, or get some sort of battery holder to hold the battery in place. You may not be able to get these parts off the shelf.

"Note the internal resistance. It gives you a theoretical short circuit current of over 400A" Should I be worried about that?

Only if you short circuit one of these batteries. My recommendation is not to do that.

And one last thing is that... Can I successfully charge it faster then it discharging as I stated earlier?

Sure. Don't exceed any ratings that you might be given, and remember that slower charge/discharge typically results in longer cell life. Don't push things too far.

Your calculated charge/discharge rates seem fine. Ensure that your charger is both voltage and current limited.

 

[Moha99]

I assume you're not going to employ someone to hold the wires onto the end of each cell.

In that case you'll need to attach wires and secure the battery, or get some sort of battery holder to hold the battery in place. You may not be able to get these parts off the shelf.

Ah! hahaha no, no I'll solder the wires to the terminals of the batteries.

 

[zamilac]

Yeah; it's depend upon your battery condition, of course it'll take more energy.

 

[Moha99]

I found a good re-chargeable Li-Ion battery from Tenergy that i find fairly good
here it is: http://www.tenergy.com/30012

Now I only worry about the charging and discharge rate.
The batteries is rated at 2200mAh and the maximum discharge current is 1C = 2.2Amps will I be able to draw the 2.2Amps from the batteries if my appliance needs to?

and the rapide charging is Rapid: 1.0C x 2.5 hours, does that mean if i supply the battery with 2.2Amps it will be charged after 2.5 hours?
Im just asking could I charge it with 4.2volts and 2XC = 4.4 Amps to charger it quicker than discharging it?

I don't really know what the best way if you all can see whats best please share it
my goal is to charge it faster than discharging it.

 

[Moha99]

So far could not find proper batteries that can fulfill my goal some batteries even supplied with more energy will take double the discharge time...

Most fast chargers are 4 times or even 10 times more than the rated current for the battery to charge it faster.
But those batteries are discharged for example in an hour of use and dies then recharged with that high current in 10 or 15 or 20 minutes. But I want to balance it... 1 hour of discharge and 1 hour of charging.

 

[jackorocko]

I don't think you want to apply 2.2A constant current to a li-ion cell till it's charged. There is a proper method

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

 

[Moha99]

I don't think you want to apply 2.2A constant current to a li-ion cell.

why?

Please give me some details and if you know what best types of small rechargeable batteries specific brand would be perfect

 

[(*steve*)]

The point is not what batteries would be best, but that you need to follow the charging rules for the battery that you use.

In the case of Lithium rechargeable batteries, the appropriate source is a current limited voltage source (this is not appropriate if they're really flat). This will cause the current to reduce as the battery nears full charge. After a certain minimum current has been reached, the charging should terminate (actually there is a delay here, but it's not so important)

 

[Moha99]

The point is not what batteries would be best, but that you need to follow the charging rules for the battery that you use.

In the case of Lithium rechargeable batteries, the appropriate source is a current limited voltage source (this is not appropriate if they're really flat). This will cause the current to reduce as the battery nears full charge. After a certain minimum current has been reached, the charging should terminate (actually there is a delay here, but it's not so important)

I've contacted a specific battery brand that are very good.

The technical assist that i received was perfect.

And the person I'm working with will stay up to date with my work he recommended me the NiMH batteries and told me the proper steps I need to re-charge it with my specific conditions.

He told me its possibile to re-charge the batteries faster than discharge and I had to apply more energy IN the charging process

but the problem with that is... It kills the battery fast which is not a priority to me right now anyways

Anyways everyone I appreciate the help thank you all.