Look at this Optima and tell us the color of the battery base. It should be the light gray as shown under the Yellow-Top. Ignore the top color as that just indicates the terminal configuration.
I have a Blue-Top with the light gray base in my TT and a Yellow-Top in my TV.
John, yest thats them: D31M
Ok, after having set the charger to "hot agm", resetting it, and letting it run for three days, I unplugged the coach from the wall. I left the fridge on, and of course it auto-switched to LP. I also left the water pump on (same as I'd do at the track). Nothing else is on. I waited 15 minutes and recorded 12.78 volts at the batteries using a hand held digital multi-meter. I recorded volts this way every couple of hours, and the drop is fairly linear. This afternoon I recorded 12.05, 30hrs after I started. I plugged the coach back in.
Something else interesting...when I measured 12.05 at the battery, I went inside and hit the volt test on the control panel of the RV and it only showed 11.75.
Thoughts on dropping from 12.78 to 12.05 over 30hrs? FYI the RV is parked inside a garage, so its not getting the full blast of the sun. Its low 90s here during the day, probably low 80s inside the garage.
CMC5 wrote: John, yest thats them: D31M
Ok, after having set the charger to "hot agm", resetting it, and letting it run for three days, I unplugged the coach from the wall. I left the fridge on, and of course it auto-switched to LP. I also left the water pump on (same as I'd do at the track). Nothing else is on. I waited 15 minutes and recorded 12.78 volts at the batteries using a hand held digital multi-meter. I recorded volts this way every couple of hours, and the drop is fairly linear. This afternoon I recorded 12.05, 30hrs after I started. I plugged the coach back in.
Something else interesting...when I measured 12.05 at the battery, I went inside and hit the volt test on the control panel of the RV and it only showed 11.75.
Thoughts on dropping from 12.78 to 12.05 over 30hrs? FYI the RV is parked inside a garage, so its not getting the full blast of the sun. Its low 90s here during the day, probably low 80s inside the garage.
Voltage tells you state of charge(SOC) if the bank is at rest for a sufficient time for a meaningful reading. However, voltage tells you little about the AH left in your bank. A reasonably measured load test can be useful to guess bank capacity.
It is difficult to learn anything about bank status by taking voltage measurements while a bank is being charged or discharged.
15 minutes is not enough time at rest to take a voltage reading. It would have been better to use the bank for 15 minutes and then disconnect and take a reading.
The 12.78 reading is too low for an AGM after three days of charging. At the battery, I would be looking for closer to 13 and surely more than 12.8. My 55AH AGM reads 12.7 in the AM before solar kicks in and I am running two Vortex fans 24/7 with PWM motor controllers. What is your charging source?
After the 30H draw, the battery needed to be disconnected and the Voltage observed for at least 15 minutes. The bank voltage should quickly bounce back and then slow down and level out.
With these voltage readings we could make an estimate of the AH used and also an educated guess re remaining AH.
Your driveway testing to simulate a weekend is valid. We need to learn more about your actual loads as a means to evaluate your bank. My gut tells me you have more loads than you think.
HTH;
John
* This post was
edited 06/18/12 10:07pm by full_mosey *
The charging source is a Freedom Combi 15, 75amp max, plugged into a/c wall current, 50amp service. Its set to "wet agm", which according to the owners manual means bulk charging to 13.8 volts, a max acceptance charge time of 3hrs or 10amps whichever comes first, and a float voltage of 13.3 volts. Optima spec sheet states charging can be anywhere from 13.8 to 15 volts and float between 13.2 to 13.8.
Unfortunately I did not validate the voltage while charging, nor the current draw while discharging. The only way I have to check current is with a portable meter, you know, the kind where you put the plastic hoop around the wire. There's a battery off switch so I can isolate the batteries from all draws.
CMC5 wrote: The charging source is a Freedom Combi 15, 75amp max, plugged into a/c wall current, 50amp service. Its set to "wet agm", which according to the owners manual means bulk charging to 13.8 volts, a max acceptance charge time of 3hrs or 10amps whichever comes first, and a float voltage of 13.3 volts. Optima spec sheet states charging can be anywhere from 13.8 to 15 volts and float between 13.2 to 13.8.
Unfortunately I did not validate the voltage while charging, nor the current draw while discharging. The only way I have to check current is with a portable meter, you know, the kind where you put the plastic hoop around the wire. There's a battery off switch so I can isolate the batteries from all draws.
So, what would a more valid test procedure be?
So long as the batteries are around 90F as you previously reported, The 13.8V will charge them. I would charge 24H minimum, then disconnect for at least 6H and read Volts. Do this until consecutive readings show no increase in volts. By disconnect, I mean remove the cabling unless you have a disconnect right there at the battery post(s). A remotely located disconnect may not actually disconnect everything.
Now we can load test. The result we want is to know is the AH capacity of the bank.
We need to eliminate all parasitic draws so we can load the battery with a known draw. A sure way is to remove the batteries for a bench test. Do you have anything with a known Amp draw that you can connect for a test? An ideal draw would be the 20H rate of 7.5A(20H x 7.5A = 150AH for 10 hours. That should draw the bank down by 75AH, or 50%. By reading the starting and ending volts, we can use a SOC% table to estimate the remaining AH. Warm batteries should have no problem with this test.
If the ending volts represent a discharge > 50%, the batteries could be damaged. This charge-load test can be repeated with a target of 75% discharge which would be 15H at 7.5A.
At this point you will have a good idea of the AH capacity of your bank and we can know if you have a draw issue.
I will let others with Class A rigs help you with learning more about your draws.
Those voltages are a little low. 13.41 would be correct for minimum charge voltage at 32 C (90 f) and 14.13 would be gassing voltage (which should be avoided), these are conservative figures (low) as I prefer to wear a belt and suspenders.
13.2 will still charge the battery bank--but probably won't reverse the loss of capacity he is experiencing, at least not in 24 hours. He should try charging at 13.2 for 168 hours.
My guess is there are phantom draws that our poster is unaware of.
Those voltages are a little low. 13.41 would be correct for minimum charge voltage at 32 C (90 f) and 14.13 would be gassing voltage (which should be avoided), these are conservative figures (low) as I prefer to wear a belt and suspenders.
13.2 will still charge the battery bank--but probably won't reverse the loss of capacity he is experiencing, at least not in 24 hours. He should try charging at 13.2 for 168 hours.
My guess is there are phantom draws that our poster is unaware of.
Low, yes, but at 90F we don't want the 'cold agm' setting.
Yes, it could take days to charge. That is OK because CMC5 is weekend dry-camping and has charging days available between weekends.
I am sure we will find that the draws are the problem because the new bank has not performed from the beginning, instead of a having a gradual loss over time.
I will let others with motor home rigs help with learning more about the draws.
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