Chargery BMS now with Low Temp Cutoff

I'm not sure if it's going to make any difference, but I did notice that your LCD is at version 4.0 ..... not the new 4.01.

Bob B said:

I'm not sure if it's going to make any difference, but I did notice that your LCD is at version 4.0 ..... not the new 4.01.

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Hello Bob,

I'll try updating the LCD software to see if that fixes it

I'm looking to order a BMS8T-300 plus the required DCCs. The DCC manuals mention that I would only need 1 DCC since they are bidirectional, but I want to confirm that if the BMS disables the charging due to low temperature, it will still allow load so that the SCC/battery heater is powered?

If you are building your setup as Common-Port then yes, you only need one DCC Contactor.
Yes, the Low Temp function was added into the firmware this spring and it does work as expected. Charging will be disabled if the temps are too low or too high obviously. With a Single DCC is "should " still allow for discharging (LFP can discharge up to -20C temps generally), some lower, depends on specific cell chemistry, Always refer to Cell Manufacturer Documents for your specific cells.

Do note, the BMS is only responsible for managing the cells within its own pack, it's the "Guard Dog" and last-ditch safety system for the cells/pack. The SCC & INverter/Charger systems should cutoff for Hi/Lo Volt conditions on their own BEFORE the BMS forces it off. Depending on SCC / Inverter System, some can monitor temps and act on it, while others cannot. This is NOT like the Temp Sensors used for Lead Acid Battery packs, which serves an entirely different purpose (compensation voltage for temp differentials).

Hope that helps, Good Luck.

PS: I started this thread, which I will be adding to later this week or early next week as I complete a set of builds & installs.

Steve_S said:

If you are building your setup as Common-Port then yes, you only need one DCC Contactor.
Yes, the Low Temp function was added into the firmware this spring and it does work as expected. Charging will be disabled if the temps are too low or too high obviously. With a Single DCC is "should " still allow for discharging (LFP can discharge up to -20C temps generally), some lower, depends on specific cell chemistry, Always refer to Cell Manufacturer Documents for your specific cells.

Chargery BMS, DCC (Solid State Contactor) thread.

Good Day folks, I am starting this thread related to the Chargery DCC, so the first post will be a basic "intro". See the following posts for more info. The DC contactor is designed specially to work with the CHARGERY BMS', the following are some features: Bi-directional connection, one...

diysolarforum.com

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@Steve_S .... Sorry, but I can't get my head around this ... could you please do a diagram that shows how a single DCC would cut of charging but still allow load? Seems to me that 2 SSR's would be required to do that .... or does one DCC have 2 SSR's?

You would need two DCCs for separate control.

As I understand the way it's made but I could very well be wrong, the DCC has a built-in pre-charge circuit and some sort of opto-coupling to handle the job. When it's used in separate-prt with two DCC's, the wire is split so one pair to Charge DCC and one pair to Discharge DCC, as if using two standard type contactors. I opened mine up but with the heat sinks attached you can't see much.

For more specifics, we'd have to get info from Jason directly.

Bob B said:

@Steve_S .... Sorry, but I can't get my head around this ... could you please do a diagram that shows how a single DCC would cut of charging but still allow load? Seems to me that 2 SSR's would be required to do that .... or does one DCC have 2 SSR's?

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I cant diagram for sure but as I see it there is actually 2 directional switches , for lack of better term, inside the dcc one to shut off input and one to shut off output.

But in all honesty I am a skeptic as to how well these will work. I have some on order but do not recommend them as of yet. Personally I do not like the idea of shutting off the connection between the inverter and SCC from battery I would rather shut the device down, use a device that takes 12v input from the Chargery or shut down the between the panels and SCC or inverter and load since the amps at those two points are the least. Even though I am not afraid to shut down SCC with panels attached. I do not think it is a good Idea to have it boot up every time there is an overcharged cell.

Craig said:

I cant diagram for sure but as I see it there is actually 2 directional switches , for lack of better term, inside the dcc one to shut off input and one to shut off output.

But in all honesty I am a skeptic as to how well these will work. I have some on order but do not recommend them as of yet. Personally I do not like the idea of shutting off the connection between the inverter and SCC from battery I would rather shut the device down, use a device that takes 12v input from the Chargery or shut down the between the panels and SCC or inverter and load since the amps at those two points are the least. Even though I am not afraid to shut down SCC with panels attached. I do not think it is a good Idea to have it boot up every time there is an overcharged cell.

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That's the approach I'm taking .... trying to avoid switching the battery power.

This might be a dumb question, but why not use a load-side lockout relay or some kind of disconnect that's triggered by the BMS vs having a NO power sucking relay on the Chargery?

zacharyk said:

This might be a dumb question, but why not use a load-side lockout relay or some kind of disconnect that's triggered by the BMS vs having a NO power sucking relay on the Chargery?

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A couple of reasons that come to mind are that the power relays do use a lot of power .... and, to get a good one they are also very expensive. The cheap relays just don't cut it. ..... Oh, and another thing was that there were a few people who had problems with the Chargery because of the power draw when the large relays were engaged at the same time.

zacharyk said:

This might be a dumb question, but why not use a load-side lockout relay or some kind of disconnect that's triggered by the BMS vs having a NO power sucking relay on the Chargery?

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That would work but not with a Chargery.

So I have updated my 16t main unit to 4.0 and the LCD to 4.01.

I am having trouble setting the Watt Hours.

The lower button is the only one that works FOR THIS SETTING ONLY. I can increment or decrement any other setting.

Due to trying so many times I am now down to minus 15,000 WH and cannot raise this value at all. I can only make it a larger negative number.

Any idea what to try next?

Did you reset defaults?

Bob B said:

Did you reset defaults?

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I don’t want to lose the factory shunt calibration, will that happen if I reset defaults?

Note that I can adjust every other value in the settings. Just Watt hours will not increase, only decrease.

JoeHam said:

I don’t want to lose the factory shunt calibration, will that happen?

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You should read the install instructions carefully. The shunt calibration should not be lost .... but many of us are not happy with the SOC tracking anyway.

Bob B said:

You should read the install instructions carefully. The shunt calibration should not be lost .... but many of us are not happy with the SOC tracking anyway.

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I’ll take another look but it’s very odd that just one value can be adjusted in just one direction.

I’ve never been impressed with the SOC over the six months plus I have used it but a battery capacity Watt hour amount of minus 15,000 Wh is ridiculous to look at ?

JoeHam said:

I’ll take another look but it’s very odd that just one value can be adjusted in just one direction.

I’ve never been impressed with the SOC over the six months plus I have used it but a battery capacity Watt hour amount of minus 15,000 Wh is ridiculous to look at ?

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Is that setting truly watt hours of battery or is it something else. I don't see the need to set Wh and Ah. Gonna ask Jason next week.

Craig said:

Is that setting truly watt hours of battery or is it something else. I don't see the need to set Wh and Ah. Gonna ask Jason next week.

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Thanks, and I don’t know the answer to your question.

Since it’s a new feature I thought I would try to use it.

I remain happy with the 16t for the real reasons I chose it. Simply to monitor at the cell level and keep them balanced.

Airtime said:

Hypothesis: The Chargery current sense input appears to have an ADC without an input anti-alias filter than can reject the 120Hz ripple before sampling. So with a sample rate (update rate of current display) lower than the 120Hz ripple, it aliases, resulting in the slow, large current variation I observed.

Possible solutions:
- Software: I don't believe this can be fixed in software, as the aliasing can result in very slow variation, all the way down to DC, and can't be filtered after the fact.
- Hardware: Could insert a lowpass filter that can reject 120Hz in the current sense lines, to act as an input anti-alias filter. For example, a 10k series resistor followed by a 2.2uF shunt capacitor would have a corner frequency of about 7Hz and provide about 24dB of rejection on the ripple. Or maybe an LC 120Hz notch filter for more rejection.

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I might try this myself but I'm confused exactly where to insert this filter ... a resister in series on one of the current sensing leads from the shunt to the BMS and a capacitor after the resistor between the leads heading to the BMS?

Thanks!

cinergi said:

I might try this myself but I'm confused exactly where to insert this filter ... a resister in series on one of the current sensing leads from the shunt to the BMS and a capacitor after the resistor between the leads heading to the BMS?

Thanks!

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Yes on the sense leads from the shunt. Series R followed by shunt C. Depending on the input circuit if you want to keep it balanced you could put a series R on both sense lines (same value on each lead) and then a shunt C after the two Rs.

BTW after my earlier post I looked at the Electrodacus SBMS0 schematic and it uses a series 1kohm shunt 2.2uF anti-alias filter. Same 7 Hz corner frequency as I was thinking, just different impedance. I have one, it seems to work well.

ARE YOU SEEING RIPPLE ON THE BMS ?
Do you have EMI/RFI ISSUES ??
Are Amps In/Out or Voltages "fluttering" ???
It could be your Wiring Layout !

Case in Point: My Wire runs are 14'/4.26m, of that 5'/1.52m is from batteries to DC Bus Bars. I am using 4/0 Royal Excelene for my 24V system due partly to run length (avoiding line loss) and to reduce EFI and the wires are bound (paired) together as much as possible. Ripple would be quite pronounced on my BMS Shunt Readings as well as the Shunt Readings from the Midnite Classic WizBangJr (which is a Deltec 500A/50mv with electronics add-on module)

QUOTE FROM SAMLEX MANUAL --------------------
1.3.4 Electro-Magnetic Interference (EMI) and FCC Compliance
These inverters contain internal switching devices that generate conducted and radiated electromagnetic interference (EMI). The EMI is unintentional and cannot be entirely eliminated. The magnitude of EMI is, however, limited by circuit design to acceptable levels as per limits laid down in North American FCC Standard FCC Part 15(B), Class A. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a residential environment. These inverters can conduct and radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. The effects of EMI will also depend upon a number of factors external to the inverter like proximity of the inverter to the EMI receptors, types and quality of connecting wires and cables etc.

EMI due to factors external to the inverter may be reduced as follows:
• Ensure that the inverter is firmly grounded to the Ground System of the building or the vehicle.
• Locate the inverter as far away from the EMI receptors like radio, audio and video devices as possible.
• Keep the DC side wires between the battery and the inverter as short as possible.
• Do NOT keep the battery wires far apart. Keep them taped together to reduce their inductance and induced voltages. This reduces ripple in the battery wires and improves performance and efficiency.
• Shield the DC side wires with metal sheathing / copper foil / braiding.
• Use coaxial shielded cable for all antenna inputs (instead of 300 ohm twin leads).
• Use high quality shielded cables to attach audio and video devices to one another.
• Limit operation of other high power loads when operating audio / video equipment.

3.5.9 Taping Battery Wires Together To Reduce Inductance Do not keep the battery wires far apart. Keep them taped together to reduce their inductance. Reduced inductance of the battery wires helps to reduce induced voltages. This reduces ripple in the battery wires and improves performance and efficiency. For details, refer to Limiting Electro-Magnetic Interference" at Section 1.3.4.

This may not solve your specific problems BUT in many cases it may apply to your installation. MANY people do NOT consider keeping the Battery Cabling together because the effects are not immediately apparent and for some reason this is rarely mentioned.

Hope it helps, Good Luck.
Steve.

PS: Future Chargery Manuals will include a section on EMI/RFI (If I am doing he update again).

Am i correct in saying, that version 4.0 of the BMS8T comes from the factory with the shunt pre calibrated, so no further calibration needed and also that no adjustments to the 'current calibration' tab in the munu necessary either? (so no need to set against a bench supply etc)

Set up my chargery for a 8S 280Ah pack @ 280AH and 3.2x8x280=7168Wh in the settings(should this in actual fact been set to 3.64 x 8 x 280, since this is what i charged it up to ie 8154Wh). I thought i had read to use the nominal cell value? If i have screwed this up, can i simply go into settings and amend, whilst the capacity test is running or will i need to redo from scratch?
I'm presuming i'm correct but as i do my capacity test the % Ah bears no reflection to the % Wh left in the pack. I was wondering at the discrepancy....or have i done something wrong in set up? Remaining Ah looks to be 20% higher than Wh %
I note on the display, that the percentage SOC is taken from the Wh figure. Does the Ah figure lag drastically, then plummet at the tail end of the discharge?
Any opinions?

Getting the SOC to track is one of the most difficult things with the Chargery. I never did get mine to track WH correctly.

I had to reset defaults on mine a 2nd time and start over .... Then do a 100% charge. After doing that and setting it all up again, the %Charge tracked fairly close, but the WH reading was still off.
I think 26 X the AH rating is the way the manual recommends for the WH setting on an 8S pack. It should reset to 100% SOC when the battery full setpoint value is reached. It should also reset to zero when the battery empty value is reached.

I re-read that portion of the manual several time and it was still clear as mud. Make sure you have the 4.01 manual.

Bob B said:

Getting the SOC to track is one of the most difficult things with the Chargery. I never did get mine to track WH correctly.

I had to reset defaults on mine a 2nd time and start over .... Then do a 100% charge. After doing that and setting it all up again, the %Charge tracked fairly close, but the WH reading was still off.
I think 26 X the AH rating is the way the manual recommends for the WH setting on an 8S pack. It should reset to 100% SOC when the battery full setpoint value is reached. It should also reset to zero when the battery empty value is reached.

I re-read that portion of the manual several time and it was still clear as mud. Make sure you have the 4.01 manual.

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cheers Bob.