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LibreSolar / mppt-2420-lc

Hackable and open source MPPT solar charge controller
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how do you protect the ADC input from reverse polarity of the battery? #18

Closed kikiloaw closed 6 years ago

kikiloaw commented 6 years ago

i am trying to figure out your circuit. the output voltage of voltage divider will go higher because of reverse polarity.

martinjaeger commented 6 years ago

The output reverse polarity is achieved with the fuse and the body diode of the LS MOSFET Q4. This should happen fast enough so that the large output capacitor can hold down the voltage until the fuse is blown. Otherwise also the capacitor would be damaged. The reverse polarity protection does not work if using a low-power current-limited device, such as SMPS, instead of a battery.

kikiloaw commented 6 years ago

so it means doesn't need to add polarity protect at the battery side?

kikiloaw commented 6 years ago

can this build protect from reverse polarity at adc and capacitor without fuse? i cant find high current fuse here. i am trying to build at 60->100 Amps

martinjaeger commented 6 years ago

I think for high current applications you need to think about another way of reverse polarity protection. Maybe MOSFETs?

kikiloaw commented 6 years ago

hi, i am having a problem with my mppt. i try to calibrate each of my voltage divide separetely. but then when the it starts charging. the voltage at the battery side will detect arround 20 volts. i dont know that wrong with that

On Tue, Feb 6, 2018 at 2:26 AM, Martin Jäger notifications@github.com wrote:

I think for high current applications you need to think about another way of reverse polarity protection. Maybe MOSFETs?

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/LibreSolar/MPPT-Charger_20A/issues/18#issuecomment-363175223, or mute the thread https://github.com/notifications/unsubscribe-auth/AhOMVGOP2sI2o5p7v5IX4rJfqrNwMfgKks5tR0fggaJpZM4RWyTZ .

martinjaeger commented 6 years ago

Did you rebuild the Libre Solar MPPT? Which revision?

Please describe your problem in more detail.

kikiloaw commented 6 years ago

I build my own version using ir2104 since it is the driver I already have., I use your schematic as reference on how you build and how you code them all ., can please take a look at mine? Ican send you my schematic

On 8 Feb 2018 11:21 p.m., "Martin Jäger" notifications@github.com wrote:

Did you rebuild the Libre Solar MPPT? Which revision?

Please describe your problem in more detail.

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/LibreSolar/MPPT-Charger_20A/issues/18#issuecomment-364144869, or mute the thread https://github.com/notifications/unsubscribe-auth/AhOMVDzDynpZQF_Ph-Di-Fysf9DKCkiAks5tSxESgaJpZM4RWyTZ .