Why are the new AGM (3) coach batteries unable to power fridge?

Hi @nan_c

Just curious whether the Progress Dynamic controller is charging the batteries at the correct rate.

Maybe check the voltage across the battery terminals when they're being charged.

if it is undercharging, this might explain the quick voltage drop to 11V when under load.

If the charging voltage is OK then when the batteries are being used to supply power to the vehicle, try pulling the fuses (breakers?) one by one and check if the voltage goes back up from 11V to hopefully isolate which circuit is dragging it down.

Without a schematic, just some things I'd check first.

Hi @nan_c

I'd worked out before about the "hot links" in the manual you uploaded but the schematics were in a format that I'm not used to. Never come across schematics where you had to "search" for the other end of a wire. Usually they're fully drawn out or have reference points to tell you where it is, not just a wire colour (if that's what it is).

According to the 2018 model 12V wiring diagram you linked the LP detector is on fuse #7 in the 12V panel. It is not shown anywhere else on the diagram, although assuming that a "WB" (White/blue?) wire is run to the fuse from it, the only other mention of a "WB" on the diagram is for the switch designated as "CL" in the diagram which is located below the sink - see image

(hover your cursor over the image and then click on the magnifying glass icon that appears to enlarge, then click on the newly opened image again to enlarge further)

What is fuse #7 designation in the fuse box in your van, LP detector or perhaps toilet? (Is there a toilet in your van?)

Is there a switch under (inside the cabinet?) the sink as shown in the image as "CL" and what is it used for?

Is fuse #7 powering whatever is connected to the switch? (remove the fuse if unsure to prove it).

I don't think that it will be the LP detector as it is a safety device and usually these aren't wired so that they can be disabled by a switch (inadvertently or deliberately). If there is a problem (alarm?) with them then the power is removed by taking out the fuse but only after verifying that there isn't a gas leak.

Not sure what LP detector means but am assuming it is a LPG (liquified petroleum gas) leakage detector but maybe it means something else where you are e.g. low pressure?? I don't know

Only asking all this because in the 2020 model 12V wiring diagram I linked, is that fuse #7 is for the toilet, it has a WB (white/blue wire colour?) notation next to it, but there is no other mention of WB (or Switch detail CL under the sink) and there is no mention of an LP detector and the diagram for the 2018 model doesn't mention the toilet. This is not to say that the fuse can't be used for something else etc.

(click on image to enlarge).

Talk about confusing???

Hi @nan_c and @brandon_k

Looking at the manual for the Novakool current refrigerator series from 2018, from this link it seems that the Novakool refrigerator may be a dual voltage model. (both AC and DC) (see wiring diagram on p.5 of 8 {pdf numbering} of the manual) and not just works on AC supply only as I thought it might do i.e. AC from inverter supplied by battery or solar

So perhaps there is a problem with it when on DC as the AC/DC module is in the fridge!

What is the model number of the refrigerator @nan_c, so this can be verified?

If it is a dual voltage model, check that the DC voltage and connections are correct at the refrigerator and maybe also the 12V DC fuse #10 (and fuse wiring) in the 12V panel. Check the DC wire gauge size (example only) especially relating to distance from the 12V fuse panel and the -ve or earth wiring as per p.4 of the manual. The -ve wire may not be run all the way from the battery, it may be connected to a convenient chassis earth point as the battery -ve terminal may also be connected to the chassis. The +ve wire should run to fuse #10 in the 12V fuse panel (if the van wiring diagram is correct although it shows a 10A fuse and the fridge manual shows a 15A fuse). If they're all OK it may be the refrigerator.

According to the manual there is a limited 2 year warranty on it so something to bear in mind if you can't find anything wrong with the DC power to the refrigerator.