# MultiPlus 12/3000/120 all of a sudden not reading battery voltage correctly **URL:** \ **Category:** DIY\ **Tags:** rv, multiplus, diy\ **Created:** [19 October 2026 23:49 UTC](https://community.victronenergy.com/t/multiplus-12-3000-120-all-of-a-sudden-not-reading-battery-voltage-correctly/64161 "2026-10-19T23:49:45Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![tpearce63](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tpearce63](https://community.victronenergy.com/u/tpearce63)\ **Post date:** [19 October 2026 23:49 UTC](https://community.victronenergy.com/t/multiplus-12-3000-120-all-of-a-sudden-not-reading-battery-voltage-correctly/64161/1 "2026-10-19T23:49:46Z")
Hi - I purchased a system from AM Solar in Arizona, USA, 6 or so years ago, including a Victron Multiplus (12/3000/120) inverter. The system has been absolutely great, and the support I have received from AM Solar has been top notch. However, they have gone out of business and I don’t know where to turn for help. I just seem to have developed a problem with the Multiplus. It seems to be reading erroneous voltage from the battery bank. It jumps all over the place, between 13.2 volts up beyond 5 volts. This causes the charger to erroneously think it needs to go into absorption mode, or float mode, and doesn’t charge the battery bank. I have checked all of the connections, especially the connection of the voltage sensing probe going to the MultiPlus, and even swapped out the battery bank (was going to upgrade, anyway). Meanwhile, the BMV-712 shows a steady 13.12 volts (as does my VOM). I also have 2 Orion DC-DC chargers, and they also show the steady 13.12 volts. I have perused a number of posts that call out that the MultiPlus reading is different/off from other sources, but that isn’t my issue. It seems that something has failed/changed in the circuitry for reading the battery voltage. This was working correctly for years. This issue just appeared in the last few months. I just got around to seriously trying to fix it. Can you help? Please let me know if you need any more information. Thanks! ---
**Author:** ![MiPaul](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/mipaul/32/41338_2.png) [@MiPaul](https://community.victronenergy.com/u/MiPaul)\ **Post date:** [20 October 2026 03:22 UTC](https://community.victronenergy.com/t/multiplus-12-3000-120-all-of-a-sudden-not-reading-battery-voltage-correctly/64161/2 "2026-10-20T03:22:06Z")
> [@tpearce63](#): > > the BMV-712 shows a steady 3.12 volts (as does my VOM) Assuming you mean 13.2V? Measure voltage from battery neg lug to inverter neg lug, do the same for the positive side. If either are more than a few hundred millivolts, you have a bad connection in that leg. ---
**Author:** ![tpearce63](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tpearce63](https://community.victronenergy.com/u/tpearce63)\ **Post date:** [20 October 2026 12:18 UTC](https://community.victronenergy.com/t/multiplus-12-3000-120-all-of-a-sudden-not-reading-battery-voltage-correctly/64161/3 "2026-10-20T12:18:38Z")
Yes, thanks for the correction, and for responding. It’s definitely something in the MultiPlus path to read the battery voltage. Just wondering if these things can be repaired or if an alternative way is available for the MultiPlus to get its battery voltage reading. Thanks again! ---
**Author:** ![tpearce63](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tpearce63](https://community.victronenergy.com/u/tpearce63)\ **Post date:** [20 October 2026 19:02 UTC](https://community.victronenergy.com/t/multiplus-12-3000-120-all-of-a-sudden-not-reading-battery-voltage-correctly/64161/4 "2026-10-20T19:02:28Z")
Well, I come hat in hand. I figured it out. Paul, you were on the right track but my tunnel vision didn’t let me put two and two together. I guess I was thrown off by the symptom - it didn’t occur to me that the voltage might read something, even something close to what it is suppose to be, if the positive lead to the MultiPlus is not connected to the batteries. In hindsight, the fact that the voltage was jumping all over the place constantly should have been a clue. Long story short, it was my battery cutoff switch. The positive lead for my batteries connects to one end of a 400A fuse. The other end of the fuse connects to one terminal of the battery cutoff switch. The other terminal of the switch connects to a bus bar. The positive battery lead for the MultiPlus connects to that bus bar: Batteries -----\>400A fuse ----------\> Battery cutoff switch -----------\> 12v bus bar So, the path to the batteries’ positive side for the MultiPlus goes through the fuse and the cutoff switch (and all of their associated connections). The battery switch was suppose to be rated for 600A. Apparently, the one they shipped me was only rated for 275A. I never checked before installing it 6 years ago. It looked fine from the outside, and seemed to mechanically function fine. However, when I checked continuity through the switch I got high resistance at a minimum, sometimes completely open. When I opened it up the contacts were fried. I recently had a situation this summer where I set up my RV for some guests. However, I only have a 15A AC circuit at home, so I limit AC current to 12.5A in the MultiPlus. When I set up the RV at my brother-in-law’s house for the guests, I plugged it into a 50A service. I forgot to change the current limit in the MultiPlus from 12.5A to 50A. I usually put the MultiPlus in Charge Only mode when hooked to 50A shore power, but forgot to do that as well. Once the air conditioners kicked on it sent the AC current draw way past the 12.5A, putting the MultiPlus in “supplement AC power with the inverter” mode. It didn’t take long to drain the 400AH battery capacity, and I imagine that was a huge current draw on the batteries during that time. I believe that’s when the 275A rated switch burned up, even though the 400A fuse didn’t blow. Thanks again to Paul for responding, and to everyone else that viewed my situation and gave it a think. ---
**Author:** ![system](https://europe1.discourse-cdn.com/victron/original/1X/21a9a7b5db7c6339715f993568736a7053199995.png) [@system](https://community.victronenergy.com/u/system)\ **Post date:** [3 November 2026 19:03 UTC](https://community.victronenergy.com/t/multiplus-12-3000-120-all-of-a-sudden-not-reading-battery-voltage-correctly/64161/5 "2026-11-03T19:03:26Z")
Closed on 3 November 2026 19:03 UTC This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.