Midnite Solar Classic 150 and AES Discovery 48 volt Battery

crazycanuk · April 2020

I have purchased the Discovery battery Lithium to replace my bank of lead acid batteries. Worked great. Finding an issue now with not fully charging the batteries off the solar panels even in full sun but Midnite controller thinks battery is at capacity when at about 80 percent charge. All settings were set to the specs from AES and still an issue. I have reached out directly to Midnight Solar to see if they had some suggestions but have not heard back yet. Was curious if someone here had run into this?

System is
8 Panel Trina Brand
2 Midnite solar Classic 150 with whizbang Jr ( Only utilizing one, other is for second tower of solar)
1 Schneider XM 6658 Inverter
1 AGS (Starts 10 KW Diesel for backup)
1 Conext Combox
1 AES Discover 48 volt with xanbus and BMS 42-48=6650

I purchased the battery from this site and it is operating very well. I am looking for some help to optimize the solar charging as it appears some settings that I was not told to change or should know how to change are incorrectly configured. If I here from Midnite, I will post here but overall this is minor and I am very please with unit. Goal once this is ironed out is 2 additional units. For my off grid home even with heat running right now i am getting 12 hours of battery time which only discharges to 45 percent.

Estragon · April 2020

How are you determining the 80% SOC?

Dave Angelini · April 2020

Probably a mistake to not use the mppt that was designed to work with the Discover / xanbus enabled network. You can get the schneider mppt for 500 and have a system that closes the loop and works as designed.

Dave Angelini · April 2020

For Estragon, the battery shows up on SCP, gateway, etc as a device, and SCP displays Soc

mike95490 · April 2020

Midnight may have new firmware for the Classic with Lithium settings.

Be aware, many times, Li systems are only set to use the middle 80% of the battery, to avoid the danger of either complete discharge or overcharge of a unbalanced cell in the pack, and to increase the lifetime of the battery

Dave Angelini · April 2020

Not this battery Mike !
It is fully integrated (closed loop) with all Schneider devices. Complete plug and play! No brains/programming setpoints required besides common sense. The battery is an LFP designed by ex Schneider engineers who have approval to use xanbus. Sell the Classic and do it right.

Estragon · April 2020

I'm inclined to agree with Dave. I like the Classic but having a controller integrated and networked with the battery is pretty compelling.

In the meantime, I would look for any difference in voltage between the classic output terminal and the battery post (with significant charge current flowing). There is a setting in the classic to offset a difference if needed. The classic may be getting to what it thinks is a "full" voltage but voltage drop over the connection to battery may be fooling it.

Also, the main use for the WbJr is to get a fairly accurate "end-amps". Very useful for lead acid charging but likely just a complication in this application.

Dave Angelini · April 2020

The problem with any controller that is not in the loop is they also lose the ability to quickly charge a lithium battery. If you sat there with the set-points and changed them manually you could come close to how fast a closed loop charger can charge a lithium battery. Discover says it is 30% faster when closed loop for lithium. I know from my Alaska and Canadian clients that the fuel savings on a genset is easy to see.
Charging lithium faster on solar in winter is not something to miss if there is sun up there

Another way to look at it is the AES battery is the master controller of charging. All other charging sources are just slaves and setpoints are being adjusted by the AES bms.

mcgivor · April 2020

crazycanuk said:

I have purchased the Discovery battery Lithium to replace my bank of lead acid batteries. Worked great. Finding an issue now with not fully charging the batteries off the solar panels even in full sun but Midnite controller thinks battery is at capacity when at about 80 percent charge. All settings were set to the specs from AES and still an issue. I have reached out directly to Midnight Solar to see if they had some suggestions but have not heard back yet. Was curious if someone here had run into this?

System is
8 Panel Trina Brand
2 Midnite solar Classic 150 with whizbang Jr ( Only utilizing one, other is for second tower of solar)
1 Schneider XM 6658 Inverter
1 AGS (Starts 10 KW Diesel for backup)
1 Conext Combox
1 AES Discover 48 volt with xanbus and BMS 42-48=6650
I purchased the battery from this site and it is operating very well. I am looking for some help to optimize the solar charging as it appears some settings that I was not told to change or should know how to change are incorrectly configured. If I here from Midnite, I will post here but overall this is minor and I am very please with unit. Goal once this is ironed out is 2 additional units. For my off grid home even with heat running right now i am getting 12 hours of battery time which only discharges to 45 percent.

The text above states the Midnight controller thinks the battery is at ~80% SOC not a SCP or Gateway, this could be because the controller assums the battery is lead acid and is not reaching the voltage required to indicate 100%, rationale being how else would the controller know the SOC.

My observations using Schneider controller and SCP / Combox is when the controller transitions to float, only then dose the SOC go to 100% even though the battery, a DIY LiFePo4 bank, is not actually at 100% due to the voltage settings being below the 100% value.

Perhaps the only close to accurate method would be to use compatible equipment which communicate with one another as Dave has said, if this information is of importance to the operator. A question for Dave, dose the AES battery communicate via Xanbus that it, itself is fully charged or is it determined by the controller, battery monitor or other means? Just for curiosity sake.

crazycanuk · May 2020

Thank you all for responding. I will try to respond to questions all in one response and my apology for not getting back sooner. Business took precedence.

1) Between the battery monitoring system on the AES battery, Xanbus integration and the multiple tools in the Schneider tool box is how I got to the 80 percent by comparing the midnight solar readings to to the Schneider readings. Plus or minus they were close.
2) In my original configuration with my off grid system, I have two (2) midnight controllers that worked extremely will with my 48 volt stings (3) of Rolls batteries and ran the house without any real issues until the batteries go to be about 8 years old. Stretched them out for 2 years while I waited for technology in batteries to stabilize so made the plunge. I actually have ordered a Schneider MPPT Unit even though I think it is not quite a good as Midnite so I can the integration as someone recommended. good call!

It is nominally fixed now after working wtih Midnite Solar team and the AES Discovery support team. I removed the whizbang JR, not just disabled it. Took out the temperature sensor and reset the MPPT 150 back to factory and reprogrammed. It now runs the house when there is solar an trickle charges the lithium battery at a low charge until sun sets. I am working with the BMS on the new battery system and the techs to tweak it to new setings so it accepts faster charging and once I get the Schneider unit installed, this may all be moot point.

This is a great forum. I will report back on the process here until it is completed as I believe this battery is fantastic. With normal sunny day on one unit, I am getting 17 hours of run time before the generator kicks in and that was expected. Once we get the charging straightened out I will add another unit and we should be golden.

I had someone reach out directly about the house. I wont bore everyone with the details of draw etc. , but house is:

1) Log cabin (real logs) with in floor heart (liquid). 1200 square feet with 9 foot ceilings in full basement
2) Home was designed from ground up to be off grid from heating and appliances to all LED bulbs and 10 KW back up military generator.
3) House normally just running with heat in the winter draws about 260 watts sitting still. Unless you run well, microwave etc. it is very efficient.
4) House is 100 percent off grid and as such is dependent on this system to operate. Local power grid estimates for bringing power in was 150 to 200 K dollars!

Again, thanks again for all the advice and insight. I hope to contribute more myself in the future.

Vic · May 2020

mcgivor said:

The text above states the Midnight controller thinks the battery is at ~80% SOC not a SCP or Gateway, this could be because the controller assums the battery is lead acid and is not reaching the voltage required to indicate 100%, rationale being how else would the controller know the SOC.

My observations using Schneider controller and SCP / Combox is when the controller transitions to float, only then dose the SOC go to 100% even though the battery, a DIY LiFePo4 bank, is not actually at 100% due to the voltage settings being below the 100% value.

The Classic CCs count Ah into and out of the battery to try to track SOC, Remaining Capacity, etc , when using the WbJr (inexpensive) accessory. The Net Ah is reset to 0, on the transition from Absorb to Float. The SOC is is also reset, and is temp compensated, based upon the settings that were entered, on setup. FWIW, Vic

Wheelman55 · May 2020

Crazy...some observations on my recently commissioned Discover AES battery. It’s the 48 volt with onboard BMS, connected to XANBUS. I run it with all Schneider gear.

I consulted with Dave Angellini, who’s knowledge is worth his weight in gold.

DA asked me to run the system down to 20% SOC five times to “proof” the reliability of the system.

The first night I actually took it down to 0% SOC. I was concerned but Dave said not to worry and asked me to run it down to zero again to see if the system would restart on it’s own in the morning. It did and works fine.

I put my Fluke multimeter on the 0% SOC battery and it read 50.4 bolts, which is 20% SOC according to Discover. The SCP showed that all 130 AH were removed from the AES battery, while the voltage said that there was still 20% capacity.

Dave explained that the battery actually has around a 150 AH capacity but that the BMS only allows access to 130 AH.

Could this be causing the Midnight gear to read 80%?

Vic · May 2020

Hi Wheelman..,

When charging from Solar, does the Classic get to the Absorb stage? Many Li batteries that are charged from Solar, have an Absorb stage that is about as short as it can possibly be (as I read it). Then, the transition from Absorb to Float resets the SOC to 100%. Without this Abs>Flt transition, the CC must use Ah counting only, and can become less, and less accurate with each passing cycle.

The Net Ah and SOC can be reset Manually from the Classic MNGP front panel. Should you need to: Push the left small round button on the display (IIRC, this is the Status Button), about four times (from the Main Status page) -- this takes you to the WbJr Status screen. Press the Left Soft button (square one, upper left). This takes you to the Net Ah screen. Hold down the left Arrow button, while pressing Enter. (it may take a second or three, but,) This should reset the Net Ah to 0, and the SOC to 100%.

I am no expert on charging Li batteries. FWIW. Good luck, Vic

Vic · May 2020

Wheelman..,

When setting up the WbJr, there is a setting for the Ah Capacity of the battery, and its Charge Efficiency ... but, if you have removed the Wb, then this does not apply ...

And, there is a Lithium Topic on the MidNite Solar Forum (as you probably know. Here is some discussion on charging Li batteries:
http://midniteftp.com/forum/index.php?board=63.0

FWIW, Vic

Wheelman55 · May 2020

Vic. Thanks however my gear is all Schneider:)

With the XANBUS the Schneider/Discover Combo was literally plug and play. The only thing I had to do was to set the date and time.

Super simple.

aksala · May 2020

Like @Wheelman55, I have no issues for the past year with 3 AES 48V batteries and the Schneider mppt 80 600. Plug and play in that regard. SOC at 100% and then floats until the sun goes down.

Image: https://us.v-cdn.net/6024911/uploads/editor/az/ay3llp2ee65r.png

Wheelman55 · May 2020

Aksala...how many watts are in your array to support the 3 Discover batts?

aksala · May 2020

Wheelman55 said:

Aksala...how many watts are in your array to support the 3 Discover batts?

I have 7kw on the roof. 22 320W Rec panels. It's well over built for summer but makes up for it during our shoulder seasons. And on very cloudy summer days we still manage to run the house and top up. I average about 13.5 - 14kw/day consumption. Located in Willow Alaska.

Midnite Solar Classic 150 and AES Discovery 48 volt Battery

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