• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

max current on rechargeable PP3 battery ?

Status
Not open for further replies.

defcon31

New Member
hello,

i have something that normaly works with an 220V->9V adapter, but on that thing is mentioned that it asks 500mA...
now, i changed the adapter with a (rechargeable) PP3 battery (9V) of 150mAh... so in the beginning its normal that i have to recharge my battery after 20minutes...
but that after everytime recharging my battery the 20min became less and less and after a few weeks i can only work 4min with it...

is it possible that the rechargeable batteries become damaged because of the large current they have to provide ???

thanks in advance
 

Nigel Goodwin

Super Moderator
Most Helpful Member
NICAD batteries do deteriorate with use, and are only rated for a relatively low number of recharge cycles. If it only lasted 20 minutes from new, presumably it's been through a LOT! of recharge cycles in a very short time?.

It's probably not a good idea to run something that takes that much current off a small battery, you really need something much larger, which will be more able to provide those current levels.
 

defcon31

New Member
so it is possible that my rechargeable batteries are damaged (after recharging not more than 15 times) because of the high current they have to provide ?????

so isnt it a good idea to take 5 of those batteries in parallel at te same time ? so they have to provide each a fifth of the current.... is this a solution ?
 

Sebi

Active Member
This 150mAH battery pack need only 15mA charge current and 14hours.
Apply a serial resistor or current limiter.
BTW: the simply 9V 500mA adapter give most of case about 13...15V with smaller load!
 

Nigel Goodwin

Super Moderator
Most Helpful Member
defcon31 said:
so it is possible that my rechargeable batteries are damaged (after recharging not more than 15 times) because of the high current they have to provide ?????

so isnt it a good idea to take 5 of those batteries in parallel at te same time ? so they have to provide each a fifth of the current.... is this a solution ?
It's quite possible they could be damaged, how are you charging them?.

I wouldn't advise paralleling NICAD's, use bigger batteries - single cells in series would be far better - eight would give you 9.4V, which is a reasonable replacement for a 9V dry battery.
 

Trini

New Member
That is about right. Running a 150mAH battery at 500mA will only give you about 20 minutes when the battery is new but it will very quickly deteriorate. The normal discharge rate for a 150mAH battery is 15mA for 10 hours.

Your best bet is to use Nickel Metal Hydride (NMH) batteries..... eight in series. You can get them as "penlight or AA" size at Radio Shack. If you buy the 1800mAH ones, they should last about three and one half hours before they need recharging.


Trini
 

Nigel Goodwin

Super Moderator
Most Helpful Member
defcon31 said:
Trini said:
eight in series.
Trini
eight in parallel you mean, isn't it??? eight in series will give me 8*9V=63V or am i wrong ???
Yes, you're wrong! - as I mentioned above, it's not a good idea to put batteries in parallel. The batteries mentioned were specified as AA cells, these are 1.2V each - 8 in series will give you 9.6V (not 9.4V as I previously typed wrong).
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top