Jump to content
Sir Traveller

best way to test house batteries ?

Recommended Posts

Hello Everyone…

 

I have a 2003 Ford F-53 RV

 

What’s the most accurate way to test house batteries using multimeter and hydrometer? Disconnect from shore power then keep few lights on inside the RV to give a bit of load?  Do I have to disconnect the 2 batteries from each other and test each one separately? or no need to disconnect anything ?

I appreciate any suggestions…

Share this post


Link to post
Share on other sites

Sir Traveller, What do you think the problem is? By the way welcome to the forum. Giving them a little rest to blead any "float charge" off will give you a reading. It may be better to take them and have a load test to see if  they have any problems.

Bill

Share this post


Link to post
Share on other sites

there are no problems except that recently I noticed  there is some sort of leak from one of the 2 connected house batteries, I am not sure if this is normal due to batteries being charged ( my RV has a built-in charger that charges when hooked to hsore power and I am constantly hooked up )

Share this post


Link to post
Share on other sites
3 hours ago, Sir Traveller said:

there are no problems except that recently I noticed  there is some sort of leak from one of the 2 connected house batteries, I am not sure if this is normal due to batteries being charged ( my RV has a built-in charger that charges when hooked to hsore power and I am constantly hooked up )

Where are they leaking? From the caps or from the cases somewhere else?

If they are leaking from the caps, first thing I'd do is check to see if they are overfilled or overcharging. They should not be filled to the top of the filler neck, as this will cause leaking from the caps, and if they are being charged at too high a voltage you'll also have similar things happen.

Have you confirmed the voltage they're charging at?

If they are leaking from elsewhere in the case or lids, disconnect them immediately and carefully remove them from the coach while wearing rubber gloves. Batteries should never leak from the case. Ever. A leaking battery can cause lots of damage very quickly.

Share this post


Link to post
Share on other sites

they are leaking from the caps, I haven't added any distilled water in over 8 months ( the RV was in storage for 6 months from May to November ) 

the charger is built in so I have no idea what type it is ( I do not know if it is smart charger or not,  my RV is 2003 )

Share this post


Link to post
Share on other sites

The most accurate way to test batteries is load test.  I use the inverter and a 1500 watt heater.  Hook up the inverter only to the battery bank.  Use the output of the inverter to power the heater and an electric alarm clock.  Set the clock at 12 noon and plug it in with the heater.  Use the charger in the inverter until it goes to float.  The inverter will shut off the output when the preset voltage is reached.  If you use the same inverter and heater you can get repeatable results.  The clock will indicate how many hours and minutes life in the batteries.  If you do this when the batteries are new then you have a baseline.

 

Share this post


Link to post
Share on other sites

Do you know how to measure voltage with a multimeter? Simple test instrument you can get at Walmart for under $20.

If they are leaking from the caps, likely they were over filled or are over charging. You can check over filled by removing the caps and looking. The over charging part you check with a multimeter. If it's too high it will cause the water in the batteries to boil over.

Share this post


Link to post
Share on other sites

Now the real check to determine the over all condition. First buy a specific gravity hydrometer. Follow directions and check each cell and note it. Each cell needs to be checked of every battery. When done you will know the cundition of each battery.  Prerequisite to the check is to be sure all have a full indicated charge and have been allowed to rest after charge for an accurate reading. A load test will give you an idea of where they sit but that is it. Full charge is going to fall at 12.7 or 8 volts at rest.  12.28 is 60% charged, 12 volts is 25% and 11.90 volts Is fully discharged

Share this post


Link to post
Share on other sites

That's why I have AGM's!  At 78, I'm basically lazy....I was that for 15 years prior, but now I have an excuse! 😂 

Share this post


Link to post
Share on other sites

So I disconnected the shore power and turned off the house battery switch, I tested the batteries,  and the measurements were as follows: the voltage ( using a millimeter was 12.83 , and when I used the hydrometer, the first battery tested 1.3 and the second battery 12.65 , are these too high? Is it possible to be because of overcharging?

Share this post


Link to post
Share on other sites

Did you check each cell on each battery? If so and the 1.3 and 12.65 were averages then you have a bad battery. If it were me I would replace both.

I just replaced two 31A Duracell 12 volt batteries in our coach. I purchased them at Sam's. The ones that I replaced were 4 years old and had served us well. The price per battery was $109.00 each.

Herman

Share this post


Link to post
Share on other sites

Sir Traveler, I apologize for a misstep in describing what you need to ck accurately the battery health. What you need is a REFRACTOMETER available on Amazon for 40 buck +-. It will measure the specific gravity of the acid and advise as to condition. The other suggestions get you close. It is far better than a hydrometer.

 

Edited by rsbilledwards

Share this post


Link to post
Share on other sites
7 hours ago, hermanmullins said:

Did you check each cell on each battery? If so and the 1.3 and 12.65 were averages then you have a bad battery. If it were me I would replace both.

I just replaced two 31A Duracell 12 volt batteries in our coach. I purchased them at Sam's. The ones that I replaced were 4 years old and had served us well. The price per battery was $109.00 each.

Herman

I did check each battery cell separately, these readings were consistent, so one battery each cell measured 1.3, the second parallelly connected  battery each cell measured 1.6 to 1.65 , these batteries are 3 years old

Share this post


Link to post
Share on other sites
4 hours ago, rsbilledwards said:

Sir Traveler, I apologize for a misstep in describing what you need to ck accurately the battery health. What you need is a REFRACTOMETER available on Amazon for 40 buck +-. It will measure the specific gravity of the acid and advise as to condition. The other suggestions get you close. It is far better than a hydrometer.

 

thank you for the idea... is the REFRACTOMETER more accurate than a load tester? I do not have neither that is why I used the multimeter and hydrometer 

Share this post


Link to post
Share on other sites

If you do not have a load tester, why not pull both batteries out of the coach, then using a good charger that will stop charging when the battery is fully charged, do this on the other battery, then let the battery rest for thirty minutes. Now take both batteries to a battery store that can load test each battery separately. They can tell you the condition of each battery. Be sure to take pictures of the wiring to the batteries before disconnecting them and also label each wire so that you can connect them back correctly. The OP stated that the batteries are three years old.

Share this post


Link to post
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now

×
×
  • Create New...