Forum Discussion

TheWanderer's avatar
TheWanderer
Explorer
Nov 19, 2019

Battery drain issues!

Hey everyone!
Been a while since I posted last but I am happy to say after having the transmission replaced on my motorhome she has been running well for me and I am back on the road!
I have ran into a bit of an issue recently though with my house battery I am hoping y'all can help me investigate.
Generally the battery seems to behave as it should. Takes a charge fine while driving or running my generator, and charges to 2.6-2.8v. Generally I can charge my phone on that, run lights, a small 12v fan overnight, and thats about it before recharging the next day around 12-12.2v.
I am not currently using my fridge nor furnace so they should not be causing much or any draw.
There has been a couple mornings however where I have woken up to a terrible voltage reading of only about 10v! ??
It happened a week ago or so and I was worried my battery might be bad, but after charging it that time it seemed to work correctly for a week without overdischarging until last night. Woke up this morning and another 10v reading. Double-checked at the battery with voltmeter and confirmed at 10.5v.
What could be causing such a drastic difference or drain randomly like that?
My suspisions are either bad battery (i sure hope not), bad ground possibly, or some other drain/connection issue.
Thanks in advance for any advice you can give. :)
  • I hate to say it but you have a bad battery. Batteries are 2 volts per cell. If you're reading 10 volts you have a bad cell. You can mess with and try to keep charging it for a while. But start saving money now because the current one is dying fast.
  • Unfortunately all of the responses are just well-meaning guesses. This is completely a result of there being no information. Yes, you have a new transmission, but as I recall, this is an old coach.

    How old is the house bank and what is it precisely?
    Also, what is the make and model of your converter/charger?

    A voltmeter can provide very little information. A hydrometer or refractometer can give better, but those only provide information this moment. The age of the jars and how often they have been deep discharged may have a lot to do with your current situation.

    What ever you do, if you do not try to charge the bank to full and let it sit => Disconnected<= before measuring anything, you will never get an answer that is worth anything. When you do that, come back and someone should be able to tell you how much trouble you are already in.

    Matt
  • Your symptoms are a classic battery failure. Have it load tested.

    "I doubt I have any drain on the battery that intense I wouldn't know about."

    Failed batteries don't necessarily require heavy loads to fail. Ammeters eliminate that doubt. And clampon ammeters require no disconnection of wires which can change the result.
  • Gjac's avatar
    Gjac
    Explorer III
    After you do as rk911 suggested, check your parasitic loads with an ammeter or your multimeter set to 10 amp scale. After these two tests you will know what the problem is.
  • hydrometers are inexpensive. pick one up for your tool box at the hardware store when you take your battery in to be load tested. but don't ignore the importance of clean and corrosion free battery terminals and cable ends. i'd still check and clean them as needed. good luck.
  • Well I do not own a hygrometer currently but I am planning on taking the battery in to have it tested whenever I leave camp. I can get by a couple more days out here with or without the house battery's help. Haha but yeah I am kind of leaning towards the bad battery as being the culprit. Just with how heavily drained the battery has gotten (10 volts only), I doubt I have any drain on the battery that intense I wouldn't know about.
  • i’ve always believed in doing simple things first. if it were me and assuming you have the typical lead acid batteries...

    - charge your batteries as you usually do then disconnect the cables and let them rest (zero draw) for about 20-mins. then check each cell with a hydrometer to see the actual state of charge.

    - before reconnecting clean the battery posts and cable ends till they shine before reconnecting

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,201 PostsLatest Activity: Feb 19, 2025