Outer Limits 4x4 Board

G'Day All Got an original Green and Yellow 29 litre engel 20 years old Draws up to 4.5amps per hour. How long will a 80Ah Deep Cycle Battery keep it running without the vehicle turned on. What recommendations would you make to drive this old reliable engel.

Running flat out, you'd get a little less than 20 hours to dead flat - which you shouldn't do if you want your battery to last a few years.

Deep cycle batteries handle repeated deep discharges much better than conventional starting batteries, but you should still avoid draining them dead flat. You'll get arguments about an appropriate depth of discharge, but the answers will be in the range of 50% to 80% DoD.

So, 50% DoD means you should only draw 40Ah out of your 80Ah battery, 80% means you can draw a little over 60Ah before recharging.

Next, you need to know how much your Engel is going to draw over a 24 hour period. It should cycle on and off to maintain your set temperature, rather than run all the time. I don't know about yours, but my 32l Autofridge, with similar compressor, is rated at approximatley 24Ah/24 hours if left cycling on a low (warmer - not freezing) setting. Presuming your Engel is similar, 2 full days will put you somewhere between the 50% and 80% DoD figures, which should be pretty safe. At a pinch, you could go three full days, but I wouldn't recommend it.

Note that this presumes your battery begins each "camp" FULLY charged. Depending on your charging system, that's not guaranteed to happen with one day's driving, so on longer trips you may start to have trouble.

Good luck,

Scott

Thanks Scott, good info. Dual battery system is a TJM on my Patrol, use to
have a disco and fridge on that system went OK for a day trip stopping and starting however traded up to a 05 nissan Patrol. WE are doing a Victorian High country trip in Decmeber for 7 days and hopping the old engel won't drain the life out of the battery. We will be travelling during the day and camping overnight so would assume the down time over this period will be OK with the travelling during the day to recharge.

I'm a bit green with fridge usage and power drainage as I have had no experince over a longer trip.

I should add the engel goes up to 4.5 amps per hour, I don't know what that translates to over a 12 or 24 hour period. Cheers

I'd guess your usage over 24hrs would change depending on the ambient temp. If your main worry is leaving it on overnight during your High Country trip then you should be right running off the battery @ night and charging during the day.

Might see you down there if you're doing high country in x'mas, new years