Discussion Batteries

GC64

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GC64

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I just bought some new 18650s because I thought I damaged the old ones (they were draining significantly fast), but I'm having trouble with the new ones so I'm starting to think nothing was wrong with the old ones. Basically I have two sets each wired in series and then the two packs wired in parallel (should total to 7.4v at 6800mah). Apparently, "BM" on the PCB is where the "battery middle" should be wired from each set (the line of each set that connects positive of one to negative of the other). Basically I just connected my batteries in series like normal, and attached a wire going from each set to the BM. The only way for both to be connected is to have the middle wire of each set connected to each other, so now they are. Can they be connected? I used my multimeter and nothing is being read from the +P and -P. It also says positive and negative are connected (but I didn't connect them). I honestly don't know what the problem is, but I feel like it has something to do with BM..

EDIT: forgot to add pics, sorry.
IMG_4115.JPG IMG_4116.JPG IMG_4117.JPG
 
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GC64

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Did you connect the charger to P+ and P-? The board won't output power until you do that
I actually don't have the charger yet (I'm waiting till I'm able to spend another 40$ for it), but I shorted B- and P- and that actually got it working. My only issue is, the battery life still seems amazingly short for what it should be. Do I have to fully charge them or something before they can last their normal time?
 

GC64

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Yeah, lithium batteries can't legally be shipped fully charged, and most manufacturers only charge them a little bit to save on costs
Well they came at 7.1v but died to around 5.8v within about two days. Is it normal for them to lose this much voltage in this amount of time? Like I said, I hadn't charged them at all so I'm not sure if chargining beforehand will make this range last longer or not.
 

cheese

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Well they came at 7.1v but died to around 5.8v within about two days. Is it normal for them to lose this much voltage in this amount of time? Like I said, I hadn't charged them at all so I'm not sure if chargining beforehand will make this range last longer or not.
Go ahead and charge them and try again.

Open circuit voltage (aka putting multimeter on ends of battery) don't tell you how charged the battery is (with the exception of very high/low voltages). For reference heres a picture with voltage vs percent charge.
 

GC64

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Go ahead and charge them and try again.

Open circuit voltage (aka putting multimeter on ends of battery) don't tell you how charged the battery is (with the exception of very high/low voltages). For reference heres a picture with voltage vs percent charge.
Alright, I'll order the charger soon and hopefully charging them will fix it. Thanks for the help
 

Marnario

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what type of batteries should i pick for my ps2p? how many volts? what if i do not include the CD drive anymore?
It depends on the motherboard your using. I know that if you use the 79000 series board (the small ones), You can use 7.4v batteries. Removing the disk drive will let the portable play for a longer amount of time. This is a question you should ask @Gman
 

cfc_12

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It depends on the motherboard your using. I know that if you use the 79000 series board (the small ones), You can use 7.4v batteries. Removing the disk drive will let the portable play for a longer amount of time. This is a question you should ask @Gman
How do I get a charger? Will the 8.5v ps2 adaptor will be my charger?
 

Vonn

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Having never worked with batteries before, what's a good, single resource for learning about fundamentals of Li batteries and wiring them into projects? Something I could easily reference.
I've skimmed the forums and gathered that you need a protection circuit with lithium batteries, but how can I determine for myself what I should be looking for in cells, PCMs, and how to hook it up to the board and project?
 

Aurelio

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Having never worked with batteries before, what's a good, single resource for learning about fundamentals of Li batteries and wiring them into projects? Something I could easily reference.
I've skimmed the forums and gathered that you need a protection circuit with lithium batteries, but how can I determine for myself what I should be looking for in cells, PCMs, and how to hook it up to the board and project?
Read every single word from this website: http://batteryuniversity.com/
There's a lot of stuff in there :D
 
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