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Victron BM702!!!


KLEVA
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Yay, bought it, installed it and turned invertor back on... But now what??? I have absolutely no idea what the Victron settings should be and I can't make head/tail out of some of them - HALP!

So, On a single Axpert with 2 banks of 48V Calcium/Calciums (yes, still those monsters, but I am treating them as standard lead acid). Connected the midpoints (24V) to B2 of the Victron, and B1 to 48V as per the install diagram (and obviously connected the shunt on Ground)... But seriously, I have no idea what settings to configure yet on the 702... Do I just leave it alone, or do I need to make some changes? Read the manual, but am still a bit lost.

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Please don't leave me hanging - according to the current/default setup - Victron reckons my batteries are 100% but Axpert is telling me 46%. I understand the Axpert is notoriusly wrong, but thats a big difference. Voltages (both) at around 52.5V. And the rest of the values tie up nicely, including the KLEVA Solar manually calculated. I am sure I am missing something out of the nearly 70 settings on the Victron... I will trust the Victron over the Axpert, but only if I know it is set properly. For now, the Axpert still has control.

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+1 on Mark.

Make sure there is no in/out of the batteries, then Zero it, after they have been fully charged to float level to ensure SOC is correctly set to 100%.

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Ok, pennies starting to fall into place... So, if I understand this right:

  1. Switch to Utility charging until batteries full
  2. Turn off invertor (again)
  3. Disconnect ALL power in/out of invertor (both AC/DC)
  4. Check that batteries are at required Voltage (eg: 54V)
  5. Sync the Victron (+ & - keys)

But I still feel as though something is missing, do I not need to set up anything else? @jdp can you offer any further insight specific to the Axpert? According to what I get in the manual, the defaults should be fine if treating as normal lead/acid.

Can do all these steps tonight, and the manual isn't helping because some of the terms are like Owls flying above my head today.

Have set option 1 - 210Ah & Option 69 - Mid (as per the quickstart), but thats about all I have touched, not following the rest properly, dunno, maybe my brain just isn't in work mode today. Would love to blame @Camel, but he did not force me to have 4 draughts last night:D

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You have it then, the only other settings you change but them you learn as time goes by is charged time, charged voltage (Should just be under your float voltage 0.1-0.2v) and tail current on the bmv, for a start you can adjust the charged time to at least 30 minutes as the default seems to be way too short.

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Feck, just popped a fuse, the Victron lost it's settings (seriously) when it lost power and went back to default GRRRRRRRR. Start again!

Was testing the high power load (geyser & AC), and apparently (or obviously) a 35A fuse on the batteries told me to F-off and popped, cutting all power (like it's supposed to)...

But I suppose this is what playing with new toy learns you :D

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Yup, brain not quite on today... But even with max, the monitoring software only shows 15A max each way (Charge vs Discharge)... The new Victron also said 11A, so was a bit confused when a 35A popped... And it at least popped with aplomb (made a shower of sparks) like there was a short somewhere (I was in garage at time, and left a brown trail as I departed - if you know what I mean!)

Only installed the fuse this morning, so it may just be a dodgy unit - Everything still reading correctly so far (Axpert and Victron close enough values).

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Oh, but I like the maths - 35A is about 1.7kW, I was trying to draw about 6kW (although with solar feed as well)... Did also pick up something odd on the Axpert while installing a DC breakers this morning - Even when off and no power - there is a huge voltage difference on the DC (Solar/PV) side (enough to spark). Why is the Axpert allowing power out on the PV side?

Maths is definately my enemy today... Will carry on tomorrow and think a bit more carefully, maybe I will have an answer then.

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I have a DC isolator on the PV string... before I do anything on the inverter or battery bank I then disconnect the PV. Axpert doesn't switch off power from PV... Bus is still live.

Dangerous if you don't disconnect PV...

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Hi Mark, Solar DC was isolated at the time - Completely zero (tested - because have already learned that mistake), but while working on the Axpert side of the PV input (and this was while everything theoretically off (no DC battery input, no AC Input, No Load and Unit turned off!) there was a huge DC type spark across the + & - of the PV input leads (enough to leave black residue and eat a bit of the copper), which indicated a high power on the PV Input wires, even when isolated from the panels...

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Ok, did all the above, but still confused by the % readings... Has not dropped below 95% yet even though the voltage on has been down to 44V (on both Victron and Axpert - I deliberately set the switch over lower on the Axpert). Right now it's sitting at 99.5% at 50.82V (Utility charging at 1.2A)... It just feels wrong... I don't think the % is reading right.

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Remember to do a set with no load on the system. Only the BMV must pull power. And the bank must be 100% full.

And then let it charge and discharge a couple of time.

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Chris - Come back! There is a wrong way round?:blink:

Battery Negative -> Shunt -> Invertor Negative

If I look at the shunt/wiring the Battery Negative is connected to the brass bar at the top, the B1 & B2 connections plug in from the right hand side and the Invertor Negative is connected to the Brass bar at the bottom...

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With the shunt horizontal and the UTP at the top my order is +B2 then +B1 and UTP.

  • +B2 to Post on Bat
  • +B1 to Mid Point Pos on Bat
  • Left of Shunt -> to Negative on Inverter (or Busbar)
  • Right of Shunt -> to Negative on Battery

 

 

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