Solar Charging of Starting Battery

Hi Tony,

Is there anything stopping you from using the auxiliary battery in the vehicle to help the cranking battery turn the motor over? I assume the auxiliary battery is under the bonnet and still has charge? Just need some jumper leads.

Otherwise, if that's not possible, I don't believe you can go "backwards" with the charging process via the isolator switch. The isolator needs the charge in the 1st battery (cranking) to be above a certain voltage before it opens up to allow charging of the auxiliary battery, at least that's is my understanding of the way it works. Others will know better than I (Derek Bester from ABR Sidewinder might be able to help here).

Failing that, direct connection of the solar panel to the cranking battery will do the job, but you'd better hope for a sunny day and a 12 hour wait to get the voltage up in the cranking battery as it might take some time to recharge.

Cheers

Rob K

Hi Rob K, I tried to jump start from the 2nd batt. but as the starting batt. is dead there has been no charge flowing over to the 2nd batt it's a deep cycle not for cranking. And don't care if it takes 2-3 days to charge so long as it starts
Thanks

Tony, just because a battery is a deep cycle unit it does not mean that it will not start a motor (unless of course you have run it down more than you should have.) Just use your jumper leads to start the motor with our deep cycle battery. If your leads are not too light it will work, make sure you carry a quality set of jumper leads and not K-mart specials.

Be very careful if your motor is computer controlled (efi) as a spike will render the computer dead. The best option is to jump the aux to the main,+ to + and neg to the motor, then remove the earth from the main, so it is not dragging extra current from the aux when you start the motor, and once the motor is running put the earth back onto its post with the jumpers still attatched and let the motor run for 5 minutes that way to charge the main. Stop motor, disconnect auxiliary jumper leads and start straight away. If there is not enough charge, your battery is stuffed it should fire straight up after 5 minutes of charging.

Thanks John & Val, looks like No (2) thats what I thought of but do I require a fuse on the leads with battery clips one end and anderson to solar panel on other that the question ?

Hi Tony,

I confess, my battery clips to anderson plug cable, and battery clips to cigarette lighter socket do NOT include fuses. (I use cigarette lighter plugs for lots of gear such as chargers for phones, camera batteries, torch batteries, laptop supplies, soldering iron, etc. They are a horrible, crude device, but are universally available in any vehicle, so something of a standard.)

Any permanent wiring such as an anderson plug connected permanently to a battery should include a fuse. Why? There's a lot of energy stored in a battery and it can come out fast and can damage wiring, even cause fire, if something goes seriously wrong. A fuse is a cheap way of disconnecting the battery from everything if disaster does strike.

If I were mounting an anderson plug permanently to the sidewall, and permanently connecting it to the battery I would certainly include a fuse in the positive line. If just a temporary connection using clips, I would not include a fuse, but remain mindful of the risks.

Cheers

John

Tony,

Forgot to mention - I've fitted an inline fuse holder linking input (cranking battery) to output (Aux battery in your case) across the under-bonnet isolator. On the rare occasions when I might need to link the two, I simply insert a fuse. For normal operation no fuse is in place, but it's easy to insert one should you need to feed current into your cranking battery from further back, as you could do with your solar panels through the rear mounted anderson plug.

Cheers

John

Thanks for all the help, as we only travel remotely a couple of time a year I will go with the Solar Panel and clips if required for now and look at fitting a better 12v charging system in the near future
again thanks

Ditto

Same here.

We actually have three batteries under the bonnet, with two isolated as the auxiliary "battery" to run our two fridges, lights and all the other junk we use when camping through outlets at the back of the cabin. The isolator is the 200 amp one with the over-ride switch in the cabin with the red status led for the redarc. The switch allows me to temporarily add the two extra batteries to the cranking battery if needed to assist with cranking.

I cannot see how the main battery should get flat unless I muck up and leave the radio, lights and everything that runs off the start battery, switched on. Or it goes crook.

Maybe I missed something.

PJR the starting battery ran flat at home as I was working under and around the vehicle all day Saturday with radio and interia lights on did not think they would flatten the batt. but only been doing short trips to work and back, so not fully topping both batts.
Thanks

Aaahhh Tis a trap Tony. And not topping up does not help.

With your isolator, can't you switch the auxiliary batteries to cranking?

To get the motor running and put bit of charge in the cranking/start battery for next time.

GT had radio on all day Saturday will working on the 4x4 also rear interia lights I found were on