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staszek avatar image
staszek asked

Smartsolar 100/50 incorrect light

I have 2 100/50s both with 2 panels each.

Sometimes one will have the absorption light on before the other and when the absorption voltage hasn't been reached. I usually reset by disconnecting panels and battery and re connecting. This gets rid of it and goes back to bulk.

Today I tried this and the absorption light came on again. I checked the current and was pulling around 300w which suggests the charger is still in bulk mode. Also the same current as the other MPPT which has the bulk light on.

So it appears the controller is functioning but the lights are doing their own thing!

Not sure why this would happen!?

Both controllers are set up the same.

14v absorption and 13.5 float on a lithium battery

MPPT Controllers
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kevgermany avatar image kevgermany ♦♦ commented ·
Same battery or separate batteries?
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secessus answered ·

I suspect resistance in the charging circuit is causing premature Absorption because the controller is "seeing" artificially-high voltage from the battery.

If this is the case then adding a Smart Battery Sense or (IIRC) SmartShunt to the VE.smart network will pass correct bank voltage to the controllers.

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staszek avatar image staszek commented ·
Thanks, v.e smart network now set!
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staszek answered ·

I already have a shunt connected to the smart battery monitor. Bmv712. Can I use this to communicate with the mppts?


The fact that there are 2 mppts connected via a lynx distro to a battery with very short and large capacity cables means there shouldn't be much resistance.

But seems strange that the 2 controllers are showing different things.

Also even though the absorption light was on. The controller was still acting as if in bulk and the current in hadn't been limited down.

The affected controller has shown higher voltages that the other in the max battery voltage history


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secessus avatar image secessus commented ·

The affected controller has shown higher voltages that the other in the max battery voltage history

I think that's telling us something useful; fits the pattern of seeing higher voltage so entering Abs prematurely.


I already have a shunt connected to the smart battery monitor. Bmv712. Can I use this to communicate with the mppts?

I have no experience with it. My reading of the specs and manual suggests it does support VE.smart BT network, which could inform the controllers. Since you already own it I'd say it's worth trying. I think all it would involve would be adding all the players to the same VE.smart BT network. Hopefully folks with more experience will chime in.


even though the absorption light was on. The controller was still acting as if in bulk and the current in hadn't been limited down.

The batteries limit current acceptance in Absorption, not the controller (which just wants to hold the voltage setpoint steady).

Lithium doesn't taper much in "between the knees" so the difference in current between Bulk and early Absorption may be minimal. Lead had more of a consistent taper from Absorption to FLoat.


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staszek answered ·

Have set up my smart network now so will see how that goes! Thanks

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