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Battery down to 9.7v ??

jornvango
Explorer II
Explorer II
We have one 12v battery in a travel trailer. After driving for 5-6 hours on Friday, we boondocked in Texas. 40s at night, 50s during the day. We only used 1 led light in the evening and the water pump a few times. The fridge is on all the time (battery/propane).

Yesterday Saturday, in the morning when we used the water pump, it kept rattling away as if it didn't have enough power. Fridge and lights worked.

We plugged in the portable 100w solar panel. The charge controller read 9.7v! After a few hours of solar charging, it went up to 12.2v but by the time the sun set, it showed 11.57v even though nothing but the fridge was on in the camper.

This morning (Sunday), when we plugged in the solar, it read 9.7v. Water pump kept rattling away after we washed our hands and the led lights were dimmer with the pump on.

Some facts:
- flooded battery dated 2013
- type marine (it shows cranking amps on the label)
- fluid level is ok

Is the battery dead / beyond repair? How come the fridge and lights still work?
Based on my limited knowledge, a battery shouldn't be below 12.3v ... Based on the past experiences, one night of light usage after driving, the battery should still be around 12.6v...
42 REPLIES 42

Harvey51
Explorer
Explorer
The voltage on a battery is overly optimistic after charging. Wait a few hours after any charging to measure voltage and use the 12V side of life voltage chart that says 12.0 is 50%, 12.6 is 100%. As an example, my batteries have been disconnected since September and still read over 12.6 V.
If you want to more accurately and conveniently see the state of charge, get a battery monitor that counts amp hours in and out.

If you choose to buy regular batteries instead of AGM which donโ€™t like low temperatures, I recommend the Costco ones that say Deep Cycle on the side. Mine are 6 years old and still excellent. This time Iโ€™ve kept them over 80% charge with solar and engine charging. Never plugged in or used a generator.
2004 E350 Adventurer (Canadian) 20 footer - Alberta, Canada
No TV + 100W solar = no generator needed

Sam_Spade
Explorer
Explorer
jornvango wrote:
now it's showing 12.4V. (all in a matter of 2-3 minutes after unplugging and putting some load on the battery)

I'll be on the lookout for a replacement.


Probably the right thing to do but it could also mean that you have a constant high current load on the 12 V system.

Might want to disconnect the batteries to see what they measure with NO load.
'07 Damon Outlaw 3611
CanAm Spyder in the "trunk"

Sam_Spade
Explorer
Explorer
marcsbigfoot20b27 wrote:

I have 3 in series, no maintenance.


I don't think so.
3 12 Volt batteries in series would be 36 volts.
Even 3 6 V ones would be 18 volts.
'07 Damon Outlaw 3611
CanAm Spyder in the "trunk"

SoundGuy
Explorer
Explorer
marcsbigfoot20b27 wrote:
Sams club, group 31 AGM East Penn/Dekka (branded Duracell) grey case, made in USA.
I have 3 in series, no maintenance.


Surely you mean 3 in parallel. 3 G31s in series would be 36 volts. :E

Installed the same battery in our Freedom Express - no complaints. Here in Canada they're distributed by East Penn to RV Care dealers under the branded name Traveler's Choice.
2012 Silverado 1500 Crew Cab
2014 Coachmen Freedom Express 192RBS
2003 Fleetwood Yuma * 2008 K-Z Spree 240BH-LX
2007 TrailCruiser C21RBH * 2000 Fleetwood Santa Fe
1998 Jayco 10UD * 1969 Coleman CT380

2oldman
Explorer
Explorer
jornvango wrote:
When I unplug, the battery shows 12.9V as you would expect.
Check it again after 10 minutes. Too bad Santa didn't get you a new battery.
"If I'm wearing long pants, I'm too far north" - 2oldman

time2roll
Explorer II
Explorer II
Be careful continuing to use a bad battery. Easy to overheat, get low on electrolyte and and have a minor explosion.

jornvango
Explorer II
Explorer II
Merry Christmas!

We've been at an RV park and plugged in. The battery correctly shows 13.5V while plugged in. When I unplug, the battery shows 12.9V as you would expect.
Then I run the water pump, lights, etc. and in a matter of minutes it went down to 11.9V and now it's showing 12.4V. (all in a matter of 2-3 minutes after unplugging and putting some load on the battery)

I'll be on the lookout for a replacement.

marcsbigfoot20b
Explorer
Explorer
Sams club, group 31 AGM East Penn/Dekka (branded Duracell) grey case, made in USA.
I have 3 in series, no maintenance.

Sam_Spade
Explorer
Explorer
opnspaces wrote:
Batteries have 2 volts per cell.


Not correct.

A conventional wet cell battery has 2.1 volts per cell, for a total of 12.6.
An AGM has about 12.15 per cell.

The part after the decimal point is IMPORTANT since one that reads just 12.0 is more than half discharged.
'07 Damon Outlaw 3611
CanAm Spyder in the "trunk"

opnspaces
Navigator
Navigator
jornvango wrote:
We just arrived at our next destination after driving for 6 hours. Battery level shows 9V

Looks like we need to look for a place to order a replacement on the road.


You have a bad battery. Batteries have 2 volts per cell. A 12 volt battery that mysteriously drops to 10 or 9 volts has a dead cell. You'll need to replace it, If you want a true 6 volt you'll have to buy two to get the needed 12 volts. Costco and Sams Club carry them for about $85 each, I don't think you'll be able to find a true deep cycle 12 volt at a Walmart or auto parts store.

But, what do you use the battery for? If you are constantly off the grid then a true deep cycle would be a good idea. But if you almost always have an electrical hookup, then almost any cheap starting battery from Walmart should work fine.
.
2001 Suburban 4x4. 6.0L, 4.10 3/4 ton **** 2005 Jayco Jay Flight 27BH **** 1986 Coleman Columbia Popup

drsteve
Explorer
Explorer
free radical wrote:
SoundGuy wrote:
Chainwright wrote:
I'm thinking if your battery is 5 yrs old, it's pretty much on it's last leg. The DW and I just changed out our 4-5 yr old battery on our cars too. They gave out on us. Just be safe change your battery. JMHO.


My Silverado had an AC Delco Professional Plus battery with a 42 month, full replacement value warranty. It pooched on me just weeks after that 42 month expiry :R so I anted up for the Group 48 AGM recommended for my truck, sold by Canadian Tire with a 5 yr warranty. I'd consider 5 yrs out of any battery pretty respectable.

They must be making them much worse then back then.

I had 85 Chevy truck then and Delco batery lasted me 9 years..

My 08 Silverado batt died in couple years,but it was my fault as I left 12V Engel cooler on few times with engine off.

My 2nd batt lasted 5 years.


My 06 Silverado still has the OEM Delco battery...
2006 Silverado 1500HD Crew Cab 2WD 6.0L 3.73 8600 GVWR
2018 Coachmen Catalina Legacy Edition 223RBS
1991 Palomino Filly PUP

Sam_Spade
Explorer
Explorer
jornvango wrote:
We just arrived at our next destination after driving for 6 hours. Battery level shows 9V

Looks like we need to look for a place to order a replacement on the road.


AND....you MUST check the voltage when you think it is charging.
It likely is NOT.

If you just put in a new battery, it might be ruined in a few weeks.
'07 Damon Outlaw 3611
CanAm Spyder in the "trunk"

SoundGuy
Explorer
Explorer
Chainwright wrote:
I'm thinking if your battery is 5 yrs old, it's pretty much on it's last leg. The DW and I just changed out our 4-5 yr old battery on our cars too. They gave out on us. Just be safe change your battery. JMHO.


SoundGuy wrote:
My Silverado had an AC Delco Professional Plus battery with a 42 month, full replacement value warranty. It pooched on me just weeks after that 42 month expiry :R so I anted up for the Group 48 AGM recommended for my truck, sold by Canadian Tire with a 5 yr warranty. I'd consider 5 yrs out of any battery pretty respectable.


free radical wrote:
They must be making them much worse then back then.

I had 85 Chevy truck then and Delco batery lasted me 9 years..


Maybe. I have no complaints though, the fact the battery started dying just after the 42 month warranty ran out is just bad luck on my part. Actually the truck was starting fine, it wasn't until the DIC indicated the battery was "weak" that I even noticed. It probably would have continued working just fine for many months but with winter approaching I decided I'd rather swap the battery out for a new one while the weather was still tolerable rather than in the dead of winter @ -10C.
2012 Silverado 1500 Crew Cab
2014 Coachmen Freedom Express 192RBS
2003 Fleetwood Yuma * 2008 K-Z Spree 240BH-LX
2007 TrailCruiser C21RBH * 2000 Fleetwood Santa Fe
1998 Jayco 10UD * 1969 Coleman CT380

gbopp
Explorer
Explorer
Have you ever read The 12 Volt Side of Life?
I found it helpful.