Keeping batteries charged

G'day Richard,
My Hilux often sits for months between trips & I just disconnect the cars Negative cable then put my charger on it for about 24 hrs then I move the charger to the second battery & put that on charge for 24hrs. I do not disconnect the Negative cable on this one.
I do this every month so as too keep them in good condition.

I also have portable 130 A/H battery that I do the same way. Basically I treat them all separately as they are all different capacities.

Cheers
Stu

If your batteries are in good health,and there are no significant drains in the vehicle , you should be able to leave the car alone for at least a month no problems.

However you can simply hook up to the cranking battery and that will charge both batteries.

BUT
some of these modern multistage battery chargers can get confused.....what they all like is a one on one relationship with a single battery that is not being used.

One of mine for instance will not cope with a battery & a fridge.

If ya want to do tis long term, I would go for a relativly old fashoned regulated power supply type battery charger set to the appropriate voltage.

second car second battery charger.

One of my brothers customers out west on one of the cattle stations, has a long flat carport where all the vehicles are parked there is a battery charger on a shelf at roof height in front of every parking position...some of the vehicles wont get driven for weeks, and with so many these days being electricaly dependent, they take no risks.



cheers

For not to many dollars you can buy a timer switch & programme it to work once a week for a few hours or what ever you want

Be careful in disconnecting any battery cable in a modern vehicle as you may lose settings in the vehicle management system, radio, etc.

There should not be any need to disconnect battery leads. Just connect the charger (positive lead first in a negatively grounded vehicle) and turn it on.

Also, you may have to charge each battery separately. (No need to pull them out)
Most dual battery isolators require the ignition sensing wire to be active before they will work and swap over to the auxiliary circuit after determining that the primary battery has sufficient charge.

Hi Richard,

try the easiest way first:

connect your multi stage charger to the starting battery and let it charge away.
As soon as the battery terminal voltage reaches about 13.2V, the isolation solenoid switch (if you have one) cuts in and connects the aux battery in parallel to the starting battery.
This will cause a spike in the charging current and may cause the charger to terminate charging.
But if it can tolerate this, the charging process continues like normal.
From this point in time on, both batteries are being charged to the same charging end voltage e.g. 14.4V, and after a while the charger switches back to the float voltage of 13.6~13.8V.

If this works, next time you can link in the other vehicle's starting battery by a pair of jumper leads hooked up to the starting battery.

You may want to connect a multimeter across the starting battery and observe the voltage trend.

cheers, Peter

Thanks guys for the very quick responses.

I have a redarc isolator. I am not sure if this will function if ignition off but do see a light in it after I turn it off, at least for a short while.

The reason I ask is that earlier this year I went away for two months, I did not do anything but when I got back the two cars were flat as a tack. The batteries were not new and had to replace them, the aux battery was ok.

So I bought a projecta charger for future travels,.

So to summarize the above it seems like I can just put the charger on the start battery and This will charge both batteries, but will need to test if the isolator will charge aux battery.

With respect to the wifes battery is connect it via jumper cables .


Richard

Hi

As my vehicle is only used for tours and personal outback trips it spends up to a couple of months per year parked up.
On my battery isolator I connected a fuse block between the cables for both batteries. When hooking up the charger I put a 30 amp fuse in the holder to open the circut so all three batteries receive a charge.
Without the fuse in place only the start battery gets the charge and this saves me connecting the charger to each battery.

I don't know what the Projector charger does. I am currently using a M100
C-Tek , probably the same sort of charger, and that works fine for me.


Cheers Teza

Hi,
I keep my boat batteries topped up by this method;

I put a small solar panel, 2w, on the roof and run a lead with a cigarette lighter plug on the end down to the battery. I split the cord into two with two plugs for a double battery setup.

I wire a cord to a cigarette lighter socket and attach the cord to the terminals with the socket outside the battery box (cable tied on). Two for a double battery setup. A wine cork is stuck inside the socket when I am using the boat.

The batteries are hooked up, all day every day I am away with a trickle charge going in.

Both batteries are sealed so no worries with topping up with fluid.

Over the last three years, the batteries have always been ready to start the boat, instruments etc.

I do not disconnect the batteries from the boat wiring.

Should work for a car too and no need to worry about a mains connection while you are away.

This setup also keeps a battery alive at a mates bush shack for his toilet light (its away from the house and the sheilas won't walk out in the dark!) Once again a sealed battery. Been there for 4 years, always charged.

Bill