Rechargable batteries

[anothervictim]

Hello all,

Im asking this question in here because I know that Patrick has covered batteries on system in the past.

So this past weekend I bought a ps3 and rockband, and after playing rockband all weekend long we wore out the batteries on the guitar. So I went to the local target and bought a charge and extra batteries. I figured that since I was going to be playing rock band alot I would just invest in some rechargeables. I bought the rayovac hybrid batteries that are supposed to be ready to use out of the box.

So needless to say when I put them into the guitar, the guitar didn't turn on. So I thought maybe those batteries were dead (even though they were supposed to be ready out of the box) so I switched them with the other pack that I bought.

I noticed that those batteries were rated at 1.2v and the guitar says it needs 1.5v batteries.

So to get to my question after that long over exhausted story is, should it matter that I bought 1.2v and the guitar needed 1.5?

[tehboris]

should it matter that I bought 1.2v and the guitar needed 1.5?

Absolutely, when the voltage of the batteries drops below a certain voltage (even if there is plenty of charge left in a battery) devices that need a specific voltage will fail to work properly if at all.

I recommend to get some NiMH (nickel metal hybrid) battries rated for 2000mAh minimum.

NiMH batteries are designed to hold a constant voltage until they are totally drained.

Disposable alkaline batteries are a big no no here. Their voltage drops as they lose charge.

[lordbyron]

I recommend to get some NiMH (nickel metal hybrid) battries rated for 2000mAh minimum.

NiMH batteries are designed to hold a constant voltage until they are totally drained.



I believe they are only rated at 1.2vdc also. The 2000mAh is the current rating of the battery. Voltage and current are 2 different things, Even though you can't have one without the other. Almost all times 1.2vdc will work in place of 1.5vdc there are times the just will not. If the guitar won't work on Nicads just buy a big pack of good quality alkalines that way when they go dead just put new ones in that way you don't have to wait for them to charge...

[anothervictim]

Well I went to return the rechargeable batteries that I got, and went to look at getting some new ones. It turns out that all of the rechargeable batteries there are 1.2v. The batteries that I purchased the first time I think were rated at 1800mah or 2000mah. So I got some energizers that were rated at 2600mah, I hope these work. It would really suck that I couldn't use rechargeable batteries.

Does anyone know why rechargeable AA batteries are rated at 1.2v, if traditional AA batteries are rated at 1.5v?

[tokenuser]

I recommend to get some NiMH (nickel metal hybrid) battries rated for 2000mAh minimum.BTW - It Nickel Metal HYDRIDE, because it is a hydrogen absorbing alloy (metal), rather than a specific element (like Cadmium - the CD in NiCD).

Definately avoid NiCD batteries. A NiMH have better energy storage rating.

[anothervictim]

A NiMH have better energy storage rating.

Yes from my understanding the "mah" pertain to enery storage and not to the voltage. I think I remember that from the ep Pat and Dave did on batteries.


But why are they only rated at 1.2v and not 1.5v. Wouldn't all components that need 1.5v batteries not work if you stick in 1.2v?

[splat]

NiMH and NiCD battery cells are 1.2 volts by definition. That is the only voltage they are made in. As an example, that DeWalt 18volt cordless drill lying in your garage is constructed of 15 NiCD 2400 mAH "sub C" cells running in series. In contrast, primary (non-rechargeable) AAs are generally manufactured in Alkaline, Oxy Hydroxide, or Lithium (note: different from Li-Ion). These batteries are all 1.5 volts.

Some devices that require AA batteries will accept a lower voltage (ie. 1.2v vs. 1.5), others will not. Xbox wireless controllers as an example run well on the Duracell rechargables (1.2v) I am using.

Also, on a side note, it is not good blanket advice to say "avoid NiCD batteries." NiCD have their purpose. NiCD batteries have two distinct advantages:
1) They can withstand more charge cycles (1000 for NiCD to about 500 for NiMH)
2) They have a severe voltage drop, rather than a gradual one.

For example one, NiCD are sometimes a good use for a home phone. When I use a phone, I usually talk briefly, then place the phone back on the charging cradle. Each time I remove and replace the phone, the battery goes through a charging cycle. I will be able to do this approx. 1000 times with my NiCD battery compared to about 500 with a NiMH. Note: if you talk on the phone for extended periods of time (ie: women) a NiMH with a higher capacity may be right for you. The typical cordless phone battery (sometimes called a size 5, used in most Panasonic handsets, among others) has a NiCD version rated anywhere between 400 and 600 mah while the NiMH versions can get as high as 2500 mAH.

For example two, anyone who knows anything about cordless tools will choose NiCD over NiMH. When working with your tool you don't want he voltage to slowly drop (NiMH) you want it to perform at 100% (or close to it) until it completely dies and needs a charge.

Both NiMH and NiCD suffer from Voltage depression, sometimes referred to as memory. Although the problem is more documented with NiCD and generally more severe, cycling both chemistries in a educated manner is essential for maximum longevity.

[anothervictim]

Thanks Splat, that answers my question as to why the difference in the two.

Well I charged up the new energizers that I bought and placed them into the guitar and it worked just fine.


So A) The Original "ready to use out the box" were really dead and needed charging

or

B) The higher mAh really did matter.

a small correction to my last post, the energizers that I bought are 2500mAh

[splat]

Always willing to help.

You are correct, it's not possible to be 100% charged out of the box. Typical NiMH cells experience a 1-2% discharge per day. It was most likely that they were on the shelf for a few weeks and we around 80% charged.

Also, its not possible that the mAH mattered. All the would effect is run time. An application that can take a 1.2v 2mAH AA could take in theory a 1.2v 2222222222mAH battery and vice versa.