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jetwire asked

Orion-Tr Smart entering float immediately on engine start

I recently installed an Orion Tr Smart DC-DC charger 12/12-18. I also installed the BMV Bluetooth Shunt.

It is charging a small Chins 20AH 12V LifeP04 battery. Engine start is working well. Cabling is an 8awg pos and neg cable from start battery to the Orion and battery under the back seat of the truck.

Sometimes throughout the day on engine start up it will go straight to float even though my BMV shunt is indicating 50 or 60 percent (Voltage on the LifeP04 is around 13.1v). This causes the charge rate to be very low compared to when it is in bulk state.

I have solved it by setting Absorption to 14.5 and Float to 14.4. That's not a good long term solution for the battery though.

This is a work truck that has an 300w inverter for tool batteries and also laptop charger and wifi system.

Is it possible this battery is too small and it's thinking it's full? I am planning on adding a 2nd identical battery in parallel soon.

I am going to try and install a larger relay/contactor and just turn the Orion completely off on engine shutdown to see if it will go to bulk between engine starts.



screenshot-20230817-140954.jpgscreenshot-20230817-141018.jpg


orion-tr smartfloat
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jetwire avatar image
jetwire answered ·

TL:DR: I dumbed down the Smart-TR


I appeared to have solved it. I added a 100Amp Relay that disconnects the 12v input on the Orion. It basically shuts the unit completely off. It is switched with the ignition key. Added bonus I was able to disable the engine shutdown detection since it's off when the engine is off as the Chevy Colorado will occasionally drop it's Smart Alternator voltage to 12.5. Now it enters Bulk or Absorption no matter what now. I left the lock out voltage at 11.9 just in case the key is left on with the engine off. I still don't know why it was doing that, but now it is acting the way I like.

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seb71 answered ·

I have solved it by setting Absorption to 14.5 and Float to 14.4.

You have a very short Absorption time (only 15 minutes).

Default setting in Orion for LiFePO4 seems to be 2 hours (I don't have any Orion chargers, but I checked the VictronConnect Demo library).

For a 20Ah battery, if Orion is charging with 18A, the battery voltage might rise quickly. Once it hits the Absorption voltage, it stays there for only 15 minutes, then drops to Float voltage.

So better increase the Absorption duration (how long it should be will results from testing), and set Float voltage to 13.4V (corresponding to 3.35V cell voltage, if all cells are the same).


Any BMS on that LiFePO4 battery?

If yes, then for Absorption voltage, set it at 14.2V (and in SmartShunt set "charged voltage" 0.2V or so lower than the Absorption voltage in the charger). If you can measure each cell voltage, check the values when the battery is closing on full.

If no BMS and if you can measure cell voltages, you can establish a safer value by progressively increasing the value from say 13.8V. If all cells have same voltage when full, you can rise the Absorption voltage. Use small steps. Don't get above 14.2V (absolute maximum for a cell would be 3.6V, which would correspond with 14.4V battery voltage).


On that inverter, if it has any adjustments (of settings), set it to shut down if cell gets down to 3V (you can use a higher value - such as 3.1V for more safety margin, but not lower). For perfect cells 3V cell voltage means 12V battery voltage. Same thing here: if you can to measure individual cells, watch when a cell gets down to 3V and take a note at the battery voltage. Set that as the inverter shut down voltage. Even if the battery has a BMS which disconnects the battery if empty.

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jetwire avatar image jetwire commented ·

Thanks for the response. The battery does have a BMS inside (it's one of those pre packaged Amazon LifeP04 batteries) I will change the Absorption time to 2hrs and check back in a few days after driving the truck.


I was really hoping it would go back to absorption after each work stop. Tech is usually at a stop for 1-2 hrs and the battery usually has a constant 60 to70 watt draw on during that time (Wifi LTE router, tool battery charger, laptop). When he gets back in to go to the next stop we're really hoping it would start another bulk charge cycle since the battery is usually at 60 percent or less. It just seems odd that it goes instantly to float on startup. I'm pretty sure if I set Float to 13.4 it's just going to sit at 60 percent and not even charge as that's only .2v higher than the resting voltage at half charge. Battery specs state to have Float at 13.8v and Absorption at 14.5v

616vvqsax5l-ac-sx679.jpg

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jetwire avatar image
jetwire answered ·

Here's a video showing the problem. I used a 30a battery charger to simulate starting the truck.


screen-recording-20230817-162322.mp4 (1.1 MiB)
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seb71 avatar image seb71 commented ·

Maybe Orion remembers the last charge stage it was in? Or maybe it remembers the cumulative time it already was in Absorption. I don't know. But you can test this.

Was it in Float when the engine was last turned off?

What happens if previous state was Bulk or if previous state was Absorption when you start the engine? Does it still go straight to Float?

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kevgermany answered ·

The Orions are voltage driven, ignore SOC information. LiFePO4 batteries have a very flat discharge curve. So on restart it sees a 'charged' voltage and drops into float. It will only go back to bulk if battery voltage drops below float - re-bulk voltage offset.

If increasing the absorption time doesn't help, you might have to revert to increasing float as you've done. Sorry if this sounds like conflicting advice.

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kevgermany answered ·

Another thought.

The Orion can be switched manually using the L and H terminals.

Your BMV has a relay that can be switched on SOC. If you set the Orion so that it always goes to high charge voltage, (i.e. high float) and still has engine detect working, you can control the Orion using the shunt relay. Set the BMV to kick in if SOC drops below 80% and drop out at 95%. This should allow high charge as needed, but avoid overcharging the battery, while allowing the BMS to balance the cells in the battery.

@Seb71 what do you think?

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seb71 avatar image seb71 commented ·

I just added a comment while you replied.


I do not have an Orion (I would experiment with it if I had one), so I don't know how it behaves if you keep turning the engine off then on during Absorption or after already was in Float. Does it remembers the time it already was in Absorption?

If it keep this count, and it was already in Float, possibly the battery voltage has to decrease enough to get back to Bulk stage.

The manual does not say anything about this.

I would expect that if you start from a discharged battery (in Bulk) and let the engine running, the charger will go through Bulk, Absorption, Float stages correctly.

But if you stop the cycle by turning off the engine, I don't know how Orion behaves.

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He has a Re-bulk offset voltage set very low (0.01V). But if Float is set that high (13.8V), it will take a while to switch back to Bulk. Even more so with Float set to 14.4V.


I think it is preferable to switch back to Bulk and start another charging cycle, with a limited time at high voltage (whatever time it takes to reach Absorption voltage, plus the Absorption duration), than to set a very high Float voltage.

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kevgermany avatar image kevgermany ♦♦ seb71 commented ·
Mine does seem to work the way I described. But it's on auto engine detect and I have solar at the same time.

Not sure I agree over higher float making it worse, rebulk is based on dropping below float. So with lithium the higher the float setting, the sooner a drop will be detected.


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seb71 avatar image seb71 kevgermany ♦♦ commented ·

Yeah, don't know how I wrote that (about taking longer to re-bulk when Float is set higher). :)

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I was thinking for a way to avoid keeping the battery at high voltage practically non-stop (which happens if Float is set to 14.4V or something like that). Not the best thing for LiFePO4.

This is why I think is preferable to set Float at correct voltage for LiFePO4 (3.35V cell voltage; 13.4V battery voltage) and rely on starting a new Bulk-Absorption-Float cycle, based on battery voltage, with a long enough Absorption duration.

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At 12.75V he has in the video, it should re-bulk. The video ends too soon after "starting the engine". For MPPT re-bulk needs one minute to start. Not sure how much time is needed for Orion.

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jetwire avatar image jetwire commented ·
I really like this option. I might look into it. The BMV and the Orion are close by. It would be even better if the Orion had a Ve.Direct cable and talked to the BMV like the MPPT units. (Hint Hint Victron)
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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

The voltage and current at the SmartShunt are not changing at all.
My guess is a loose connection or blown fuse between the Orion output and the lithium battery, check that.

Also measure the voltage at the output terminals of the Orion.

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kevgermany avatar image kevgermany ♦♦ commented ·
Good to check/eliminate.
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seb71 avatar image seb71 commented ·
With a blown fuse or disconnected wire, the battery would never charge.
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seb71 answered ·

Sometimes throughout the day on engine start up it will go straight to float even though my BMV shunt is indicating 50 or 60 percent (Voltage on the LifeP04 is around 13.1v).

With battery voltage at 13.1V, according to the Orion settings from that first screenshot ("Float voltage" set at 13.8V and "Re-bulk voltage offset" set at 0.01V), Orion should switch to Bulk after a minute (or whatever the time to re-bulk Orion has).

If it does not, possibly the Orion is defective.

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