Tale of Two Batteries

Chris,

You must have had more than "minimal lights" and some radio, to flatten the starter battery.

Why run the lights off the starter when you have the advantage of an auxiliary battery and solar cells?

Trust you have learned something mate.

I have a "third line of defense", in the form of a high capacity Thumper battery pack. This also enables me to jump start the vehicle if necessary, but I make sure NOTHING is draining the primary battery while camping.

Actually the Thumper is my primary power source when camping.
The auxiliary battery under the bonnet powers the fridge when driving, then I swap over to the Thumper, which also has a solar panel to provide some recharge capability. I have the option of connecting the fridge up to the auxiliary, if the power pack ever gets a bit low.
The thumper is also charged again while driving via a separate in-car charging kit.

Like Sandman I'm a little perplexed as to why you were using any power from your starting battery?

In remote areas when I'm camped for more the 24 hours in one spot I run the vehicle each day to test and ensure the integrity of the main battery.

I would never use my starting battery to power anything - lights and radio I can do without - a vehicle to get me out of there I cannot.

Mike Harding

Quote:
" Luckily a series 75 was close enough to hear the non-start. Jumper leads were found and we gave it a try – good battery to flat battery. Yep – just that one whirr."

Sorry, but are you saying that even the 75 series wouldn't start your vehicle? Was the 75 series' motor running at the time? I would be VERY surprised if your vehicle didn't spring into life quite quickly if it was being jump-started off the 75 series if the motor was running.......

I would NEVER try to jump start a vehicle without the "donor" vehicle's motor running.....that's just asking for trouble.

Maybe I've misread the original post??

Everyone trying to save starting battery and I am doing quite on the contrary. When I camping I disconnect auxiliary battery and run everything from main. Just to clarify I have two identical Excede Extreme (i.e. in-between charging and deep cycle) usually running in parallel. Reason been – I *CAN NOT* guarantee that nothing drawn from mail battery, but I can guarantee that auxiliary completely disconnected. Obviously during camping I recharge main battery if I feel I need to do so. When time comes to start vehicle I trying to start it from main (partially discharged) battery (with aux still disconnected) and actually I have not fail yet. My escape plat is – if it fails, then I physically replace them and try again.
Cheers
Serg

Leads me to an interesting similar situation...

We have a Pirahna dual system. Main starter is a N70ZZ and aux is a Trojan 115AH deep cycle about 3 years old.

Few months ago Toyota replaced the main battery at a service due to a faulty cell. The new N70ZZ had been in for only a week when I went to go to work one morning and it was flat. Just enough to produce a click.

The pirahana DBS isolator/controller has a "Link" button on it. The salesman at TJM told me after the install that it can be used to overidde the isolator to link the two battries in parallel for winching or for starting off the aux should the main battery fail.

I dutifully pressed the link button and tried the starter and managed to get the motor winding over but not fast enough to fire it up. Bugga.

Plan B was the Toyota Extra care guy who came and jumpstarted it in no-time and it was off to Toyota for another replacement as the new battery also had a bad cell.

My point/question is: how effective is it to use this link button for this purpose when the main battery is down/flat? Obviously not real effective in MY case but also the aux battery is getting close to replacement anyway. Would I have been better off physically swapping the aux into the main slot to get me going?

Ok in the city as Toyota Extra care sorted me out quite quickly but not so good if I am out bush.

In the meantime I have bought a 900cca 17AH jump pack that I can keep in the back just in case!

Cheers
Muddy

Hi Chris

We travel solo quite often.

When camped in one spot for a day or more I run the engine every morning for 20 minutes, then again for 20 minutes at midday and 20 minutes again in the evening. This way I re-charge both batteries. The starter battery lies dormant fully charged as it is only used for cranking.

I use the aux battery for powering the Engel and Twozone on freeze at all times. The waterpump, shower, night light, rechargeable battery charger and the laptop are run on a need to basis. The system works for me.

I will be acquiring something like a 'Thumper' in the near future for emergency use as I got caught short the other day with two flat batteries.

Cheers

Hi Chris

Never agreed with that philosphy myself which i think is technically flawed.

I would put the charge into your starting battery first if
your confident its just low from over discharge.

The reason for this it that little power is required to start
a car but it must come for a low resistance source so that the starter motor will turn over correctly and hold voltage up
for the other devices to work correctly.
The starting battery , not the deep cycle is designed to
provide the heavy short term current.

I.E. assume it takes 10 units in one second to start a car,
it doesn't matter if your deep cycle has 50 units in it,
if it can't deliver 10 per second.
(P.S. its a good exercise to test start the car with your deep cycle
1/2 charged for next time)


As an exercise, I have started a car with a flat barrery with a
pack of AA cells by using them to first drain into the starter
battery. (Dick Smith 10 cell holder = 15v at 2.5amp hrs)

This is hardly an ideal solution and normally I carry a small gell
cell for this purpose, but it illustrates what can be done.

Do always carry the 10 pack though which is a convient way to take spare batteries for torches etc.

The simple way is the best way, run ALL the radios and lights off the Auxiliary battery.
If you want to you can also charge the Cranking battery with the Solar panel so it's never flat when you have to use the Cranking battery to run lights that are wired into the Cranking battery.
Simply run a 'small' jumper lead from one side of the battery isolator (eg, Solenoid, Redarc, Rotronics etc..) to the other, or one battery to the other.
That way you never have flat Cranking battery.