Absorbed Glass Mat (AGM) batteries offer numerous benefits over traditional wet-cell batteries. First and foremost they require no maintenance or watering as they are sealed. Like wet-cell batteries, AGM batteries are still technically lead-acid batteries, but the electrolyte in them is encased in a fibrous glass mat that can't be spilled. AGMs use the same battery charger as wet-cell batteries and since there is no liquid in them they are practically impervious to freeze damage. Most AGMs, like those made by Lifeline, have very thick positive plates that can suffer more discharge cycles than hybrid batteries commonly found in many RVs. More importantly, AGMs charge up to 20% faster and also have a slower self-discharge rate, about 1-3% a month. Since AGM batteries contain no liquid they can also be mounted on their side, an important benefit for some battery and storage compartments.
The fact that AGM batteries can be mounted on their side was a HUGE benefit for me. The small size of my battery compartment, which measures 12" tall, 16" wide and 14.5" deep, basically left me with two, very limited choices: two miniscule Group-24 batteries or two beefy, power-packing 6 volt AGMs. Let's see. Should I stay with two hybrid 12 volt wet cell batteries that together provide only 160 amp hours or buy two deep-cycle 6 volt, 220 amp hour batteries that require no maintenance? For one who likes to boondock and dry camp it was a no brainer. Especially when you consider all the benefits that AGM batteries provide over wet cell batteries.
|Out with the old Interstate Group-24 batteries and..|
|...in with the new: two 6v Lifeline AGM batteries, side-mounted.|
Wiring a pair of 6 volt batteries so that they're compatible with your 12 volt electrical system is actually pretty easy. Simply wire your positive leads to the positive post on one 6 volt battery, then wire the negative leads to the negative post on the other 6 volt battery. Lastly, wire the empty positive and negative leads between the two batteries, as illustrated below. That's it! See, I told you it was easy.
It's often claimed that AGM batteries require no venting because they are sealed. The Lifeline owner's manual, however, states that their batteries produce minimal gas during charging, so proper ventilation for AGM batteries is required. I quote: "WARNING: All batteries must be adequately vented during charging to avoid accumulation of explosive hydrogen gasses. Never install or charge in a sealed container or room." Yes, it's true AGM batteries produce very little gas during normal charging, but the real issue arises if they are ever overcharged. Excessive amounts of hydrogen gas would be produced if that scenario ever occurs. The bottom line is that it's best to be safe than sorry to ensure that your AGM batteries are properly vented, period!