Possible RTS Failure

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cgarai
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Posts: 94
Joined: Tue Feb 15, 2005 10:35 pm
My RE system: Off Grid System:
Flexware 1000 system with
4 VFX3648s, X-240, 2 Flexmax 80s, FN-DC, HUB10 and a Mate3
controlling 30 Sharp 240w panels and
charging 48V HUP Solar 1 SO-6-85-33 batteries
12kw Isuzu/Mecc Alte diesel generator
Location: Healdsburg, CA
Contact:

Possible RTS Failure

Post by cgarai » Sat Mar 05, 2016 2:06 pm

Hi,

My neighbors system with one FX, one Flexmax 60 is having trouble with the generator running too long and Charge Conditions not being met. I have tracked it down to the RTS reading the wrong temperature. At 55 deg F it is reading Stat/DC/Batt/System battery Temp=01C and the A/D (Stat/FX/Batt/battery temp) = 188 (not sure I have that path right). When I disconnnect the RTS the A/D reading jumps to 255, but the System Battery Temp only goes to -02C.

I'm fairly sure their problem is the RTS because when I disconnect it (while absorption charging with a generator, 55F ambient) the voltage drops from 30.5 to 29.4 (abs volt =29.6) so I infer that the system has been thinking the temp was quite cool and the Abs V was raised and then dropped when it detected no RTS.

Why does the System Batt Temp not reflect what is going on? Without the RTS, shouldn't the temp go to 25C?

I found the RTS_table.pdf but I can't open it. Can someone point me to another link?

Thanks,

Chris

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tallgirl
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My RE system: 16 Kyocera KC175GT (2,800 watts DC), MX-60, 2 OutBack GVFX3648, 8 GC2 batteries (6v @ 215AH),
Location: Austin, TX

Re: Possible RTS Failure

Post by tallgirl » Sun Mar 06, 2016 5:19 am

Chris -

Temperature sensors can fail. That's what it sounds like in this case - the reading going to "255" when the sensor is removed means it isn't something like a broken wire, because it would have reported "255" all the time of that weren't the case.

When the system detects that it has no RTS, it "assumes" the temperature os 25C indirectly - it doesn't perform any temperature compensation at all.
Julie in Texas

I ride bicycles. A lot.

cgarai
Forum Virtuoso
Posts: 94
Joined: Tue Feb 15, 2005 10:35 pm
My RE system: Off Grid System:
Flexware 1000 system with
4 VFX3648s, X-240, 2 Flexmax 80s, FN-DC, HUB10 and a Mate3
controlling 30 Sharp 240w panels and
charging 48V HUP Solar 1 SO-6-85-33 batteries
12kw Isuzu/Mecc Alte diesel generator
Location: Healdsburg, CA
Contact:

Re: Possible RTS Failure

Post by cgarai » Sun Mar 06, 2016 11:49 am

Hi Julie,

Thank you. I knew both that the 255 was an open circuit reading and that the system defaulted to 25C. Do you know what the system temp should display under that condition?
Also, it would be handy to have the RTS profile.

Thanks,

Chris

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tallgirl
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Posts: 4334
Joined: Wed Sep 26, 2007 9:59 am
My RE system: 16 Kyocera KC175GT (2,800 watts DC), MX-60, 2 OutBack GVFX3648, 8 GC2 batteries (6v @ 215AH),
Location: Austin, TX

Re: Possible RTS Failure

Post by tallgirl » Sun Mar 06, 2016 12:17 pm

cgarai wrote:Hi Julie,

Thank you. I knew both that the 255 was an open circuit reading and that the system defaulted to 25C. Do you know what the system temp should display under that condition?
Also, it would be handy to have the RTS profile.

Thanks,

Chris
I forget and I'm not going to disassemble my system to find out? I know that the FNDC reports "99" as the sentinel value in the data stream, but I forget what the reported temperature is. I do know that all the device work "correctly" without a temperature sensor since they aren't mandatory, even if they are a very good idea.
Julie in Texas

I ride bicycles. A lot.

Vic
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Re: Possible RTS Failure

Post by Vic » Sun Mar 06, 2016 1:28 pm

Chris,

My FX RTS SECRET Decoder Ring does say that an A/D Count of 188 = 1.9 degrees C.

Have asked OB for the Decoder Table, and if all of the OB RTSes are identical -- that was only about one month ago, and as yet, NO REPLY from OB.

For the reading of 188, the corresponding RTS Resistance value should be about 2.8 K Ohms.

An ambient temp of 55 F may not be close to the battery temperature, as batteries have a lot of thermal mass, and integrate, very slowly, the average temperatures, unless the battery bank is tiny.

Decoder Ring says that A/D of 99 = 35.4 C.

FWIW, Vic
4/20/08: 18 Shell SQ 175-106 Vmpp, Stacked 5548 SW+, 1350 AH Surrette 4KS25's, MX-60, Kubota SQ-3250 25 KVA Polyphase Diesel genset. Thanks OutBack for this Forum + the great Support and Service.

cgarai
Forum Virtuoso
Posts: 94
Joined: Tue Feb 15, 2005 10:35 pm
My RE system: Off Grid System:
Flexware 1000 system with
4 VFX3648s, X-240, 2 Flexmax 80s, FN-DC, HUB10 and a Mate3
controlling 30 Sharp 240w panels and
charging 48V HUP Solar 1 SO-6-85-33 batteries
12kw Isuzu/Mecc Alte diesel generator
Location: Healdsburg, CA
Contact:

Re: Possible RTS Failure

Post by cgarai » Sun Mar 06, 2016 1:54 pm

Thanks Vic. That's what I got as well. The link to the table returned a blank pdf, so I found the link by Scott Payne and made a spreadsheet out of the formula he presented there.

http://www.outbackpower.com/forum/viewtopic.php?t=427

Understood about the actual battery temp, but I know for sure it was nowhere near 1-2C! We rarely see those temps and never long enough to integrate the battery mass to that temp.

Thanks,

Chris

Vic
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Re: Possible RTS Failure

Post by Vic » Sun Mar 06, 2016 4:53 pm

cgarai wrote:Thanks Vic. That's what I got as well. The link to the table returned a blank pdf, so I found the link by Scott Payne and made a spreadsheet out of the formula he presented there.

http://www.outbackpower.com/forum/viewtopic.php?t=427

Understood about the actual battery temp, but I know for sure it was nowhere near 1-2C! We rarely see those temps and never long enough to integrate the battery mass to that temp.
Thanks,
Chris
Yea, did notice your location, and assumed that the average temps over the past week might have been around 45 -50 F depending on altitude and environment that the batts see.

I DO have a Table for OB FX RTSes, which are probably all the same, but have not gotten P E R M I S S I O N from OB to post it, and would like a confirmation that ALL OB RTSes ARE the same ...

It IS rare for there to be an error in an RTS. Usually the cable fails open, often from rodents gnawing on the cable.

What is the color of the cable on that RTS? Believe that OB does brand their RTSes with their Logo.

If you happen to have a MidNite BTS, you might try substituting it, as OB and MN use identically-curved NTC Thermistors. 10 K Ohm at 25C.

It is possible that there might be some cable damage that could cause a parallel resistance with the RTS Thermistor.

All, FWIW, Vic
4/20/08: 18 Shell SQ 175-106 Vmpp, Stacked 5548 SW+, 1350 AH Surrette 4KS25's, MX-60, Kubota SQ-3250 25 KVA Polyphase Diesel genset. Thanks OutBack for this Forum + the great Support and Service.

cgarai
Forum Virtuoso
Posts: 94
Joined: Tue Feb 15, 2005 10:35 pm
My RE system: Off Grid System:
Flexware 1000 system with
4 VFX3648s, X-240, 2 Flexmax 80s, FN-DC, HUB10 and a Mate3
controlling 30 Sharp 240w panels and
charging 48V HUP Solar 1 SO-6-85-33 batteries
12kw Isuzu/Mecc Alte diesel generator
Location: Healdsburg, CA
Contact:

Re: Possible RTS Failure

Post by cgarai » Mon Mar 07, 2016 2:02 pm

Thanks Vic. I don't have a Midnight. It appears to be an OB RTS with a green cable. I agree with it being odd that it has failed neither open or shorted.

Chris

Vic
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Posts: 995
Joined: Sun Jul 09, 2006 12:56 pm
Location: San Joajuin County, CA

Re: Possible RTS Failure

Post by Vic » Mon Mar 07, 2016 2:49 pm

Hi Chris,

Yep, it is a strange anomaly.

And, all of the OB RTSes that I've seen have dark green cables, but those were on ten-year-old OB equipment.

Could possibly result from water getting into the connecter on the CC, or equally unlikely, might be the result of acid getting into the RTS, or the cable ... but that seems like a long-shot.

Good Luck, Vic
4/20/08: 18 Shell SQ 175-106 Vmpp, Stacked 5548 SW+, 1350 AH Surrette 4KS25's, MX-60, Kubota SQ-3250 25 KVA Polyphase Diesel genset. Thanks OutBack for this Forum + the great Support and Service.

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