Solar and Battery Charge Gurus' .... please advise!!

There is a diode in the solar panel charging circuit??

There is a diode in the solar panel charging circuit??

Sounds to me like your battery is not holding a charge, or the total draw from the fridges exceeds the input from the solar panels.

If you get a reading of 10.5 volts directly across the battery terminals then that battery is dead flat. Even though you then get a reading of 14.4 volts coming in from the solar panel input, it may well be that the battery is "calcified". This means it has been discharged too often and now won't recover enough to hold a full charge.

If there is one "negative" concerning the Engel fridge, it is that the fridge will try to run on whatever voltage it is supplied and because it does not have a low voltage cutout, will drain the battery down to zero, zilch, nada. Taking a deep cycle battery below 30% (about 11.6 volts) a few times and it will become permanently damaged.

Two things I can suggest.

1. Charge the auxiliary battery via an external 240 volt battery charger, then get your battery "load tested" to see if it maintains that charge. This will identify any problems or damage to the battery.

2. Install a low voltage cutout device to protect the battery from ever being discharged beyond the point of practical recovery.

Oh! One other possibility. I'm not familiar with the Supercharge battery you mention, but when you state the rating of 950CCA, this relates to the Cold Cranking Amps of the battery and my guess is that it may not be a deep cycle battery which is rated in Ah. (Amp Hours)

If it is a "starting" battery, it is not designed to provide continuous current draw like a deep cycle battery does and this may well be your problem.
Changing over to a purpose designed Deep Cycle battery would be your best solution in this case. The best deep cycle battery is the AGM type, but limitations in footprint (physical) size may restrict the capacity size that fits inside your engine bay.

Also, running two fridges off the one battery is very demanding on that battery. Each fridge is capable of drawing around 2.7 amps each and the total input from the 85 watt solar panel will probably not be sufficient to maintain a respectable charge on its own.

Good luck with your problem resolution Pedro.

Firstly, that regulator seems a bit under-capacity at 6.0 amps for an 85 watt panel.

Theoretically an 85 watt panel will deliver 7 amps at 12 volts. Taking "losses" into account, say 15% loss, that would still only bring it to 5.95 amps, which is only just under the max capacity of your regulator. You may be losing panel amps in heat as the amps can't get through the regulator.

However, I don't reckon that's casuing the problems. I reckon you need a bigger panel(s) for the job. I have a 35 litrte Autofridge that has superior insukation to an Engel and that needs 2 by 85 watt panels to maintain it's low temps - but as a freezer and not just a fridge. When used as a fridge, the 2 panels and the Autofridge will do the job easily.

Which goldfield are you in? If you're around WA, in Laverton or Leonora the panel, battery and the Engel should handle things OK at this time of year - as a fridge, However, as a freezer it could be borderline. If you're up north at all - Pilbara, North Queensland, then the panel is too small and needs another panel.

You need to know the amps used by your Engle in a 24 hour period, i.e amps and duty cycle to see how much power it's using, Then compare this figure with how much power (amps) you're getting from your panel.

If the panel is delivering MORE than is needed to run the fridge within it's duty cycle then yer battery's not holding the excess and it's knackered. At 5 months old, it shouldn't be knackered. Unless as said by others above, it's been flattened once too often during its short life

Also remember that it may be a nominal 85 watt panel, but you won't get that unless the panel is sitting at exactly the right angle to the sun and it's set up to track the sun all day long. You prolly only get about half of that is the panel simply sits on yer roof rack, flat - like mine does. That's why I need 2 panels!

If you need to buy another battery, get an AGM battery. I find they put up with far more abuse than any liquid lead/acid. I've flattened mine many times and it just bounces back.

Bilbo

Hi Pedro

I'd start by sorting out the issues 1 by 1 and the real issue will become easier to find.

If I read your note correctly you say that your 2 volt meters read different on same battery (12.6-8 & 11.8 )

This is a specific issue which can be solved seperately , just drop by any auto elec and they'll probably check you voltmeter reading for free.

You have to be able to have confidence in your test equipment.

Robin Miller

Pedro, your using a Cranking battery and expecting it to work like a Storage battery - which it won't, as posted above.

You post-> ""Likewise, running the Troopy engine gives 14.4v to the Main Battery [Supercharge 760cca] then ..... delivering 14.2v [per the fitted voltmeter] to the Auxiliary battery (SuperCharge 950cca) .""
You 'appear' to loose 0.6v between the two batteries, why is it so, is it your measuring skills or an equipment fault ??

Under these conditions your question can only be guessed at, however if as you say the 'peep-hole' indicator is grey there is a definite problem there with the lack of charge in the battery - why it's lacking in charge is uncertain because of uncertain charge information by the "fitted voltmeter" and the "trusty multimeter" one has to be wrong and it's likely the fitted voltmeter is the culprit, unless the user is reading it incorrectly.

The 85 watt panel puts out ~4.8 amps, so the 6 amp reg should work ok, was it installed by a competent person ??
Why do you "disconnect the solar panel at night" ??