Rechargeable batteries - how many times?

Reply

  #1  
Old 01-19-18, 10:21 AM
Member
Thread Starter
Join Date: Jan 2015
Location: USA
Posts: 463
Received 2 Votes on 2 Posts
Rechargeable batteries - how many times?

My wife and I are frequently at odds over TV remote batteries. Our xfinity remotes are lit so they seem to drain quickly. My wife favors cheap batteries from the dollar store while I want to go with rechargeable ones. So far dollar store batteries have won out.

My question is a simple one on rechargeable battery life. The batteries I'm considering (eneloop) claims they can recharge up to 2,100 times - which basically means forever. (If a charge lasts a month, 2,100 charges is 175 years.) Broadly speaking, for rechargeable batteries, is this anywhere near realistic? Or is there some other number of recharges that is still worthwhile, perhaps 210 recharges? Or are rechargeable batteries and dollar store batteries the same overall cost, just with different approaches?
 
Sponsored Links
  #2  
Old 01-19-18, 10:35 AM
Forum Topic Moderator
Join Date: Sep 2005
Location: USA
Posts: 4,639
Received 19 Votes on 18 Posts
The 2100 number might be the number of times the battery can be recharged, but NiCad/NiMH batteries (like the AA or AAA) you'd be getting, store a bit less charge every time they are recharged. So maybe 200 recharges is a more reasonable number. Older NiCad would probably be 100, NiMH maybe 200-300?

Even if you get 20 charges out of it, a rechargeable battery will be cheaper, but you have the hassle of waiting for them to charge, or having a second set already charged. If you go through a lot of them, rechargable is the way to go.

But then again, as the saying goes... "happy wife, happy life". How much are those dollar store batteries really worth?
 
  #3  
Old 01-19-18, 10:48 AM
core's Avatar
Member
Join Date: Jan 2007
Location: Des Moines, IA
Posts: 1,127
Received 0 Votes on 0 Posts
I have been an Eneloop junkie for many many years now. I've never had one fail on me or even begin to go bad, unlike the other inferior NiMH rechargeables like Energizer, etc. Since I've never had an Eneloop go bad, I have no idea how many recharges it will withstand.

Let's say a dollar store 20-pack of AA "heavy duty" batteries sells for $3. These are not alkalines (which would cost more); these are way cheap zinc-chloride ones. Let's assume 1000 mAh in those "heavy duty" ones. Cost is $0.15 per AA battery. Let's say an AA Eneloop costs $2.40 and has a 1900 mAh capacity.

Using those numbers, and ignoring the negligible cost of electricity (a fraction of a penny), the break-even point is 8.4 recharges. So if you can get just 9 recharges (!) you've come out ahead $$-wise with the Eneloops. To say nothing of the environmental gains and all the fuss saved by not having to buy the batteries.

So you can see it's not even a contest regardless of how accurate Sanyo's claims are. Tell the wife she can continue to use the Dollar Store ones for devices that benefit from higher voltages. Remotes aren't generally on that list, and I ain't saying what is on that list.
 
  #4  
Old 01-19-18, 11:29 AM
Member
Thread Starter
Join Date: Jan 2015
Location: USA
Posts: 463
Received 2 Votes on 2 Posts
Using those numbers, and ignoring the negligible cost of electricity (a fraction of a penny), the break-even point is 8.4 recharges.
Core: Thanks for the info. I don't doubt your statement but would appreciate an explanation of the calculation so I could understand it going forward.
 
  #5  
Old 01-19-18, 01:57 PM
core's Avatar
Member
Join Date: Jan 2007
Location: Des Moines, IA
Posts: 1,127
Received 0 Votes on 0 Posts
would appreciate an explanation of the calculation so I could understand it going forward
Dollar store $0.15 zinc-chloride ones, 1000mAh (1.0Ah)
= $0.15 / 1.0 Ah = $0.15 per amp hour

Eneloop $2.40, 1900 mAh (1.9 Ah) for _one_ charge
= $2.40 / 1.9 Ah = $1.26 per amp hour

So you can see that the Eneloop is 8.4 times as expensive ($1.26 / $0.15) if you were going to throw it away after one use. So logically it follows that that's exactly how many recharges it would take to break even with the El Cheapo battery. You could do the same thing with dollar store _alkalines_ if that's what she buys. The end result will be very similar.

I didn't take into account the gradual loss of capacity that Zorfdt brought up. They do lose capacity over time, but with Eneloops this is such a non-issue it's not even funny. Certainly it's not an issue with the time period we're talking about. I also didn't take into account the small voltage difference. Call me lazy.

I guess to be fair you'd also have to factor in the cost of the charger. As for power cost to recharge, I had come up with about 1/5th of a penny per AA using my local power costs of 11.5 cents per kWh, but that was just a quick estimation.

The real cost of owning Eneloops comes from the fact that you'll start buying them for everything in your house once you see how reliable they are. That turns into some real $$$. And then you have the C-size and D-size spacers that you'll find you can't live without.
 
  #6  
Old 01-19-18, 02:02 PM
Norm201's Avatar
Member
Join Date: Sep 2013
Location: United States
Posts: 7,275
Received 59 Votes on 57 Posts
Dollar store batteries are exactly what it says. $1.00 What do you expect? Spend a bit more on a name brand (Engerizer for instance) and you'll get better life. However, a light will drain a battery quickly. So don't keep the light on. I use feel on my remotes and can feel which buttons I need to touch. My batteries last at least 6 months or more.
 
  #7  
Old 01-19-18, 02:17 PM
Forum Topic Moderator
Join Date: Mar 2005
Location: USA - N.E.Tn
Posts: 46,045
Received 118 Votes on 105 Posts
Y'all must watch more TV than we do. My wife thinks the remote to the TV in the living rm might have batteries running low - they've been in it since the TV was new, 2 yrs ago. The batteries in the bed rm remote are also several yrs old. My previous PC had wireless mouse/keyboard - I couldn't keep batteries in it, go figure. We seldom buy anything but Duracell.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description: