What happens if I run 70 Volts into an VFX 3648?

Discussion about OutBack Inverters in Off Grid Applications

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ebenbayer
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What happens if I run 70 Volts into an VFX 3648?

Post by ebenbayer » Wed Jul 29, 2020 9:52 am

I know the spec sheet gives a top range @ 68 --- what happens at 68.1 -- shut off, magic smoke, or is there some wiggle room? (for instance on the low side you can set the cut off down at 38 volts).

reason: I currently run a 2S5P set of tsla modules, fully charged at 48 volts, I'm curious about moving to 3S; 70 or 71 volts would give enough high end to make this make sense (and reduce amperage across system, which would be nice)

Thank you!

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Greg T Fordan
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Re: What happens if I run 70 Volts into an VFX 3648?

Post by Greg T Fordan » Wed Jul 29, 2020 12:13 pm

When battery voltage reaches above 68V, inverter immediately shuts down and will cease to function.

It will begin to function again if it goes lower than 68. This is not adjustable like low battery protection.
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Re: What happens if I run 70 Volts into an VFX 3648?

Post by fcwlp » Wed Jul 29, 2020 12:16 pm

The inverter will shutdown at 68.1V as the max HBCO (High Battery Cut Out) is 68.0V. With appropriate wire sizes and/or buss bars the higher amperage is not going to be an issue.

ebenbayer
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Re: What happens if I run 70 Volts into an VFX 3648?

Post by ebenbayer » Wed Jul 29, 2020 1:03 pm

cool. I figured having explored the manual and settings menu but worth checking. All wires are sized appropriately. I'm running 4 VFX stacked; going "up" in voltage would just take load of the system and increase the carrying capacity of existing wires; with that said @ 68 volts I leave about 20% of the top end of these batteries behind, so I think ill stick to my current 36-48 volt range. Thanks for help!

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Re: What happens if I run 70 Volts into an VFX 3648?

Post by raysun » Wed Jul 29, 2020 1:17 pm

Lots of Lithium battery research points to charging cells to maximum capacity as one of the operations that shortens cell life due to accelerated growth of dendrites.

IMO, partial state of charge is healthier for these chemistries. Running a lithium cell between 80% and 20% SoC wouldn't necessary be a bad thing.

Just my $0.02

ebenbayer
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Re: What happens if I run 70 Volts into an VFX 3648?

Post by ebenbayer » Wed Jul 29, 2020 1:34 pm

100% correct. I should note 51.5 is fully charged. I charge to 48 v for that reason. So 20% off my 20% if I go 3p :)

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