# Can I recharge these batteries without them exploding? **URL:** \ **Category:** Factual Questions\ **Created:** [August 3, 2002, 3:34pm UTC](https://boards.straightdope.com/t/can-i-recharge-these-batteries-without-them-exploding/122180 "2002-08-03T15:34:00Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Eva\_Luna](https://avatars.discourse-cdn.com/v4/letter/e/e495f1/32.png) [@Eva\_Luna](https://boards.straightdope.com/u/Eva_Luna)\ **Post date:** [August 3, 2002, 3:34pm UTC](https://boards.straightdope.com/t/can-i-recharge-these-batteries-without-them-exploding/122180/1 "2002-08-03T15:34:00Z")
In a fit of desperation when my Walkman died, I bought some rechargeable batteries. (Cheaper per-use, better for the environment, etc.) I’ve already got a couple of sets, and they’re great, but they do hold less of a charge after numerous uses, so every once in a while they need to be replaced. My battery charger has NiCd and NiMH settings, which generally do the trick. But when I went to recharge the new set, I looked and realized they just say “rechargeable alkaline batteries.” So is this another animal entirely, or is it another way of naming one of the aforementioned types? If they are different, can I use the charger I already have without exploding them or something? If so, which setting is best? ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [August 3, 2002, 4:06pm UTC](https://boards.straightdope.com/t/can-i-recharge-these-batteries-without-them-exploding/122180/2 "2002-08-03T16:06:33Z")
Rechargeable batteries as a class are somewhat particular about the rates at which they are charged. I was a Radio Shack Manager many, many moons ago and believe me when I tell you that improperly charged batteries can be **real world dangerous**. (think explosions and fire). This [Usenet link](http://groups.google.com/groups?q=rechargeable+alkaline+batteries.%22&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=1993Nov16.212359.18871%40uicc.com&rnum=4)seems to indicate that rechargable alkalines need a specific charger . > [@](#): > > You MUST use the charger that Rayovac sells for these batteries. The trick with the charger is it’s designed to not overheat the battery, which reduces battery life and/or causes leakage or worse. There was a write-up about the patented technology (some Canadian firm developed it, I think) ini “Electronic Engineering Times”, and the trick is that current + voltage is constantly monitored and controlled during charging. If the charger detects overheating, it backs off the current, unlike a NiCd charger. A standard NiCd charger will practially fry alkalines. I cracked open the charger, and saw that Motorola is making the control chip. Having worked for Moto, I’d bet that the technology is sound. Moto probably wouldn’t make the chip if they didn’t believe the technology works. I still have to take the weasel way out and say I could be wrong. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [August 3, 2002, 5:49pm UTC](https://boards.straightdope.com/t/can-i-recharge-these-batteries-without-them-exploding/122180/3 "2002-08-03T17:49:15Z")
rechargable alks require a different charger then Nimh or Nicd. ALso that have much shorted amount a recharge cycles (IIRC about 25 as opposed to 300-1000 for the other 2 types). They might not be worth the expense of a alk recharger if you don’t plan to use rechargable alks. also a big difference is that with Nixx batts it is good to deplete each cell before recharging to avoid memory (really voltage depression) effects but with rechargable alks you should recharge them befor e their depleated. Letting them run down allt he way will limit how much a recharge they will take next time. ---
**Author:** ![Urban\_Ranger](https://avatars.discourse-cdn.com/v4/letter/u/e9c0ed/32.png) [@Urban\_Ranger](https://boards.straightdope.com/u/Urban_Ranger)\ **Post date:** [August 3, 2002, 6:04pm UTC](https://boards.straightdope.com/t/can-i-recharge-these-batteries-without-them-exploding/122180/4 "2002-08-03T18:04:12Z")
No, just NiCad because it has “memory.” NIMH and Li-ion don’t. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [August 3, 2002, 8:22pm UTC](https://boards.straightdope.com/t/can-i-recharge-these-batteries-without-them-exploding/122180/5 "2002-08-03T20:22:37Z")
Nimh batteries do have voltage depression (Li-ion doesn’t but no body’s talking about that here). It just is not as great as NiCd. Nimh are know as memory resistant but will suffer the effects if neglected enough times. My laptop has a (actually 2) Nimh batts and they each came with a note saying to avoid memory effects turn off the powersaver feature and deplete the batteries fully (basically leave the computer on till the batts die) at least once a month. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [August 3, 2002, 8:25pm UTC](https://boards.straightdope.com/t/can-i-recharge-these-batteries-without-them-exploding/122180/6 "2002-08-03T20:25:59Z")
cite > [@](#): > > Despite some manufacturers’ claims that the NiMH battery is “memory free” (not impacted by the memory effect), do not be fooled. Memory resistant is probably a more accurate way to describe these batteries. from [http://www.simplywireless.com/batteryarticle.php](http://www.simplywireless.com/batteryarticle.php) ---
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [August 3, 2002, 8:30pm UTC](https://boards.straightdope.com/t/can-i-recharge-these-batteries-without-them-exploding/122180/7 "2002-08-03T20:30:26Z")
> [@](#): > > \*Originally posted by Urban Ranger \* > \*\*No, just NiCad because it has “memory.” NIMH and Li-ion don’t. \*\* Can you confirm that? If you can it would be a great relief for me as I assumed NiMH batteries had the ‘memory effect’ and dispise having to wait until the battery is used up before I can re-charge it. In the instructions for my digital camera (which works on NiMH only) it says should wait until the batteries are fully discharged before I re-charge them. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [August 4, 2002, 3:57am UTC](https://boards.straightdope.com/t/can-i-recharge-these-batteries-without-them-exploding/122180/8 "2002-08-04T03:57:50Z")
From the Thomas Distributing ([http://www.thomasdistributing.com/](http://www.thomasdistributing.com/)) FAQ: > [@](#): > > Conditioning refers to the ability of a charger to initiate a controlled discharge and to causem the batteries to be at an optimum level for recharging. While this can be done with any battery it is most beneficial to the older style NiCD batteries. The newer style of NiMH batteries due not require this due to their chemical makeup. > > Generally speaking, NiMH batteries do not suffer from the “memory effect” and thus do not require conditioning. Nevertheless, to ensure top performance, conditioning is recommended at once for every ten charges. For Nickel Cadmium (NiCD) batteries, conditioning is recommended every time you charge your batteries. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [August 4, 2002, 1:03pm UTC](https://boards.straightdope.com/t/can-i-recharge-these-batteries-without-them-exploding/122180/9 "2002-08-04T13:03:36Z")
> [@](#): > > Generally speaking, NiMH batteries do not suffer from the “memory effect” and thus do not require conditioning. Nevertheless, to ensure top performance, conditioning is recommended at once for every ten charges this is why they are sometimes called memory resistant. They are still subject to it but doing a discharge-recharge cycle every now and then will prevent/fix the voltage depression (memory) in Nimh. If you read between the lines in the above post you can read into it that Nimh do have some form of memory effect just not as pronounced. If I do not fully discharge my laptop battery in about 3-4 months the run time on the Nimh batt goes down to about 5-10 minutes. By continously discharging and recharging I can get it back to 1.5 hours.