Quote Originally Posted by reefmagnet View Post
Aside from the obvious issue of using a deep cycle for starting (which works, just shortens the life as has already been previously noted), deep cycle AGM's should not be discharged below 30% for maximum life and taking them below 50% depth of discharge too many times will shorten the recharge cycles considerably.
Hi again Reefmagnet, that is not quite right.

All DEEP CYCLE batteries, whether they be AGM or Flooded/Wet cel type, can be safely discharged down to 20% SoC ( 80% DoD ) and will deliver a good lifespan.

The use is the governing factor in how low you discharge your battery and still get a good lifespan.

For 99% of AULRO members, because they do not live 24/7 in their caravans, camper trailers or vehicles, they will gain nothing by limiting the maximum discharge level to just 50% SoC.

While discharging a battery down to 20% SoC will result in the shortest operational lifespan for that battery, you also have to factor in the expected “natural” lifespan of that battery.

Most quality deep cycle batteries would expect to give at least 5 years of good service.

So if you went on a camping trip every weekend, and on every trip, you discharged the battery down to 20% SoC and say the battery has a rated 200 cycles down to 20%, then you would only expect to get 4 years from that battery.

But if you averaged one trip a month, then the expected lifespan now blows our to 12 years and this is WAY beyond the expected “natural” lifespan of that battery.

This single factor, of acceptable depth of discharge, is often misunderstood, leading people to buy batteries way bigger than they will ever need, and so, wasting a lot of money, weight and space.