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richi1230 asked

MPPT 30/100 and 50/100 forces Cyrix Li Charge to go into overvoltage error

I have 2 MPPT Smart Solar charger (30/100 and 50/100) together with 3 Orion TR connected on a VE.Bus controlled LiFePo battery in van.

My idea was not to load up to 100% SOC all the time (goal is to charge up to 80%). Therefore I planned to interrupt charging based on SOC measured by a BMV700 and using the built in relais to interrupt the VE-Bus signal to the cyrix Li charge relais.

So far so good, stopping the charging process works fine, BUT ....

the MPPT charger has an ideling voltage on battery out terminals of about 16.2 V when battery is disconnected. Cyrix Li Charge recognize this an overvoltage (more than 16V) and prevent to reconnect chargers to the battery.


Any ideas, how to overcome this situation?

MPPT ControllersCyrix Battery Combinerovervoltage
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2 Answers
Paul B avatar image
Paul B answered ·

I this case I would think you may need to change to a different style of relay thats not voltage sensitive if its only for charging then a BP maybe a better solution

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richi1230 answered ·

Hi Paul, thanks for your fast answer. To be honest, that's not what I wanted to read because of the complex layout, there is no space left for a 220A BP.

Any other idea how to reduce the idle voltage of the MPPTs before reconnecting to the battery?

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Paul B avatar image Paul B commented ·
Not that I am aware of
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Paul B avatar image Paul B Paul B commented ·

Just a thought are you using DVCC and shared voltage, as if this is on then the battery maybe low and the smart solar is being told its at say 13v and thus its cranking its output voltage up when the cytrix relay is open, so try turning DVCC off , Just a possible solution, as I would have thought that the MPPT would never normally go over its max set voltage, even when its open circuit. Thats if it being the MPPT is being used as the voltage reference point

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richi1230 avatar image richi1230 Paul B commented ·
Unfortunately disabling DVCC doesn't help. Ideling voltage of MPPT is slowly climbing to about 16.2V after reset (takes about 2 Minuten)
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Related Resources

Product page Cyrix Battery Combiner

MPPT Product Page

MPPT Error codes

MPPT 150/60 up to 250/70 Manual

Additional resources still need to be added for this topic