AGM batteries

[10 fan]

The above is the way I have always done it until the great helpers here pointed out that Magnum inverters require the positive be disconnected first . You can damage a Magnum inverter if negative is disconnected first.

Magnum accessories not the inverter.

[pduggs]

Originally Posted by redbaron73

Take a look at this document I wrote specifically for the magnum on a Dutch star.

Simple Guide to Battery Life in your RV – Newmar Hoots

Great write up. Thank you.

[twinboat]

Remove ONLY the inverter positive cable, then you can remove the negetive cables per industry practices.

Tape up the loose cable end.

[4thetwins]

Greatly appreciated advice and clarification Tom. Thank you 🙏

[Renipladlo]

Interstate battery stores will make up cables for you if you take in the old ones, they have the correct hydraulic presses for the terminals, not too expensive.

1. Take several pictures of the current battery layout now, and put them inside clear sleeves, and tape up close to the work area, so you always have ready reference to which is what and where what is supposed to be.

2. Take Scotch 88 Electrical tape, and wrap the wrenches you are going to use except for the end which does work to fit bolts. If screwdrivers or other metal tools, tape those as well. Keep them taped, and get a little pouch and mark it battery tools only, then they are ready for anything. Keeping a copy of the pictures and document that was written in another smaller plastic pouch (like the ones we had in school to hold all our pens/pencils/protractors, etc.) bag, and then another one for the wrenches. Then you could place all of these in a 3-ring binder, labeling it Battery Information and keep it in a cabinet so it's all ready for anything in the future. Doing this will prevent later on you asking "now where did I put that document".

Does it matter which "Positive Cable" we disconnect first, if so, then I would mark that cable with something to make is stand out, and make note of that mark in the notes you write documenting this process.

As an aside, a few weeks ago, visiting neighbor, who just got his MH back from factory to correct shimmy in front end (not Newmar). He was prying off battery caps, and arced across positive terminal and battery exploded in his face, fortunately he had sink close and was able to wash acid off his face quickly. I have never seen that before, scared the xxxx out of me I can tell you, as I was about 2 feet away, and had just turned to answer question from his wife, had I not, I would have gotten it all over me too. The noise sounded like a shotgun going off.

[TLGPE]

My apologies for my seeming misstatements. I was focusing only about the safety aspect of connecting the batteries. You are correct about Magnum, or any other specific piece of equipment; follow the manufacturer's instructions.

Again, I apologize.

Tom

[Finance]

You can download the LifeLine technical manual from their website. I recommend it. It's very precise about the charging voltage requirements. I prefer to run the custom battery settings on the Magnum rather than the AGM1 preset.

The only tricky bit with AGM is knowing when they are 100% SOC. With LifeLine that requires holding them at 14.4 until the amperage drops to .05 of capacity. It's important to regularly top them off to 100 or you'll walk down the capacity over time. I usually set Equalize on the Magnum to 14.4 and use it every other week or so to top charge them until my ammeter gets down to the .05 value. If you have solar that can be used alternatively.

There's additional instructions in the manual for conditioning the batteries with 15.5 volts. Only when diminished capacity is found. That's the equalizing voltage the preset AGM1 uses.

I suggest also take note of the recommended charging current minimum of .2 C for deep cycling applications. Few charging systems can meet that for a large bank of LifeLine batteries.