Answers.Body: <p>The two batteries and chargers are very different, in that the new one is 10V DC whereas the old one is AC (while it's supposed to be 9V, I think the transformer was actually 10V too).</p>
  
  <p>As it's AC, the polarity doesn't matter, but I don't think using DC current is recommended (even if in theory the rectifier circuitry in the old battery should be able to accommodate it).</p>
  
  <p>You should be able to buy a spare fairly easily though, whether at a local LEGO event or directly on <a href="http://www.bricklink.com/search.asp?q=9833" rel="nofollow noreferrer">BrickLink</a>. Note that it's the exact same that came with 9V trains, so you may want to look for <a href="https://www.bricklink.com/search.asp?itemID=4416" rel="nofollow noreferrer">the complete transfomer + regulator</a> as well, which may sometimes be cheaper to find.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2012-02-14T12:18:53.840Z
Answers.LastActivityDate: 2019-12-23T06:40:41.727Z
Answers.LastEditDate: 2019-12-23T06:40:41.727Z
Answers.UserDisplayName: Joubarc
Body: <p>I have an old style  9798 NXT rechargeable battery pack 7.2V 1400MnAh, but no charger.
  Can I adapt a  spare non lego 9v 200mAh charger for this? Or is voltage too high? can anyone read the output voltage from their old charger?
  As I will need  to add a new connector plug to the charger, can anyone tell me if the battery charging socket centre pin is positive or negative? 
  Also what size of plug do I need as it slightly larger than current version for current battery? 
  Thanks</p>
  
  <p>NB I have looked at my newer charger lego element 94165 10v 700mA for the current battery and it is a positive centre hole (for centre pin in battery case) and a negative outside (measured with red lead of multimeter in the centre hole of charger plug and black lead on outer tube showing +10.5v)</p>
  
Tags: <mindstorms><nxt><battery>
Title: Adapting charger for NXT 9798 battery
UserDisplayName: Zarnx
ThreadText: # Adapting charger for NXT 9798 battery
  
  (Asked by: username_0 on 2012-02-11)
  
  I have an old style 9798 NXT rechargeable battery pack 7.2V 1400MnAh, but no charger.
  Can I adapt a spare non lego 9v 200mAh charger for this? Or is voltage too high? can anyone read the output voltage from their old charger?
  As I will need to add a new connector plug to the charger, can anyone tell me if the battery charging socket centre pin is positive or negative?
  Also what size of plug do I need as it slightly larger than current version for current battery?
  Thanks
  
  NB I have looked at my newer charger lego element 94165 10v 700mA for the current battery and it is a positive centre hole (for centre pin in battery case) and a negative outside (measured with red lead of multimeter in the centre hole of charger plug and black lead on outer tube showing +10.5v)
  
  **Tags:** mindstorms, nxt, battery
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2012-02-14. Score: 2
  
  The two batteries and chargers are very different, in that the new one is 10V DC whereas the old one is AC (while it's supposed to be 9V, I think the transformer was actually 10V too).
  
  As it's AC, the polarity doesn't matter, but I don't think using DC current is recommended (even if in theory the rectifier circuitry in the old battery should be able to accommodate it).
  
  You should be able to buy a spare fairly easily though, whether at a local LEGO event or directly on [BrickLink](http://www.bricklink.com/search.asp?q=9833). Note that it's the exact same that came with 9V trains, so you may want to look for [the complete transfomer + regulator](https://www.bricklink.com/search.asp?itemID=4416) as well, which may sometimes be cheaper to find.
  
  
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