Simple Guide to Battery Life in your RV - By Redbaron73

[AnotherMike]

Originally Posted by Renipladlo

The revised document link is not working, please repost it.

This might be what you are looking for: <https://www.magnum-dimensions.com/sites/default/files/MagDocs/64-0030-Rev-C-ME-ARC_CD_Web.pdf>

Mike

[sheridany]

My apologies. I meant the original document that RedBaron wrote and posted on the Newmar hoots site site that walks you through the settings and calculations.

That link is not working at least not for me.

[redbaron73]

Sorry it took so long to get back to this post. I have been traveling. The link in post#1 is now working again.


Enjoy!

[tnedator]

OK, so swapped out my RC for an ARC last night, and didn't think to check the settings before hand. Figured they would be in the inverter/charger not the remote -- wrong.

I'm going to install the BMK as soon as things get a little cooler, so for now I'm trying to get things setup with just the ARC.

MS2812 - 125 amp charger
8 (4 banks) GC2-ECL-UT batters at 225 ah or 900 ah total capacity.

Can't find specific charging info, but everything I Find on interstate is C/10 and that's what Neil recommends.


AC Search: 5 watts
AC Shore Amps: 30 (should this be 50?)
Low VAC Dropout: 80 VAC
Charge Rate: 70% of full value (calculated at .72, but it's 10% increments)
Battery Size: 400 amp/hours (should this be 900? What is it used for?)
Low Battery Cut-Out: 10.0 VDC (will this toast batteries? I assume this should be higher)
Battery Type: Flooded

I have the absorb time set to 2 hours (default), but based on ARC manual, Magnum recommends 2.5 hours, but warns about the danger of over charging. Should it be 2.5?

Are there any other settings I should change from the default?

[C.Martin]

30A is correct. It's the size of the breaker supplying AC power to the inverter.

The battery size should be 900aH. The unit can use it to calculate the tailing amps for final charge calulations.

I realize Magnum has a table of absorb time based on battery size. I found with my Victron...the solar controller uses a more advanced algorithm. Instead of a hadd and fast...it varies depending on how deep the last discharge was. For example...if I only used 5% of the battery capacity...absorb might be only 30min...if I used 40% of the battery capacity, absorb might be two hours...

I have my absorb time set for two hours on the ME-ARC. But honestly, I have to find a lot of shade for it to matter. I am using CC/CV charge profile...and I have a rebulk voltage set. Normally, my batteries don't drain enough overnight to trigger a rebulk. My Magnum charger is idle. My solar wakes up and does all the charging...then floats all day. No reason to have two chargers running all day. If I'm shaded...or anytime I am just restoring AC power...the Magnum wakes up and does a charge. Many times I just manually tell it to "Start Float"...which with Multi as a final charge it goes silent. Multi meaning you have other chargers...like solar.

If you wish to use the Magnum for absorb...I would go with two hours and occasionally ramp it up to 2.5 hrs if deeply discharging the bank. Gives it more time to get sulphate back I to solution. Or manually start an equalization charge for the same reason.

The ME-BMK also used battery bank capacity. It needs to know to calculate the SOC figure. If you said 400aH and it measured 100aH out it would say 75%. If you really have 900aH...100ah out would really be 88%...

Yes...10v is pretty poor...

The problem is...Magnum will not allow SOC for LBCO.

So you have to pick a number based on your loads to approximate a safe level.

First line of defense to prevent over discharging = YOU!

Second line of defense = AGS (and this you will be able to set a SOC trigger once you have the ME-BMK.

Okay...generator crapped out, your at Third Level of defense. This is a quick field tourniquet. It doesn't cutoff the batteries...only the inverter. But this will hopefully buy you time so you won't trash your batteries. 10.0v isn't gonna save the batteries...just the inverter. I would set a higher voltage...esp. when the only high draw item is the fridge and the coach is unattended. Of course the high number might cause the inverter to shutdown if a coffeemaker, blowdrywr, microwave are started...so when attended, and using high amp items...you may have to lower the LBCO to prevent nuisance dropouts.

Hope that makes sense.

[tnedator]

Originally Posted by C.Martin

.

Hope that makes sense.

Yes it did, thanks!

[sartor]

FYI...was just perusing this today, and went to download the referenced document at newmarhoots.com which is mentioned in the first post to this thread. At the newmarhoots.com link (https://newmarhoots.com/simple-guide...-in-your-rv-2/), the text there gives the revision history, and the latest revision is indicated as revision 4 from 29 May 2019, but when you click the link to the document itself it is coming up still indicating revision 3. Not sure if that's simply a "typo" insofar as the author just forgot to change the 3 to a 4 in the document itself, or if perhaps the link itself is errantly referencing the down-level document.

Just thought I'd mention it, and hopefully I can be sure to get the latest document. Thanks!

Tom

[Pgh01]

Thanks everyone for the great info in this thread. I finally have a basic understanding of the ags and settings.

Question: My 2020 DSDP has the factory inverter/charger/remote/ags. That means I have to use voltage setting to trigger ags if batteries are low, as opposed to the more accurate SOC setting that comes with upgraded equipment. I have learned from these threads that voltage will read higher when the batteries are at rest than when under load. That would seem to imply that maybe different voltage settings would be appropriate for the ags depending on how the coach is being used at the time? If you are camping off grid and putting high loads on the batteries maybe the 11.0 volt setting recommended by Magnum/Newmar makes sense. But what if just parked for a few days with only the fridge on? I would worry that because battery loads are low, using 11.0 for ags might allow the batteries to run too low in that scenario. Any thoughts and recommendations for ags settings based on this? Thank you.

[clawsonbob]

Following. Thought I had the basics down but now I am gonna re-read and re-think everything with 900 brand new amp hrs in the house battery tray

Thanks for all the great info !!

[757driver]

Originally Posted by Pgh01

Thanks everyone for the great info in this thread. I finally have a basic understanding of the ags and settings.

Question: My 2020 DSDP has the factory inverter/charger/remote/ags. That means I have to use voltage setting to trigger ags if batteries are low, as opposed to the more accurate SOC setting that comes with upgraded equipment. I have learned from these threads that voltage will read higher when the batteries are at rest than when under load. That would seem to imply that maybe different voltage settings would be appropriate for the ags depending on how the coach is being used at the time? If you are camping off grid and putting high loads on the batteries maybe the 11.0 volt setting recommended by Magnum/Newmar makes sense. But what if just parked for a few days with only the fridge on? I would worry that because battery loads are low, using 11.0 for ags might allow the batteries to run too low in that scenario. Any thoughts and recommendations for ags settings based on this? Thank you.

Just like the LBCO (low battery cutoff) on the inverter there are two different ways to set up a Auto Gen Start. One for in use and one for storage.

If you set up auto gen start for a high draw situation (to avoid nuisance generator starts) such as a microwave running off of the inverter for several minutes at 11.0v then the auto gen start would have to have that large load for a long time prior to it starting. With that setting in storage or non use your batteries would be nearly dead and would most likely not have enough power to start the generator.

Best to have auto gen start set at a voltage of 12.0-12.1v and either turn it off temporarily when using a high load appliance or put up with it triggering a generator start.

[Granite17]

I don’t turn on the AGS since our coach is stored at home in the garage and plugged into 50 amp.
I don’t want it starting in an enclosed area.
If I lost the 50 amp power for some period of time, I would want the low battery cutoff to kick in.

What’s the safest setting ( meaning protecting your batteries) you want the low battery cutoff to kick in and shut everything off?

[redbaron73]

For stored use, and no expectation of high loads, I would consider 12.1v.

Also, turning off the inverter may be simpler, and give the same result.

With a 12.1 setting, you will run for a while on the inverter, which if you keep your fridge stocked may be important.

[C.Martin]

Originally Posted by Granite17

What’s the safest setting ( meaning protecting your batteries) you want the low battery cutoff to kick in and shut everything off?

John, please realize that LBCO only shuts the Inverter Off. If you loose shore power...the main AC circuits will be of. You still have any parasitic load that operates off 12vdc. The STORE (salesman) switch cuts power to the items that Newmar put on what they call the diconnect battery power side o the relay. There are still many circuits on what they call constant battery power side of the relay.

[Granite17]

Originally Posted by redbaron73

For stored use, and no expectation of high loads, I would consider 12.1v.

Also, turning off the inverter may be simpler, and give the same result.

With a 12.1 setting, you will run for a while on the inverter, which if you keep your fridge stocked may be important.

Thanks for the advise. Power outages weren’t ever a problem before, but now who knows when the grid will crash again.