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mikedefieslife avatar image
mikedefieslife asked

Can the Battery Protect be used as a HVC

Can the smart battery protect be used as a simple HVC on the charge side of a set of LiFePO4 batteries without any kind of external relay or communication from a BVM?

Intended use would be to set a cut off voltage, and rely on the SBP to be the first line of defence to disconnect charging sources if they ever rose above whatever voltage I'd set on the SBP?

I'm presuming it has bluetooth so I can set the required disconnect voltage?

Battery Protect
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4 Answers
kosio86 avatar image
kosio86 answered ·

I am interested in the same question.

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Justin Cook avatar image
Justin Cook answered ·

@mikedefieslife, I'll say a couple of things regarding this, though ultimately of course I defer to Victron staff regarding the possibility of using it this way:

First, the "Smart BatteryProtect" has Bluetooth, the "BatteryProtect" does not. Be mindful of your product selection when ordering these, because the different models look identical other than that some say "Smart" and some don't.

Second, there is no replacement for a BMS. Your lithium system needs one. Neither this, nor any other battery protection device, is a replacement for a BMS.

Third, the BatteryProtect is a unidirectional device only; reverse current through the device will irreparably damage the device and potentially cause damage to your other components. Although it's technically possible to connect this device between a charger (charger only, NOT an inverter/charger) and a battery by connecting the "in" to the charger side and the "out" to the battery side, due to the high risk of doing this incorrectly I would strongly advise against it.

Bottom line: get a BMS for your batteries. Once you've made the investment in a LiFePO4 battery system, the components that monitor and maintain its health are not the place to try to cut corners.

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mikedefieslife avatar image
mikedefieslife answered ·

Thanks for the input. I have a BMS for my batteries. Most people use the BMS as an absolute last line of defence and use a high voltage disconnect and low voltage disconnect. Sometimes these are controlled by the BMS, sometimes by a battery monitor (such as the BVM 712), or sometimes operate independently.

Since the Smart and the normal battery protect are unidirectional, I would imagine that all load outputs from MPPT controllers would need to be removed to prevent the risk of reverse current. There is no risk of reverse current with a regular battery charger or DC to DC charger.

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Justin Cook avatar image Justin Cook ♦♦ commented ·

@mikedefieslife, I see... I read the question to mean that you were trying to find a way around using a BMS, which is a question I see fairly frequently at the Victron/Sterling/Blue Sea distributor where I work.

While the BatteryProtects are primarily designed for low-voltage cutouts, I've run a demo product in VictronConnect and can confirm that yes, you can set the "shut down" voltage higher than the "reconnect" voltage (so, shut down the output at, say, 14.5v and restart at 12.7v); ignore the battery presets and select "user defined" and you can set your thresholds to 1/100th of a volt, so you should be fine there.

As far as MPPT controllers, those are already smart 3-stage controllers, so there wouldn't be any purpose to running them through a high-voltage disconnect... I'd expect any respectable charger to be the same; all Victron and Sterling chargers already have high-voltage protection in place.

So, in closing, yes, you can do this as long as you connect the device "backward", that is, the "in" to the charger and the "out" to the battery. My only concern in this case, other than the apparent degree of redundancy, is the potential for "bounceback" - that is, if your charger is for some reason malfunctioning and running at full-bore while your batteries are already charged and your BatteryProtect shuts down the output, the current "bounceback" could read as a reverse current in the BP, which fries the FETs in a matter of milliseconds... and since I run the test bench at this distributor, I have seen firsthand the damage to the BP and connected components when reverse current is applied.

If you're set on using something of this kind, I'm inclined to recommend the Sterling ProLatch R instead, which is a bi-stable and programmable latching relay that is much more robust and will accomplish what you're going for without running the risk of frying itself. It's a royal pain in the absolute nuts to program, but once it's programmed it's an absolute beast... Food for thought. Good luck!

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mikedefieslife avatar image mikedefieslife Justin Cook ♦♦ commented ·

OK good to know. I have Victron Smart Solar MPPT controllers, and am looking forward to getting the new Orion Smart DC-DC charger to charge my LFP bank from by starter battery/alternator combo. So yes I suppose the smart battery protect on the input side would be overkill.

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Brian Johnson avatar image Brian Johnson Justin Cook ♦♦ commented ·

Hello

I was trying to use the 65amp SmartBattery Protect as you mention above to act as a HVD for solar coming into a battery bank (with the solar coming to the "in" terminal and the battery on the "out" terminal).

While I am able to set the shutdown voltage higher than the reconnect voltage when in demo mode I am not able to do so live. I can input the 14.5V for shutdown but it will not save that value.

Could you confirm that your unit still functions with the current firmware installed?

Thanks

-Brian

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jonathanv avatar image jonathanv Justin Cook ♦♦ commented ·
I know I am reanimating this thread but I too was hopeful that you could set the Battery Protect shutdown voltage higher and the reconnect lower but the current firmware does not seem to support this. I have my BMS controlling it by remote on/off but it would be a great feature to add. Is there a feature request option?
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jonathanv avatar image jonathanv jonathanv commented ·
I've just seen in the firmware updates that they have taken the ability to set the disconnect voltage higher than the reconnect voltage out of the Demo mode.
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Hi @mikedefieslife

Yes your bms should normally not have to engage, therefore you set the charging devices to the correct level.
The same goes for 'intelligent' discharging devices, like inverters, you set the minimum discharge voltage in those.

remains: 'unintelligent' discharge devices (loads), these you use the Battery Protect for.

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mikedefieslife avatar image mikedefieslife Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Excellent thanks. I do have a Victron 12/500 inverter. can that connect to the battery protect on the load side via VE?

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ mikedefieslife commented ·

@mikedefieslife

No you program the inverter to stop inverting at a safe voltage.
Also you can use the external on/off contact to shut down the inverter.

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nebulight avatar image
nebulight answered ·

I use a BPs in conjunction with my BMS for both the HVC and LVC. If any individual cell is too high, my BMS will drop the high signal to a Smart BP100. That BP100 has my mppt 100/50 and a non-victron DC to DC charger. It may not be good for the chargers to be turning on and off a lot, but my battery pack is pretty well balanced and has yet to trigger them. On the LVC I have a BP65 for my DC loads setup in the same way.

My Multi does NOT go through the BPs. I use the two wire assistant with optocouplers off the same hvc and lvc of the bms.



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