National Lunar auxiliary battery and new solar panel set up

[Peter Green]

For our latest trip to Namibia I added a solar panel charger set up to enable me to run my National Lunar freezer when camped for more than one night.
Assuming that the National Lunar dual battery system prioritizes the main battery (charging it before switching to the second battery) I connected the solar regulator to the second battery.
Seemed to work fine for few days.
Then I developed a problem with the main battery. Even after driving for four or five hours, soon after stopping for the day, the National Lunar Battery system alarm would go off to indicate the main battery voltage was below normal.
Thinking there was now a problem with the main battery holding a charge and not being able to check or replace it, I thought I needed to switch the solar charge connections to the main battery to make sure the main battery remained able to start the vehicle each day. More important than cold beer??

My thinking being that if the National Lunar first charges the main battery then tops up the second battery, this should be the same regardless of whether the charge was coming from the alternator or the solar panel.

It seemed to work and I have left the set up like this.
Can anyone confirm my thinking?

On returning to civilization I had the battery checked and it surprisingly passed the test but now after standing for week in my garage it has lost it's charge and failed to start the vehicle, so it looks like a replacement is necessary.
It is 2 years and four months old, so four months out of warranty. So this is par for the course for me and batteries.
Any comments or advice most welcome.

[swakop_toe]

My National Luna dual battery setup ( the solenoid with the timer function), always favours the main battery to be charged, first.

So, when driving, the solenoid timer will allow the main battery to be charged for 10-15 minutes first , then only switch to charging the auxiliary battery.

With the solar charging option, only the auxiliary battery is charged.
No option function for the main battery to charge too.

I have an override option to use the auxiliary battery to start the vehicle, should the main battery prove too flat, but you have max 2 tries from the auxiliary battery.
It also shortens the deepcycle's lifetime , doing the heavy discharge needed to power a starter motor.

The theory is that the main battery should never charge to auxiliary, and vice versa.
Alternator charge mains for a set period, then the auxiliary.
Additional solar is for the auxiliary only , unless connected as you describe, in an emergency.

What you describe, unless specifically installed or designed as such, does not sound correct.

Edit: My conclusion is either your main battery is showing signs of end of live or your setup is incorrect.

[swakop_toe]

https://www.sa4x4.co.za/workshop-dua...9QEwAHoECAYQBQ

Read the part from the heading "The battery isolator."

[Andrew Leigh]

Have you perhaps damaged the controller and it is no longer servicing the the primary battery?

Have you independently charged the primary battery?

[Peter Green]

I agree my battery is on it's way out.
I need to take it for a second test.

I just wondered, if providing voltage to the main battery (via the solar panel and not the alternator) the National Lunar controller would, once the primary battery was charged, then feed the auxiliary battery, as described.

When set up as it is I avoided the starter battery from letting me down in the bush, so that's a plus.

I'm going to to reposition the solar leads to the auxiliary battery, as they were in the first instance, and see if it still works to charge the second battery.
Hope I've not damaged the circuitry.

Thanks for the feedback.

[Fluffy]

Holy cow.

And I mean that in the nicest way.

When my head stops spinning I will try to give a half decent coherent response.

So so so many mistakes and urban legend solutions.

[An3s]

No offence, it's just "National Luna", no "r"...

I do not trust the basic load test that most corner battery shops do - have had batteries given a so-called clean bill of health, only to be let down at a most inconvenient time.

I suggest waiting for Fluffy's feedback, it's sure to be spot on.

[BobMabena]

I do not trust the basic load test that most corner battery shops do - have had batteries given a so-called clean bill of health, only to be let down at a most inconvenient time.

My personal experience says those load tests are useless!!!
My "perfect" batteries passed the load test with flying colours... but couldn't keep my fridge running for more than an hour... complete BS

[HobieDave]

You have a problem with excess current draw on your vehicle, that is why on holiday and when standing for a week it drained the main battery. If your vehicle stands then charge the battery fully, disconnect charger, then disconnect your battery, and check after a week - that will be your proof. That would explain why the battery passed the test. Good thinking on your part to connect the solar to the main battery. You may need an auto electrician to find the current drain or depending on your capabilities you can do it.

I am not a fan of the solenoid delay, I want the solenoid to kick in as soon as the alternator is charging - I bypass the delay. The logic was that with the older alternators didn't have a high charge rate so the main battery needed extra time to charge to put back all the energy used from starting. It was to ensure the main battery had as much as a full charge as possible.

Load testing the battery is an excellent test especially if a midtronics and a Hawkins is used. I used to use both testers after charging the battery fully, no use load testing a flat or semi charged battery. It is a definitive test - it is either pass or fail.

[Dwayne P]

National Luna solenoid + intelligent hardware are timed for 5 minutes before kicking in with a constant supply of voltage. If interrupted via bad connection or variable output, this would influence the second battery only.

It seems you battery has gone on the main vehicle or you might have something drawing current while switched off (tracker or aux port with something connected.)

[An3s]

My personal experience says those load tests are useless!!!
My "perfect" batteries passed the load test with flying colours... but couldn't keep my fridge running for more than an hour... complete BS

Haha, yes! For sure. I know my vehicle. I can hear when the starter is not as spunky. Had the batt. tested, "sir, it is still fine!" Less than I week later I was stuck/stranded in a most inconvenient spot (very narrow driveway) where jump-starting or push-starting was impossible. Lesson learnt.

[Peter Green]

National Luna solenoid + intelligent hardware are timed for 5 minutes before kicking in with a constant supply of voltage. If interrupted via bad connection or variable output, this would influence the second battery only.

It seems you battery has gone on the main vehicle or you might have something drawing current while switched off (tracker or aux port with something connected.)

The only thing 'connected' is a (new and updated) tracker unit. I always unplug all devices connected to the various cigarette/ports.
Will probably have to take it to the auto elec. so he can, a: do another test and b: check to see if there is a 'leak' somewhere.

Some good advice on first fully charging the battery before doing a stress test. Did not know this was necessary. I'll make sure it is fully charged. TX.

Lastly thanks for the 'Luna' spelling correction