Greetings,
Just as the title says, I want to make a portable recharger circuit for a phone, but I have a problem with the choice of batteries. I got some unused Li-ion phone batteries (about 3 or 4), I really want to make use of them, is it okay to use them in a parallel connection to the recharging circuit ?

 

In general, you can only do that IF they are all they exact same kind at the exact same voltage, used always together. Otherwise you need a ton of protection/charging circuits. But ALWAYS be careful with those explosive lion batteries.

Edit: Li-ion

 

In general, you can only do that IF they are all they exact same kind at the exact same voltage, used always together. Otherwise you need a ton of protection/charging circuits. But ALWAYS be careful with those explosive lion batteries.

Edit: Li-ion

Sorry if i ask many questions, but I believe they are nearly 3.7 volts, one of them is written on it 3.6v, is it going to be fine ? is there another type of Li-ion battery, a non-explosive type you mean ?

 

Don't those phone batteries have their own protection circuits built into them? I believe I tore one apart and used the circuitry (didn't tear the battery apart, just the jacket covering the electronics). Used it on another LI-on battery that didn't have one but fit inside my dash cam.

LI-on batteries can be very dangerous. If they short out they can quickly overheat, vent gas and even explode. I had one that was swollen like a bed pillow. That's why I replaced it in my dash cam. As long as the batteries are identically rated and are of identical chemistry then chances are you're good. But when you start mixing different sizes (amperage I mean) when you charge them as a group one battery will draw more current than the rest. Without protection circuitry you could have a dangerous situation on your hands. And in your face too.

Personally, I wouldn't try mixing batteries. If I want a portable power source then I'd just buy one. It's a lot cheaper to replace one of those than to replace my beautiful bald head.

 

Don't those phone batteries have their own protection circuits built into them? I believe I tore one apart and used the circuitry (didn't tear the battery apart, just the jacket covering the electronics). Used it on another LI-on battery that didn't have one but fit inside my dash cam.

LI-on batteries can be very dangerous. If they short out they can quickly overheat, vent gas and even explode. I had one that was swollen like a bed pillow. That's why I replaced it in my dash cam. As long as the batteries are identically rated and are of identical chemistry then chances are you're good. But when you start mixing different sizes (amperage I mean) when you charge them as a group one battery will draw more current than the rest. Without protection circuitry you could have a dangerous situation on your hands. And in your face too.

Personally, I wouldn't try mixing batteries. If I want a portable power source then I'd just buy one. It's a lot cheaper to replace one of those than to replace my beautiful bald head.

They are old Nokia batteries I took from Symbian OS phones, their capacities and sizes are close to each other but I'm afraid of charge rate if I'm going to build them to be recharged all together, is safe if i build a recharging circuit with few diodes as protection to an AC source ? if it isn't safe, can I just use them together to charge another battery and then recharge them one by one, i mean they would be only discharging in this case.

I truly agree with you on the case of safety, I'd give up on it if it causes even a slight effect, I just want to know if it's possible.

 

They are old Nokia batteries I took from Symbian OS phones, their capacities and sizes are close to each other

Two things you say puts me off from telling you to go ahead with this project. At least two. Likely there are a few other issues that need to be covered.

First, I'm NOT the expert on this subject. But of these two things that bother me are that they are "OLD Batteries" I'd doubt it, but I fear if they don't have protective circuitry within them. So that's the first issue I see. The second I see is the "Capacities and sizes are close". Close isn't what anyone said. We've said if they're a match in voltage and capacity. IF not then no, you can't mix them together. It's like the bible story about yoking a bull and a donkey. One will cary the lion share of the burden while the other will do very little. One will give out and can potentially cause you serious problems. So I wouldn't use batteries that are "Close".

You ask other questions as well, and frankly, I don't get a feeling of confidence that you know what you're doing. I know asking is the right thing to do but what you may refer to as (oh, lets say "Banana") we might call a Carrot. Unless we're speaking the same basic language there's potential for misunderstanding. And I wouldn't want to be misunderstood and have that cause injury to anyone. "A charging circuit with some diodes attached to an AC source" is what bothers me most about communication. So I think we'd need to take you from the very most basic part of understanding what you're doing and get a clear picture of where you start LONG before you start connecting batteries together. Maybe it's me who doesn't understand, but a few diodes as a protection circuit doesn't strike me as a wise choice. Unfortunately I have to go out and won't be able to give this any more attention before this evening. If someone else can pick up and run with it - as long as you are clear and have a clear understanding I think you'll be OK. But still, mixing batteries that aren't "The Same" is a "No - No."

 

Parallelled batteries do not need to be the same capacity. They do need to be the same chemistry so that the charging merhod is the same for both of them, and they need to be at the same terminal voltage when they are parallelled. Once that is done, the voltage of each must stay the same during charge and discharge since that is forced by being in parallel. They basically act as one battery then.

Bob

 

Two things you say puts me off from telling you to go ahead with this project. At least two. Likely there are a few other issues that need to be covered.

First, I'm NOT the expert on this subject. But of these two things that bother me are that they are "OLD Batteries" I'd doubt it, but I fear if they don't have protective circuitry within them. So that's the first issue I see. The second I see is the "Capacities and sizes are close". Close isn't what anyone said. We've said if they're a match in voltage and capacity. IF not then no, you can't mix them together. It's like the bible story about yoking a bull and a donkey. One will cary the lion share of the burden while the other will do very little. One will give out and can potentially cause you serious problems. So I wouldn't use batteries that are "Close".

You ask other questions as well, and frankly, I don't get a feeling of confidence that you know what you're doing. I know asking is the right thing to do but what you may refer to as (oh, lets say "Banana") we might call a Carrot. Unless we're speaking the same basic language there's potential for misunderstanding. And I wouldn't want to be misunderstood and have that cause injury to anyone. "A charging circuit with some diodes attached to an AC source" is what bothers me most about communication. So I think we'd need to take you from the very most basic part of understanding what you're doing and get a clear picture of where you start LONG before you start connecting batteries together. Maybe it's me who doesn't understand, but a few diodes as a protection circuit doesn't strike me as a wise choice. Unfortunately I have to go out and won't be able to give this any more attention before this evening. If someone else can pick up and run with it - as long as you are clear and have a clear understanding I think you'll be OK. But still, mixing batteries that aren't "The Same" is a "No - No."

I'm really sorry for any misunderstanding, this has to be because I didn't write enough explanation for the project, I'll write down everything I can explain :
The first link for a BLC-2 battery for old Nokia phones, 3.6v and 950mAh. The second link is for a BL-4U Nokia Battery of 3.7v and 1000mAh, I have 2 of these. Both types of batteries are in a good condition, they were lightly used, one of them is unused, and have not taken a pillow shape yet, I feel a little sad if i just throw them away when they still can be used in something.

I thought if we could use a simple circuit as a protection for the batteries but not to protect from the AC source, actually to prevent batteries to charge one another, connecting diodes between batteries to prevent reverse current and voltage. I'm just gathering information about the safety of the project, I saw other projects using a 18650 Li-ion type batteries with few modules ( http://www.instructables.com/id/Homemade-DIY-Power-Bank-Using-18650-Battery/) , but only 1 was used which made me worried if i have to use more than 1 battery. so if its all okay, I'll start working on an actual circuit.

https://www.ebay.com/itm/NEW-GENUINE-NOKIA-OEM-BLC-2-BLC2-BATTERY-3-6V-LI-ION-900MAH-/261393064681
https://www.ebay.in/itm/Genuine-Bat...212-6216-6600-8800-E66-E75-3120-/272577198974

 

connecting diodes between batteries to prevent reverse current and voltage.

Not necessary, did you read my post? Once they are paralleled it is impossible for them to have different terminal voltages since the two + terminals are shorted together and the two - terminals are shorted together.

Bob

 

What if you put them in the same pack but used them as individual batteries? You could have fets or optos or something that connect and disconnect the right batteries so only one is being used at a time. Then they got charged seperatly too. It seems like it may be the only way.

 

What if you put them in the same pack but used them as individual batteries? You could have fets or optos or something that connect and disconnect the right batteries so only one is being used at a time. Then they got charged seperatly too. It seems like it may be the only way.

This is a good alternative, if multiple batteries wont work together, I'll try to work on this.

Not necessary, did you read my post? Once they are paralleled it is impossible for them to have different terminal voltages since the two + terminals are shorted together and the two - terminals are shorted together.

Bob

that sounds great. Is it safe to use the batteries I linked above with those specifications ? is there also a method to use all the batteries or maybe the same kind together ?

 

that sounds great. Is it safe to use the batteries I linked above with those specifications ? is there also a method to use all the batteries or maybe the same kind together ?

If they are the same chemistry, yes. There are a few variants of lithium ion batteries, which have sightly different votages.

Bob

 

didn't tear the battery apart

Don't ever never ever take apart the ion battery they can gas out and it can kill you, If you breath in the gas.

 

Don't ever never ever take apart the ion battery they can gas out and it can kill you, If you breath in the gas.

Iam trying to use batteries without modifying them. would they leak if I charge them together ?

 

Phone batteries would have to be the same I don't think you'll have much luck with charging 3 phone batteries at one time.

These newer batteries take a lot to charge and older ones wouldn't be much good cause of life span of these things are not that great.

3 newer one's would take a 5 volt 4 amp supply to charge. Plus a charger made for 3 batteries