Running 2 40 lt engels

[dads tractor]

Need some advice gurus .I have 2 x 40lt Engels and they run off a second battery charged by a redarc 50 amp charger,but I run out of power 11.8 volts in the morning.Is it purely a storage capacity problem so the solution is to run 2 x Delco slow discharge batteries in series or go too lithium and what size and brand if I went to doen that track? The charger soon gets then back up above 12.5 volts thats not a drama.

[dads tractor]

Cuppa where's a run down on your electrics as that's where I'm headed in the near future camper trailer wise.

[pollenface]

It could be either battery capacity or battery condition.

I have found a brand new 130amp agm to run a 40lt waeco for 5-6 days without extra charging in coolish weather, so I would assume 2-3 days with 2 fridges. If you're getting down to 11.8v over night and you have a 100-130ish deep cycle it's a fair bet the battery is flogged and cannot hold charge any more. Obviously the bigger the battery bank the better and it helps if they're all in good condition. A good rule of thumb with AGM is to not discharge more than 40% of their capacity (~12.3v) and the less that you can discharge them, the longer they will last.

I have dabbled with 4S lithium (14.8v) and decided it's too much headache (for me) charging them properly unless you have or are willing to spend the money setting up the charging system properly. A lot of MPPT chargers have to be manually programmed to charge your lithium and most pre-set programs I have seen are only suitable for 3S batteries. Some MPPT controller suppliers are able to pre-program the controller to suit your battery type (3S 4S 6S 8S ... etc). It would almost be easier running a 240v charger from an inverter which I've done as well.

When they're all set up properly and running sweet they are awesome and can be cycled down to 20% on a regular basis without damage which gives them a good service life. They're also able to deliver alot of current in one hit if you need it.

I would suggest sticking with lead-acid unless you really need the weight saving (100amp lithium is 13kg and has 80 usable amps). If you look after your lead acid batteries with a decent DC-DC charger they should serve you well for a few years at least.

[dads tractor]

Thanks pollen face the battery is only 12 mths old and the last one only lasted 2 years but I was only using a solenoid system back then. i'm in central QLD and like my beers to be two shakes off freezing so run both fridges one on freeze and the other 2deg. so am asking a lot i guess. My second battery is behind the cab under the tray in a side box which also houses the 50 amp dc charger but will record too 13.3 v resting by a good quality ampmeter and the fridge leads just run up into a fiberglass canopy.Maybe time to direct wire the fridge leads to the battery.

[Cuppa]

Hi dt, I run a separate fridge & freezer successfully. There are a variety of issues which could be causing your problem so I'm more inclined to ask questions than to make suggestions, at least initially.

[dads tractor]

Fire away mate your input would be good.

[Cuppa]

Fire away mate your input would be good.

I meant to include that I'd send a PM soon. Just finished it & sent it to you. :)

[Shephead]

Definitely sounds like the battery is done. You could use one of those inline amp hour meters off eBay to test over night, will tell you exactly how many amp hours have been used.