<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>

CC BY-SA 4.0
2012-02-14T12:18:53.840Z
2019-12-23T06:40:41.727Z
2019-12-23T06:40:41.727Z
Joubarc
<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>

<mindstorms><nxt><battery>
Adapting charger for NXT 9798 battery
Zarnx
# 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


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## 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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