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House Battery Problem
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I have watched the amp draw today with the batteries being fully charged. The amp draws can be very minimal and the batteries do not hold a charge very long. How long should the bulk charge last? (mine go from being down to fully charged in 1.5 hours which seems very short). The battery manual says to equalize every three months and I have not done that in 6 months; could this be a problem? It also states the charge should be: “Max current .3C, constant voltage 2.45V/Cell Charge 24h.” I think this means 14.7 volts for 24 hours? That seems like a very long time and my equalization charge is set at 15.5. Not sure what to do?
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Eric,
If your batteries are disconnected from all loads you have a battery problem. Equalizing, and any other efforts you make are not going to correct the problem.
As a benchmark, I remove and replace my batteries on a 5 year schedule. I have never felt the need to equalize, and when they are removed they are still performing well. I am talking about over 26 year’s experience.
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All the batteries new in March of 2016, six months ago, and now will hold a full charge with minimal amp draw for 90 minutes? All of them load tested fine? Something is wrong.
Are you sure there isn’t some kind of draw on them the gauge isn’t picking up? Something incorrectly wired into the system by a previous owner or well intended mechanic?
Have you contacted the battery vendor about a warranty claim?
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Why not put a clamp on amp meter on t he inverter cables and measure the real draw. This will tell you the real current draw.
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The more I think about this the more it seems something doesn’t add up.
Those of us that have a lot of year’s experience with our batteries know that your 8 batteries will take a long time to discharge with light or no loads. With phantom loads, the refrigerator, use of some lights and the inverters on, but no incoming 120V power from shore or generator your at-rest starting voltage is going to be around 12.8 volts and by morning is going to be 12.4 or 12.5 at the least.
You have never mentioned a lengthy charge time required to get to float voltage. If you had a large current draw or a bad battery such as one with an internal short, it would take an excessive amount of time to get to float.
I think Mikee has a very good suggestion, but if you don’t have the ability to measure the amperage draw at the very least stop any draw by disconnecting the batteries from the chassis and monitor voltages. Keep in mind the voltages at float are likely going to be over 13 volts, but the resting voltage after the surface charge has gone is going to be near 12.8. That is not a voltage loss. That is normal.
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I spent alot of time testing the amp draw directly from the batteries and did not find anything that was excessive or unusual at all. I then ran about 75 amps for 1.5 hours and the batteries went from 12.9 volts to 11 under the load. When the load was off they went back to 12.75 volts. I thought I knew something about batteries and voltage now I’m not sure! What I do know is I have a battery problem and a warranty claim. I have a 100 amp load tester; is this too low of amp to measure the batteries? Also, unrelated but I can only see the “edit and reply” buttons about 20% of the time when I login. I have used different computers, and my I Phone and do know the login is case sensitive. Any ideas about this?
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If you are having issues cut and paste your user name and password to log in on all of your devices. Then you have no issues posting, editing or replying.
I know this has been said often but have you disconnected the batteries, and separated them?
Just let them sit. If the voltage(s) drop the battery is bad. If not look elsewhere for the problem. BTW, every one of us has our batteries lose voltage when we dry camping and the time between needed charges is directly as a result of the loads. Some can go all night, some several hours. It varies based on how many devices are drawing power and what the owner considers the voltage at which to recharge. Maybe your expectations are too high.
I still think you have a battery problem. You don’t need a tester to know that once you separate them when fully charged and see if you get voltage drops.
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Jon, the cut and paste worked, thanks. I have disconnected the batteries from each other, load tested separately and have let them sit idle. How long would they need to sit without being connected for it to be a fair test?
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Eric,
When a battery is bad enough to draw down a set the voltage drop is noticeable pretty quick.
Bottom line is your at rest voltage right now is going to be almost the same on good batteries later today, tomorrow morning and even after a few days.
Now that they are disconnected and separated if they are not losing any voltage over time the issues are elsewhere and should be found before the batteries are re-installed.
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Do you have any DC loads that do not go thru the DC distribution panel. ie maybe the aux air compressor, webasto and such. On my coach I tied in the aux air compressor to the chassis battery and 3 days later I could not start the coach. I change that, but I do notice that the converter ( Beaver) tied the Commnad Center and webasto directly to the house batteries with the DC Distribution panel and off and on switches. So after the batteries have been solved I would follow the cables from the batteries to the Distribution panels. You never know what the previous owner did and Jon pointed out. You problem may not be in the VAC side.
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What is the end result of this issue? Inquiring minds want to know.
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If this issue is not resolved, look into the following. As
I recall, the Country Coach battery system operates in two separate battery
banks (4 batteries each bank), top and bottom, if you have 8, 8D batteries like I do. The top and
bottom bank are joined together in the power panel, located on top or the
battery housing, between inverters. Each bank (upper and lower) is tied
to main battery buss with a fuse for each bank, 200 amp (don’t remember exact value, but big) or higher I
think. Check each fuse to assure one has not blown.It sounds (my guess) to me you could be running off of one half
of your batteries. There is a nut that needs to be removed, then slide
the power panel out to check the fuses. Remember, this is a high amp
area, so be careful.You can check the amps on each bank when charging (after
draining your batteries to lower state) with both inverter/chargers. If one bank is significantly different, check
the power panel fuses.Again, be careful, this a high DC amp area, one slip of an unshielded
tool can cause major problems.I also own a 1995 Country Coach and have rebuild the battery
compartment and replaced both inverters with Magnasine, pure sine wave
inverters. They have run flawlessly
since installation 7 years ago. I also
upgraded all the wiring and connectors in the battery box area. Country Coach did no invest in high quality
wiring or connectors in this area.Good Luck.
Hector
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I appreciate all of the input. I still don’t know what the problem is. I had to run the bus again so I connected the batteries and I have again disconnected them now that I will have more time to let them sit and see if they hold a charge. There are four batteries on top and four on the bottom, but when amps are being drawn I have tested them on top and on bottom and the amp draw is very close to being the same. I have not found a difference between top and bottom at all. I don’t think there is anything drawing extra power. I can shut off the inverters and the battery disconnect switch and the amp draw is below one. I can account for the power being used as I individually turn on different equipment as I test the amp draw directly from the batteries. Couple questions that may help: When batteries are at 50% what is an approximate amount of time they should stay at the bulk charge level? My batteries when fully charged are at 13.3 volts (even 24 hours after unplugging from shore power); is this normal? If I use a load tester bigger than my 100 amp load tester, say one that draws 300 amps, would this definitely tell if the batteries are the problem?
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Did you buy the new batteries locally? If you did, take the coach to whoever you bought the batteries from, have them take the batteries and individually charge each battery, and have them load test each battery load test them. Its possible there is a problem with one or more of the batteries.
For batteries only eight months old, I’d take them back to whoever I bought them from. They should have a warranty.
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The float charge voltage is likely at the 13.3 you mention, but resting voltage with no current draw after the surface charge has dissipated is probably going to be 12.8.
The time at bulk charge is dependent upon the charge rate.
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