Battery issues

[Striegs]

I’m not knowledgeable on my two 12 volt batteries, so am looking to increase that knowledge. Any advice would be greatly appreciated.

Issue: First I believe that the battery is fully charged and they are connected in parallel. I have used a hydrometer to test my two, 4 year old 12v batteries. The hydrometer says one battery, all cells are “fair” (near the recharge stage). The second battery, all cells are in the recharge stage.
My volt meter reads that I have 13.1 volt reading.
My question is the volt meter probably reading only the one battery, not both?

[Brad Wilf]

Disconnect batteries so you have 2 independent 12v units. Re measure each battery voltage. Sounds like you may have to equalize batteries. Make sure you check fluid levels in each cell, if you have to add use distilled water. Good time to check connections and cables.



https://batteryuniversity.com/learn/...alizing_charge



Hope this helps.

[OldWEB]

Yeah, as Brad mentioned, disconnect any load and power to the batteries and then disconnect them to get accurate readings. I suspect the 13 volts you see may be charging voltage.

[twinboat]

Freshly charged batteries or charging batteries will show a surface or charging voltage.

You will need to seperate and disconnect them from any load, wait at least 4 hours and measure each ones voltage.

12.6 or 12.7 volts is a resting voltage of a 12 volt battery.

If the batteries spicific gravity, on parallel batteries, is different, a equalization charge may help.
I doubt that you have any way of forcing 15 volts into them for 4 or more hours, so my advice would be to charge each one ( by leaving one disconnected ) overnight, using the onboard charger.

Do that and see if they are about the same SG. If not, its probably replacement time, at least for the weakest one but probably both.

[Striegs]

I do have the battery switched off so not being charged at this time.

I will disconnect all lines and try again.