question

torrmundi avatar image
torrmundi asked

How to overcome Batt line losses?

Setup is this:

Solar: four of Kyocera KD140GX-LFU, Pmax 140watts, Voc=22.1vdc, Isc=8.7A, Vpm=17.7v, Ipm=7.9A, all panels mounted skyward on salon roof.
Regulation: four of Blue Solar MPPT 75/15 regulators, firmware v1.46
Batteries: three of Lifeline GPL-4DL AGM batteries, 210 AH each
No loads are connected to any regulator. Line losses to Batt terminals can be 1.0volts.
No Smart Battery Sense or BMV.
Magnum Energy shunt and battery monitor.


I could add a Smart Battery Sense, but will four MPPTs all connect to one SBS?

How can I get correct voltages to the MPPTs, when I know there is about a 1 volt difference when charging at a few amps from 2 of 4 MPPTs, in bulk charge? The other two are in float.

Should I play with higher absorption and float voltage thresholds? How high? I'm using the Factory Default Gel Victron deep discharge(2) profile.


MPPT Controllers
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2 Answers
klim8skeptic avatar image
klim8skeptic answered ·

Hi Torrmundi,

Yes you can use a SBS for all 4 mppt's. Do you have BT dongles for each mppt?

Something else you can look at would be to have a new bus close to the mppt's. Nice thick wire + fuse between the battery and bus, and regular wire between the bus and mppt's.

Image pinched from Wiring Unlimited.


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torrmundi avatar image
torrmundi answered ·

Thanks Klim8sceptic. Yes, I have added Smart Bluetooth dongles to each MPPT and a Smart Sensor to the battery. At this point, the algorithms should be based on optimal information. Too late to rewire the boat!

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