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RHD51 · 09-21-2019, 06:46 PM

Have been working on my TT for a several weeks, repairing a leak and remodeling the bathroom. While sitting in driveway has been plugged into 20A house receptacle. I had measured voltage at batt. when plugged in and read 13.6V, seems right while plugged in and charger operating. Only possible problem, I noticed, while working is that the bathroom light (LED) would flicker when the water pump ran. I unplugged from power about a week ago to see what voltage the batt. maintained. After a week, unplugged, with nothing running except the carbon monoxide detector, I measured 6.58V at the battery. I assume that means my batt. is toast?
Also remembered that before I started working on the TT, about a month ago, It had sat for a few weeks without being plugged in and the batt. was dead, lights would not come on. When plugged in all worked as expected.
Batt. was existing when purchased used, from dealer, approx. two years ago.
Don't know if dealer put new batt. in or not.
I did check cells and were full (lead Acid Flooded). checked Specific gravity and all cells read in Red on float. (when discharged at 6.58V).
Again I assume I can't just charge it up and it will be OK.
So I want to know if my assumption that the batt. is toast is correct?

Jayco19 · 09-21-2019, 06:59 PM

Yep.Time for new battery.

Kaptain2 · 09-21-2019, 07:03 PM

Based on what you wrote, its difficult to say whether the battery is totally dead.
A well maintained battery can last 5 years. I recommend to to a battery charger that has a function to recondition a used battery. After the battery been reconditioned, put on a maintainer for a week or so, check again the capacity. Some chargers won't charge when it detects the voltage of the battery is too low. There are ways to force it to charge. If after you have re-conditioned and charged it, the capacity is measured to be too low compared to its rating (say it has lost 75% of its rated capacity) then you need to replace with a new set of battery.

jwrober · 09-21-2019, 07:21 PM

Make sure distilled water level is right in there before you give up. I always seem to forget that one when I notice battery issues.

carl.swoyer · 09-21-2019, 07:28 PM

My self....,,
I got tired of wet cell batteries and changed over to Deka group 31 AGM batteries.
No more worries of low water in the batteries.
Much better application.

RHD51 · 09-21-2019, 08:10 PM

Thanks for the input. I have a 7 stage charger, I bought for a new AGM boat batt. Not sure if it has a "recondition mode" but I will try that.
Did check the water and all cells are good. But as mentioned the water tester showed in red.
As I only have a week before I head out west for a few weeks, I went ahead and ordered a new VMAX 125 AH AGM. I have been happy with the VMAX 85 AH AGM, I bought for the boat trolling motor. The only down side may be the weight of 75 lbs. Although I won't have to carry it around much I hope the extra weight on the tongue doesn't affect my weight distribution.

Teamfoxy · 09-22-2019, 07:31 AM

I have brought lead/acid batteries back from the dead many times and gotten another year or two out of them. Top off with distilled water, charge and then check the cells with a hydrometer. If they read Ok just continue to use them and keep an eye on them to make sure they are holding the charge.

Gary RVRoamer · 09-22-2019, 11:52 AM

If the "water tester (hydrometer?) showed in the warning range (red?) for even one cell, I'd replace the battery. You may be able to squeeze a little extra time from it via an equalizing charge, but a weak cell doesn't ever get strong again. Just a little less weak. If you want reliable battery power, replace it.

RHD51 · 09-22-2019, 03:21 PM

Quote:

Originally Posted by Gary RVRoamer

If the "water tester (hydrometer?) showed in the warning range (red?) for even one cell, I'd replace the battery. You may be able to squeeze a little extra time from it via an equalizing charge, but a weak cell doesn't ever get strong again. Just a little less weak. If you want reliable battery power, replace it.

Thank you Gary, Yes the Hydrometer (couldn't remember the name when writing) read in the red range for all cells.

I since have looked at the existing batt. and found it is an Exide 24MDPST with 625 CA, 500 CCA and 70AH dated Nov 15.
So at 4 yrs. old I think it performed adequately and has reached the end of it's life or I killed it with negligence. It is a dual service RV/Marine batt.
Probably not the best choice for an TT house batt.

I will soon be receiving my VMAX 125AH AGM replacement. Should get approx. 8 yrs. of service for <$300.00. I think I will be happy with that.

Gary RVRoamer · 09-22-2019, 08:20 PM

4 years is about all that can be expected from a hybrid marine/RV type battery. Often they barely manage 3 years.

The specific gravity will always be low if the battery is discharged. Take the SG reading when it is as much charged as it can get.

Searching_Ut · 09-22-2019, 08:31 PM

When you get the new battery in, make sure your parasitic drains on the system aren’t higher than you think they are. My last two rigs had fairly significant power drains if the main battery switch was on, and would easily drain a single group 24 in a week.

RHD51 · 09-23-2019, 08:46 PM

Quote:

Originally Posted by Searching_Ut

When you get the new battery in, make sure your parasitic drains on the system aren’t higher than you think they are. My last two rigs had fairly significant power drains if the main battery switch was on, and would easily drain a single group 24 in a week.

Thanks for the tip.I have been looking at battery monitor meters. Thinking I need to get one to read voltage, current and percent of charge. Any brand recommendations are welcome.
I may consider solar panels and a gen.,at some point, but for now I mostly camp in State Parks W/ elec. (need to use CPAP to sleep)
I'm thinking I could boondock for a long weekend with a good batt. using an inverter to power CPAP