twice a day charging

[Ela1948]

Im sure this has been asked before but how much does it shorten battery life to run a generator twice a day versus once a day. My battery compartment limits me to just 2 group 27 batteries. it would take major alterations to add more batteries. We have camped for more years then I care to remember but not a lot of dry camping. I want to spend a couple months this winter in the West mostly boon docking. Your thoughts would be appreciated.

[Mustang65]

What type of batteries are we talking about? How old are the batteries? Marine/RV or TRUE deep cycle batteries? Does your TT have a newer model charge controller or older model? What year is your TT.
Don

[Ela1948]

2011 31.5 RLTS 5th wheel. Has a multistage converter. The current batteries are original to the trailer. They are group 24 marine batteries. I intend on replacing them with group 27 deep cycle from US battery. The size of the battery box(not tall enough)dictates 12 volt instead of the preferred 6 volt.

[Rustic Eagle]

Originally Posted by Ela1948

snip..... how much does it shorten battery life to run a generator twice a day versus once a day......snip

I guess it depends on the DoD (Depth of Discharge) at each recharge.

A shallower average DoD will increase battery life. A deep cycle battery with an average 50% DoD will last at least twice as long as an 80% DoD. A typical GC-2 deep cycle battery will average 225 cycles at 80% DoD, but will increase to 750 cycles at 50% DoD.

With a standard RV/Marine battery one doesn't get as many recharge cycles as a true Deep Cycle battery under similar DoD conditions, and can't take as deep of DoD as a true Deep Cycle on a regular basis.

Bob

[Ela1948]

I have been "dry camping" out in the shed in front of the house for the last week or two trying to simulate real life conditions. A 1600 watt inverter that I installed has compounded the issue to some extent. I have spent the evenings and nights in the camper watching a little TV and doing pretty much what we do on the road. I sleep with a CPAP machine that runs on dc power. All lights are now LED. By morning we are approaching 50% battery use. This is on those 3 year old group 24 batteries. Even with new group 27's I question if i could go all day with one charging without a deep discharge.

[Mustang65]

Is your CPAP power transformer a 12VDC transformer? Look at the voltage/amp specifications on the transformer. If the transformer output is 12VDC then you are in luck, you can convert it to run only off of your TT battery and not use the inverter.

US Battery has some GREAT batteries, they will be my next ones that I buy... funny I am wearing one of their Tee shirts as we electronically speak....

Let me know.

Don

[Rustic Eagle]

I agree, the inverter and CPAP add to your personal battery power usage when dry camping. Everyone's battery usage and recharge requirements are different.

In my case I can go 2-3 days before having to recharge my (2) 6V Deep Cycle's, and I average a 30% DoD.

Bob

[Ela1948]

Originally Posted by Mustang65

Is your CPAP power transformer a 12VDC transformer? Look at the voltage/amp specifications on the transformer. If the transformer output is 12VDC then you are in luck, you can convert it to run only off of your TT battery and not use the inverter.

US Battery has some GREAT batteries, they will be my next ones that I buy... funny I am wearing one of their Tee shirts as we electronically speak....

Let me know.

Don

The CPAP runs directly off of a 12 volt outlet. It runs off of a DC transformer. I in truth have been pushing the envelope some with this inverter try to establish my limitations. I have run water thru our coffee maker in the morning which takes 960 watts of power for 10 minutes. We have always used an electric coffee pot and would like to continue. Hence the question comes up about running the genny twice a day.

[Ela1948]

Thanks to both of you for your input!!!

[SmokerBill]

In my opinion, it would keep your batteries in better shape by charging twice a day. Doing that, the batteries will experience less of a depth of discharge than when charging just once a day.

And you mentioned that your limiting factor to moving up to only group 27's instead of 6 volt batteries was the battery box. That can be changed out. My TT came with one group 27 originally. I wasted money by buying another group 27 and a second battery box, because one year later I bought a pair of Trojan 6V batteries and an appropriate box. You might as well spend more money up front and upgrade to true deep cycle 6V batteries, instead of going with Marine batteries again. JMHO.

Good luck. A TT electrical system is a joy to learn about.

Edited: Just re-read your post and realized that you didn't mean a battery box, but a compartment that would be difficult to modify. Check out the Trojan website. I believe there are true deep cycle 12 volt batteries of the correct size you could use instead of using Marine batteries.

[Big Sky]

Ela1948 - How are you measuring your actual battery depth of discharge?

[Seann45]

Wet cells dont have memory so frequent charging is OK..

[Rustic Eagle]

Originally Posted by Seann45

Wet cells dont have memory......snip

I like that statement, can I use it

Bob

[Owen Stubbs]

Excuse my ignorance, but what about "marine" deep cycle batteries makes them "not true deep cycle"?

[Rustic Eagle]

Owen Stubbs,

Rather then attempt to explain it myself, I found the following explanation summarized it rather well:

""So-called “marine” batteries are an attempt to make a compromise design that combines the characteristics of starting and deep cycling. As with most compromises, they aren’t great for either need, but they may be suitable for some RV battery situations. A marine battery trades a lower CCA rating for somewhat better deep cycle performance. It’s main advantage is that it is a variation of a starting battery and can be produced by the same manufacturing process, making it a less expensive battery than a true deep cycle.""

Source: http://www.doityourselfrv.com/best-r...osing-reviews/

Bob

[tnmcouple]

Yes I would like to know how to measure Dod also? As soon as I unplug my panel on the inside of the trailer drops to 2/3's in a matter of a minute or less. I know that it is not 66% at that point. They should have better gauges for all the tanks and battery read outs instead of the E,1/3,2/3 and full measurements.

[Rustic Eagle]

Originally Posted by Big Sky

Ela1948 - How are you measuring your actual battery depth of discharge?

I use a TriMetric Battery Monitor with my battery bank.



My installation: http://www.jaycoowners.com/forums/sh...attery+monitor

Bob

[Ela1948]

Originally Posted by Big Sky

Ela1948 - How are you measuring your actual battery depth of discharge?

I installed a voltage meter on the kitchen panel.

[Ela1948]

When I have used the inverter, there is a period of time that the batteries haven't had time to recover from heavy use. But always in the morning after a time of light activity, the voltage which has been running from 12.35 volt to 12.45 volts. This seems to give very accurate readings on battery conditions. That indicates to me that I've got 75 to 80 percent left. I really don't like discharging below 60 percent..

[Big Sky]

Originally Posted by Ela1948

the voltage which has been running from 12.35 volt to 12.45 volts. This seems to give very accurate readings on battery conditions. That indicates to me that I've got 75 to 80 percent left. I really don't like discharging below 60 percent..

I would encourage you to read about the Tri-Metric Battery Meter. I have the model 2025-RV model installed. After you've read about them and why you may want one, feel free to visit my pics on the link on this mod. It is really the only true "gas gauge" you can hope for with a battery bank.

Rustic Eagle has a tri metric install link above as well.

http://www.jaycoowners.com/forums/album.php?albumid=488