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correll / advancedrobotics

Advanced Robotics class repository
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Jaguar battery cells unbalanced #68

Closed Branden-Romero closed 9 years ago

Branden-Romero commented 9 years ago

img_20151109_153041

Jorge-C commented 9 years ago

Does running cell balancing not fix it?

Branden-Romero commented 9 years ago

It fixes it, but this is the second time after use that the battery has become unbalanced since we attached the laser scanner.

Jorge-C commented 9 years ago

We should recharge more often. A lot of low battery alarms for RC airplanes/quadcopters go off at about 3.3V per cell (under load, so 3.2V with no load is much more problematic).

Re. unbalancing by discharge, that might simply suggest that the BMS of the jaguar is not great. Does it even have a Battery Management System?

2015-11-10 13:21 GMT-07:00 Branden Romero notifications@github.com:

It fixes it, but this is the second time after use that the battery has become unbalanced since we attached the laser scanner.

— Reply to this email directly or view it on GitHub https://github.com/correll/advancedrobotics/issues/68#issuecomment-155554438 .

ikemole commented 9 years ago

Just an observation...

I've noticed that the same cell seems to discharge faster than the other five cells. Every time I was about to charge it, the lowest number always shows on the bottom left position on LCD (as in this picture). I am guessing that the same cell is represented in that location on the screen.

I am not sure how relevant that is.

On Nov 10, 2015 1:39 PM, "Jorge Cañardo Alastuey" notifications@github.com wrote:

We should recharge more often. A lot of low battery alarms for RC airplanes/quadcopters go off at about 3.3V per cell (under load, so 3.2V with no load is much more problematic).

Re. unbalancing by discharge, that might simply suggest that the BMS of the jaguar is not great. Does it even have a Battery Management System?

2015-11-10 13:21 GMT-07:00 Branden Romero notifications@github.com:

It fixes it, but this is the second time after use that the battery has become unbalanced since we attached the laser scanner.

— Reply to this email directly or view it on GitHub < https://github.com/correll/advancedrobotics/issues/68#issuecomment-155554438

.

— Reply to this email directly or view it on GitHub https://github.com/correll/advancedrobotics/issues/68#issuecomment-155559099 .

mcguire-steve commented 9 years ago

The Jaguar does not have a battery management system to prevent over-discharge or over-charging. Cell unbalancing is related to manufacturing differences between individual cells - the fact that a single cell is perpetually the weak link is consistent. Long-term solution would involve a ROS node with some A/D hardware to actively monitor battery voltage and current draw so that we can estimate the amount of charge remaining and not damage the LiPo packs due to over-discharge. -Steve

On Tue, Nov 10, 2015 at 2:01 PM, David Emole notifications@github.com wrote:

Just an observation...

I've noticed that the same cell seems to discharge faster than the other five cells. Every time I was about to charge it, the lowest number always shows on the bottom left position on LCD (as in this picture). I am guessing that the same cell is represented in that location on the screen.

I am not sure how relevant that is.

On Nov 10, 2015 1:39 PM, "Jorge Cañardo Alastuey" < notifications@github.com> wrote:

We should recharge more often. A lot of low battery alarms for RC airplanes/quadcopters go off at about 3.3V per cell (under load, so 3.2V with no load is much more problematic).

Re. unbalancing by discharge, that might simply suggest that the BMS of the jaguar is not great. Does it even have a Battery Management System?

2015-11-10 13:21 GMT-07:00 Branden Romero notifications@github.com:

It fixes it, but this is the second time after use that the battery has become unbalanced since we attached the laser scanner.

— Reply to this email directly or view it on GitHub <

https://github.com/correll/advancedrobotics/issues/68#issuecomment-155554438

.

— Reply to this email directly or view it on GitHub < https://github.com/correll/advancedrobotics/issues/68#issuecomment-155559099

.

— Reply to this email directly or view it on GitHub https://github.com/correll/advancedrobotics/issues/68#issuecomment-155564574 .

Jorge-C commented 9 years ago

Closing as it is just an artifact of not having a BMS ( #56 ).