# Trying to charge a Lithium Ion battery with a universal charger - what setting? **URL:** \ **Category:** Factual Questions\ **Created:** [August 12, 2007, 7:18pm UTC](https://boards.straightdope.com/t/trying-to-charge-a-lithium-ion-battery-with-a-universal-charger-what-setting/415363 "2007-08-12T19:18:56Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [August 12, 2007, 7:18pm UTC](https://boards.straightdope.com/t/trying-to-charge-a-lithium-ion-battery-with-a-universal-charger-what-setting/415363/1 "2007-08-12T19:18:56Z")
I’m trying to charge the Lithium Ion battery in a GPS unit. Unfortunately, the store didn’t have the charger unit, and the supplier wasn’t able to provide the charging unit, so I bought a universal AC adaptor/charger. I’m trying to figure out what setting to use for the charger. The battery is a “Hitfar 900 mAh Lithium Ion Battery.” The GPS is a “Magellan Explorist 500.” I’ve gone to their web-site and can’t find out what rating to use for the charger. I tried calling their technical support, but they weren’t very supportive… On the back of the charger is a sliding switch with the following numbers: 3 3.5 5 6 6.5 7 8.4 I’ve been using it on the lowest setting, but the battery doesn’t seem to be charging very quickly. Obviously, I don’t want to set it so high that the damn thing bursts into flames. If I can’t get a charge into the Lithium Ion battery, the alternative is 4 AAA cells, but I’d prefer to use the re-chargable battery if possible. Anyone have any suggestions or info? Thanks ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [August 12, 2007, 7:46pm UTC](https://boards.straightdope.com/t/trying-to-charge-a-lithium-ion-battery-with-a-universal-charger-what-setting/415363/2 "2007-08-12T19:46:31Z")
WAG I assume those numbers are for voltage. 4xAAA would be 6 volts IIRC so I would assume it would be set to 6. Your best bet is to find out for sure what that setting is, and match it with the battery. For example, if that setting is for voltage, and the battery is 6 volts, that’s the setting I would use. Do you have the directions for the charger, or the model number? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [August 12, 2007, 8:04pm UTC](https://boards.straightdope.com/t/trying-to-charge-a-lithium-ion-battery-with-a-universal-charger-what-setting/415363/3 "2007-08-12T20:04:51Z")
[QUOTE=Joey P] WAG I assume those numbers are for voltage. 4xAAA would be 6 volts IIRC so I would assume it would be set to 6. Your best bet is to find out for sure what that setting is, and match it with the battery. For example, if that setting is for voltage, and the battery is 6 volts, that’s the setting I would use. Do you have the directions for the charger, or the model number? [/QUOTE] Don’t do it. Unless this charger is specifically designed for Lithium batteries, you run the very real risk if destroying the battery, and a smaller risk of starting a fire. Lithium batteries require a different charging program than other rechargeable. ---
**Author:** ![Myglaren](https://avatars.discourse-cdn.com/v4/letter/m/f1d935/32.png) [@Myglaren](https://boards.straightdope.com/u/Myglaren)\ **Post date:** [August 12, 2007, 8:24pm UTC](https://boards.straightdope.com/t/trying-to-charge-a-lithium-ion-battery-with-a-universal-charger-what-setting/415363/4 "2007-08-12T20:24:53Z")
4 x AAA cells will provide a nominal 6v. Presumably the Li-on battery will provide the same, so your charging voltage needs to be slightly higher. the 6.5 or 7v settings should do to start with. I believe however that Li-on batteries need a constant charging voltage and current and the charging time is critical. You may well damage your cells with a charger not completely suited to the correct charging regime. Pay particular attention to them increasing in temperature indicating them approaching charge completion. Don’t allow them to charge more than a couple of hours at least initially. ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [August 12, 2007, 8:26pm UTC](https://boards.straightdope.com/t/trying-to-charge-a-lithium-ion-battery-with-a-universal-charger-what-setting/415363/5 "2007-08-12T20:26:35Z")
[QUOTE=beowulff] Don’t do it. [/QUOTE] x2!! Unless you have one of these: [MAHA MH-C777PLUS-II](http://www.mahaenergy.com/store/item.asp?idproduct=185) or something similar, you could start a fire. Lith-Ion chargers are specific to that cell type. ---
**Author:** ![groman](https://avatars.discourse-cdn.com/v4/letter/g/73ab20/32.png) [@groman](https://boards.straightdope.com/u/groman)\ **Post date:** [August 13, 2007, 12:38am UTC](https://boards.straightdope.com/t/trying-to-charge-a-lithium-ion-battery-with-a-universal-charger-what-setting/415363/6 "2007-08-13T00:38:58Z")
Here are some videos [Li-On](http://www.youtube.com/watch?v=sNeeIzaeYDo), [LiPo](http://www.youtube.com/watch?v=KpUXuEg3fNE), [More Li-On](http://www.youtube.com/watch?v=WeWq6rWzChw), [More LiPo](http://www.youtube.com/watch?v=z3o_2mwRPdw), demonstrating clearly why you should not charge Li-Ion and LiPo batteries without a proper computer-controlled charger ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [August 13, 2007, 5:12am UTC](https://boards.straightdope.com/t/trying-to-charge-a-lithium-ion-battery-with-a-universal-charger-what-setting/415363/7 "2007-08-13T05:12:35Z")
Thanks, guys. Triple A it is!