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Old 06-17-2019, 04:22 PM   #1
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Default Setting low voltage cutoff

I run 5000 mAh 2s and 3s batteries on a mabma X / 3200 kv brushless setup. This is a fairly new setup for me and I just killed a battery running it too long. I've never had to program a voltage cut off before. What should I set it as, and should the cutoff be the same for 2s and 3s?

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Old 06-17-2019, 04:51 PM   #2
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Default Re: Setting low voltage cutoff

By default the Mamba X should have a cell detection and cutoff at 3.2v/cell. In Castle Link you can set the cutoff voltage to be between 3.0 and 3.5V per cell in 0.1V increments. You should set 'Cutoff Voltage' to 'Auto-Lipo' and 'Auto-Lipo Volts/Cell' to '3.2 Volts/Cell'. Some people like to keep their packs from going down to 3.2v/cell, but that has proven to be a very safe voltage for the cells. If you want to, you can set the 'Auto-Lipo Volts/Cell' to '3.4 Volts/Cell'. You will lose a bit of runtime, but you will have a little better peace of mind.

When you power it up, it should make our start up sound, chime once per cell that it detects, and then play our arming tone. You can count the chimes to ensure that it is detecting your packs correctly. There should be youtube videos of people showing this off. If it doesn't make the cell count chimes, then it is not set to use Auto-Lipo.

The Auto-Lipo system looks at the initial voltage it sees when powering up to detect the number of cells. A 2 cell pack starts at 8.4v and cuts off at 6.4v. A 3 cell pack starts at 12.6V and cuts off at 9.6V. Even a fully discharged 3 cell should identify as a 3 cell unless it was already way under voltage.
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Old 06-20-2019, 05:19 PM   #3
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Default Re: Setting low voltage cutoff

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Originally Posted by robert@castle View Post
By default the Mamba X should have a cell detection and cutoff at 3.2v/cell. In Castle Link you can set the cutoff voltage to be between 3.0 and 3.5V per cell in 0.1V increments. You should set 'Cutoff Voltage' to 'Auto-Lipo' and 'Auto-Lipo Volts/Cell' to '3.2 Volts/Cell'. Some people like to keep their packs from going down to 3.2v/cell, but that has proven to be a very safe voltage for the cells. If you want to, you can set the 'Auto-Lipo Volts/Cell' to '3.4 Volts/Cell'. You will lose a bit of runtime, but you will have a little better peace of mind.

When you power it up, it should make our start up sound, chime once per cell that it detects, and then play our arming tone. You can count the chimes to ensure that it is detecting your packs correctly. There should be youtube videos of people showing this off. If it doesn't make the cell count chimes, then it is not set to use Auto-Lipo.

The Auto-Lipo system looks at the initial voltage it sees when powering up to detect the number of cells. A 2 cell pack starts at 8.4v and cuts off at 6.4v. A 3 cell pack starts at 12.6V and cuts off at 9.6V. Even a fully discharged 3 cell should identify as a 3 cell unless it was already way under voltage.

How about adding voltage sensing for each individual cell? It is being used in the vaping community when the boxes use li-po's so I know it can be done. It doesn't make sense to try and sense cell levels by total pack voltage. Especially with higher loads.
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Old 06-21-2019, 05:51 AM   #4
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Default Re: Setting low voltage cutoff

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Originally Posted by DRTMI View Post
How about adding voltage sensing for each individual cell? It is being used in the vaping community when the boxes use li-po's so I know it can be done. It doesn't make sense to try and sense cell levels by total pack voltage. Especially with higher loads.
For a few dollars off ebay you can buy a buzzer that does that, which plugs into the balance plug. A decent charger can also let you know when a cell is going bad. On a Good battery they will discharge at the same rate.

I don't think most people want to pay extra for this feature tbh.

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Old 06-21-2019, 06:50 AM   #5
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Default Re: Setting low voltage cutoff

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Originally Posted by DRTMI View Post
How about adding voltage sensing for each individual cell? It is being used in the vaping community when the boxes use li-po's so I know it can be done. It doesn't make sense to try and sense cell levels by total pack voltage. Especially with higher loads.
It certainly be done, and like Voodoo said, a lipo alarm would do this for you. But, if you are balance charging the cells should be drawn down at about the same rate, making the individual monitoring of each cell redundant and unnecessary. To add a little cushion, people up the cutoff voltage to 3.3 or 3.4VDC to make sure they are not damaging their packs. In fast RCs where you have big amperage draws this is a bigger issue, but in our little niche of the hobby, were our packs last for hours and not minutes, it is not that big of a deal.

But, this hobby is all about what puts a grin on your face. If you want to make sure you do no over-discharge your packs, just bump the cutoff voltage a little, or get a lipo alarm.

Last edited by Greatscott; 06-21-2019 at 06:58 AM.
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Old 06-24-2019, 02:15 PM   #6
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Default Re: Setting low voltage cutoff

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Originally Posted by Greatscott View Post
It certainly be done, and like Voodoo said, a lipo alarm would do this for you. But, if you are balance charging the cells should be drawn down at about the same rate, making the individual monitoring of each cell redundant and unnecessary. To add a little cushion, people up the cutoff voltage to 3.3 or 3.4VDC to make sure they are not damaging their packs. In fast RCs where you have big amperage draws this is a bigger issue, but in our little niche of the hobby, were our packs last for hours and not minutes, it is not that big of a deal.

But, this hobby is all about what puts a grin on your face. If you want to make sure you do no over-discharge your packs, just bump the cutoff voltage a little, or get a lipo alarm.
I have lipo alarms NOW to combat this. My batteries are ALWAYS balance charged so according to you, completely necessary. Packs do not run down at the same rate, especially when you get closer to a 3.2 setting. I have t o use a cutoff of 3.5 to protect my batteries because the manufacturers are too stubborn to implement new features. Also, my comment asked Robert a question. Not you. I don't want or need your opinion.
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Old 06-24-2019, 02:17 PM   #7
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Default Re: Setting low voltage cutoff

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Originally Posted by Voodoobrew View Post
For a few dollars off ebay you can buy a buzzer that does that, which plugs into the balance plug. A decent charger can also let you know when a cell is going bad. On a Good battery they will discharge at the same rate.

I don't think most people want to pay extra for this feature tbh.

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No way. Thanks, Captain Obvious.
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Old 06-24-2019, 06:02 PM   #8
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Default Setting low voltage cutoff

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Originally Posted by DRTMI View Post
I have lipo alarms NOW to combat this. My batteries are ALWAYS balance charged so according to you, completely necessary. Packs do not run down at the same rate, especially when you get closer to a 3.2 setting. I have t o use a cutoff of 3.5 to protect my batteries because the manufacturers are too stubborn to implement new features. Also, my comment asked Robert a question. Not you. I don't want or need your opinion.


Quote:
Originally Posted by DRTMI View Post
No way. Thanks, Captain Obvious.


Now, here is just another opinion of mine brother, but if you only wanted a response from Robert, you might have maybe sent him a PM, instead of posting on a public forum who's purpose is the exchange and solicitation of other people's experience, thoughts and opinions.

Last edited by Greatscott; 06-24-2019 at 08:13 PM.
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