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fredivar avatar image
fredivar asked

Smart BMS CL 12/100- Persistent A-B11: Under voltage Error

img-20220607-095555-01.jpgPurchased recently a Smart BMS CL 12/100 and connected to boats Lead acid start battery and LiFePo4 service battery. Configured it to use 60A current limit by using 60A fuse, and setting the same in Victron Connect App. But it seems to be a persistent error message I’m not able to clear no matter what I do. Tried “Facory reset”, use “Mode switch” to turn OFF and then ON again, but to no success. Voltages seems to be correct, but no charging of Lithium battery from the alternator, see screenshots attached. Could it be a configuration issue, or something else?

BMSalternator
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fredivar avatar image
fredivar answered ·

No one have any suggestions or comments?

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fredivar avatar image
fredivar answered ·

This is very strange. Received another Smart BMS CL 12 /100 from my Dealer in Norway, but the new one act exactly the same as the previous one, same A-B11 Under voltage error. No matter what I do, the error is there all the time, even though voltages is at full charge on both battery banks. Firmware V. 1.06


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nebulight avatar image
nebulight answered ·

Next thing I would check would be the cables from the batteries to the BMS. Make sure there are no bent pins or connections that are loose. My guess is the BMS isn't getting a signal from the battery that the allow to discharge is triggering a low voltage alarm on the BMS.

Stupid question, but you are using Victron Smart lifepo4 batteries, correct?

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fredivar avatar image fredivar commented ·
Thanks for your comments, your last question is not stupid and I am not using Victron Smart Lifepo4 batteries, but Meritsun 12v200ah battery, so connection to batteries is simple, just the straight connection to batteries/alternator and ground connection. I cannot see from documentation that a Victron Smart Lifepo4 is required? It should be possible to use standard batteries too?
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Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

Hi @fredivar

The Smart BMS CL is exclusively for Victron Lithium Smart batteries and cannot be used with your battery.

See also the Description in the manual or the Product description.

edit: I just had a look at your battery. It has an internal BMS. So I suggest to read the manual of your battery and see how you can control your devices.

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fredivar avatar image fredivar commented ·

Hi @Stefanie

Thanks for you feedback, I really hoped that this unit was able to be used with other off the shelf LifePo4 batteries, to be able to protect the alternator from excessive heat and possible failures, and if only possible to be used with Victrons own smart LifePo4 batteries, this was really bad news. Is it political by Victron to only support own batteries, or is it electrically impossible because the Smart BMS CL 12/100 only controls the internal BMS inside Victron batteries, not that it actually is able to limit current by itself without the Victron batteries?

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ fredivar commented ·

Hi @fredivar

Yes, I am very sorry for you. But that's why we have our data sheets and manuals, which you can look at in advance, i.e. before you buy.

This is not possible electrically. Our lithium smart batteries have built-in balancers (we call them BTV modules) that indicate a corresponding alarm condition, e.g. low cell voltage, to the external BMS. The BMS processes these signals and controls the loads or chargers accordingly via load disconnect or via charge disconnect.

These signals are not provided by other batteries, especially not by so-called drop-in batteries.

Whether the Smart BMS CL 12/100 is able to limit the alternator current without Victron lithiums? I don't think so. But I haven't tried that. It will not change the situation either. In order for the Smart BMS to work properly at all, it needs the signals from the Victron battery. Without this, the error message remains and a low voltage error is still reported.

Since your battery already contains a BMS, which takes care of the battery in case of low and high cell voltage and hopefully also low temperature, there is no need for a second BMS. You can limit the alternator current by other means, for example by using a DC-DC charger like a Orion smart charger between the starter battery and the house battery.

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fredivar avatar image fredivar commented ·

Hi @Stefanie

I read many of the Victron manuals, and especially the Victron Smart Lithium battery where it was thoroughly explained how connection and functionality towards different BMS are. And also read different threads here on the community, and it was eventually obvious to me that the M8 Circular BMS cables needs to form a closed loop either with one or several batteries, and wondered if it would be possible to just make a similar closed loop, but without the Victron Smart Lithium battery in between. So I connected from the Male M8 to the Female M8 signals (through resistors) , and saw that "Under voltage" error disappeared and Charging to Lithium battery started. I find it strange that on many websites that sell Victron equipment, many do not list the M8 Circular BMS cables as "related" to the SmartBMS CL 12 /100 . Since my Lithium battery have its own BMS and protection circuits, I assume I don't need the BMS functionality here, but I would need the Alternator protection circuit in the Smart BMS CL 12 /100, and assume this will still function even though the BMS functionality do not. In my system, the alternator current limit would be around 50A since 60A fuse is in place and also selected in the App.

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ fredivar commented ·

Hi @fredivar,

Using the Smart BMS in this way (short-circuiting the BMS cable connections) is not intended. If that's how it works for you, then that's your choice. But it must also be clear that using it for anything other than its intended purpose will void the warranty and there will be no support for it.

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olivier-dubreuil avatar image olivier-dubreuil fredivar commented ·
Hi fredivar, same mistake here, i also use a non victron lifepo with its own BMS. I don't understand how you managed to make it work. Did you connect the bms from your battery to the M8 male and M8 female? Or did you just plugged a cable from the Victron M8 female to the victron M8 Male? Through resistors? What kind? I might be out of my league here and probably just wasted money. Just needed to protect my alternator and isolate the batteries. No BMS needed. Thank you if you find the time to reply
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nunoo avatar image nunoo fredivar commented ·
Hello! Can you please explain more in detail how you've done it? Taking the battery BMS is a possible solution?
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