Fridge battery/charging/solar advise

**Rick1970** · 23rd December 2013, 10:57 PM

In the process of doing a few mods to my '93 V8 Disco for camping. At the moment it has 2 x NS70 cranking batteries and a VSR to link them. I use 2 x NS70's in the Rangie as well (with second alternator to charge the second battery), but feel it wanting with the fridge (Engel 40L) going...something I would like to resolve with the Disco.

Thinking the easiest option is to simple replace the second battery with a 80AH deep cycle and use a solar panel as required.

But, as it will be getting a winch, thought the NS70 may be a better option there, and maybe swap the VSR for a simple solenoid setup + a 80AH AGM battery in the rear for the fridge.

I have been told my a local battery/solar supplier that I can't charge the AGM off the alternator and I need a DC/DC charger so I don't kill the battery due to a too high charging currant.
True or just sales BS?
Can I reliably charge the AGM using the VSR and maybe 6 B&S cable to the rear?

Was also thinking a solar panel, maybe roof mounted, maybe separate unit. If I could get 4 days without running the car, or over discharging the battery, I would be happy.
The Engel draws suposidly 2.5A max...so running 1/3-1/2 the time...20-30AH/day???
Would a single 40w panel, easier due to space restrictions, get me to the 4 day mark? or would I be safer with 60-80w?

I also tow a small camper with a small battery that would have to be charged from the vehicle, but its only running 2 x LED lights and I have no trouble going a week or more without recharging its battery.

Lastly cheap Ebay panels and controller's, OKish or forget it?

Cheers
Rick

**Mick_Marsh** · 23rd December 2013, 11:18 PM

You can't just hook up a solar panel to the battery. You need a controller.

Some of the ebay panels seem ok. I have one. A 120W from these guys. outbaxcamping
I reckon it's really an 80W. It has a controller built in.

**Rick1970** · 23rd December 2013, 11:25 PM

Yeah did realise that, was just hoping to get away with as small as panel as I could if it was to be permantly mounted. If using a separate (folding???) panel, would probably just go 120w and be done with it.

**isuzu110** · 24th December 2013, 07:20 AM

I've been charging Remco brand AGM batteries off an alternator for years with no issue. One of the key features of this type of battery is that they accept a high charge current.

One of issues you may have is that some AGM batteries don't like heat under the bonnet. As I own a 110 and the batteries are under the passenger seat, this not such an issue. This may be an issue with the Disco.

As a general rule (for south east Queensland), I'd recommend at least 100W of solar panels if you want to camp during summer with a 40-60L danfoss based fridge/freezer.

**roverrescue** · 24th December 2013, 08:49 AM

I also have a 120W panel from OUTBAX, running through a cheapy MPPT controller it will make me just over 8A at about 14Vso no way is it "only an 80W panel"

This hooked up to a pair of N70s with no isolator and I have indefinite engel power supply.

Batteries linked for winching

After running down all night the batts are fully charged by about 9.30 am

Simple and not much to go wrong!!!

S

**Rick1970** · 27th December 2013, 02:46 PM

So an 80ah AGM mounted in the rear, charged with a VSR and 6B&S cable off the second battery under the bonnet will be ok?

The OUTBAX 120w panel kits look to be the easiest way out....thinking will probably go that way.

Is it really worth upgrading to a MPPT reg over a PWM one?

**Keithy P38** · 29th December 2013, 06:02 AM

80ah is quite small (even though you can draw AGM batteries down further than lead acid). Have you considered a bigger battery?

I run an 80L ARB fridge for days off a 105ah lead acid battery with no solar. That is, I go for a drive on the third day with the battery hitting 12.3v.

Cheers
Keithy

**Rick1970** · 29th December 2013, 08:10 AM

Only reason I'm looking at an 80ha is ease of fit into the rear of a D1. If I can accommodate a 100ah, then will get one.

I have ordered a 120w folding solar kit from Outbaxcamping last nite. Should have done this earlier, heading to Barrington Tops with the Rangie in the morning.

**bob10** · 29th December 2013, 06:00 PM

Originally Posted by Rick1970

Only reason I'm looking at an 80ha is ease of fit into the rear of a D1. If I can accommodate a 100ah, then will get one.

I have ordered a 120w folding solar kit from Outbaxcamping last nite. Should have done this earlier, heading to Barrington Tops with the Rangie in the morning.

I purchased a 105 amp no name cheapo battery from the camping show, it came with 120 amp folding solar panels, charged it up from 240 volt [ with 240- 12 volt gizmo ] when charged connected it to my Techni-ice 45 lt fridge, upstairs, let it run. Lasted almost 6 days on -2 degrees. Charging it up again, going to have it on -15 degrees, see how it goes. I reckon, with the solar panels, I should be confident of at least a week. [ normal use] Even more when I buy a better battery. Even longer when I incorporate the Techni-ice dry ice packs with it. Bob edit - in an Ark Power battery pack, the first one]

josh.huber · 29th December 2013, 07:57 PM

AGM batterys should be fine next to lead acid, they are full of lead and acid just the acid is suspended in the gm (glass matt), traxide recommends the d34 yellow tops which are an agm battery to go in the d4s with the dual battery kits, calcium batterys do like a dc dc charger and most shops say the use dc dc chargers for dual batterys because the majority of vehicles are Toyotas which run a charge voltage of 13.3v (hilux prado cruiser) and therefor wont put a charge back into the battery to a 100% which reduces the life of the second battery. An alternator of suitable amperage would charge the battery through a VSR quite well.

Solar would be good to help keep the batterys from discharging which would shorten the recharge time with the alternator running.

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