Battery voltage

[rickr]

I have 2 Trojan 105 batteries in my rv. Yesterday I charged them to 12.97 volts.(100%) a couple of hours later they read 12.52 volts (85%) bought a cheap hydrometer, but didn't like the inconsistency of those readings. So, my question is, are these batteries about to die? Thanks,Rick :huh:

 

[othatoneguyo]

Sounds like you need to do an equalizing charge. There are battery chargers that have this feature and basically, it takes the voltage up to 14.7-16 volts or so and it boils the electrolyte to mix the water and acid in the cells. Try that first, then when it's finished, the resting voltage after a couple hours should be around 12.6 volts

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[othatoneguyo]

Make sure you top off the cells with distilled water first, though. Fill to the point where the plates are just covered and a smidge more

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[John61CT]

Voltage does not give accurate state of charge, especially if batt hasn't rested say 48 hours.

What is your charger set to, Absorb voltage, minimum Absorption time?

Do you have an accurate ammeter? If not use the hydrometer, but that needs resting period too.

Bank's likely fine but you want to **know** you're getting to 100% Full as often as possible.

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[Almost There]

I have 2 Trojan 105 batteries in my rv. Yesterday I charged them to 12.97 volts.(100%) a couple of hours later they read 12.52 volts (85%) bought a cheap hydrometer, but didn't like the inconsistency of those readings. So, my question is, are these batteries about to die? Thanks,Rick :huh:

First, what did you charge them up with? How long did you charge them for? How discharged were they before you started charging them? Was there any load on them for the couple of hours between readings? Have you practiced using the battery hydrometer well?

In all likelihood the 12.97 reading was taken right after you turned off the charging source. If so, you were getting a false reading. The reading taken a couple of hours after stopping charging might be closer to the truth but not the whole truth. IIRC from Sternwakes' posts, you don't get an accurate reading until many hours after charging and with no load applied. Temperature has something to do with accuracy too IIRC.

How old are the batteries and how much abuse have you put them to? How do they behave under load?

 

[jimindenver]

If you charged them until they got up to 12.97v, then they were no where near full. The normal procedure would be raise the voltage by charging until they hit absorption voltage likely 14.4 or so and hold that for three hours. Then they would drop down to 13.6v and keep finishing off the charge for many hours. After that you can remove the charger and let them rest for 24 hours to get a true reading.

You can find the exact procedure for your batteries from the manufacture right down voltage, times and even temperatures.

 

[Hermes1]

If you charged them until they got up to 12.97v, then they were no where near full. The normal procedure would be raise the voltage by charging until they hit absorption voltage likely 14.4 or so and hold that for three hours. Then they would drop down to 13.6v and keep finishing off the charge for many hours. After that you can remove the charger and let them rest for 24 hours to get a true reading.

You can find the exact procedure for your batteries from the manufacture right down voltage, times and even temperatures.

Correct, 12.97v is definitely not full charge.  What are your using for a meter?

 

[Ticklebellly]

Yesterday I charged them to 12.97 volts.(100%) 

I'm assuming you stopped charging at that point?   No where near fully charged in that case.   If you can see the electrolyte, at this point I recommend you put them back on charge and charge until you see vigorous bubbling in the electrolyte.   Sometimes called "boiling the battery" (it's not, it's gassing), the process is good for battery health and is an indication of a slight overcharge.   After that charge cycle, rest the batteries for at least 24 hours, then check the terminal battery for a valid indication of the battery health and SOC.

 

[frater secessus]

Make sure you top off the cells with distilled water first, though. Fill to the point where the plates are just covered and a smidge more

Aren't cells supposed to be topped off after equalization, assuming water is already safley covering the plates?  I think it's done that way to avoid overflow.