diy solar

diy solar

Solar Powered Lighted Address Wall

Midknightoil

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Joined
Jun 28, 2021
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7
I am building the Solar portion of a soon to be driveway wall. I have built the solar portion to include a customer Ammo Can 18650 3S24P Battery running a Daly 3S BMS. The MPPT is a WIN-500 MPPT designed for RV integration and it offers a basic Wireless Management interface from an Android device. My question is regarding the Battery Chemistry and subsequent MPPT settings as it pertains to the following:

Charge target voltage(CVT) setting range: 10.0-32.0V (default: 14.4V)
Charge recovery voltage(CVR) setting range: 9.2-31.8V (default: 14.0V)
Low voltage disconnect(LVD) setting range: 9.0-30.0V (default: 10.6V)
Low voltage reconnect(LVR) setting range: 9.6-31.0V (default: 12.0V)

The default Lithium settings have me a bit confused. Based on a typical 18650 Battery in a3S configuration I would expect the CVT to be 12.6 and the CVR to be something slightly lower. Are those relative to Lithium Phosphate vice Lithium Ion? I fear doing damage to a significantly sized custom battery pack so any advice is sincerely appreciated. For now I am erring on caution and adjusting the CVT to 12.7 and the CVR to 12.4 If anyone has feedback on all the custom setting listed above as it pertains to a 3S Lithium Ion battery pack I would be grateful.

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Revision:

I attempted to modify as indicated above and made several observations. The Battery reports as 14.4v in the MPPT interface. Additionally I was only above to adjust the CVR to 12.7 and the CVT to 12.9. But as I noted previously by my calculations as 3S 18650 pack would be 100% charged at 12.6v give or take a small bit.
 
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Yet another observation, my concern regarding the above voltage settings gave me the impression the PV charging is over charging for the battery chemistry in use. I removed the PV connections in the late afternoon and as soon as the PV was disabled the voltage dropped from 14.4 to 12.6 (indicative of 18650 in 3 Series. I left the lamp run through the night to see what affect it had on the Battery for the consumption and it was 12.4 by morning. I would welcome any feedback regarding the MPPT controller settings. I am thinking more and more that the WIN-500 MPPT controller is not suited to a li-ion implementation but given that it has a Lithium setting and with my inexperience with Lithium Phosphate do either of them have a 14.4v CVT?
 
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