DC - DC Charger

[jono1967]

Hi Guys
Its been a while since I've been on but I have a question for all you technical guru's out there
I run two D34 Yellow tops in a 2013 JK Rubicon wired in Parallel (so its like one big battery)
plus a camper trailer with an AGM battery wired to it which connects to the car via an Anderson plug while traveling
I charge the Camper Trailers battery off some good quality solar panels that I plug straight into the anderson plug while we are camping and it usually keeps the fridge running the entire time we are away (approx 5 - 10 days) as long as there is sunshine.
My issue this time (i have plenty) is the fridge in the car doesnt run much over 12 hours before it wont start its cycle. It trys continually but wont fire up unless it start the car run it for 30 sec then it appears the alternator gives it enough charge to fire it upp in the fridge motor will run until it needs to cycle again.
I hope that all makes sense.
My question if i run a DC - DC charger while it allow the batteries to run the fridge longer? I still would like the run them in parallel.
Should I be running a second DC - Dc charger in the camper trailer?
Finally am I damaging the camper trailers battery buy just plugging in the solar panel directly into the Anderson plug?
The solar panels I run are the Kors Panels with their 10amp digital controller
Thanks in advance
Jono

[Banshee]

How old is the AGM in the camper trailer? Could it be losing capacity due to age?

I don't know anything about the panels you are using, but the purpose of a DC-DC charger is to bring the voltage at the secondary battery up to what is required to properly charge it. You can get voltage losses from the length of the cable run, meaning that the battery on the trailer may not have been charging fully when attached to the JK. If this happens over a long enough time, a lead acid battery, of any type, will lose capacity.

If the fridge is not starting from just the battery, do you have access to a multimeter to check the resting charged voltage on the battery? It probably is not coming up to full charge. Should be ~13.8V. 2.3V per cell in a lead acid battery at max charge, but this drops to ~2V each, from memory, as the cells degrade.

[humdingerslammer]

Here is my 2c worth.

1. Charging the camper trailer batteries with the solar panels is OK... it has clearly been working. I would switch to a 15 or 20 amp controller as 10amps may blow in a really strong sun day (it has happened to me)... the ones that come with the panels r usually not very good quality. The Anderson plug connection is fine. It is what I use.

2. the fridge in the car doesn't run much over 12 hours before it wont start its cycle. Is it a Waeco? Sounds like it. I assume this occurs only when u r not connected to the camper trailer.

This means that u r using up the stored car battery power in the 12 hour period, which I assume only charges when the car is running. This is suggested by the story and the fact that the batteries re-charge enough when u turn on the car: the fridge then runs for a while then starts its "playing up" which is how it is intended to work (if it is a Waeco). Waeco fridges won't run unless there is a minimum power charge in the battery... this is to prevent you flattening the (starter) battery and being stranded. You could connect a solar panel to the batteries of the car and this would keep them charged throughout your camp time.. I do this with my set up.

How old r your batteries. R they on the way out? Why have parallel batteries. Also starter batteries r not deep cycle batteries.

3. Better still, connect a 2nd battery setup in your car (Jeep?) via a DC-DC charger and a solar panel. The battery will charge when your car is running and via the solar panel. This will allow u to run the fridge off the 2nd battery without drawing down on your starter batteries and potentially flattening them, leaving you stranded. But, given the solar panel setup u have on your camper, u may not need this. My set up is with a separate camper solar panel and deep cycle battery in the trailer plus a separate DC-DC charger and solar panel charging a 2nd deep cycle battery in the back of the Wrangler.

4. R all your connections etc getting full power through to them from the car batteries to the fridge. Check that the voltage at the battery is also being received at the connections.

If u r running a Waeco, it is running correctly. U need to revise your power system set up. Also, make sure u r using thick gauge wire throughout your system.

Hope this helps. I have had all the "problems" u describe with my Waeco and it is always something else that is the problem. Oh, and check that your Waeco plug is ok. These burn out from time to time and r a constant source of problems.


Cheers

[rjl3175]

If you are using the power outlet in the back of your Jeep, that will be your problem most likely. The voltage loss through the piddling wire will trip the protection prematurely. A cigarette lighter plug is also not the best connection.
I no longer have a fridge in the back but when I did I ran some serious cable to the unit and it would run for longer than 12 hours off a single starter battery and still had no problem starting the car.

[Thol]

Waeco and some other fridges also have a voltage setting to protect the battery. They switch off when the battery gets low.
Is yours set Hi,Med or Low. Low setting means battery can be down around 10.5v. If it's on Hi then fridge will stop as soon as it drops bellow 12.5v. Med is in the middle.

[jono1967]

The fridge is a Primus 45 litre
The start up must draw a fair amount once started the fridge runs fine.
There is .5v drop from the main battery to the fridge
I run the d34 Yellow top batteries in parallel because of the simplicity the strength while winching and i have seen dual battery systems fail in out back travel which I just cant afford
both batteries were installed new together less than 12 months ago
I'm going to get the agm battery in the camper load tested during the week to make sure its still ok

[ren0vator]

This guy explains most things you need to know about
charging, dual batteries, fridges, wiring etc
But it takes him an hour
He must be half alright, he drives a Jeep

You Tube