Orion Charge Rate Tapers to about 40% of Max

DIY
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1

hello,
I have a perplexing situation with the orions in my truck camper. (This issue looks similar but not identical to one reported by @GuyPlanner and addressed by @pwfarnell.)

Here’s my truck camper system configuration:

12V System

Truck:
2 (smart) alternators 160A and 240A for a total 400A capability.
2 starter batteries, new-ish, AGM.
engine running signal connected to orions.
#00 gauge wire from batteries to camper, about 3m, both pos and neg.

Camper:
3 SmartLithium batteries 12/330ah
Lynx SmartBMS
2 Orion XS 12/12/50

Camper (other):
CerboGX
SmartSolar 150/70
BatteryProtect 12/24/220A

Configuration notes:
Orions are wired per victron dual orion recommendation.
engine running signal wired in to both orions
Orions are BMS controlled
absorption voltage 14.2
float voltage 13.5
storage voltage 13.5
eq voltage disabled
connections appear tight, ir thermometer doesn’t show any hot spots.

Scenario example:
Battery SOC 50%, start engine and idle or drive (same behavior).
Orions initially each deliver max current but gradually taper down to about 40% of rated max current after about 10 minutes (about 20A per orion).
Each Orion delivers approx the same current (within 4A) and their output is mostly independent of engine rpm.
IMO, the orions should be delivering near max current at this SOC.
Orion input/output voltage levels are approx the same throughout the scenario - 13.1V/13.5V
Battery voltages and temps approx the same throughout the scenario - 13.3V/79F

Any thoughts much appreciated.

Thanks!

2
  1. During this behaviour is the BMS calling for 13.5V or 14.2V CVL, charge voltage limit, see the GX, settings, devices list, BMS, parameters. If the BMS is only requesting float, 13.5V then your behaviour is understandable, but at 50% SOC you should be requesting absorption. If it is requesting 13.5V what are your BMS settings for SOC threshold and repeat absorption interval.
  2. Have you disabled engine shutdown detection to stop the Orions throttling the current down if the smart alternators voltage reduces.
3

Hello @pwfarnell,

Many thanks for getting back so quickly. Problem solved.

The BMS charge voltage limit is 14.2V. But “Engine Shutdown Detection” was enabled, and the problem disappeared after disabling it.

It now charges at max current with no taper (from 60% SOC). (I assume it will begin a gentle taper at around 85%).

I misinterpreted Victron’s admonition when selecting “disabled”, which reads “When disabled, the engine is always considered to be running.” I thought this meant the truck battery could drain into the house battery semi-arbitrarily. I didn’t realize the “is running” wire connected to the Orions becomes the master of that arbitration. Thanks so much for the fix!