Rapid Discharge of Coach Batteries

[JFitzloff]

We have 2005 Beaver Santaim 40 PDQ.  I installed 1370 Watts (Four 335-Watt Panels) of Solar on the roof, 60 Amp MPPT Renology Charge controller, a 500-amp Renology  battery monitor with the factor Magnum Sudo-Sine Wave inverter Charger. I operate the inverter at night to power my C-Pap. We just finished an eleven-day dry camping trip. My solar keeps us topped off really well. I had what appears (we were Sleeping) to be rapid discharge of our battery bank (four 235 ah 6-volt batteries) The last night there i was up at 1:00 am with the battery monitor reading 75% of 235 ah. At 2:30 am the battery monitor alarmed with zero capacity left. Needing the C-Pap I left the inverter and made it till morning.

Ok now the question the only device in the system with large enough fuses and conductors to survive this type of discharge is the Magnum.

I have been an electrician since 1974 and electrical inspector now. I cannot witness this as it happens at night.

Have any of you had this type of issue?

[MyronTruex]

How old are your batteries? Have you used a hydrometer on them and checked individual battery voltages? You need to do this at night or turn the solar and any other charging source off.  

Do the battery voltage with and without the inverter running and providing power to your CPAP.

A bad battery bank could be crashing. Even new batteries can crash. 

With the recent modifications, I suspect all connections are tight but it is easy to overlook one. 

 

 

[johncvandoren@gmail.com]

8 hours ago, JFitzloff said:

We have 2005 Beaver Santaim 40 PDQ.  I installed 1370 Watts (Four 335-Watt Panels) of Solar on the roof, 60 Amp MPPT Renology Charge controller, a 500-amp Renology  battery monitor with the factor Magnum Sudo-Sine Wave inverter Charger. I operate the inverter at night to power my C-Pap. We just finished an eleven-day dry camping trip. My solar keeps us topped off really well. I had what appears (we were Sleeping) to be rapid discharge of our battery bank (four 235 ah 6-volt batteries) The last night there i was up at 1:00 am with the battery monitor reading 75% of 235 ah. At 2:30 am the battery monitor alarmed with zero capacity left. Needing the C-Pap I left the inverter and made it till morning.

Ok now the question the only device in the system with large enough fuses and conductors to survive this type of discharge is the Magnum.

I have been an electrician since 1974 and electrical inspector now. I cannot witness this as it happens at night.

Have any of you had this type of issue?

Are you aware that your battery bank will only provide two times the listed AHs? The first series connections will double the voltage to 12vdc, but not the total AH.   Furthermore, lead acid, and even AGM batteries can only be drawn down to 50%.  So the most you can get out of your battery bank is 235AH.  That may be plenty, but only if the batteries are in good shape and performing as expected.

[Tom Cherry]

Couple of things.  If you have not converted to LED lights, the incandescent are energy hogs.  Next.  Put a power strip on the front and read entertainment center.  Turn it OFF when not in use or at night.  The Standby mode eats power.  If you have a Residential refrigerator, use the Energy Saving mode,  regardless of which refrigerator, turn OFF the icemaker.  The heater coil in it zaps the batteries.

As to the Amp Hours.  Each battery in series has the same amp hours….so 2 Six Volt 225 AH batteries….is still 225 AH.  Now, the two banks in parallel, are additive.  So, that means you have 450.  BUT, the recommended draw down is 50%.  Know you have a better system than the Magnum, but be aware of the way and how the voltage is read.  On the magnum, the Remote Voltage is 0.15 lower than the real, at the battery measured.  So, you can safely drain, based on voltage, the bank to 11.8 or 11.9 VDC.  For an occasional drain overnight, 11.8 will be a smidge under 50%.  That is read at the Magnum remote.  It will be closer to 12.0 at the batteries,

You also need to exercise the batteries every 4 - 6 months.  Use a 350 watt halogen trouble ot work light.  Draw the batteries down to 11.9 VDC, measured at the batteries.  Then refill the cells and recharge,  Buy an accurate SG meter and test the cells.  Usually takes 2 or 3 times and they will start to give good consistent readings.

Also, use your AGS.  Set it to around 11.7 or 11.8.  Let the Genny run for 3 - 3.5 hours….set the charge rate to 80%.  

Hope  this helps.

[JFitzloff]

Yes I have four 6 volt batteries at 235 each for 470 ah total at 12 volts in a series parallel configuration which should give me 235 usable without damage to the batteries. 

[JFitzloff]

22 hours ago, myrontruex said:

How old are your batteries? Have you used a hydrometer on them and checked individual battery voltages? You need to do this at night or turn the solar and any other charging source off.  

Do the battery voltage with and without the inverter running and providing power to your CPAP.

A bad battery bank could be crashing. Even new batteries can crash. 

With the recent modifications, I suspect all connections are tight but it is easy to overlook one. 

 

 

The batteries are two years old. When they were new i install a watering system and I have my phone calendar set to remind me to check the water. They have taken one gallon in two years.

I have not tested the batters with Hydrometer. I will check next weekend.

The C-pap runs on the inverter.

Yes I checked my connections first.

 

This does not happen every night, only once in 11 nights most nights at bedtime i have 100% at 235-amp hours 12.8 volts and morning it is 75% at 176-amp hours 12.5 volts. When the Battery monitor alarms it is 0% o amp hours and 12 volts.

14 hours ago, Tom Cherry said:

Couple of things.  If you have not converted to LED lights, the incandescent are energy hogs.  Next.  Put a power strip on the front and read entertainment center.  Turn it OFF when not in use or at night.  The Standby mode eats power.  If you have a Residential refrigerator, use the Energy Saving mode,  regardless of which refrigerator, turn OFF the icemaker.  The heater coil in it zaps the batteries.

As to the Amp Hours.  Each battery in series has the same amp hours….so 2 Six Volt 225 AH batteries….is still 225 AH.  Now, the two banks in parallel, are additive.  So, that means you have 450.  BUT, the recommended draw down is 50%.  Know you have a better system than the Magnum, but be aware of the way and how the voltage is read.  On the magnum, the Remote Voltage is 0.15 lower than the real, at the battery measured.  So, you can safely drain, based on voltage, the bank to 11.8 or 11.9 VDC.  For an occasional drain overnight, 11.8 will be a smidge under 50%.  That is read at the Magnum remote.  It will be closer to 12.0 at the batteries,

You also need to exercise the batteries every 4 - 6 months.  Use a 350 watt halogen trouble ot work light.  Draw the batteries down to 11.9 VDC, measured at the batteries.  Then refill the cells and recharge,  Buy an accurate SG meter and test the cells.  Usually takes 2 or 3 times and they will start to give good consistent readings.

Also, use your AGS.  Set it to around 11.7 or 11.8.  Let the Genny run for 3 - 3.5 hours….set the charge rate to 80%.  

Hope  this helps.

Yes, I am all LED.

I have a never cold refrigerator.

I am in process of installing a power strip. my all off parasitic load reads at 3 amp @ 12 volts.

I have not exercised the Batteries. I will do this!

[Tom Cherry]

EZRED SP101 Battery Hydrometer

look on Amazon for the above.  Very accurate.  There is a “fill” mark at the top.  Hold it level and overfill and squeeze a little to get it on the mark.  You’ll easily get the hang of it.  This is the procedure from Trojan, which applies to any wet cell.

fill, in your case, verify the level.  I made up a wooden dowel with a scored mark that is about 2/3 the distance from top of  plate to bottom of well.  I use the Battery Miser Caps.  Folks that do rarely put in a pint every 6 months as the caps prevent moisture loss.  Your one gallon sounds right for a non water conservation system.

With fully charged, record all your data.  Check the SG on each cell.  Also pull the jumpers and measure each battery voltage.  Between the voltage and SG, you get a pretty good idea.  The voltage is important as it will show a shorted cell and the SG will show a weak or damaged cell.  
 

Start the load draw down.  Obviously disconnect your solar farm or cover.  Record the voltage across each series bank or individual battery.  Use 15 minute intervals. You want to get down to 11.9 VDC.  Set the inverter to 11.5 LOW BATTERY CUTOFF…keeps it running.  Pull jumpers….wait 15 minutes….read voltage on each.  Read the SG.  Use the table in the Trojan Battery Manual (download it) . That gives you a good idea of how low you went

install jumpers.  Recharge.  Pull jumpers and repeat measurements.  Then do it again.  Maybe 3 times.  If you look at the data, you want to get each batteries cell SG stabilized….or reduce the spread.  Then that is your baseline.  Also look at each battery in comparison to the others.

when you recharge the last time and pull jumpers and wait and measure, use the Trojan chart.  Whatever that level is, that is the best….hopefully around 100%….or even 90….

you need obviously to leave your watering system disconnected….I doubt you see any substantial loss of electrolyte during the test.  That assumes you kept the original caps and install them for safety as you are generating HYDROGEN….KABOOM….

that’s it