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Old 05-26-2024, 11:04 PM   #1
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BCC SDC-107A House bank charging

Questions re my Battery Control Center ---

First quick background info - I believe I heard noise(s) / smell coming from the BCC area a while back, but after opening everything appeared OK

My converter works fine charging my House bank and start battery.
My alternator charges the start battery, but does not appear to charge the house bank while I drive - at least not significantly - I need to reverify in a few days when I am on the move again.

Question I have (can not recall) is does the alternator charge the house bank while driving? If yes, what may be wrong with the BCC (if that is the problem)? Is there a particular part (?fuse) to be replaced or does the entire unit have to be replaced. does the BCC even control the HOUSE Bank charging from the alternator?

If it doesn't, then there is no question to answer, but my gut tells me something is wrong in the BCC stopping the house bank from being charged.

TIA
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Old 05-27-2024, 10:28 AM   #2
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Troubleshooting docs are at the bottom of this page: https://rvcustomproducts.com/sdc-107a

RV Custom Products also seems to have excellent support.

It's fairly common for some solenoid with that BCC to fail and then the house batteries will not charge from the engine alternator. Some people have bought a replacement solenoid at an auto parts store for about $80.

Ray
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Old 05-28-2024, 06:46 PM   #3
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Quote:
Originally Posted by NXR View Post
Troubleshooting docs are at the bottom of this page: https://rvcustomproducts.com/sdc-107a

RV Custom Products also seems to have excellent support.

It's fairly common for some solenoid with that BCC to fail and then the house batteries will not charge from the engine alternator. Some people have bought a replacement solenoid at an auto parts store for about $80.

Ray

Thanks for your reply. I seem to recall this information from a while back. The test procedure is a bit involved. I can do it, but It should be a much simpler design. Thanks for reposting. I'll call them tomorrow. Early closing time.

After talking to them, I'll probably just replace the relay - without testing most likely due to hearing noises and a "burnt" smell.

Because of my 2nd 800Ah house bank (look at previous posts), I am able to charge the OEM House Batteries with it and the inverter I have installed - driving or not.
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Old 05-29-2024, 02:19 PM   #4
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Been trying for 24 hours to call them, line is always busy. Does anyone have the part number and/or specifications for the relay before I take it out?
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Old 05-30-2024, 05:47 AM   #5
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Finally got through at tge end of the day, but the lady that answered was only there to take orders over the phone, but provided a phone number to another individual at another location that discussed the testing process in the pdf mentioned here. In addition to the large 80 amp continuos solenoid, there is another on/off switch under the circuit boards that can cause a problem. Unfortunately, I was driving and couldn't pay deep attention to himself I'll open everything up when I get a chance (probably when I return home) abd do the proper diagnosis. Like many things in the rv industry design is not their forte. I'll update eventually.
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Old 05-30-2024, 02:51 PM   #6
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My SDC-107A died a few years ago. See: My coach batteries stopped charging from the alternator. (Bad SDC-107A).

After installing a new SDC-107A, I was able to adjust it for my Battle Born LiFePO4 batteries. Working fine since 2019.

See SDC-107A Battery Control Center Schematics below:
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Old 05-31-2024, 09:37 AM   #7
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I didn't notice what you did to the BCC to allow the lithium batteries. Did you replace the entire bcc?

After talking to the technician, I'm just going to purchase locally, when I return home, a 200 or 300 amp continuous duty coil solenoid vs the OEM 80 Amp coil for longer life. Cost is apx $15 vs $55 plus shipping from BCC company.
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Old 05-31-2024, 10:55 AM   #8
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Quote:
Originally Posted by newer View Post

After talking to the technician, I'm just going to purchase locally, when I return home, a 200 or 300 amp continuous duty coil solenoid vs the OEM 80 Amp coil for longer life. Cost is apx $15 vs $55 plus shipping from BCC company.
what alternator you got?
did technician know what amps your alternator is designed to put out?

you need a heavy duty one to withstand the extra amp draw
solenoid simply connects the 2 batteries the wiring is usually sufficient to allow the lithium to take a heap of amps from the alternator

a heavily depleted lithium.... may be too much for a smaller standard < 200amp alternator therefor they put in a heavier alternator

OR some method to lessen the amp draw.
A) a DC-DC charger
B) Li-BIM
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Old 05-31-2024, 01:00 PM   #9
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what alternator you got?
did technician know what amps your alternator is designed to put out?

you need a heavy duty one to withstand the extra amp draw
solenoid simply connects the 2 batteries the wiring is usually sufficient to allow the lithium to take a heap of amps from the alternator

a heavily depleted lithium.... may be too much for a smaller standard < 200amp alternator therefor they put in a heavier alternator

OR some method to lessen the amp draw.
A) a DC-DC charger
B) Li-BIM
If you are asking me, I don't have lithium. I upgraded the FR OEM 200Ah wet cell house bank to 300Ah AGM. I also have a separate 800Ah second bank to run my AC units via a 3Kw inverter and as backup to the 300Ah bank. 99.99% tell me it's impossible. Lol
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Old 05-31-2024, 01:40 PM   #10
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somehow got impression you were swapping to lithium
my bad

If the converter charges both the house and start... that would indicate 'solenoid' is working
I would more look at the LOGIC part ... of the BCC
is a signal going to the solenoid to join the batteries together?

check all the fuses

If your starting battery is LOW ... the BCC won't connect the solenoid to parallel the house.
I would check all battery connections on the starting side
test battery voltage .... with battery disconnected.
test alternator voltage when motor is running

work out how to jump the solenoid and test it BEFORE buying a new one
multimeter and a jumper wire is all you need at first...
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Old 05-31-2024, 04:11 PM   #11
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somehow got impression you were swapping to lithium
my bad

If the converter charges both the house and start... that would indicate 'solenoid' is working
I would more look at the LOGIC part ... of the BCC
is a signal going to the solenoid to join the batteries together?

check all the fuses

If your starting battery is LOW ... the BCC won't connect the solenoid to parallel the house.
I would check all battery connections on the starting side
test battery voltage .... with battery disconnected.
test alternator voltage when motor is running

work out how to jump the solenoid and test it BEFORE buying a new one
multimeter and a jumper wire is all you need at first...

Thanks, but in my first post, I mentioned that is not the situation. House is not being charged. I'm not the average rv'r. I don't have problems with spending $ on parts, even if they end up as spares - lol.

I'll test it when I get back home, but I'm 99.9% sure the solenoid is dead. Both batteries charge on shore power. Just doesn't from the alternator.
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Old 06-01-2024, 03:06 AM   #12
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How to adjust SDC-107A BCC for Battle Born LiFePO4 batteries

Quote:
Originally Posted by newer View Post
I didn't notice what you did to the BCC to allow the lithium batteries. Did you replace the entire bcc?

After talking to the technician, I'm just going to purchase locally, when I return home, a 200 or 300 amp continuous duty coil solenoid vs the OEM 80 Amp coil for longer life. Cost is apx $15 vs $55 plus shipping from BCC company.
As the SDC-107A has three relays, $15x3=$45.

In Sept 2019, I paid $240.59 for a new SDC-107A '$55 plus shipping' is a deal. :
  • $68.32 UPS ground freight is to Alaska.
  • $172.27 SDC-107A
  • $240.59 Total
It has done the job since 2019.



How to adjust SDC-107A BCC for Battle Born LiFePO4 batteries
My coach batteries stopped charging from the alternator. (Bad SDC-107A) #17


For the voltage measurements below I used both my Victron BMV-712 & a multimeter.
  • Victron BMV-712 monitored both the Battle Born house batteries & the chassis (starter) battery.
  • Multimeter monitored the testpoint 'voltage drop out point.'
John Mock @ RV Custom Products
Tue 10/15/2019 10:15 PM :: "A better approach would be to use the same adjustment we use to calibrate the electronics. We put 13.2v on the unit and adjust the potentiometer in the upper left corner of the board until the comparator just trips. Since there is a delay between the trip point and relay pull in, we measure the voltage on the test point (the 1/8in. pad at the upper right corner of the potentiometer. At trip, the test point goes high around 12.5v and when the drop out point (12.7v) is reached, the test point drops to around 0.1v. If the pot were to be adjusted to 14.2v, the drop out point would probably be 13.6v ( the normal difference 0.5v will increase slightly as the trip point is raised)."

Thu 10/17/2019 4:03 PM :: "That is the test point. Clockwise on the pot increases trip voltage. Don't know how far it will go.
Your converter output must exceed the trip point for this to work. I don't know how high the pot will go."
Using the directions above, I was able to adjust the BCC BIRD trip voltages.

First I cleaned off the paint from the potentiometer and took a picture:
Potentiometer at 2 O'clock

Next I disconnected shore power and all battery chargers. IE: Inverter/Charger & Solar Charge Controller.

I used a multimeter to measure the voltage at the test point.


I could only lower the battery voltage by turning on the headlights.

The Battery voltage started at 13.6v after the charger was shut off. I turned the potentiometer clockwise until the voltage dropped. Ten seconds later the relay opened with a clunk. I then turned the charger back on until the the relay closed again. I was not able to tell what the voltage was as it rose too fast. It looked like it was about 14v.

I turned the potentiometer counterclockwise alittle and turn the charger off again. As the voltage dropped I measure the voltage on both Victron BMV-712 & a multimeter at the test point. When the test point drop out point, the Victron BMV-712 read about 13.5v.
I repeated the process of charging until the relay closed & discharging utli it opens. When it opened at about 13.45v, I stopped.

I started the engine & watched the voltage rise & relay close at about 13.9v.

The after picture of the potentiometer:
Potentiometer at 4 O'clock

I repeated the process, and remeasured the voltage points that the relay opened & closed. see the graph below:

Conclusion:
I am happy with the results. The SDC-107A BCC is now safe to use with my Battle Born batteries. I have isolation when there is no charger raising the voltage above 14v.

Also, I noticed that when my Battle Born batteries were below 50%, I could get about 120 amps from the alternator. Which means a Class A or C install of Battle Born batteries should be a minimum of three to support the 120 amp.
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Old 06-01-2024, 09:22 AM   #13
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Thanks for your info. However, the SOC for lead acid(including AGM) batteries is INCORRECT. 100% SOC is 13.2Vdc NOT 12.65. 6 cells @ 2.2/cell is 13.2.

Also the $15 I mentioned was just for the Big silver relay not the entire BCC.
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Old 06-04-2024, 08:27 PM   #14
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Quote:
Originally Posted by newer View Post
Thanks for your info. However, the SOC for lead acid(including AGM) batteries is INCORRECT. 100% SOC is 13.2Vdc NOT 12.65. 6 cells @ 2.2/cell is 13.2.

Also the $15 I mentioned was just for the Big silver relay not the entire BCC.
I was only worried about my Battle Born LiFePO4 SOC.




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Old Yesterday, 01:17 PM   #15
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Finally fixing

I just returned from my 6 week trip - another story - outstanding!! I am pleased to report no problems other than the windshield rock chips.

And now I am finally fixing the SDC107A that was preventing house charging from the alternator. I purchased a replacement 85A solenoid locally from West Marine - Amazon would take a week. Everything is almost finished, but in all of the pictures I took during disassembly, this white wire is not visible.

It is soldered on the back of the board and it is labeled Coach Battery on the front. Unfortunately, this is the only Item left I need to attach before I reinstall the BCC and connect the external wires.

So if anyone has this actual location information, I'd appreciate it. Pics attached to show this specific wire.

Please no guesses or possibilities.

TIA.

John (tech support) has been GREAT, but he is currently unavailable. I'm hoping to finish today vs waiting until Monday.

Updatw: I was able to get in touch with John. The white wire goes to the bottom stud of the black disconnect box.
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Old Yesterday, 04:38 PM   #16
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Almost Finished

Everything is back together and with a new solenoid ($28 on amazon with a week wait or $34 at West Marine same day pickup) installed. Everything works and no sparks - Yeah!

All that is left is to discharge the house bank and start the engine to verify the solenoid was the problem and it is now fixed.

I don't suggest doing anything with the BCC if you are not a competent ..... there are too many ways to get hurt or damage something. There are plastic centering "washers" on the studs (if you didn't notice during disassembly - I did not - it is dark in there)) where the cables connect. If not done correctly, you WILL FRY EVERYTHING! Also, extensive documentation (pictures) may not be enough for reassembly (see previous posts). I disconnected the house banks (I have 2), but I did not disconnect the engine start battery and its wire was hot - I wrapped its end .....

When I start the engine, I'll post my last. 2 Day JOB, it seems simple, but ... - not fun and very time consuming for a first time event.
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