How long will the interstate batteries last?

Our 2015.5 Unity has the original interstates (34 months). With the 160 watt solar panel the system has maintained the charge just find. During the last 6 months of use we find that the charge drops off much faster than the first 2+ years during dry camping. I am thinking its time for new batteries?

how often do you check the battery fluid level, and how much distilled water have you had to add?

I use a hydrometer monthly and add water as needed maybe 8 oz total for both batteries. The readings for specific gravity have been 100% but by the end of last season they were a little lower. Between trips the solar is only thing charging them. The thing that has changed in last few months is the quick drop off from 100% SOC.

Battery life can very significantly. My experience 4 to 10 years. My last battery, labeled Strong Box that came with my John Deere tractor lasted almost 8. The tractor is always garaged, used about a half-hour, once a week to take out the trash . Those factors may have contributed to its longevity. Keep it clean and keep it charged. Use a battery maintainer.

Bobnoxious said:

Battery life been very significantly. My experience 4 to 10 years. My last battery, labeled Strong Box that came with my John Deere tractor lasted almost 8. The tractor is always garaged, used about a half-hour, once a week to take out the trash . Those factors may have contributed to its longevity. Keep it clean and keep it charged. Use a battery maintainer.

Click to expand...

Agreed. My current set of 4 in my class A are going on their 9th Year since I installed them. Proper charge rate and never letting them go dead are the biggest deciding factors for battery life.
One issure with a new coach is, how long did it sit in EEE's yard before, during and after manufacture. And what about the selling dealer? Were they ever run down during that time?
Variables you had no control over that could be a factor in how long your batteries last.

The other factor is charge rate. When you are plugged into shore power or on Solar, what is your maximum battery voltage? 13.7 VDC is the maximum you should see.

When I replaced mine, I added 4 Oz of Mineral Oil to each cell the first time they needed water. In the years since I've never had any corrosion issues. I top off with distilled water only about every 4-5 months.

I guess the decision to replace before the batteries fully die depends on how well the current performance meets your needs.

and how much of an impact further drop in performance would have on you.

it sounds like you are careful to watch the performance.

would waking up in a cold coach mean just an adventure, or would this stress you and any companions?

my recent experience with car batteries is that they seem to go from starts the car fine to funny noises overnight.

not sure how deep cycle batteries behave at end of life, but it seems like we have tools installed (voltage and a mapping of voltage into %charge) to help monitor.

the other thing to think about is if you would replace with a similar battery ,or plan to move up in technology to AGM or Lithium Ion battery. (both of which have slightly different needs than the batteries installed at the factory.

a last thought (for now) is to note that recent temperatures are on the cold side. wondering if your recent data points are tied to the weather. cold batteries provide less power than warmer ones, and the charge accepted has a similar relationship. not sure, but I do not think the solar charge controller installed in 2015 was temperature compensated.

Quote//When you are plugged into shore power or on Solar, what is your maximum battery voltage? 13.7 VDC is the maximum you should see//Quote

13.7 volts ? is this float, absorption, bulk voltage? I wasn't sure what you meant.

If you have the stock GoPower! charge controller installed by LTV, even though the product manual says that it is temperature compensated, there is no sensor attached to the unit that goes to the battery box. If it has a temp compensated function, it must take its temp from the coach, not the battery post. Not optimal.
Though lead acid battery AH capacity diminishes some with age and can take a hit from repeated full discharges or not watching water levels, the biggest issue over time leading to diminished battery life may be chronic undercharging. This gets back to having proper charging algorithm with appropriate voltages for the battery type. I know that all charge controllers have lead acid, AGM, etc settings, but a call into tech support for that battery manufacturer would be a good idea to get their recommended charging parameters.
I learned a lot about batteries, charging, etc, from reading this long web page.

https://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/

Also, in response to overzealous recommendations from some battery companies in the last couple years:
https://handybobsolar.wordpress.com/2018-warning-turn-the-voltage-down/

And to amplify wounded's comments: the factory installed charge controller is certainly not correctly temperature compensated and the voltage actually delivered to the batteries is not sufficient to fully charge them especially during non optimal weather days. It may be that your batteries were not as well cared for as you think especially during the winter. Perhaps they were chronically undercharged during your time away from them. You would not know this.

As for specific info related to the Interstates: while I had no real complaint with mine in my previous MB I did not have good luck getting more than a couple of years out of them in previous rigs. I plan on replacing the batteries in my new Wonder with LiFePo. Another option I considered was a pair of Crown 6V if I can make them fit.

mikeme said:

I guess the decision to replace before the batteries fully die depends on how well the current performance meets your needs.

...

Click to expand...

Very good points.

For most users the house battery bank isn't as critical as a starting battery.

I also agree that close monitoring of the house bank gives critical information as to the battery condition. That is more readily available to most owners than starting battery condition.

vic

At a replacement cost of $300 I plan to replace
them every two years. But I run them hard with 2 Cpap s running off the inverter every night.

Flexcor said:

At a replacement cost of $300 I plan to replace
them every two years. But I run them hard with 2 Cpap s running off the inverter every night.

Click to expand...

Just beware that "new" batteries may not have been properly maintained while in storage at the retailer/wholesale shop, just has Dennis raises the issue of improperly maintained batteries while the coach is awaiting sale. I discovered this when getting a new 12V battery for a troll motor.

If the batteries seem to be having a stable capacity, why change them? Having a true battery monitor, rather than the more typical less exacting means of measuring static voltages, as most RV's are sold with, would be helpful to owners.

I will stay with a flooded style battery. Although the AGM route has advantages, the charger in the stock WFCO 8955 can't be made to charge these batteries properly. In 2016 LTV added a proper charger/inverter that does a better job at fully charging the battery. For the cost to upgrade our charger to the 2016 style Magnum unit we can replace the flooded batteries 3 to 4 times. The flooded batteries with the solar charger keep us powered up day to day without need to run the generator. So the stock setup while not perfect works for our needs. Batteriesplus.com sells a Duracell Ultra Battery for $90.00 with similar specs as the stock Interstates. When the spring comes and we get ready to use the coach again I will do a run test on the original batteries but I think 3 years and they are done.

Flexcor said:

At a replacement cost of $300 I plan to replace
them every two years. But I run them hard with 2 Cpap s running off the inverter every night.

Click to expand...

Flexcore, You might want to look at the voltage your cpap's use. My wife's cpap uses 12 volts stepped down from 120 VAC so I was able to buy a 12 volt power cable and run it off the battery without having to use the power hungry inverter.

Bob

My brand of cpap is 24 volt and I use humidifier which is a power hog.

Twin Peaks said:

I will stay with a flooded style battery. Although the AGM route has advantages, the charger in the stock WFCO 8955 can't be made to charge these batteries properly. In 2016 LTV added a proper charger/inverter that does a better job at fully charging the battery. For the cost to upgrade our charger to the 2016 style Magnum unit we can replace the flooded batteries 3 to 4 times. The flooded batteries with the solar charger keep us powered up day to day without need to run the generator. So the stock setup while not perfect works for our needs. Batteriesplus.com sells a Duracell Ultra Battery for $90.00 with similar specs as the stock Interstates. When the spring comes and we get ready to use the coach again I will do a run test on the original batteries but I think 3 years and they are done.

Click to expand...

I think we have very similar LTVs. ( I think ours is number 22 of the 50th anniversary run)
we purchased it used last spring.

do you have the part number for the Duracell battery you are considering?

Mikeme,

Our Unity IB was made in March 2015.

www.batteriesplus.com/battery/rv/deep-cycle/6/sligc110

Item Number: SLIGC110
Brand: Duracell Ultra
Voltage: 6
Format: BCI Group GC2
Lead Acid Type: Deep Cycle
Battery Type: Basic
Capacity 20hr: 215AH
Chemistry: Lead Acid
Lead Acid Design: Flooded
Made in the USA: True
Maintenance Free: No
Product Category: Golf & Scrubber
Product Sub Category: Starting Lighting And Ignition
Terminal Type: DT, SAE/M8 Stud, SAE/M8 Threaded Post, WNT
Usage: RV
Warranty: 12 Month Free Replacement
Weight: 60.5 lbs
Length: 10.25 in
Width: 7.125 in
Height: 10.875 in

That's interesting - 430 Ah for $200. At that price you can use them hard if you dry camp a lot - take them down to 25-30% when you need to. You'll shorten their life, but they're so cheap to replace that it doesn't matter <g>... I'm really serious about this! - at less than 1/5 the cost of lithium batteries, it would still be just as cheap if you had to replace them every 2 years or so.

I compared specs of Duracell group 27 12v and the GC2 6v at Batteriesplus. Both list for 99.99and if you order online, you get 10% off. Both are FLA chemistry.

12 v 90 AH
Weight: 53 lbs
Length: 12.5 in
Width: 6.75 in
Height: 9.375 in

6v 215AH
Weight: 60.5 lbs
Length: 10.25 in
Width: 7.125 in
Height: 10.875 in

Same money, same charger and only 15 pounds additional weight for twice the amp hours. Seems to be a no brainer if a pair of the 6v will fit in the battery box. Looks like 5/16 wider and a full inch and a half taller. Previous forum discussions indicate divided opinion as to whether these will fit in older Unity coaches. Going to measure my 2013 Unity MB.

kmay said:

I compared specs of Duracell group 27 12v and the GC2 6v at Batteriesplus. Both list for 99.99and if you order online, you get 10% off. Both are FLA chemistry.

12 v 90 AH
Weight: 53 lbs
Length: 12.5 in
Width: 6.75 in
Height: 9.375 in

6v 215AH
Weight: 60.5 lbs
Length: 10.25 in
Width: 7.125 in
Height: 10.875 in

Same money, same charger and only 15 pounds additional weight for twice the amp hours. Seems to be a no brainer if a pair of the 6v will fit in the battery box. Looks like 5/16 wider and a full inch and a half taller. Previous forum discussions indicate divided opinion as to whether these will fit in older Unity coaches. Going to measure my 2013 Unity MB.

Click to expand...

when you put two 6 volt batteries together in series, the amp hours stay the same.

two 12 volt batteries in parallel, the amp hours add.

Correct mikeme. Very important point: the factory batteries are about 220AH (if you believe Interstate) at 6V. Two in series will provide 220AH at 12V. The Batteries Plus batteries are speced a bit lower but are very cost effective. I kinda like the idea of running them hard and replacing them often. Hmmmm.

The thing about lead acid batteries in general: for the same amount of lead (weight of the battery) and same amount of acid (volume of the battery) you get about the same amount of AH. Some manufacturers build a better product (plate size, etc.) and will have slightly better specs but not dramatically better. It's a simple chemistry problem and you never get something for nothing in a chemical reaction. All energy is accounted for. So for those of us in restricted weight/volume environment, like Unity RVs, we can only get so much power in the space! LiFePo changes the game dramatically both in power and cost. But if you want to dramatically change your world plan on spending more.