Battery drain issues!

[TheWanderer]

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. 🙂

[wopachop]

Got a pic of the hydrometer? Some auto stores sell the little testers with floating balls. You do not want that.

I would skip the hydrometer and put the money towards a clamp on meter. That tells you lots of goodies.

How many amps is your charger putting out?
Do you have a mystery load you're trying to isolate?

Ideally you would have both. Just seems hydrometers are better for guys who closely monitor their batteries. Maybe a solar setup and they want to see what state of charge they reach on an average sunny day.

I suppose for your situation you could test and batteries and confirm they're toast. But you sorta already know that info by the batteries age and waking up to 10v. Sure you could bust out gloves and play with battery acid. I do it more for fun than anything. If you want a super fancy hydrometer check out the Hydro Volt. Made in Germany and auto compensates for temp. It cost around $40 though.

[2oldman]

TheWanderer wrote:
Cool thanks I just saw one for batteries at advanced auto online for about $10

Of course you can skip all that and get an AGM battery.

[TheWanderer]

2oldman wrote:

TheWanderer wrote:
I have a hygrometer

hydrometer is what you need.

Cool thanks I just saw one for batteries at advanced auto online for about $10

[2oldman]

TheWanderer wrote:
I have a hygrometer

hydrometer is what you need.

[TheWanderer]

Thanks for the heads up, yeah this older rig has both batteries in yhe engine bay. Vhassis on one side, house on the other. The house is an RV/Marine deep cycle but if I am replacing I am going to look a bit more into possible upgrade.

[CA_Traveler]

If it's actually a 2005 battery then there is no need to have it tested just replace it. If it's a deep cycle marine battery then it's only slightly better than a starting battery vs a true deep cycle battery. Something to consider.

[TheWanderer]

Well checking again this morning I think I am more prone to feel the battery is bad.
I will do some further testing once I have a hygrometer and can charge and sit for a bit and all that. Sorry for the lack of info, and yes this motorhome is much older (1988 ford gulfstream) but the battery was replaced since.
There is a 45 amp rated power converter and battery charger with fuse block and power routing. I believe is likely the original, and it seems to do a very good job charging the battery. even with current issues the battery still takes a full charge (rests at 12.6-12.8v 20-30 min after charging by running the generator or plugging in).
The battery is a Duracell Ultra deep cycle battery however today I noticed there is some yellow fluid buildup near the negative post for the battery. Positive terminal is dry but negative was soaked and seems to be beginning to rust now. 😕 I guess I will be replacing that! I will have it tested but I have a feeling I know the answer.
Also...this battery is from '05 I think??? It is marked with a sticker labeled "L5" which should mean shipped from factory December 2005?
Thanks for getting me off my butt to look further into it again!

[Flute_Man]

Bad batteries can cause some strange symptoms.

[Yosemite_Sam1]

Symptomatic of battery failure. Have it checked.

[2oldman]

Matt_Colie wrote:
How old is the house bank and what is it precisely?

x2

[opnspaces]

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.

[Matt_Colie]

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

[CA_Traveler]

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]

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.