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tom53934 asked

How do I lower the high voltage in a 12v system after BlueSolarMPPT 100/30 charges a Battle Born 100amp Lithium ?

I have voltage of (18-20 volts depending on the sun) that goes through to my 12 volt electronics in the camper. I have NO inverter. Have a 200 watt panel on top, wired to a BlueSolar mppt 100/30-shunt-BMV 712-BattleBorn 100amp Lithium. The system works great until the BattleBorn is charged, then the voltage keeps climbing up. I have tried numerous resets and disconnected wires, have the mppt rotary dial set to #7, what should I do next or redo...lol? On the bluetooth app I can't find a 12v or 24v system setting. Oh the mppt stays in bulk after the battery is charged...tx...Tom

battery charging
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tom53934 avatar image tom53934 commented ·

PV wiring on the left. Shunt has negative load on the right.

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JohnC avatar image JohnC ♦ tom53934 commented ·

Yeh, I should have explained that you'll need a bluetooth dongle on that model mppt to change anything in there. Sorry..


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JohnC answered ·

In the app for the mppt, click on the 'Cog Icon', select Battery, and it should show. Good luck.

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tom53934 avatar image tom53934 commented ·

Thanks John, I have been in the battery setting through the 'cog icon'. I have no battery option for 12v or 24v. I have just the BMV-712 app firmware v4.01, do I need another app specifically for the MPPT?

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JohnC avatar image JohnC ♦ tom53934 commented ·

Same app, just a bluetooth dongle to connect to that mppt. And yeh, I hate recommending more expense, but there it is..

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tom53934 avatar image tom53934 JohnC ♦ commented ·

Thanks John, The only way to change the setting from 24v to 12v is with this dongle? https://www.amazon.com/Victron-Energy-VE-Direct-Bluetooth-ASS030536011/dp/B01CGFF8Q2/ref=cm_cr_arp_d_product_top?ie=UTF8

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JohnC answered ·

Okaay. Now the real truth is revealed. :)

Remove the 50W intruder and see what happens. The mppt may well be working correctly, and when the Battle Born BMS? shuts down it's charge when full, the 50W panel is feeding just the downstream circuits with V that could go anywhere. With no current in your 12V system, the V could be expected to approach the Voc rating of the panel.

It's why panels should always have a controller. You could still use it to help charge before Absorb/Float V's are reached (it mightn't do much away from it's mppt optimum), but don't use it once the batt is up to V.

The mppt should show 0W once it's V settings are exceeded (barring a possible zero error).

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tom53934 avatar image tom53934 commented ·

Hi John, The 50W Intruder (I like that) was hooked up for about 5 mins. I disconnected the mppt and reset the BMV712 after that curious move. That extra voltage must have changed the mppt to a 24V setting? Like you said that downstream V could have went anywhere, my newbie fault. Thanks for pointing out that the 50W panel should have a small controller. Yes your right, the mppt did show 0W after the V setting was exceeded. Any recommendation for a small controller? I'm thinking an inexpensive PMW or ?

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JohnC avatar image JohnC ♦ tom53934 commented ·

Yeh, any-ole cheapy should do. Victron even still make em..

Not sure where your issue stands now, but it's good to see you having a go, and learning along the way. Keep asking if you need, someone here will always help such a personable fella as you.

Happy camping too..

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tom53934 avatar image tom53934 JohnC ♦ commented ·

John, I appreciate you taking your time to help me ;-)

I'll let you know how the system works after the bluetooth dongle is installed.

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tom53934 avatar image tom53934 JohnC ♦ commented ·

Hi John, Got the Victron bluetooth dongle installed and bingo, was able to change the mppt 100/30 from 24v to 12v. Thank you very much for pointing me in the right direction on my first solar install. Appreciate it, Tom


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