# Queston about the battery\_state topic

**URL:** <https://forum.ubiquityrobotics.com/t/queston-about-the-battery-state-topic/1079>\
**Category:** General Questions\
**Created:** [September 25, 2023, 1:45pm UTC](https://forum.ubiquityrobotics.com/t/queston-about-the-battery-state-topic/1079 "2023-09-25T13:45:27Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![MarkCuck334](https://forum.ubiquityrobotics.com/letter_avatar_proxy/v4/letter/m/6f9a4e/32.png) [@MarkCuck334](https://forum.ubiquityrobotics.com/u/MarkCuck334)\
**Post date:** [September 25, 2023, 1:45pm UTC](https://forum.ubiquityrobotics.com/t/queston-about-the-battery-state-topic/1079/1 "2023-09-25T13:45:27Z")

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Hey, I have a question about the battery\_state topic.

Recently, the battery\_state voltage hasn’t been the same as shown in my multimeter when I measure my batteries.

It usually has a 0.5v difference, rn, on my multimeter my batteries have 25.1v, but on battery\_state it shows that it has only ~24.5v

I remember that a couple months ago my battery\_state was almost equal to the measures in the multimeter, having only a .2 or .1 difference.

Would it be a problem with my batteries? Something on the mcb? Or is it a normal behavior?

Thanks in advance.

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**Author:** ![mjstn2011](https://forum.ubiquityrobotics.com/user_avatar/forum.ubiquityrobotics.com/mjstn2011/32/30_2.png) [@mjstn2011](https://forum.ubiquityrobotics.com/u/mjstn2011)\
**Post date:** [September 27, 2023, 7:38am UTC](https://forum.ubiquityrobotics.com/t/queston-about-the-battery-state-topic/1079/2 "2023-09-27T07:38:31Z")

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Please tell me the version of the MCB board that you are running with the serial number on the white tag of the board. There were issues in older boards.

Next I will say a lot of that as far as the level read for voltage also changed in both the more recent firmware, v42 as well as the more recent kernel images.

Give me an idea of both of these things to continue this discussion best.  
Cheers, mark

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**Author:** ![MarkCuck334](https://forum.ubiquityrobotics.com/letter_avatar_proxy/v4/letter/m/6f9a4e/32.png) [@MarkCuck334](https://forum.ubiquityrobotics.com/u/MarkCuck334)\
**Post date:** [October 4, 2023, 1:06pm UTC](https://forum.ubiquityrobotics.com/t/queston-about-the-battery-state-topic/1079/3 "2023-10-04T13:06:21Z")

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Hey, sorry for the delayed response.

Unfortunately, I’m not with my robot right now, so I can’t provide the exact information you asked for. However, I might have a clue as to what it could be:

Recently, we installed a Buck converter in parallel with our batteries to ensure more safety with our LiDAR. Our batteries can go up to 29.4V, and although the MCB can handle it, the LiDAR is rated for a maximum of 27V. After discussing this with my team, we suspect that the issue might be related to the Buck converter, as this problem started around the time we added it.

Please let me know what you think.

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**Author:** ![mjstn2011](https://forum.ubiquityrobotics.com/user_avatar/forum.ubiquityrobotics.com/mjstn2011/32/30_2.png) [@mjstn2011](https://forum.ubiquityrobotics.com/u/mjstn2011)\
**Post date:** [October 5, 2023, 6:56am UTC](https://forum.ubiquityrobotics.com/t/queston-about-the-battery-state-topic/1079/4 "2023-10-05T06:56:47Z")

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Ah yes, the most likely candidates for something no longer working are the most recent changes.

Glad you have made some progress. Take Care, Mark