24V victron battery charge with Orion Tr 12/24-15 from another lithium battery - voltage drop problem

DIY
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1

Hi all,

I have a 24V 200Ah Victron battery charged with my other lithium 12V 200 Ah battery with Orion 12/24-15.

My idea was to set my Orion to start charging when the solar panel or alternator starts charging my 12V lithium and not to discharge the 12V battery more than 20% (80% SOC), so I have disabled the engine shutdown option and set Input voltage lock-out options to:

  • Lockout value: 13.0
  • Restart value: 14.2

Now Orion did start when the solar or alternator started charging, but my voltage dropped down to 13V in a minute, so I tried to lower that setting, and even at 12.5V it still dropped down in a few minutes (usually it stops around 12.5V). Now my distance from the 12V battery to Orion is 4m one way, i have put 25mm2 cables and when I measure voltage from my bus bar it is 13.2V but when i measure the voltage on the input wires on Orion it shows 12.6V, the current being drawn is around 40Amps.

So my question is why so much voltage drop and how can I set Orion not to discharge my 12V battery more than 20%, if I lower lockout voltage that would mean my 12V is probably more than half empty.

2

Voltage drop should be lower than that. Check all your connections, crimps, fuses and any isolators. Use you voltmeter to check the voltage at each connection to identify where your voltage drop.is occuring. A lot of DIY installs use resettable breakers like these below, they have a track record for high resistance.

breaker2
breaker21000×932 60 KB

breaker1
breaker11000×976 56.3 KB

3

Hi there,
Thank you for answering, my last connection before Orion showed 13.1V (bus bar), and from there the cable from bus bar to Orion is 1.5m long one way and they are 16 mm2 cable (i think the biggest one that Orion can accept and all cables are marine grade tin-copper).

The fuse i am using is this one (100Amps )

image
image720×291 51.9 KB

4

You just need to check all your connections are tight as 0.5V drop in 1.5m is high. Try to check with the multimeter probe on the wire strands and equipment terminals. Also see if any connections are warm when operating at maximum current.