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Zaxcom Nova and MRX414 battery setup


MartinTheMixer
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Hello gang, These are the batteries I will be using to power the Zaxcom Nova with MRX414 receivers. The tall purplish one will be the "main' battery, and is rated at 5000mah and thanks to the extreme efficiency of the Nova and the MRX414 receivers, 4 of these will power the Nova and all 8 receivers and Zaxnet for a minimum of 3 hours 45 minutes. That pack will weigh about 12 oz. (340 grams). The AA energizer is there for size reference. The small battery will be my "backup" battery that will be plugged into the other Hirose 4 pin port on Nova. They are rated @ 1100mah. 4 of those batteries will run Nova with 8 receivers and Zaxnet for a minimum of 35 minutes and weigh about 6 oz. (170 grams).  That is really an impressive number to me. Did I leave anything out? I usually do. 

 

Martin

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Your idea has a couple flaws – the first is that there isn't any fall over between the power inputs on the Nova – they will just draw from whatever battery has the highest voltage. So your "backup pack" will add to the battery life of your system but not work the way you want it to.

The Nova has a power range of 8 - 18v.

A 4S lithium battery (with 3.7v 18650 cells) has a nominal voltage of 14.4v and a useful range of 16.8v to a low voltage cutoff of 10v (but a safe cutoff of 12v)
A 3S lithium battery has a nominal voltage of 10.8v and a range of 12.6v to 7.2v (with a safe cutoff of 9v)

So with those 2 battery configurations, you can safely cover the voltage range of the Nova with a smooth handoff of current draw from one battery to the other (as the current will come from the battery with the highest voltage)

 

The second flaw in your proposed batteries is a battery management system (board) as raw cells can be easily destroyed if you draw them down too low, which the Nova would happily do as it's cut off voltage is lower than the battery's discharge limits. Additionally "raw" cells aren't supposed to be used out of battery packs, they are, but it is risky.

Something I've been considering (but haven't pulled the trigger yet) as I already use the smart batteries, is to get a small 3S battery as power backup, like https://inspired-energy.com/products/n-series-batteries/details/3/4-nc2040hd29 as it can be charged on the same chargers and use the same battery connector – and will work as a fall over supply

but the other option, and probably more reasonably, is to just use that second shoe and just add a fresh battery when the first one gets low (as the new battery will take the load, as it is fresh off the charger, and the voltage is higher)

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Raw battery cells are the individual batteries (like the 18680 lithium cell in your photo). A battery package contains the required number of cells in series/parallel arrangement and a Battery Management System (BMS) board. A BMS is required in front of any multi-cell battery. The board protects against over discharge, hight/low pack temperature, shot circuits, uneven cell voltages, and a number of other things that can at a minimum impact the life of the battery and at most keep it from exploding.

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9 hours ago, Shastapete said:

Raw battery cells are the individual batteries (like the 18680 lithium cell in your photo). A battery package contains the required number of cells in series/parallel arrangement and a Battery Management System (BMS) board. A BMS is required in front of any multi-cell battery. The board protects against over discharge, hight/low pack temperature, shot circuits, uneven cell voltages, and a number of other things that can at a minimum impact the life of the battery and at most keep it from exploding.

Pete, Thank you. I just wasn't clear what you were meaning there.  I will go back and address your first reply. 

Thank you, Martin

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On 11/13/2021 at 2:40 PM, Shastapete said:

Your idea has a couple flaws – the first is that there isn't any fall over between the power inputs on the Nova – they will just draw from whatever battery has the highest voltage. So your "backup pack" will add to the battery life of your system but not work the way you want it to.

The Nova has a power range of 8 - 18v.

A 4S lithium battery (with 3.7v 18650 cells) has a nominal voltage of 14.4v and a useful range of 16.8v to a low voltage cutoff of 10v (but a safe cutoff of 12v)
A 3S lithium battery has a nominal voltage of 10.8v and a range of 12.6v to 7.2v (with a safe cutoff of 9v)

So with those 2 battery configurations, you can safely cover the voltage range of the Nova with a smooth handoff of current draw from one battery to the other (as the current will come from the battery with the highest voltage)

 

The second flaw in your proposed batteries is a battery management system (board) as raw cells can be easily destroyed if you draw them down too low, which the Nova would happily do as it's cut off voltage is lower than the battery's discharge limits. Additionally "raw" cells aren't supposed to be used out of battery packs, they are, but it is risky.

Something I've been considering (but haven't pulled the trigger yet) as I already use the smart batteries, is to get a small 3S battery as power backup, like https://inspired-energy.com/products/n-series-batteries/details/3/4-nc2040hd29 as it can be charged on the same chargers and use the same battery connector – and will work as a fall over supply

but the other option, and probably more reasonably, is to just use that second shoe and just add a fresh battery when the first one gets low (as the new battery will take the load, as it is fresh off the charger, and the voltage is higher)

I will respond in the order you listed.

 

 

You typed:

 

"Your idea has a couple flaws – the first is that there isn't any fall over between the power inputs on the Nova – they will just draw from whatever battery has the highest voltage. So your "backup pack" will add to the battery life of your system but not work the way you want it to."

 

Me:

In my testing the Nova power system, with the 2 Hirose inputs is not wired in a true parallel.  My reference to the amount of time the "backup" battery would last was if the main battery were to fail. The time I listed for the backup to power the Nova was listed lower than the actual capability of the battery.

 

You typed:

 

"A 3S lithium battery has a nominal voltage of 10.8v and a range of 12.6v to 7.2v (with a safe cutoff of 9v)"

 

Me:

That is actually a good idea, that would convert the 2nd battery into an absolute take over battery after the main pack had been exhausted. The problem I have with that, I have never powered a mixer with 12 volts,  I am not a fan of lower voltage/higher amperage. So, I don't think I could talk myself into a 3 cell pack. But it is a good idea. I 

had a conversation with Glenn about this a while back. I might make a board that would "switch on"  the second battery at a select voltage in order to turn on that pack after the primary pack drops to a select voltage. In doing this, I could have the 2nd pack turn on while the primary pack has 20 percent left in that pack. That would then turn on the 2nd pack and in effect, turn the primary now to backup duty, so should the 2nd battery fail, the primary pack would then have 20 percent power left to power the unit. That circuit would probably utilize a zener diode to do the switching, because I am a zener fan. And it has a really cool symbol. Can someone draw superhero  Zenerman? 

 

You typed:

 

"The second flaw in your proposed batteries is a battery management system (board) as raw cells can be easily destroyed if you draw them down too low, which the Nova would happily do as it's cut off voltage is lower than the battery's discharge limits. Additionally "raw" cells aren't supposed to be used out of battery packs, they are, but it is risky."

 

 

Me:

I took a picture of just the cells. There are many parts missing, nickle strips, BMS board, balancing connectors, wire, cell holders, heat shrink, power connector,  etc. I will take another picture of all the parts that it takes to make a battery pack. You referenced "out of a pack". It's not in a pack until I build it. I have been using my own packs for years, as well as my own  battery distribution system. I have never used a distribution system or battery pack manufactured by anyone other than me. I have been using lithium batteries for 21 years with no problems so far. My post was just showing the smaller cells I am switching to because Nova/MRX uses so much less wattage than my previous Nomad/QRX setup. Nova with 8 receivers going and Zaxnet transmitting uses about 15.5 watts. That is still amazing to me. 

 

You typed:

 

"but the other option, and probably more reasonably, is to just use that second shoe and just add a fresh battery when the first one gets low (as the new battery will take the load, as it is fresh off the charger, and the voltage is higher)"

 

Me:

The problem that I have with that is there is then no protection for a Hirose female connector failure, a Hirose male connection failure, or a battery pack failure. In my Nomad setup, I ran 2 packs in Parallel, so if a pack component failed, Nomad would continue to run. I would only know if there was a failure later, when the charging showed a disparity in the 2 packs. My charger would also indicate if there was an individual cell starting to degrade. I have never had a pack failure, they have just simply aged and been removed from service. 

 

 

Thank you again for your input, Martin

 

 

 

 

 

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