audio-talk

New on the block(?) to me anyway I bought some AAsize rechargeable lithium ion batteries ( to give my busking amp a chance to extend my performance up to 5 or so hours as Roland claims is possible.

These batteries do not at all like chargers that are quick charge for nimhs (?) and from adverts it looks like usb from your laptop is used to get 5 volts at 1 or 2 amps. This'll take a couple of hours per battery I'm guessing.

Can anyone throw light on this issue ( no one in Bedford knows what's up and why, that I've asked even if all they do is sell batteries) ?

I'm not really familiar with lithium ion, more a lithium polymer boy....but

do they have a 'C' rating amongst the print, and a capacity figure?
I beleive that ion are similar to poly in characteristics but a slightly smaller nominal voltage, i.e 3.7 for poly and 3.6 for ion.

if they have a 'C' rating it will determine the max current you can safely draw and capacity will indicate the best current to charge at.
the 'C' rate will tell you that the max current is the C number x capacity.
Most advertise a standard charge at 1 x capacity, I usually charge at 1/2 C.
quick charge can be 5 or 10 times capacity.
e.g if the battery has a capacity of 2000 mah(milliamp hours) then I charge at 1000 ma(1 amp)

I'm not sure what the domestic chargers do to lithium batteries but the chargers we(modellers) use for LiPo charge multiple cells in balance and have many safety features such as temp sensors and adjustable cut-off points. These chargers have settings for the type of battery being charged and can adjust for many types, e.g Pb NiMh NiCd LiOn LiPo LiFe and display warnings such as never charge a LiPo with NiCd or NiMh settings etc.

the above may, or may not help

generally domestic chargers have a fixed current and will have a voltage slightly above the fully charged voltage of the target battery. A fully chatged LiOn cell should be 4.1 volts so the charger should show slightly more than that. I would imagine that a fixed charger should supply current less than or equal to the capacity of the cell.

Complicated innit. Much to think about, thanks Ed.

hang on...it seems, after some googling, that I may have given you some mis-information, or at least info not pertinent to what you have.

breaking news to me that domestic lithium batteries now come in 1.5v flavours for AA sizes.
If this is the type you have then I can only suggest you try the proper charger, as advertised on Amazon.

paenitet me

Yeeeeehhhhsssssd, rather expensive because they give you so much data. I just want z full charge!

andrew Ivimey wrote: ↑Sat Sep 04, 2021 9:25 am Yeeeeehhhhsssssd, rather expensive because they give you so much data. I just want z full charge!

expensive?



https://tinyurl.com/2mkth34d

Hmmmm that's reasonable!

So it's been a while and I have been using AA li-ion batteries in a busking amplfier (boss ex street) and AAA batteries in ( flashing( bike lights.

They last a very long time.

I don't have much experience of AA and AAA batteries but nim-h rechargeable are weedy drippy crummy batteries in comparison.

So far these li-ions appear to be very good indeed. They seem not to wind down so much as be full on until they are off.

Li go unstable when low on charge, so better topping up before <30%. Hence the early days of Vapes spontaneous combustion when put on charge, was because the vape’rs were flattening them too low to the batterie’s instability point, then plugged into a non intelligent mobile charger. We were banned from charging vapes in British Gas Van’s as a result.

I had a quick look, seems as I suspect from Andrews post that most of them now include battery management hardware, and that may well include switching converters to maintain the voltage a 1.5v until discharged when they will shut down. So you cant misuse them. The native voltage is closer to 3.2v. Also seen some with USB plugs and sockets to allow direct charging. Just don't use them for valve bias

“Just don't use them for valve bias ” good point.