Thread: Aux battery sugestions

Yeah your alternator might need a service.
With the engine running our Defender sits right on 14 volts. With a load such lights at night that only drops to about 13.9.
Your dual battery controller should connect the batteries when the starting battery gets to about 80% charged.
Can't remember if you have mentioned this, but how heavy duty is the wiring between batteries 1 and 2? If its too light that will slow charging of 2. Ours is rated to 60 amp fuses.


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Originally Posted by DiscoMick

Yeah your alternator might need a service.
With the engine running our Defender sits right on 14 volts. With a load such lights at night that only drops to about 13.9.
Your dual battery controller should connect the batteries when the starting battery gets to about 80% charged.
Can't remember if you have mentioned this, but how heavy duty is the wiring between batteries 1 and 2? If its too light that will slow charging of 2. Ours is rated to 60 amp fuses.


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The Magnetti Marelli Alt. was Brand new, the previous MM Alt. was replaced because the alloy body cracked and was only held together by it's mounting bolts, actually fell to bits when I removed it. The new MM alt. had a Dyno sheet with it showing 14.8V when tested, on my Ammeter it showed 13.8 at idle and 14V at above idle.
So the Alt. performance had nothing to do with the low charge in the Aux., which BTW was a Deep Cycle Supercharge 120amp.
As I stated the constant (almost) use of the main/starter battery through the Dual Battery system (Redarc 100 (I think) solenoid ) didn't allow the Aux. battery to receive a full charge and the run home was only an hour at less than 60ks..
Plus the fact that the Engle 38L (plastic case model) would run the aux deep cycle down to as low as 7 volts and still be operating, I found this so when I checked the aux. with my Ammeter, this killed the aux., I need a cutout for the Engle so that it shuts off at around 11 to 12volts (flat). Auxillary Deep Cycle batteries might be OK for a few emergency starts but should never be connected to a winch, all of the battery and winch cables are the correct max. size and the best quality, over $30/metre.
The DC toDC charger is now connected by battery cable through Anderson plugs to the C/T (12.8V) when driving and receives 19V from the solar panels, I will go and take some pics of my system and post up later, thanks for your input, Regards Frank.

Originally Posted by Tank

.... Auxillary Deep Cycle batteries might be OK for a few emergency starts but should never be connected to a winch....

Aha! ... didn't know that your aux was a deep cycle type.
Makes sense now.

Is your Redarc the SBI12 model? This is the 100A rated solenoid type.
The other (current) model is the SB212, which is 200A rated.

Originally Posted by DiscoMick

....
Your dual battery controller should connect the batteries when the starting battery gets to about 80% charged.
....

I don't think it really works in this manner(kind'a sort'a, but not exactly!)
I think the way it works is that once the battery has reached 12.7v, it reconnects them both up, so they both receive current from the alternator at the same time.
Once the engine is running, you have well over 12.7v, so it's basically 'connected' all the time with the engine running.
What it does is: when you stop(ie. no charge current to main battery), it disconnects the two batteries to stop any further draining of the main battery.

So: if you're using a redarc, and have a load on the aux battery, it actually drains both batteries until the situation exists where the main battery dips below 12.7.
Once this point is reached, then the batteries are isolated from each other.

For the past week I had the issue where my alternator didn't charge more often than it did.(Friday arvo of course, just after all the shops couldn't get one .. etc). Didn't have time to sort it out Mon - Wed, and Thu I had some other stuff to do too.
I still had to get to work, and all the other stuff so had regular use of the car. By Wed tho I had no alternator at all. Before that it'd work for 15mins and then stop. home to work and back was usually 45-ish mins.
Thursday it rained all day(hard) and I had to drive around and do lots of stuff .. about 3 hrs driving all up with about 10 starts.

Because of the way the Redarc works, it isolated the main battery which drained to about 11.9v but I could see that the aux battery was still nicely holding about 12.5-12.7. So even tho I ran with lights and wipers and so forth, I was still secure that I still had enough battery somewhere to start the car(via the momentary override switch) if needed.

On Monday and Tuesday tho I connected up the battery charger to the main battery only, obviously with the car OFF, and the redarc still fired itself up, so in effect the charger charged both batteries at the same time.
Aux battery held up to 12.9v overnight after about 8 hrs off the charger, and the main battery held up to 12.7v one night and 12.6v the other night.

I'm thinking, maybe it's more important to have two equally powerful batteries considering that the one source is charging both of them at the same time.
I don't know if having two different capacity batteries will affect their ability to hold charge when charged from the one source .. but I thought that once the smaller capacity battery charged up fully before the larger capacity battery charged up, then the larger capacity battery wouldn't fully charge(or it won't hold it's charge for as long).

Originally Posted by AK83

I'm thinking, maybe it's more important to have two equally powerful batteries considering that the one source is charging both of them at the same time.
I don't know if having two different capacity batteries will affect their ability to hold charge when charged from the one source .. but I thought that once the smaller capacity battery charged up fully before the larger capacity battery charged up, then the larger capacity battery wouldn't fully charge(or it won't hold it's charge for as long).

If you have a standard dumb alternator, that puts out a steady ~14V, you won't have a problem charging any combination of 12V lead-acid batteries in parallel. The large one will still charge when the small one has finished charging, and the small one will not be over charged as the large one continues to charge.

Aaron

Yes, although starting batteries may charge faster than AGMs.

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Originally Posted by Tank

The Magnetti Marelli Alt. was Brand new, the previous MM Alt. was replaced because the alloy body cracked and was only held together by it's mounting bolts, actually fell to bits when I removed it. The new MM alt. had a Dyno sheet with it showing 14.8V when tested, on my Ammeter it showed 13.8 at idle and 14V at above idle.
So the Alt. performance had nothing to do with the low charge in the Aux., which BTW was a Deep Cycle Supercharge 120amp.
As I stated the constant (almost) use of the main/starter battery through the Dual Battery system (Redarc 100 (I think) solenoid ) didn't allow the Aux. battery to receive a full charge and the run home was only an hour at less than 60ks..
Plus the fact that the Engle 38L (plastic case model) would run the aux deep cycle down to as low as 7 volts and still be operating, I found this so when I checked the aux. with my Ammeter, this killed the aux., I need a cutout for the Engle so that it shuts off at around 11 to 12volts (flat). Auxillary Deep Cycle batteries might be OK for a few emergency starts but should never be connected to a winch, all of the battery and winch cables are the correct max. size and the best quality, over $30/metre.
The DC toDC charger is now connected by battery cable through Anderson plugs to the C/T (12.8V) when driving and receives 19V from the solar panels, I will go and take some pics of my system and post up later, thanks for your input, Regards Frank.

Sounds like your alternator is fine.
So your Engel doesnt have the option of setting to battery protection mode? It must be one of the older ones like ours which doesn't have that function.

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Originally Posted by DiscoMick

Sounds like your alternator is fine.
So your Engel doesnt have the option of setting to battery protection mode? It must be one of the older ones like ours which doesn't have that function.

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No, it's actually one of the newest models, a cheaper version of the metal body fridges, plastic body, on off switch and temp. adjustment and that's it, about $300 cheaper than the 40L steel body Engel, Regards Frank.

Deep cycle batteries are typically quite slow to charge, for the same reasons that you shouldn't use them as an engine cranking battery. They are designed to be charged over many hours, not just the one hour play on the tracks or the two hour drive home. They are good if you are solar charging all day. If you only have an hour or so to charge the battery after running the fridge for a day, you are probably better using a battery that has a decent cranking rating as it will charge quicker.

Aaron