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davidsteverson

Batteries?? Electrical System Problem

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Greetings everyone. Been awhile since I’ve had an issue but seem to have one that I think I know the answer to but want input please.  This morning they turned shore power off in our resort to install a new transformer. Said it would be about 3 hours. After about 15 minutes I noticed I was down to 12.3 volts when I’m normally at about 13.3 to 14.4. I hit my battery check on the panel and it had all 5 lights lit indicating batteries were fully charged. Decided to turn on generator and it ground a little but wouldn’t start. Then tried to start engine and it ground a little but wouldn’t start. 

After a couple of hours shore power came back on and I plugged in and power went to 13.4 immediately. I tried to start generator and it fired right up. I tried to start the engine and it still won’t start. 

I went and got a friend who also has a Newmar and is parked here. We checked the batteries and the 4 house batteries are 6.9 to 7.1. The 2 chassis batteries were 13.54 and when I turned the engine key on they immediately dropped to 4. Also when they went to 4 the generator went off. 

Im thinking I need new chassis batteries. It’s interesting they show a nice charge when setting there but when you try to use them the bottom falls out. Do I also need new house batteries? They seem to be fine but I don’t think I’m really giving them a good stress test. 

Also, when the shore power was out shouldn’t my inverter have kicked in and run clocks and things?  All the clocks were out. Lights worked but not things that normally work on the inverter. 

Thanks for any suggestions. David. 

Update. Just came in a couple hours later and everything fired up fine. The 12 volt chassis batteries that register 13.5 when just sitting there went down to about 10.5 for just a fraction of a second as the rigs engine fired up. Earlier, they were going down to 4 almost immediately and the engine wouldn’t start. I’m hopelessly dumbfounded but glad it started. 

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David, the description would lead me to look at the coach battery connections !

The process would be to clean the battery cable and terminal connections. I do use a Drummel tool with a wire wheel brush. Steel or SS. They also have a nice soft brass wheel and polyester wheel that cleans the finer contacts and wires of oxidation. 

The Drummel is one of my must have tools that can be used for a number of jobs with the proper bits or brushes.  

After cleaning the cable and battery connections - spray some battery terminal pant or just some oil on the connections. Isolates the metal from the off gassed acid. Also , protects the battery mounting hardware. 

Battery condition can be checked with a meter and each cell can be tested using a hydrometer made to test the acid charge level.(Remember you are working with Sulfuric Acid)

  Same type tool one uses to test the freeze point of the cooling system - BUT they are not interchangeable !!!  

Rich.

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I would agree with Rich. To protect the terminals after a through cleaning as Rich suggested, coat all the connections with "dielectric" grease. It is a bit messy but works far better than the spray, as the coverage is better, no missed spots under where the spray does not go. The stuff is available from NAPA in a small tube that will last you quite a while. This is a normal maintenance procedure, done periodically. He mentions a hydrometer. There are a variety of these things. it is best to buy the instrument type as opposed to the type with the squeeze tube and floating balls generic type. The more sophisticated instrument type costs  more but the information supplied is more beneficial to knowing the precise condition of the batteries since you spent a whole lot of money to get and install them. It gives the specific gravity numerically of the acid over a scale rating condition. This information can be tracked in a notebook over time to see how they are holding up. 

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David.  Do you have Acid batteries or AGM's?  Even with AGM's if discharged low enough you may have to replace them, or one.  Clean as Rich & Bill E suggested,  I would put a slow battery charger on for 24hours and then put the normal charge on them....my concern is that your batteries did not at anytime go to bulk charge at around 14.4.

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The voltages you were reading when shore power was on (13-14 volts) is the output from your invertor/charger.  When shore power is on it will always try to bring the batteries up to that range.  However, a fully charged battery will only read 12.65 when all charging equipment is removed (or turned off or shore power removed) and that is with no load applied.  

It will read higher than 12.65 immediately after the charge source if turned off but it will soon drop to 12.65 or lower if any load is applied and your coach will ALWAYS have a small load applied.  Thus, the 12.3 volts you were reading is probably normal.  If your really concerned when it reads 12.3 the next time go to your battery bay and disconnect the battery(ies) negative lead and measure (with a multimeter) the voltage at the battery(ies).  This will give you an accurate state of charge (SOC) reading.  Here is a chart to show  voltage versus SOC:

Remove charger and turn on a light for five minutes to remove surface charge before measuring
Voltage Charge Remaining
12.66 100%
12.61 95%
12.57 90%
12.53 85%
12.49 80%
12.45 75%
12.41 70%
12.37 65%
12.33 60%
12.29 55%
12.25 50%
12.21 45%
12.17 40%
12.13 35%
12.09 30%
12.05 25%
12.02 20%
11.99 15%
11.96 10%
11.93 5%
11.9

0%

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6.9 to 7.1 indicates a dead battery.

Mine go to Bulk charge 14.3 to 14.6, then charging at 13.6, then drops to 13.3 on the panel, when Generator or SP is on.  On just Inverter, both banks will show 12.8 and then start dropping until 11.3, then the Generator comes on automatically...as long as it has enough fuel, it will continue to cycle on and off.  My engine batteries are on a trickle charger, plugged into coach.

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" We checked the batteries and the 4 house batteries are 6.9 to 7.1. The 2 chassis batteries were 13.54 and when I turned the engine key on they immediately dropped to 4. "

You need to fully charge both battery banks and have them LOAD TESTED.  Most places that sell batteries will do that for free. Voltage dropping that fast is a good indicator of bad batteries that is masked by being on the inverter/charger.  If wet cell batteries, be sure to check water level.  Exposed plates kill batteries.

 

As far as inverter-powered circuits not working, are you sure your inverter control panel was set to INVERT?

 

 

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Agree, had my chassis batteries discharging in two days. Had my trickle charger on when parked. I would check it one time and the light would be blinking sayings it wasn't charging. Unplug and plugged it in and it would begin to charge. Got both Fully charged, disconnected both and load tested both. One in the green the other in the red. Replaced both and now the Trickle Charger stays in the Green (fully charged and maintaining).

I have told this before, but will tell it again. I have a small Trickle Charger that stay connected to my Chassis Batteries. It is plugged into the Block Heater outlet in my engine compartment. When driving down the road the plug is dead. When on the Gen. or shore power the plug is how. This help maintain the chassis batteries to off set those troublesome trolls that always seem to draw in the batteries. Works well for me.

 

Herman

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Thanks for all the input. Here we are 24 hours later and things seem to be ok. Engine cranked, generator cranked and now on shore power. Your responses prompted a couple more questions. 

The house batteries are 6 volt - correct?  I think I hear a couple of you saying that they are paired and this 12 volt?  Is this correct?  Does that mean that when I want to test them instead of putting the red prong of the tester on the red of the battery and the black prong of the tester on the black of the same battery that I should see which 2 are connectedted and put one prong on one and the other prong on the other?  

I have 4 house batteries. My friend who was with me yesterday has a 2016 Dutch Star and I have a 2008 MountainAire. He has 8 house batteries while I only have 4. His are 6 volt as well.  We both have 2 chassis batteries that are each 12 volt. 

In looking at my magnum energy system this morning it says float charging 13.4. This is fairly normal. 

Ill go today and get the instrument to test the battery acid. I watch he levels closely and do add distilled water from time to time. Since I’ve had the coach (2 years) they have never been dry. 

Thanks again everyone. David

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While it is common to use 6 VDC batteries for house batteries (least expensive deep cycle batteries, since a LOT of them are used in golf carts) they are ALWAYS wired in series (to make a "12 VDC battery in two pieces").  Said another way, your coach systems all run on 12 VDC. You could just as easily use 6 two volt batteries in series-- again the goal is 12 volts to the house systems.

So, to check batteries individually (positive of that battery to negative of that battery) they should be 6.4 VDC or so (so the pair in series would be about 12.8 VDC) with the batteries at rest.  Yes, higher with charger on.

 

It is the speed at which you had voltage drop that indicates a likely bad battery.  So, with the inverter/charger working (shore power or generator) all looks good as the inverter/charger is doing all the "lifting".  But when shore power is off/no charging going on, voltage should quickly drop to about 12.8 VDC (as voltage above that is just surface charge and easily dissipated ) then drop very slowly from there.  The drop you experienced indicates either a very heavy load on the batteries or bad batteries.

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Each time we return from a trip, I check the Water level on all 4 of my 6 volt deep cycle batteries and fill as necessary.  Then I do the same just before we leave on our next excursion. To top off my batteries I have a pump up sprayer filled with Distilled Water. I cut the spray nozzle off and just use it to top off each cell.

Herman

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One other thing. There are 6 batteries back there in the battery bay. I looked to see if I could figure out how old they were. On one battery there is a sticker that says 5/13. I’m assuming that means it was installed in May of 2013. So it will soon be 5 years old. So I’m thinking I need to replace. 

One other thing if I’m going to replace. If the system is always looking for 12 volts would I be better off to buy 4 12 volt batteries as opposed to 4 6 volt batteries and pair them up into 2 12 volt systems. My accountants mind says I’d have 2 times the battery power if I got 4 12 volt batteries. I’m sure there is a reason not to do that but thought I’d ask. David

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David,

The 6 volt Batteries you have now are golf cart deep cycle batteries. If you are looking to replace them with 12 volt deep cycle batteries you will find that they are much larger batteries. I have seen newer coaches and newer Golf carts using 12 volt deep cycle batteries.  Here an other case where size does mater. You might check with someone like Interstate Batteries and see what they have in size and Amp Hours and Cold Cranking Amps. You may have more Amp Hours with 4 6 volt than with 2 12 volt.

In either case be sure you are discussing Deep Cycle Batteries and not Start Batteries when talking to a dealer. 

Herman

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In most cases you will get more capacity with four six volt batteries connected in the series/parallel configuration.  The individual six volt batteries are easier to handle than twelve volts batteries would be .

Jim

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Thx in advance for your response's: We have a 2012 Tiffin Open Road, purchased used this year. Not understanding many items on the MH, I had been turning "off" the "house Battery" switch located at the entrance door steps (Do not do so today). When I turn the switch to the "On" position there was not house battery power. I discovered that after I had ran the onboard generator 20-30minutes, the house batteries were at a combined 12.2-13.2 volt tester measurement. The MH voltage indicator also displayed 12.5-13.2 volt. After a couple of two days (non-usage of any AC/DC devices) I had the same issue with the house batteries going dead after a couple of days of non-use, thought maybe I had damaged the two 6 volt batteries which were 3+ years old. Replaced with two new Allstate 6 volts, I'm experiencing the same dead battery issue. After 2-3 days of non-use, I would check the voltage on the new batteries-2.0 combined voltage.

I purchased a solar battery tender of which I connected this week, measured power coming to the house batteries after solar battery tender hook-up, all was good. Prior to the solar battery tender hook up to the actual batteries I ran the MH generator to charge the batteries- result, onboard panel indicated 13.9volt, measured with voltage meter, at batteries-combined 13.5volt, two days ago.

Today house batteries measure at 2.0 combined voltage same dead house battery issues. I would appreciate any suggestions? thx

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MyDog,

Welcome to the FMCA Forum.

Sure sounds like you have a 12 VDC draw somewhere. 

Use an ammeter to check for electrical draw.  After hooking up the ammeter, start pulling fuses until you locate the culprit.  One commonly missed one is basement lights.

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My house batteries go dead sitting too .

i turn off the switch by the door that says store but still go dead in a couple days. Batteries are new 40 ft American Tradition. With everything off my investor charter panel says 12 amps. What could draw 12 amps that I can hear run all lights are off

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Sounds like something might be plugged into an outlet being powered by the inverter. Try turning off the inverter and see if the batteries still discharge.

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44 minutes ago, DickandLois said:

Wayne,  12 amp load indicated on the inverter 12 volt side ?

Rich.

I ASSUME he means his INVERTER/CHARGER panel reads 12 amp draw with inverter turned on.  If I have misinterpreted, please let us know exactly what is happening.

What is draw with inverter turned OFF?

And, inverters take some power even if nothing is running-- called standby-mode.  So when storing, the inverter should ALWAYS BE OFF.

The salesman switch by the door does not control power to the inverter/charger.  The inverter/charger is wired directly to the battery bank with large-gauge cables and likely a very high amp slow-burn fuse.

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19 minutes ago, FIVE said:

12 amps is a big load...my ACs draw nearly that much.

WAIT-- the roof A/C is 12 amps AT 120 VAC.

VERY, VERY different than 12 amps at 12 VDC.

But, totally agree, we need clarification from the OP.

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