Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Thee is source code for this on GitHub too. There are APK's and also for other OS platform like NIX but I'll leave the digging to you, not hard to find. If google fails, try DuckDuckgo.
Chargery BMS communications.
- Thread starter Craig
- Start date
Great read! I needed a Modbus serial solution, to took the following approach:
[Chargery]-[RS232toTTL converter]-[Arduino MEGA]-[RS232toTTL converter ]-[cellular RTU]
The MEGA was a good fit for this since it has several UARTs onboard (no need for the added complexity of SoftwareSerial library). The MEGA parses the byte stream and stores the data in an integer array. The RTU polls the integer array every 5 seconds then texts me if anything is amiss, otherwise it sends a daily report via email.
[Chargery]-[RS232toTTL converter]-[Arduino MEGA]-[RS232toTTL converter ]-[cellular RTU]
The MEGA was a good fit for this since it has several UARTs onboard (no need for the added complexity of SoftwareSerial library). The MEGA parses the byte stream and stores the data in an integer array. The RTU polls the integer array every 5 seconds then texts me if anything is amiss, otherwise it sends a daily report via email.
mariovanwyk1
Electrician
Hi all.
After much struggling I managed to get the BMS16T onto plain old simple excel. See pictures below:
After much struggling I managed to get the BMS16T onto plain old simple excel. See pictures below:
mariovanwyk1
Electrician
With a little more tweaking on excel, it now also show the Max & Min voltage cells on every update just as the display unit does.
Mario,
Thanks for the screenshots! Impressive job!
Are you open to sharing a little context on how you chose 0 seconds for your cut-off delay time? Is there a scenario where if you set this for a few seconds you'd have some risk of catastrophe?
I realize our systems are different, mine is 12V, 280Ah in an RV. I had thought a bit of delay, say up to 15 seconds may allow for some motor in-rush or other high-draw startup.
Also, what is the max delta V that you've experienced? I have very few cycles and under high load (150A) I saw 35mV or 40mV. So I moved my max to 75mV, but maybe 100mV is better. I don't want the battery to disconnect unnecessarily.
Thank you,
Doug
Thanks for the screenshots! Impressive job!
Are you open to sharing a little context on how you chose 0 seconds for your cut-off delay time? Is there a scenario where if you set this for a few seconds you'd have some risk of catastrophe?
I realize our systems are different, mine is 12V, 280Ah in an RV. I had thought a bit of delay, say up to 15 seconds may allow for some motor in-rush or other high-draw startup.
Also, what is the max delta V that you've experienced? I have very few cycles and under high load (150A) I saw 35mV or 40mV. So I moved my max to 75mV, but maybe 100mV is better. I don't want the battery to disconnect unnecessarily.
Thank you,
Doug
I would definitely set it at 100 or even above. I set mine at 300 to me it is more important to not go above or below certain voltages and if the cells are off balance in the middle. I would like to know that but no need to shut things down because of it.
mariovanwyk1
Electrician
Hi Doug.
The default for the cutoff time is 10 sec. For my scenario I set it for safety to 0 seconds, I have a 1000Ah 52V lithium iron battery on my solar system for my house and can turn catastrophic if things go wrong. I do have circuit breaker protection also, but rather play it safe.
Generally my delta voltage is around 10 to 20mV if I can fully charge the battery each day. I have found that if I have 2 or 3 consecutive cloudy days where I could not fully charge the battery, that I can see up to about 40 to 50mV delta on the top end when it is fully charged again. So my 100mV is just a bit of a margin so the battery stay connected while the BMS take care of the balancing.
Mario and Craig,
Thanks for the feedback. I do have a large AGM battery as backup if the LFP were to trigger a fault, but I don't want false positives. I'll think more about the delay and voltage differential. Mostly, I need to get more cycles on my system with some manual monitoring. But hard to do on lockdown at home!
Cheers,
Doug
Thanks for the feedback. I do have a large AGM battery as backup if the LFP were to trigger a fault, but I don't want false positives. I'll think more about the delay and voltage differential. Mostly, I need to get more cycles on my system with some manual monitoring. But hard to do on lockdown at home!
Cheers,
Doug
Nice job Craig! I've been also working on BMS communication. I'm curious, have you done a data stream? I'm using an Arduino to read the stream. Here's what I get from Putty:
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
24 24 56 16 C F6 C FD C FE C F9 0 0 0 0 0 48 0 1E 5F 93
68 3A 3A 33 D A
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
24 24 56 16 C F6 C FD C FE C FA 0 0 0 0 0 49 0 1E 5F 95
24 24 57 F D 98 2 0 0 0 97 0 98 5F E3
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
68 3A 3A 33 D A
24 24 56 16 C F6 C FD C FE C FA 0 0 0 0 0 49 0 1E 5F 95
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
24 24 56 16 C F6 C FC C FE C FA 0 0 0 0 0 46 0 1E 5F 91
24 24 57 F D 98 2 0 0 0 97 0 98 5F E3
68 3A 3A 33 D A
The 68 3A 3A 33 D A is an odd ball. There's no documentation about this data packet. Have you seen it?
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
24 24 56 16 C F6 C FD C FE C F9 0 0 0 0 0 48 0 1E 5F 93
68 3A 3A 33 D A
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
24 24 56 16 C F6 C FD C FE C FA 0 0 0 0 0 49 0 1E 5F 95
24 24 57 F D 98 2 0 0 0 97 0 98 5F E3
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
68 3A 3A 33 D A
24 24 56 16 C F6 C FD C FE C FA 0 0 0 0 0 49 0 1E 5F 95
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
24 24 57 F D 98 2 0 0 0 97 0 97 5F E2
24 24 56 16 C F6 C FC C FE C FA 0 0 0 0 0 46 0 1E 5F 91
24 24 57 F D 98 2 0 0 0 97 0 98 5F E3
68 3A 3A 33 D A
The 68 3A 3A 33 D A is an odd ball. There's no documentation about this data packet. Have you seen it?
Yes I parse that data stream to get my numbers. I will look at the stream to see if i can figure it out. Do you have the doc saying how to interpret the data?
Thanks for the welcome! I'm also using Mega to data log. You are probably correct that the unknown packet is connected to the remote charger. I've found the data stream is somewhat unstable. I get some bad data. Need to use the check sum to verify. Have you noticed the same?
Here's a plot charging the 180AH battery with 19A. Vbat and Cur scale is on the right, cell voltage on the left. Time is in minutes. BMS turns off charging at 3.48V, and back on again at 3.35V. Charger set to 14V.
I have not had too much of a problem with the data stream.
What are you using to interface with your chargery?
What are you using to interface with your chargery?
Great graph by the way it shows exactly how the same batteries can be a hair different through the phases
I haven't seen any stability issues either. I calculate the checksum as data is received, then compare to the received check sum prior to parsing datastream into the array. The Mega is only 6" away from the Chargery, with a 232/TTL converter inbetween. How are you converting the 232 voltages to TTL?
Here's my circuit that converts a +/- 5V signal to 5V. The signal requires just one inversion since the Chargery signal is already inverted.
I found that I needed to implement check sum out of necessity. What happens when you eliminate check sum validity test? What type of TTL converter do you use?
I use the USRIOT device that broadcasts the raw data to a websocket. I would rather just read the raw data but have not gotten to try a stand alone converter yet.
Here's what I'm using, about a buck a piece on the 'bay.
Here's a snippet of the data stream with debug turned on:
Code:
Rx:24 Rx[0]:24 Begin
CheckSum:24
Rx:24 Rx[1]:24 CheckSum:48
Rx:57 Rx[2]:57 CheckSum:9F
Rx:F Rx[3]:F CheckSum:AE
Rx:10 Rx[4]:10 CheckSum:BE
Rx:68 Rx[5]:68 CheckSum:26
Rx:0 Rx[6]:0 CheckSum:26
Rx:0 Rx[7]:0 CheckSum:26
Rx:35 Rx[8]:35 CheckSum:5B
Rx:0 Rx[9]:0 CheckSum:5B
Rx:D0 Rx[10]:D0 CheckSum:2B
Rx:0 Rx[11]:0 CheckSum:2B
Rx:D0 Rx[12]:D0 CheckSum:FB
Rx:0 Rx[13]:0 CheckSum:FB
Rx:FB Rx[14]:FB End of string, Good CheckSum! command 57
HB[51]:10
16-bit: 16
HB[52]:68
HB[53]:0
16-bit: 26624
HB[54]:0
HB[55]:35
16-bit: 53
HB[56]:0
HB[57]:D0
16-bit: 208
HB[58]:0
HB[59]:D0
16-bit: 208
HB[60]:0
HB[61]:FB
16-bit: 251
HR[21]:4200
HR[22]:0
HR[23]:53
HR[24]:208
HR[25]:208
HR[26]:0
CheckSum:0
Rx:24 Rx[0]:24 Begin
CheckSum:24
Rx:24 Rx[1]:24 CheckSum:48
Rx:56 Rx[2]:56 CheckSum:9E
Rx:26 Rx[3]:26 CheckSum:C4
Rx:C Rx[4]:C CheckSum:D0
Rx:B6 Rx[5]:B6 CheckSum:86
Rx:C Rx[6]:C CheckSum:92
Rx:BD Rx[7]:BD CheckSum:4F
Rx:C Rx[8]:C CheckSum:5B
Rx:BD Rx[9]:BD CheckSum:18
Rx:C Rx[10]:C CheckSum:24
Rx:BC Rx[11]:BC CheckSum:E0
Rx:C Rx[12]:C CheckSum:EC
Rx:B5 Rx[13]:B5 CheckSum:A1
Rx:C Rx[14]:C CheckSum:AD
Rx:BC Rx[15]:BC CheckSum:69
Rx:C Rx[16]:C CheckSum:75
Rx:C0 Rx[17]:C0 CheckSum:35
Rx:C Rx[18]:C CheckSum:41
Rx:C4 Rx[19]:C4 CheckSum:5
Rx:C Rx[20]:C CheckSum:11
Rx:C0 Rx[21]:C0 CheckSum:D1
Rx:C Rx[22]:C CheckSum:DD
Rx:E8 Rx[23]:E8 CheckSum:C5
Rx:C Rx[24]:C CheckSum:D1
Rx:D0 Rx[25]:D0 CheckSum:A1
Rx:C Rx[26]:C CheckSum:AD
Rx:ED Rx[27]:ED CheckSum:9A
Rx:C Rx[28]:C CheckSum:A6
Rx:CA Rx[29]:CA CheckSum:70
Rx:C Rx[30]:C CheckSum:7C
Rx:C5 Rx[31]:C5 CheckSum:41
Rx:C Rx[32]:C CheckSum:4D
Rx:D3 Rx[33]:D3 CheckSum:20
Rx:C Rx[34]:C CheckSum:2C
Rx:C3 Rx[35]:C3 CheckSum:EF
Rx:0 Rx[36]:0 CheckSum:EF
Rx:EF Rx[37]:EF End of string, Good CheckSum! command 56
HB[1]:C
HB[2]:B6
16-bit: 3254
HB[3]:C
HB[4]:BD
16-bit: 3261
HB[5]:C
HB[6]:BD
16-bit: 3261
HB[7]:C
HB[8]:BC
16-bit: 3260
HB[9]:C
HB[10]:B5
16-bit: 3253
HB[11]:C
HB[12]:BC
16-bit: 3260
HB[13]:C
HB[14]:C0
16-bit: 3264
HB[15]:C
HB[16]:C4
16-bit: 3268
HB[17]:C
HB[18]:C0
16-bit: 3264
HB[19]:C
HB[20]:E8
16-bit: 3304
HB[21]:C
HB[22]:D0
16-bit: 3280
HB[23]:C
HB[24]:ED
16-bit: 3309
HB[25]:C
HB[26]:CA
16-bit: 3274
HB[27]:C
HB[28]:C5
16-bit: 3269
HB[29]:C
HB[30]:D3
16-bit: 3283
HB[31]:C
HB[32]:C3
16-bit: 3267
HB[33]:0
HB[34]:EF
16-bit: 239
HR[1]:3254
HR[2]:3261
HR[3]:3261
HR[4]:3260
HR[5]:3253
HR[6]:3260
HR[7]:3264
HR[8]:3268
HR[9]:3264
HR[10]:3304
HR[11]:3280
HR[12]:3309
HR[13]:3274
HR[14]:3269
HR[15]:3283
HR[16]:3267
HR[17]:0
CheckSum:0Thanks, I ordered a couple of those RS232 devices from China. See them maybe in June?
I've also looked at the Chargery RS232 signal with a Saleae logic analyzer. That data shows framing errors. I don't recall if I connected the analyzer directly to Chargery or to the circuit I just posted. I just noticed my circuit should have a capacitor to stabilize the 5V supply during switching.
I've also looked at the Chargery RS232 signal with a Saleae logic analyzer. That data shows framing errors. I don't recall if I connected the analyzer directly to Chargery or to the circuit I just posted. I just noticed my circuit should have a capacitor to stabilize the 5V supply during switching.
Code:
Time [s] Analyzer Name Decoded Protocol Result
-2.68125E-05 Async Serial 0x24
6.00625E-05 Async Serial 0x24
0.000146875 Async Serial 0x57
0.000233625 Async Serial 0x0E
0.000320438 Async Serial 0x0D
0.000407188 Async Serial 0xAC
0.000494063 Async Serial 0x01
0.000580875 Async Serial 0x00
0.000667688 Async Serial 0x0F
0.000754438 Async Serial 0x00
0.00084125 Async Serial 0x9F
0.000893375 Async Serial 0xFC
0.000928 Async Serial 0x00
0.001014875 Async Serial 0xAD
0.001101625 Async Serial 0xC2
0.501639 Async Serial 0x0B
0.501639 Async Serial 0x24
0.501725875 Async Serial 0x24
0.501812625 Async Serial 0x57
0.501899438 Async Serial 0x0E
0.50198625 Async Serial 0x0D
0.502073063 Async Serial 0xAC
0.502159813 Async Serial 0x01
0.502246625 Async Serial 0x00
0.502333438 Async Serial 0x0C
0.50242025 Async Serial 0x00
0.502507063 Async Serial 0x9F
0.502559125 Async Serial 0xFD
0.502593875 Async Serial 0x00
0.502680688 Async Serial 0xAE
0.5027675 Async Serial 0xC0
0.755696563 Async Serial 0x8B (framing error)
0.755696563 Async Serial 0x24
0.755783438 Async Serial 0x24
0.755870188 Async Serial 0x56
0.755957 Async Serial 0x16
0.756043813 Async Serial 0x0D
0.756130563 Async Serial 0x37
0.756217375 Async Serial 0x0D
0.756304188 Async Serial 0x1C
0.756391 Async Serial 0x0D
0.756477813 Async Serial 0x1F
0.756564625 Async Serial 0x0D
0.756651375 Async Serial 0x08 (framing error)
0.756651375 Async Serial 0x26
0.756738188 Async Serial 0x00
0.756825063 Async Serial 0x00
0.756911813 Async Serial 0x00
0.756998563 Async Serial 0x00
0.757085375 Async Serial 0x00
0.757172188 Async Serial 0x1D
0.757259 Async Serial 0x00
0.757345813 Async Serial 0x03
0.757432625 Async Serial 0x64
0.757519438 Async Serial 0x04
1.00330475 Async Serial 0x4B
1.004224938 Async Serial 0xFD
1.504979313 Async Serial 0x0B
1.5058995 Async Serial 0xFE
1.620372438 Async Serial 0xF9
1.888405063 Async Serial 0x2B (framing error)
1.889359875 Async Serial 0x08 (framing error)
2.006653938 Async Serial 0x4B
2.007574063 Async Serial 0xFC
2.508319938 Async Serial 0x0B
2.509240063 Async Serial 0xFC
3.009985875 Async Serial 0x0B
3.010906 Async Serial 0xFD
3.025011125 Async Serial 0xAB (framing error)
3.025965938 Async Serial 0x08 (framing error)
3.511651813 Async Serial 0x0B
3.512571938 Async Serial 0xFF
3.627053625 Async Serial 0xF9
4.013326438 Async Serial 0x0B
4.014246563 Async Serial 0xFF
4.15383975 Async Serial 0x8B (framing error)
4.154794563 Async Serial 0x08 (framing error)
4.514992375 Async Serial 0x4B
4.5159125 Async Serial 0xFC
5.016666938 Async Serial 0x4B
5.017587063 Async Serial 0xFC
5.286539688 Async Serial 0x8B (framing error)
5.287494563 Async Serial 0x08 (framing error)
5.518332875 Async Serial 0x4B
5.519253 Async Serial 0xFE
5.633726 Async Serial 0xF9
6.01999875 Async Serial 0x0B
6.020918875 Async Serial 0xFC
6.41924825 Async Serial 0xAB (framing error)
6.420203063 Async Serial 0x08 (framing error)
6.521673313 Async Serial 0x0B
6.522593438 Async Serial 0xFF
7.023339188 Async Serial 0x4B
7.024259375 Async Serial 0xFD
1.888405063 Async Serial 0x2B (framing error)
1.888405063 Async Serial 0x24
1.888491938 Async Serial 0x24
1.888578688 Async Serial 0x56
1.8886655 Async Serial 0x16
1.888752313 Async Serial 0x0D
1.888839063 Async Serial 0x37
1.888925875 Async Serial 0x0D
1.889012688 Async Serial 0x1B
1.889099563 Async Serial 0x0D
1.889186313 Async Serial 0x21
1.889273125 Async Serial 0x0D
1.889359875 Async Serial 0x08 (framing error)
1.889359875 Async Serial 0x26
1.889446688 Async Serial 0x00
1.8895335 Async Serial 0x00
1.88962025 Async Serial 0x00
1.889707125 Async Serial 0x00
1.889793938 Async Serial 0x00
1.88988075 Async Serial 0x1D
1.8899675 Async Serial 0x00
1.890054313 Async Serial 0x03
1.890141125 Async Serial 0x64
1.890227938 Async Serial 0x05
2.006653938 Async Serial 0x4B
2.006653938 Async Serial 0x24
2.006740813 Async Serial 0x24
2.006827625 Async Serial 0x57
2.006914438 Async Serial 0x0E
2.007001188 Async Serial 0x0D
2.007088 Async Serial 0xAC
2.007174813 Async Serial 0x01
2.007261625 Async Serial 0x00
2.007348438 Async Serial 0x0F
2.007435188 Async Serial 0x00
2.007522 Async Serial 0x9F
2.007574063 Async Serial 0xFC
2.007608813 Async Serial 0x00
2.007695625 Async Serial 0xAD
2.007782375 Async Serial 0xC2
2.508319938 Async Serial 0x0B
2.508319938 Async Serial 0x24
2.50840675 Async Serial 0x24
2.508493625 Async Serial 0x57
2.508580375 Async Serial 0x0E
2.508667188 Async Serial 0x0D
2.508753938 Async Serial 0xAC
2.50884075 Async Serial 0x01
2.508927563 Async Serial 0x00
2.509014375 Async Serial 0x11
2.509101188 Async Serial 0x00
2.509187938 Async Serial 0x9E
2.509240063 Async Serial 0xFC
2.50927475 Async Serial 0x00
2.509361563 Async Serial 0xAD
2.509448375 Async Serial 0xC3
3.009985875 Async Serial 0x0B
3.009985875 Async Serial 0x24
3.010072688 Async Serial 0x24
3.0101595 Async Serial 0x57
3.010246313 Async Serial 0x0E
3.010333125 Async Serial 0x0D
3.010419875 Async Serial 0xAC
3.010506688 Async Serial 0x01
3.0105935 Async Serial 0x00
3.010680313 Async Serial 0x0C
3.010767125 Async Serial 0x00
3.010853938 Async Serial 0x9F
3.010906 Async Serial 0xFD
3.01094075 Async Serial 0x00
3.0110275 Async Serial 0xAE
3.011114375 Async Serial 0xC0
3.025011125 Async Serial 0xAB (framing error)
3.025011125 Async Serial 0x24
3.025098 Async Serial 0x24
3.02518475 Async Serial 0x56
3.025271563 Async Serial 0x16
3.025358375 Async Serial 0x0D
3.025445125 Async Serial 0x37
3.025531938 Async Serial 0x0D
3.02561875 Async Serial 0x1B
3.025705563 Async Serial 0x0D
3.025792375 Async Serial 0x1E
3.025879188 Async Serial 0x0D
3.025965938 Async Serial 0x08 (framing error)
3.025965938 Async Serial 0x27
3.02605275 Async Serial 0x00
3.026139625 Async Serial 0x00
3.026226313 Async Serial 0x00
3.026313188 Async Serial 0x00
3.0264 Async Serial 0x00
3.026486813 Async Serial 0x1D
3.026573563 Async Serial 0x00
3.026660375 Async Serial 0x03
3.026747188 Async Serial 0x64
3.026833938 Async Serial 0x03
3.511651813 Async Serial 0x0B
3.511651813 Async Serial 0x24
3.511738688 Async Serial 0x24
3.511825438 Async Serial 0x57
3.51191225 Async Serial 0x0E
3.511999063 Async Serial 0x0D
3.512085813 Async Serial 0xAC
3.512172688 Async Serial 0x01
3.512259438 Async Serial 0x00
3.51234625 Async Serial 0x11
3.512433063 Async Serial 0x00
3.512519938 Async Serial 0x9F
3.512571938 Async Serial 0xFF
3.512606625 Async Serial 0x00
3.5126935 Async Serial 0xAE
3.51278025 Async Serial 0xC5
3.627053625 Async Serial 0xF9
3.627053625 Async Serial 0x68
3.6271405 Async Serial 0x3A
3.62722725 Async Serial 0x3A
3.627314063 Async Serial 0x33
3.627400875 Async Serial 0x0D
3.627487688 Async Serial 0x0A
4.013326438 Async Serial 0x0B
4.013326438 Async Serial 0x24
4.013413313 Async Serial 0x24
4.013500063 Async Serial 0x57
4.013586875 Async Serial 0x0E
4.013673688 Async Serial 0x0D
4.013760438 Async Serial 0xAC
4.01384725 Async Serial 0x01
4.013934063 Async Serial 0x00
4.014020875 Async Serial 0x11
4.014107688 Async Serial 0x00
4.0141945 Async Serial 0x9F
4.014246563 Async Serial 0xFF
4.014281313 Async Serial 0x00
4.014368063 Async Serial 0xAE
4.014454938 Async Serial 0xC5
4.15383975 Async Serial 0x8B (framing error)
4.15383975 Async Serial 0x24
4.153926625 Async Serial 0x24
4.154013438 Async Serial 0x56
4.154100188 Async Serial 0x16
4.154187 Async Serial 0x0D
4.154273813 Async Serial 0x39
4.154360625 Async Serial 0x0D
4.154447438 Async Serial 0x1C
4.15453425 Async Serial 0x0D
4.154621 Async Serial 0x1E
4.154707813 Async Serial 0x0D
4.154794563 Async Serial 0x08 (framing error)
4.154794563 Async Serial 0x27
4.154881438 Async Serial 0x00
4.15496825 Async Serial 0x00
4.155055 Async Serial 0x00
4.155141813 Async Serial 0x00
4.155228625 Async Serial 0x00
4.155315438 Async Serial 0x1D
4.155402188 Async Serial 0x00
4.155489 Async Serial 0x03
4.155575813 Async Serial 0x64
4.155662625 Async Serial 0x06
4.514992375 Async Serial 0x4BI get same framing errors when connecting the Saleae directly to Com 3 cable (without my circuit attached). This appears to be a BMS RS232 stability issue. I have a 100A and 300A BMS. Both have this issue.
I think my transistor circuit is good. I'll add a capacitor though.
I think my transistor circuit is good. I'll add a capacitor though.
Interesting. I'll try the same experiment this weekend to see if the framing errors are an "undocumented feature" and the Mega is masking them, or if it's specific to your unit. What is the cable distance between the BMS, your inverter ckt, and the Mega?
A photo is easier. Cable lengths are relatively short. I haven't gotten around to soldering the transistor to the Mega proto board. The proto board (sitting on top of Mega) has a real time clock and SD micro card reader. A 10 nF capacitor is now installed on the transistor board.
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