hwy17's Orion battery build

[Ampster]

Maybe @Ampster has drift setting advice.

Sorry. My system goes to 100% almost every day so I am not concerned about drift. When I say 100%, that is relative to my CV setting of 3.45 volts per cell

 

[hwy17]

I got a first working version of the 12v controls system wired up now.

 

[hwy17]

I like switches.
Ready power - Main power for BMS
Charge power - Tells the BMS it should be ready for charging, and balancing
Load contactor - Completes or interrupts the BMS load contactor latching circuit
Charge contactor - Completes or interrupts the BMS charge contactor latching circuit
Charger auto - Completes or interrupts the BMS SOC based signal which enables the Mean Well grid charger
Charger on override - Enables the Mean Well grid charger, even if Charger auto is off, or the BMS is not calling for charge
Manual precharge - manually enables the precharge contactor, for manual reclosing of the load contactor if it was manually opened.

I've added most of these to enable system online maintenance and adjustment work. I.E. if I would like to adjust the mean well charging voltage I can disable charger auto to disable charging, open the charge contactor, enable charger on override, adjust the meanwell to the desired voltage on the open charge bus, disable the charger, close the charge circuit, and re-enable charger auto.

 

[Partimewages]

I think I missed what the contactors are and where from?

 

[hwy17]

I think I missed what the contactors are and where from?

They're Altran Magnetics from Digikey.

2x AEV250-M polar, which go from main bus to the charge and load bus, polarized in the respective directions, 1x AEV250-MN nonpolar contactor between the battery and the main bus, and then 1x ASEV30-B polar 30A contactor for the precharge circuit.

All are 12v coil control (just want to clarify this for other future readers: don't copy my part numbers if you're building for 48v pack voltage control).

I'm still not sure if the Orion is actually going to fire the nonpolar contactor in correct sequence with the polar contactors, or if it's going to close them simultaneously which is not as ideal because the polar contactors can withstand it better. But I figured at least it can't hurt to be doubled up.

 

[hwy17]

The BMS powers on! The sound of contactors closing is so satisfying. Thunk

 

[hwy17]

Really filling out here in this box now, getting cozy.

I've built a bit of technical humor in, that ceramic lamp base there is my incandescent lightbulb precharge circuit. Pros: Visual indication of precharge activity. Cons: If the light bulb filament ever burned out then automatic precharge would fail unrecognized, the Orion only allows for a max precharge end amps check, and not a mid precharge min amps.

If a second DIY battery bank gets added to this system, the lightbulb will have to go for a more space saving resistor.

 

[hwy17]

That little gold tap on the top charge bus is a thermistor. I'm trying to decide if it is useful there. On one hand I would like shutdown if that bus bar were to read 90c, but want the battery thermistors to shutdown at 60c and Orion combines all thermistors into min/max/average triggers. The alternative would be to move this one to read the ambient temperature in this box, and then all thermistors could probably have a 60C shutoff.

 

[hogback]

Really filling out here in this box now, getting cozy.

I've built a bit of technical humor in, that ceramic lamp base there is my incandescent lightbulb precharge circuit. Pros: Visual indication of precharge activity. Cons: If the light bulb filament ever burned out then automatic precharge would fail unrecognized, the Orion only allows for a max precharge end amps check, and not a mid precharge min amps.

If a second DIY battery bank gets added to this system, the lightbulb will have to go for a more space saving resistor.

View attachment 198080

That's what I use too...

 

[hwy17]

Alright so I got it in place last night, and battery voltage is about to arrive at the main bus for the first time. There is no load wiring in this box yet, and ignore some of the mess on top that's load wiring in progress.

I did some more dry testing, and was disconcerted that even after I connected the cell tap harness, the BMS was still not engaging the charge and load contactors at all. But turning off auto precharge function fixed it, so something more to look into there. Until then, I will disable any fault auto recovery settings and manually precharge. That means I have to go physically babysit it every time I want to change a setting though.

 

[hwy17]

Now, what I believe I will attempt to do today is top balance this battery using the Orion's 350mA passive balancer. The batteries are helpfully all at identical resting voltage, 3.29 IIRC, thank you ezealco. Orion says the BMS is not for charging packs that are far out of balance, and gives "a pack that is 20Ah or more out of balance" as an example of one that should be separately balanced before assembling. I don't think I'm that far.

I have a 2300W and 185W chargers set to 55.2V single stage CC/CV. My plan is to let the 2300W run until any cell hits or gets near 3.4 and then switch over to the 185W to trickle the rest in without outpacing the balancing ability. I can also turn down current or voltage on the 185W at that point if it needs to go slower.

If it goes wrong, I will not be watching close enough as the first runner gets away faster than I imagined it could. Maybe it would trigger SOC drift, raising the SOC (starting from a default of 50% right now) and I have the on/off signal to the 2300W controlled by an SOC trigger already. Otherwise, I guess I would get my first loaded contactor open.

 

[hwy17]

What do you guys think the balancing current adequacy calculation is?

If you have 350mA of passive balancing can the BMS fully compensate for 350mA of pack current or 350x16=5.6A?

And by compensate I mean totally hold a cell down to steady voltage while the rest are still rising.

Current is constant through a series string, so I guess maybe it is 350mA pack current.

@sunshine_eggo @SeaGal @RCinFLA @upnorthandpersonal

 

[hwy17]

Ok first "hiccup" in my plan is that applying the 2300w charger immediately raises more than half the cells above 3.42 and starts the balancing.

Probably not surprising to anyone else, but I'm learning this stuff now.

It makes me hesitant to continue applying the big charger and I might just start with the little charger instead.

 

[MisterSandals]

It makes me hesitant to continue applying the big charger and I might just start with the little charger instead.

Higher charging current definitely charges the cells more unevenly. I fiddled with my charging to just charge to full by the end of the day. My SW4048 dialed back to 35% charge.

I have plenty of battery so don't need to top off completely.

 

[Partimewages]

Try 3.4 per at a lower current.

 

[hwy17]

Higher charging current definitely charges the cells more unevenly. I fiddled with my charging to just charge to full by the end of the day. My SW4048 dialed back to 35% charge.

I have plenty of battery so don't need to top off completely.

What kind of charge voltages are you running? The 2300W here is a simple CC/CC power supply out of the box. But they sell a programming adapter that can apply 3 stage charge profiles. I'm waiting to see if I'll need that for my purposes. The goal of the system eventually is that this power source will only be a backup, catching the battery at 20-40% or so, and only MPPT will be taking it to 100%.

 

[MisterSandals]

What kind of charge voltages are you running?

Its pretty conservative.

 

[hwy17]

Its pretty conservative.
View attachment 198331

Nice and do you find it reliably gets into balancing range that way? What BMS start balancing voltage are you using?

 

[MisterSandals]

Nice and do you find it reliably gets into balancing range that way? What BMS start balancing voltage are you using?

On one battery I have a misbehaving cell so am trying to make it work until I get a 280Ah replacement. Just knocked down balance voltage to 3.35V this morning.
Wish I were here to observe but golfing (missed yesterday for same reason).

I have 280Ah and 305Ah 48V in parallel so several days of power. I have luxury of being able to apply very gentle charging.
About 7-11A usually. Only running a couple months so you know how little sun we’ve had.

 

[hwy17]

The 185W charger was boring to watch so the 2300W is back on and I'm getting a bit more comfortable watching it. The cells aren't running away from 3.4ish they're hanging out there and doing what they're supposed to.

I have start balancing when any cell reaches 3.42 and don't balance cells under 3.4 set. I'm not sure if it feels like some of this balancing is counterproductive and too low in the voltage range. But I won't get a better since of that until after the first balance and then watching more balanced charges. Maybe this is all working as intended and this is productive balancing activity.

 

[hwy17]

The Mean Well emits a particular sort of ringing 60hz hum. I'm not sure yet if I find it unpleasant but I think I can hear it from the kitchen.

It's just slightly warm to the touch so far.

 

[hwy17]

Oh, PHEW. The 60hz ring is either coming from the 185W or an interaction between it and the 2300W. The 2300W is SILENT on it's own.

 

[hwy17]

Changed balancing to start at 3.42 and don't balance any cells below 3.42.

 

[hwy17]

The Orion is adjusting my charge current limit based on cell resistance. This is an area of battery theory that I am unfamiliar with, but it seems like a more intelligent figure than SOC based current limit curves.

 

[hwy17]

Exciting, an SOC drift event and resulting deactivating of the charger based on the SOC triggers.