# What if I don't use the right charger for my battery? **URL:** \ **Category:** Factual Questions\ **Created:** [October 18, 2005, 4:38pm UTC](https://boards.straightdope.com/t/what-if-i-dont-use-the-right-charger-for-my-battery/326763 "2005-10-18T16:38:21Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Nature\_s\_Call](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nature_s_call/32/19006_2.png) [@Nature\_s\_Call](https://boards.straightdope.com/u/Nature_s_Call)\ **Post date:** [October 18, 2005, 4:38pm UTC](https://boards.straightdope.com/t/what-if-i-dont-use-the-right-charger-for-my-battery/326763/1 "2005-10-18T16:38:21Z")
Every rechargeable battery stresses, “Only use the charger approved for use… blah blah blah” Assuming I find a transformer with the same output specs (12V, 300 milliamps) shouldn’t it work fine? Is there special circuitry in the charger that wouldn’t also be in a plain jane power adapter for my cordless phone, say? Why I ask? The recharger in my (very old) laptop seems to no workie. I’ve got two perfectly good batteries and I need to charge’em. I could buy a stand alone charger for $200, but I’m just tempted to hold the wires of a power adapter to the + and - of the laptop battery and count to 3,000 (or more, or very slowly). Is this wrong? ---
**Author:** ![mks57](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@mks57](https://boards.straightdope.com/u/mks57)\ **Post date:** [October 18, 2005, 5:08pm UTC](https://boards.straightdope.com/t/what-if-i-dont-use-the-right-charger-for-my-battery/326763/2 "2005-10-18T17:08:13Z")
If you want to go for the worst case, the wrong charger could start a fire or cause the battery to explode. If you don’t know what you are doing, use the charger specified by the device’s manufacturer. Lithium batteries in particular, respond poorly to improper charging. The battery and the charger are a matched system, designed to safely charge the battery. The charger and/or battery may contain circuits that prevent unsafe conditions in the battery. ---
**Author:** ![Si\_Amigo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/si_amigo/32/2877_2.png) [@Si\_Amigo](https://boards.straightdope.com/u/Si_Amigo)\ **Post date:** [October 18, 2005, 5:09pm UTC](https://boards.straightdope.com/t/what-if-i-dont-use-the-right-charger-for-my-battery/326763/3 "2005-10-18T17:09:46Z")
Look like the google ads may have answered your question. 🆒 If not, why not try a universal adapter like this: > **[Best Buy: Sima Universal AC Adapter SUP-60](https://www.bestbuy.com/site/sima-universal-ac-adapter/7011994.p?skuId=7011994&CategoryID=cat08117&ref=06&loc=01)** > > Shop Sima Universal AC Adapter at Best Buy. Find low everyday prices and buy online for delivery or in-store pick-up. Price Match Guarantee. You are correct, there is no special circuitry. Just match up the voltage, amperage draw and pick the right connector. hint: there is a selectable switch for amperage draw but you must pick a model with the right voltage for your need. ---
**Author:** ![Si\_Amigo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/si_amigo/32/2877_2.png) [@Si\_Amigo](https://boards.straightdope.com/u/Si_Amigo)\ **Post date:** [October 18, 2005, 5:19pm UTC](https://boards.straightdope.com/t/what-if-i-dont-use-the-right-charger-for-my-battery/326763/4 "2005-10-18T17:19:22Z")
One potential hangup. I checked out my IBM,s adapter and see that it outputs at 16V. May be hard to get a universal for that! The google ads shows one for my computer for $69.99. Not to terrible. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [October 18, 2005, 5:24pm UTC](https://boards.straightdope.com/t/what-if-i-dont-use-the-right-charger-for-my-battery/326763/5 "2005-10-18T17:24:34Z")
At the very least you need a current limiting circuit. If you connect a regular 12-volt supply to a depleted 12-volt battery, there will be enough current flow to melt the wire or blow the fuse. (I speak from experience. Hey, I was 10 years old.) ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [October 18, 2005, 6:05pm UTC](https://boards.straightdope.com/t/what-if-i-dont-use-the-right-charger-for-my-battery/326763/6 "2005-10-18T18:05:44Z")
> [@Nature's Call](#): > > Every rechargeable battery stresses, “Only use the charger approved for use… blah blah blah” And there’s a good reason for this. ---
**Author:** ![Ezstrete](https://avatars.discourse-cdn.com/v4/letter/e/7ea924/32.png) [@Ezstrete](https://boards.straightdope.com/u/Ezstrete)\ **Post date:** [October 18, 2005, 7:43pm UTC](https://boards.straightdope.com/t/what-if-i-dont-use-the-right-charger-for-my-battery/326763/7 "2005-10-18T19:43:09Z")
> [@Crafter\_Man](#): > > And there’s a good reason for this. If the dc output voltage is right,if the charger capacity in amps or milis is right,if the polarity is right --------then the battery doesn’t give a damn where the voltage is coming from. If I have a small charger go bad I dig one out of my junk box that fits the system----correct the polarity if necessary----- and it’s the light brigade all over again—or mayb San Juan Hill! Or,as the ladies like to say it,----------------CHARGE! EZ ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [October 18, 2005, 8:39pm UTC](https://boards.straightdope.com/t/what-if-i-dont-use-the-right-charger-for-my-battery/326763/8 "2005-10-18T20:39:50Z")
> [@Ezstrete](#): > > If the dc output voltage is right,if the charger capacity in amps or milis is right,if the polarity is right --------then the battery doesn’t give a damn where the voltage is coming from. Bad advice. Did you ever stop to think that perhaps there’s a _reason_ some battery chargers cost $200? Do you think it’s nothing more than a ploy by manufacturers to rip off hapless consumers? Most modern battery chargers are sophisticated devices. This is understandable, as they have a tough job to do: they must charge a battery rapidly, efficiently, and safely, while at the same not overheat it. Furthermore, each battery chemistry is idiosyncratic in how it likes to be charged. Some require a current-limited constant voltage source. Some require a constant current source. Some require both modes w/ a crossover voltage point. Some require monitoring dV/dt. Some require temperature monitoring (dT/dt). And while most chargers are linear, PWM schemes can sometimes be used for better efficiency. Click [here](http://www.maxim-ic.com/appnotes.cfm/appnote_number/666) for more info. Of course, I suppose a person can grab any 'ol charger in the junk pile and try it. But because there’s a strong likelihood that the charger will not be matched to the type & capacity of the battery being charged, the end result is that the battery will not be efficiently charged. It could also decrease the life of the battery. And in some cases the battery could overheat. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [October 18, 2005, 10:19pm UTC](https://boards.straightdope.com/t/what-if-i-dont-use-the-right-charger-for-my-battery/326763/9 "2005-10-18T22:19:15Z")
I _strongly_ urge people to use only battery chargers suitable for their particular battery pack. In particular, LiIons when they explode produce stuff that the people on staff at your local Emergency Room won’t know how to handle. Because of all the finicky things about LiIons, the chargers for them are quite complicated compared to the old ones for NiCads. The charges to the cells have to be balanced, the current carefully controlled, etc. Note that even NiCads, while chargable by simpler circuits, are not something you really want to play Mr. Science with. They contain Cadmium after all. _All_ batteries contain Very Bad Things and charging them wrong is the easiest way to have the Very Bad Things get all over you. Just look at the thread in CoCC about the article on lead-acid battery dangers. That’s very old tech with really simple charging circuits. (And I didn’t even post my “stupid BIL and a motorcycle battery” story to that thread.) ---
**Author:** ![Nature\_s\_Call](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nature_s_call/32/19006_2.png) [@Nature\_s\_Call](https://boards.straightdope.com/u/Nature_s_Call)\ **Post date:** [October 19, 2005, 12:01am UTC](https://boards.straightdope.com/t/what-if-i-dont-use-the-right-charger-for-my-battery/326763/10 "2005-10-19T00:01:12Z")
Thanks, gang, for the straight dope on this. Do-it-yerself charger? I just say NO. Oh, and tip o’ the hat to Google Ads… maybe I’ll find what I’m looking for therein, and toss a click-through nickel to the SDMB…