Simple Guide to Battery Life in your RV - By Redbaron73

[redbaron73]

I have just updated the document to Revision 2.

Revision 2: Release May 2, 2019
• Minor typographical errors corrected.
• The formula for Battery bank capacity under “Personal Settings Record” was corrected
• Additional details where added for “Why you need a current-based estimation system”

[tnedator]

Originally Posted by redbaron73

Inverter is in between frame rails in the most forward pass thru bay.

Ags is on door side in the last bay before the pegboard bay, located on the wall.

Can you put the splitter at the inverter to get it on the network, which seems closer to the batteries, or does it need to be the AGS?

[redbaron73]

Originally Posted by tnedator

Can you put the splitter at the inverter to get it on the network, which seems closer to the batteries, or does it need to be the AGS?

You can ,but because the remote is plugged in there, I was unable to get the splitter to hold in properly. They do make splitters with pig tails that would work better. It is just a 6P4C RJ-11 splitter, like this one: https://amzn.to/2V8Vd4N

[Sonic]

Excellent job putting together this very informative document Ronnie. Thanks!

[MRUSA14]

Wow, what a great piece of work. While I have been using these systems for many years and knew most if not all of this, I am very impressed with the way you presented this material and I have saved it as a reference. Your organization and writing skills are fantastic.

I have one suggestion to make. Where you wrote “Additionally, AGM batteries have a lower overall resistance, allowing for a faster charge and slower discharge”, the word discharge should be changed to self-discharge.

Thanks for sharing this excellent article. It will be especially invaluable to newcomers to these systems.

[redbaron73]

Originally Posted by MRUSA14

Wow, what a great piece of work. While I have been using these systems for many years and knew most if not all of this, I am very impressed with the way you presented this material and I have saved it as a reference. Your organization and writing skills are fantastic.

I have one suggestion to make. Where you wrote “Additionally, AGM batteries have a lower overall resistance, allowing for a faster charge and slower discharge”, the word discharge should be changed to self-discharge.

Thanks for sharing this excellent article. It will be especially invaluable to newcomers to these systems.

Thank you for your kind words. You are correct, it is self discharge. I will make the revision. Thanks!

[Mark_K5LXP]

Page 6, "Never discharge the battery below 50% capacity."

Should be "below 80%" or if watching a voltmeter, 10.5V under load. 50% is well within the ratings of any LA storage battery. To make an absolute statement like "never" implies a serious or significant impact which would be very true for >80% but not >50%. At face value one would treat that suggestion as a reason to stop using devices, run their generator unnecessarily or install more battery than they really need which is more expensive than if one were to just use the capacity in place.

The difference in lifetime delivered Ah between 50% and 80% is not relevant in the context of RV's. Much like tires that are replaced due to aging out before wearing out, RV batteries will almost universally be replaced for reasons other than cycles. And even if you do manage to wear a set out before it otherwise fails, you got all the Ah you paid for.

Mark B.
Albuquerque, NM

[redbaron73]

Originally Posted by Mark_K5LXP

Page 6, "Never discharge the battery below 50% capacity."

Should be "below 80%" or if watching a voltmeter, 10.5V under load. 50% is well within the ratings of any LA storage battery. To make an absolute statement like "never" implies a serious or significant impact which would be very true for >80% but not >50%. At face value one would treat that suggestion as a reason to stop using devices, run their generator unnecessarily or install more battery than they really need which is more expensive than if one were to just use the capacity in place.

The difference in lifetime delivered Ah between 50% and 80% is not relevant in the context of RV's. Much like tires that are replaced due to aging out before wearing out, RV batteries will almost universally be replaced for reasons other than cycles. And even if you do manage to wear a set out before it otherwise fails, you got all the Ah you paid for.

Mark B.
Albuquerque, NM

I agree that the word "NEVER" is not appropriate regarding the 50%.

A battery bank routinely discharged by 50% will provide approx 600 cycles in it's lifespan.

A battery bank routinely discharged by 80% (20% remaining) will provide approx 300 cycles in its lifespan.

300 cycles is a lot of time, and for most people this would not be a problem.

[twinboat]

Originally Posted by redbaron73

I agree that the word "NEVER" is not appropriate regarding the 50%.

A battery bank routinely discharged by 50% will provide approx 600 cycles in it's lifespan.

A battery bank routinely discharged by 80% (20% remaining) will provide approx 300 cycles in its lifespan.

300 cycles is a lot of time, and for most people this would not be a problem.

My research and experience shows over 1000 cycles at 50% DOD and data suggests 500 cycles down to 80% DOD.

Of course that's using deep cycle batteries, not the hybrid, RV/Marine, 12 volt type.

DOD charts are avalable on the Trojan battery website.

[redbaron73]

Originally Posted by twinboat

My research and experience shows over 1000 cycles at 50% DOD and data suggests 500 cycles down to 80% DOD.

Of course that's using deep cycle batteries, not the hybrid, RV/Marine, 12 volt type.

DOD charts are avalable on the Trojan battery website.

Lifeline and Trojan batteries are far superior to the batteries installed by the factory at Newmar.

[redbaron73]

Document has been updated
http://www.newmarhoots.com/simple-gu...-in-your-rv-2/

Revision 3: Release May 3, 2019
• Clarified that AGM batteries have a slower self-discharge rate. Previous wording incorrectly stated they had a slower discharge rate.
• Fixed Figure 6 image of factory wiring, it had a missing jumper wire in the image
• Clarified the maximum safe discharge of a battery bank
• Added additional instructions for utilizing the ME-BMK and ME-ARC to maximize battery consumption for maximum boon docking per charge.

[Ernie.]

Nice job RB, great info.

[Persistent]

Again, kudos to Redbaron for a great Newmar battery guide.

I have given up trying to explain about the "50%" rule. There are too many true believers. They protolyze vigorously so new RV'ers become true believers as well.

For deep draw house batteries, stay above 12.4 volts for storage. Target 50% in your planning, but stay above 20% for flooded cell and above 10% for AGM. Couple with long period full charge (14 to 18 hours) frequently and get excellent battery life and excellent value.

As for "Marine" batteries, they are designed for house use, especially the larger ones. Marine use is nearly identical to RV use. Marine use means deep draw at low levels just like RV use. Marine use also means starting small engines similar to high draw use of inverters. You may or may not use yours the same, but they are designed for the average RV'er.

As for "Trojan" brand or look a likes, they sell batteries designed for different uses. The come in both flooded and AGM. Flooded golf cart batteries bought at discounts are a good value. But even these come in different levels of performance capabilities. The major one is commercial sold to gulf courses and retail sold to consumer golf cart owners.

Trojan also makes batteries for stationary large solar arrays. These are not great for RV's. They are slow to charge and weigh more per amp hour. They make other types as well. Be sure you know what you are buying. Technical specs are available from Trojan if you can understand them.

The above recommendations are good for RV's using generator and shore power charging. RV solar will be optimized using a different battery. I don't know much about them. Solar power charging may optimize with a different design. Many batteries designed for fast charging are not optimum for slow solar charging. It is not a big difference. It reduces number of recharge cycles.

[Golfer Guy]

Nicely don Professor Baron. Although this doesn't completely correspond to my lithium /solar set up it is a great resource. I believe the BMK and ME-ARC should be on all coaches. You have obviously done a lot of homework and put it out there for us all to reap the benefits of. Thank You