Battery Charing from Car

rent a geni ..
gmd

Justin

A tricky one. Seems a lot of hoot to get a solar panel unless you are on the wallaby for months.

Some thoughts:

1. Borrow, buy or get from the back of the shed a couple of old gas lamps and use them instead of the 12 volt ones.

2. A couple of dolphin torches for some areas.

3. Turn the fridge back one notch in temperature, and cover it with a couple of damp towels and hope it uses less power and make sure its always shaded.

4. Plan on using the fridge as an Esky for the last day or so (means going to the shop to get some ice).

5. Give the wife a couple of nice hand fans with their own batteries in them for Chrissie - and take a box of batteries (and don't tell her I suggested it.)

Half an hour a day of running the engine at fast idle, if your neighbours don't get cranky and smash your windscreen, might just boost the batteries up enough to see you through the extra couple of days.

Envy you being on Fraser anyway - enough battery power or not!

Have a good one
Max

A fast idle 20/40 min per 2/3 times per day starting day 1 will see you thru , powers that be can ban gen sets all they like ,the gen set built into your car may not be the most efficient or even environmently friendly but no one has banned them yet.

Obviously the fridge consumption varies with temperature, so all is a bit of a guess until the day arrives.
Trying to put some figures on it.
If you are running 2x120ah down to 50% over 5 days, that means you are using 120 amp/hours. (That sounds like low consumption for 5 days.)
An alternator at reasonable number of revs is putting out about 80amps, or maybe you have a 100amp alternator. Less what the car uses to run. Say work on 50 amps out put (50 amps per hour). Plus allow 10 to 15 mins initial running each time to recharge the car battery after restarting.
So about 3 hours of running to get some reasonable charge back into the Alcos. The recharge also drops off as the battery comes up to full charge.
If it 30 mins a day over 6 days, that would just about do it, plus the starting battery recharge, say 45 mins a day. And the engine needs to be run at least at 2000rpm for full charge from the alternator.

Starting the vehicle uses very little power - cranking time is very short, and yours is not a diesel.

How much current your AGMs will take will depend on heaps of variables. But AGMs have a low internal resistance, and normally recharge faster than other batteries, provided they are in good nick. You will also need some nice thick jumper leads with good clamps. In good nick, a normal cranking battery will take about 30 amps over a 30 minute period (say about 15Ah). So I'd guess that for the big AGMs, you could double that figure, and with two batteries, maybe push your alternator to its limit. So Id guess you might regain up to 40Ah over 30 minutes.

I'd be check the AGM voltage with a multimeter each day. I wouldn't let them go below 12.0 volts. I'd guess you'll be recharging at least every 2nd day.

Cheers
phil

Hi Firefox

Yes using a good set of booster cables (With Spike Protection) is a quick way to charge the batteries. 30 min per day should be more than enough.

Just make sure to avoid sparks in the bonnet of the Prado. The Prado battery will be producing some explosive gases so do the disconnect / connect on the sealed AGM side of things.

Have a great Christmas.

Regards

Derek.

Hi FirefoxGC, I have customers who go through this very problem on a regular basis.

There is a cheap and very effective solution and there’s no need to have your 4x4 running at all.

Get yourself a small battery charger and an inverter to suite the power needed to to run the battery charger.

When you get back from your daily exploration of Fraser, pull up somewhere near you CT, pop the bonnet and connect the inverter to the battery.

Run an ordinary 240vac extension cord over to your CT and power up the battery charger.

Depending on how small the battery charger is, you could probably leave it on all night and not take all that much out of the Prado’s battery.

The battery charger only has to be 1 or 2 amps and it will do the job as you are not trying to fully recharge the battery, just extend it’s operating time.

Best of all, there’s no noise and no wasted fuel

Cheers

OK so i have now discovered that the campground will actually allow me to run a quiet generator for an hour or so a day..
Does anyone know if i can hire a honda generator or similar in south east qld somewhere..?
Cheers
Justin

You could spend $100 on another battery and take it with you. A 100amp/hr wet cell would probably get you by for the 2 extra days and will always be there for the future. Just keep it trickle charged in the shed?

Hi Firefox

The advice above is that you can charge your CT ok by running the car for 1/2 hour
+ per day via the normal connection, and this is the simplest way.

A gennie itself will struggle to do the job in 1 hour per day as
most only put out 8amps max, typically less.

Just continuing on from Drivesafes reply, an inverter and small charger
can transfer power from 1 battery to the other without the engine running
ok. This is better than using just some jumper leads (without the car running)
as the nominal voltage of your car battery is lower than that of the CT battery.

A similar, but very effective lower cost alternative, if you don't mind a tiny bit of
electronics is to buy a $39 laptop charger from jaycar and use it reverse
way around.

I.E. Instead of plugging it into a laptop , you plug it into your CT
instead. This will trickle charge 2amps/hr quite efficently into your C/T
battery. Disconnect after few hours.

Important note - you need to add a 1 ohm 5watt resistor in series with the
charge lead to limit start up current into your battery which will blow the
fuse in the Laptop charger.

Robin Miller

Justin, A couple of other options to consider.
Do you have a dual battery system in the Prado? If so, just swap one of your CT batteries into the Prado if you are going for a long drive to give it a charge.

If you don't have a dual battery system, but have Anderson Plugs to the rear of the vehicle for charging the CT bats while driving, make up a cable with Anderson plugs on one end and appropriate connectors (preferably bolt on) for the battery. Find a place in the back of the Prado to put one of the AGMs and connect via the Anderson plugs to charge while driving. Not sure how you will get the cable into the vehicle (not familiar with the Prado) , but I'm sure there will be a way.

If you will spend long periods at the beach and not driving and you can borrow or hire a gennie, take it with you when you go to the beach. Also take one of the batteries. Run the gennie as much as you like and fully charge the battery while you are out. This is what I do if in one of the camp grounds at Fraser. But I have 2 deep cycles permanently in the Hilux and one in the CT (fridge is in the Hilux), so I don't need to be moving batteries.

Dirvesafes plan is a good one if you already have a charger and inverter. Even if it is a bigger charger, just do it for shorter periods. If you don't have a 3 stage charger, you probably need one anyway with two AGMs in the CT to ensure they are fully charged before and after each trip (or on the occasions you have access to 240V when traveling).

Between my ideas and the others offered, I suspect you will find a solution.

But remember, if it is hot weather you probably won't get 5 days from your 2 batteries, which makes charging even more important. With three deep cycles, I get 3 to 6 days, depending on temp, usage, etc.

Good luck.