question

jason-vaughan avatar image
jason-vaughan asked

Mppt 150/35 swings wildly and misreports voltage, etc.

I'm not sure where to start, so first with my setup:

Batteries: Currently using two 100ah, SLAs in parallel.

PVs: 6 - 100W renogy panels, currently wired in series. - Max voltage detected is about 130v

Also installed: BMV 702 with shunt. Using the networking feature conntect both devices.


Issues:


The MPPT controller swings wildly and the "solar" voltage swings all over from 80v to 129v. The watts swinging back and forth as well, from 0 watts up to about 350 watts.


Before I connected the networking, the mppt would show a voltage of 14 or 15v and then obviosly shut down the charge state. I connect networking and it will sync up better but then the wattage swings wildly for awhile. Once in a while it will settle down and give me a solid 24 - 25 amps at about 320Watts - in Bulk. When it goes to absorption charge that when it starts swinging or huntling wildly, not sure whats going on. Just wondering if anyone else has seen these issues...?


I'm also about to install a 400ah (4s2p) Lithium Lipo4 system and retire the SLA's which have been kept in amazing shape over the years. BTW - the Victron MPPT is new, less than a month of use. I had bought it to replace my renogy rover which couldn't handle the voltage I wanted and I also recently installed the 5th and 6th 100w panels. They were both tested before install.


And now, while I'm writing this, the MPPT relay just clicked and I looked and I'm back in absorption charge with 0 current in / out. Somethings just not right. Any suggestions on what to check would be appreciated.


I guess a place to start is what preset would you recommend in the battery settings for SLA...? Also, the lithiums will be installed like next week, so what setting should I use for that...?


Or, would you just use custom settings...? I also just switched it to AGM Spiral, and the MPPT just turned on again and seems to be pushing a solid 24amps for about 2 minutes then starts swinging again.



Thank you,





MPPT Controllers
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1 Answer
Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

Hi @Jason Vaughan,

what are the specs for your 100W Renogy panels?

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