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paulz
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# Posted: 5 Aug 2017 10:05pm
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I have a leftover extra large phone battery I want to use in place of the two AAA batteries that power a small speaker. I tested it, works fine. Can I recharge this battery using a regular USB 5v charger, like you would if it was in a phone? It has 4 terminals, the outer two are + and -. Or do phones have circuitry that limits the charging?
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hamish
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# Posted: 6 Aug 2017 12:05am
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The charger for that old phone will give you all the information you need to know regarding its charging.
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ICC
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# Posted: 6 Aug 2017 12:13am - Edited by: ICC
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Temperature sensing. If you have a high quality multimeter measure the resistance between the two "extra" terminals; not the + and -. The resistance will change as the battery warms or cools. There is a thermistor wrapped in the battery pack. The resistance change in turn will tell the charger to decrease charge current if the cell or battery gets too warm.
3.7 volts is the nominal voltage of the battery. At full charge it will read about 4.2 volts. Going higher than that damages the cell internally. Going below 2.5 or so also damages the internal structure. Never discharge Lion below 2.5 or 2.6. I try to go no lower than 2.9 to 3.0 volts with my lion equipment. Charging after too low a discharge is one cause of those lithium cell fires the news features every so often. Discharged to 3.0 is more or less discharged, IMO.
Phones have a charge circuit built into them. They use the 5 volts from the USB port and step down. You need a charger circuit to be able to charge it. If you are handy something like this could be used. I've used a number of these cheap boards. They do NOT have reverse polarity protection and blow the chip instantly! Be careful.
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ICC
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# Posted: 6 Aug 2017 12:19am - Edited by: ICC
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OOOPs here's the link I missed inserting
http://www.mtnelectronics.com/index.php?route=product/product&path=79&product_id=135
Or just buy a charger like this and run jumpers to your battery.
http://www.mtnelectronics.com/index.php?route=product/product&path=79&product_id=177
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paulz
Member
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# Posted: 6 Aug 2017 09:30am
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Thanks! So with these I don't worry about the two middle battery terminals for the thermistor?
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95XL883
Member
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# Posted: 6 Aug 2017 09:45am
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If I may piggyback on the original question, what about the 1.5 V AA or AAA lithium batteries? To be more specific, what is the lower limit of discharge before recharging becomes a fire hazard? My apologies to the OP if they don't like the piggyback.
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ICC
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# Posted: 6 Aug 2017 01:23pm - Edited by: ICC
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Quoting: paulz So with these I don't worry about the two middle battery terminals for the thermistor
If you don't pack the cell inside a tight enclosure that can not dissipate the heat, no need to worry about the thermistor. The cell states it's 3500 mAh. That can be charged at 1 amp with complete safety. I charge 3000 + mAh cells at 1 amp all the time. The cells are open to the air. They barely get warm.
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ICC
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# Posted: 6 Aug 2017 01:37pm - Edited by: ICC
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Quoting: 95XL883 what about the 1.5 V AA or AAA lithium batteries? To be more specific, what is the lower limit of discharge before recharging becomes a fire hazard?
1.5 volt alkaline and 1.5 volt lithium cells are known as primary cells and are not rechargeable. (FYI, a rechargable cell is known as a secondary cell, can be used a second and more times.)The 1.5 volt lithium disposables have little to no fire danger, unless one tries to recharge them. That could be dangerous. And don't throw them in trash, recycle the expended cells.
As stated above, for a 3.7 volt cell, 2.5 volts is about the lowest voltage that should be used, BUT that can depend on mfg specs. I use 2.8 as my low limit and usually try to stop at 3.0. I use a circuit that cuts power output at the 2.8.
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95XL883
Member
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# Posted: 7 Aug 2017 10:13am
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ICC,
Thank you for the response. Sorry I wasn't clear. I don't try to recharge single use/primary batteries. I don't even try to recharge rechargeable alkaline batteries. (From my experience with it, it wasn't worth the hassle for me.)
I'm asking because I bought an intelligent charger for secondary NiMH, NiCad and Lithium batteries but just tried it on some NiMH. I was about to try it on some rechargeable Lithium AA's that I used and pulled before they were totally discharged. (I haven't measured the voltage yet.) I thought the battery fires were caused by poor battery construction until I read your comment that too deep a discharge will cause a battery fire. That is the statement that caught by attention. I'll measure the voltage and try the recharging tonight, maybe outdoors on the end of a heavy extension cord.
For reference sake, I tried recharging some secondary NiMH over the weekend. The results are disappointing. (These are Energizer brand, not the well regarded Sanyo Enerloops.) The charger says they are charged. My multimeter has their voltage at 1.3V.
I hope the secondary lithiums recharge much better. I am really impressed with both the primary and secondary lithiums I have purchased so far. Their lifespan in the trail cameras is really impressive, taking tens of thousands of pictures.
Thanks again.
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ICC
Member
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# Posted: 7 Aug 2017 12:20pm
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Quoting: 95XL883 ...thought the battery fires were caused by poor battery construction until I read your comment that too deep a discharge will cause a battery fire.
Charging after too deep a discharge can cause overheating and maybe a fire. Poor construction is also a big factor, I believe. There are a number of cheap Chinese made crappy lithium cells out there. Of course there are also a lot of very well made Chinese cells too.
Quoting: 95XL883 I tried recharging some secondary NiMH over the weekend. The results are disappointing. ...........The charger says they are charged. My multimeter has their voltage at 1.3V.
NiMH are rated as being 1.2 volts, at least the Eneloops (Sanyo/Panasonic) I have are stamped 1.2 volts. So yours may be fine. I normally see 1.35 to 1.38 on a fully recharged Eneloop NiMH. They work on devices that are designed for 1.5 volts as the voltage of an alkaline drops quickly under load from their rated 1.5.
Quoting: 95XL883 ...hope the secondary lithiums recharge much better.
Secondary Lithium cells are usually 3.6 to 3.7 volts except for the LiFePO4 type which are 3.2 volts. They are not direct drop in replacements for alkaline or lithium primary cells, nor rechargable NiMH cells.
In the early days of using secondary lithium cells we charged them with a plastic bag of sand suspended over the charger, in the workshop or outside. If they caught fire the heat melted the bag and dumped the sand to extinguish or suppress the fire. I only had one fire and that was in the early 90's. Don't bother with the sandbags anymore.
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paulz
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# Posted: 7 Aug 2017 12:36pm
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Well I'm go to go. Robbed a charging board out of something else, hooked it to my battery, got it up over 4v, played my speaker for a couple hours and it was still over 4v.
Thanks ICC! Carry on.
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95XL883
Member
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# Posted: 7 Aug 2017 02:05pm
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Quoting: ICC NiMH are rated as being 1.2 volts,
That's good to know. I'll pop them in a flashlight when I get home and see how they work.
Quoting: ICC Secondary Lithium cells are usually 3.6 to 3.7 volts except for the LiFePO4 type which are 3.2 volts. They are not direct drop in replacements for alkaline or lithium primary cells, nor rechargable NiMH cells.
Hmmm? Sounds like I don't know what I bought. I took them out a couple of months ago and hadn't looked at them since. I'm virtually certain they are Energizer brand but looking at the Energizer website, they don't offer rechargeable lithium AA batteries. Maybe I got secondary NiMH and just convinced myself they were lithiums.
Apparently Kentli makes rechargeable AA lithiums but I don't have a clue how they would get them to 1.5V.
Quoting: ICC In the early days of using secondary lithium cells we charged them with a plastic bag of sand suspended over the charger, in the workshop or outside.
I still better do these outside or in the garage over a concrete floor. If I damage my wife's kitchen, I'll need a lot more than rechargeable batteries. Thanks again for the help.
PaulZ, thank you for allowing the piggyback. Good luck with charging.
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ICC
Member
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# Posted: 7 Aug 2017 02:37pm - Edited by: ICC
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Quoting: 95XL883 Apparently Kentli makes rechargeable AA lithiums but I don't have a clue how they would get them to 1.5V.
They incorporate a voltage reduction "converter" circuit board ib each cell.
Less capacity than an eneloop.
Here's a review on Kentli from someone I trust.
http://budgetlightforum.com/node/40897
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95XL883
Member
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# Posted: 7 Aug 2017 11:58pm
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Quoting: ICC Here's a review on Kentli from someone I trust.
That was an interesting read. So the Kentli's aren't true 1.5V battteries and they require a specialized charger. Not quite what I would have hoped for. The other interesting point was that power for both lithium and NiMH was stable until almost full discharge and then dropped substantially. That is what I observed from the battery level indicator in my trail cameras. Basically, the batteries worked great and power levels were high and suddenly there wasn't enough power to take a picture. Before anybody misreads, the life span of primary lithiums and secondary NiMH is substantially longer than any alkalines I ever used. The lithiums lasted at least four of the coldest months of the year taking over 3,000 pictures a week. The NiMH lasted longer but the temps were milder.
My age is showing in that my memory about what I have isn't as good as I thought. I have secondary NiMH and primary lithiums in AA. Both are a substantial improvement over alkaline IME.
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