What happens when battery is disconnected abruptly

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martijn
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My RE system: Flexmax 80 4pc 135W Kyocera, 4pc 95W Kyocera, Mastervolt Li Ion Ultra 12/5000
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What happens when battery is disconnected abruptly

Post by martijn » Thu Aug 15, 2013 10:45 am

Does someone know what happens with my 2 strings of 4 panels and Flexmax80 when my system abruptly disconnects the battery's to my Flexmax (over a relay) when charging?
The relay is integrated in my sytem because of safety of the Li-ion battery. The complete system is installed in and on my rv. When the voltage rises too high or overcharging, the system disconnect the battery.

Thank you for your answer!
Kind regards from the Netherlands!

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MyEnergyWarehouse
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Re: What happens when battery is disconnected abruptly

Post by MyEnergyWarehouse » Fri Aug 16, 2013 4:53 am

When the relay opens the circuit to protect the batteries, the energy ceases to flow. Nothing begins to happen as your system is designed to operate. Sometimes nothing is good.

Once the batteries become stable and there is energy used, the relay will close and the solar once again will provide energy to the batteries and for your use.

I would really be interested in knowing what unit sends the signal to the relay to disconnect the batteries. Is it the Battery Management System? Or are they using the FM80 to send the signal when the batteries exceed a preset voltage level?

Do you know the manufacturer of the batteries? - NOTE: these questions are more for my personal education than an answer to your question. If you do not know or do not want to respond, no offense will be taken.

martijn
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Re: What happens when battery is disconnected abruptly

Post by martijn » Sat Aug 17, 2013 6:48 am

MyEnergyWarehouse wrote: I would really be interested in knowing what unit sends the signal to the relay to disconnect the batteries. Is it the Battery Management System? Or are they using the FM80 to send the signal when the batteries exceed a preset voltage level?

Do you know the manufacturer of the batteries? - NOTE: these questions are more for my personal education than an answer to your question. If you do not know or do not want to respond, no offense will be taken.
The Mastervolt Li Ion has a complete electronic sytem build in, which keeps the battery healthy and you can program events which lets other devices, which are connected to each other by Masterbus, follow this events to do something you have programmed like opening a relay when the chargingvoltage is getting above a programmed hight. To better understanding what I am trying to explain to you, look at mastervolt.com

The manufacturer of my entire system is Mastervolt.


Why I asked my question what happens with my Flexmex 80 is, when my alternator is abrubtly disconnected from my battery, it will result in a complete distruction of the alternator. He cannot react fast enough on the change of situation. for example: he's charging at 60 A 13,5 Volts...and gets disconnected....he still is charging with 60 A, but he cannot let the energy somewhere. The alternator will burn through.
So I thought, maybe the Flexmax cannot deal with this also.... :-k :-k

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MyEnergyWarehouse
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Re: What happens when battery is disconnected abruptly

Post by MyEnergyWarehouse » Wed Aug 21, 2013 5:15 am

martijn wrote:Why I asked my question what happens with my FlexMAX 80 is, when my alternator is abruptly disconnected from my battery, it will result in a complete destruction of the alternator. He cannot react fast enough on the change of situation. for example: he's charging at 60 A 13,5 Volts...and gets disconnected....he still is charging with 60 A, but he cannot let the energy somewhere. The alternator will burn through.
So I thought, maybe the FlexMAX cannot deal with this also.... :-k :-k
I'm sorry that I missed the "real" question the first time. While the FM80 can deal with it on the short term, it was not designed for that kind of shut down. I would recommend that Mastervolt would install another relay on the PV side of the FM80 that opens simultaneously with the main disconnect to shield the FM80 from the abrupt disconnect.

martijn
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My RE system: Flexmax 80 4pc 135W Kyocera, 4pc 95W Kyocera, Mastervolt Li Ion Ultra 12/5000
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Re: What happens when battery is disconnected abruptly

Post by martijn » Wed Sep 04, 2013 5:14 am

ok, so you are saying that it's better to disconnect at the PV side then on the batteryside of the FM80?
That's not so difficult to change for me. But the PV-panels can handle a abrupt disconnection without problems?

What do you think what happens with the FM80 when this abrupt disconnection happens? I've had it once, and it seems that my system is giving less Amps. Is that possible, or do I just think that. The problem is that I can't really check, because the PV-installation is on the roof of my RV and I am never staying on the same place, with same conditions, more then once.

WNY DAVE
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Re: What happens when battery is disconnected abruptly

Post by WNY DAVE » Wed Sep 04, 2013 3:13 pm

It sounds like there is an overvoltage disconnect (relay or something) to the batteries?

Do you know what the setting are in the FM80? Maybe there are setting for the AUX outputs and it controls something based on certain values you can set or that are already set in the controller.

If the PV panels are disconnected, the controller probably will think its in sleep mode, no input.

I have put cardboard over my PV panels to manually disconnect them, once the voltage starts to drop down to an acceptable level. I unplugged them when I was testing the system.

However, I do have breakers inline now so I can shut off the power from the panels if I have to or if something goes wrong and they draw too much current.

It may be putting out less amps if your batteries are fully charged or do not need charging. If they are FLOATING, the current will be very low.

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MyEnergyWarehouse
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Re: What happens when battery is disconnected abruptly

Post by MyEnergyWarehouse » Thu Sep 05, 2013 12:19 pm

martijn wrote:But the PV-panels can handle a abrupt disconnection without problems?

What do you think what happens with the FM80 when this abrupt disconnection happens?
martijn,

As far as I know most panels would have no problems with sudden disconnects that you described.

For the FM80 - the concern is on restarting after the sudden disconnect. The FM80 may no be able to recognize the battery voltage and reset its self or begin charging at the incorrect voltage. I received this information from a former OutBack technician.

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