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Open Roads Forum  >  Class A Motorhomes  >  Maintenance Issues & Tips

 > best way to test house batteries ?

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Chum lee

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Posted: 02/13/21 10:18am Link  |  Quote  |  Print  |  Notify Moderator

opnspaces wrote:

MountainAir05 wrote:

I test with them separate. Then check each with the hydrometer after they set for an hour or so. I also check each cell with the volt meter after the hydrometer test.

How do you check an individual cell with a volt meter?


With most modern automotive wet cell batteries, . . . you can't. You can only check the total individual battery voltage. (without damaging the battery casing) With some older automotive wet cell batteries, like pre 1970's, you quite easily could. With some modern industrial wet cell batteries you still can. Tesla, Hybrid batteries (Li-ion), . . . you usually can. These batteries aren't generally used in RV applications.

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Posted: 02/13/21 10:36am Link  |  Quote  |  Print  |  Notify Moderator

dieseltruckdriver said it all .
Click on word these and shows Midtronics tester
There are others as well I have Snap on .
The beauty of these is they send impulses though the battery and remove no power from the battery
The message you receive could say good battery needs charge or bad battery or bad cell replace battery. If it says bad battery you don't waist your time and electricity. load testers sell batteries. Electronic testers diagnose batteries. In the end they save you money from misdiagnosing.

MountainAir05

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Posted: 02/13/21 10:45am Link  |  Quote  |  Print  |  Notify Moderator

Chum lee wrote:

opnspaces wrote:

MountainAir05 wrote:

I test with them separate. Then check each with the hydrometer after they set for an hour or so. I also check each cell with the volt meter after the hydrometer test.

How do you check an individual cell with a volt meter?


With most modern automotive wet cell batteries, . . . you can't. You can only check the total individual battery voltage. (without damaging the battery casing) With some older automotive wet cell batteries, like pre 1970's, you quite easily could. With some modern industrial wet cell batteries you still can. Tesla, Hybrid batteries (Li-ion), . . . you usually can. These batteries aren't generally used in RV applications.

Chum lee


The OP stated to test with a multimeter and hydrometer so it would work for him. If you can check using a hydrometer then you can also check using a volt meter.

time2roll

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Posted: 02/13/21 12:26pm Link  |  Quote  |  Print  |  Notify Moderator

First evaluate the system and post the battery age and the measured charging voltage.

I would start with a full charge. This would be charging at about 14.4 volts until amps drop to less than one amp per battery. This could take 2 to 8 hours.

After fully charging disconnect all batteries to separate. Let them sit 24 to 48 hours. Check resting voltage is 12.6+ and full charge on the hydrometer. Post the results.

If they hold a charge and are evenly matched just use them. If the capacity seems much lower than previous then it is probably time to get some new batteries. If the life seemed short it is a good time to evaluate your usage, charging and maintenance routine.

* This post was edited 02/13/21 12:34pm by time2roll *


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Posted: 02/13/21 01:14pm Link  |  Quote  |  Print  |  Notify Moderator

MountainAir05 wrote:

opnspaces wrote:

MountainAir05 wrote:

I test with them separate. Then check each with the hydrometer after they set for an hour or so. I also check each cell with the volt meter after the hydrometer test.

How do you check an individual cell with a volt meter?


Saves writing and it has a video. Wash off the lead when you are finish.

https://www.youtube.com/watch?v=_8qgZoovWHI&ab_channel=BatteryChem%E2%84%A2LeadAcidBatteryDesulfatorandReconditioner
This is how I check mine also except I leave the positive probe on the pos battery terminal and dip the negative probe into each cell and subtract the difference. When ever I see a low cell I run an Equalization on the battery and also a desulphation cycle also. My batteries are not on a slide and it is difficult to get a hydrometer in there to check. I have two hydrometers and have not had accurate readings, the voltmeter is good enough for what I need.

ArchHoagland

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Posted: 02/13/21 04:12pm Link  |  Quote  |  Print  |  Notify Moderator

How old are the batteries?

Are they the original batteries?


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wallynm

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Posted: 02/13/21 09:09pm Link  |  Quote  |  Print  |  Notify Moderator

Get a load tester, fully charge all of the batteries and then use the load tester on each battery. If one is bad replace all of them at the same time!

* This post was edited 02/15/21 02:19pm by wallynm *


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Sir Traveller

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Posted: 02/24/21 08:59pm Link  |  Quote  |  Print  |  Notify Moderator

ArchHoagland wrote:

How old are the batteries?

Are they the original batteries?


no they are not
the batteries are exactly 3 years old, Duracell deep cycle batteries ( plus or ultra )

Sir Traveller

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Posted: 02/24/21 09:00pm Link  |  Quote  |  Print  |  Notify Moderator

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

pianotuna

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Posted: 02/24/21 11:47pm Link  |  Quote  |  Print  |  Notify Moderator

Sir Traveller wrote:

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


12.65 is ideal. It would be better to wait 24 hours before testing, with no loads and no charging.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, soon to have SiO2 batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

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