The 150 series Dual Battery Guide

[footoo]

At a guess I would say it is to link the batteries should your starter battery go flat. I would have thought it would at least be labeled

[BlakMoth]

It is on all the time for running your fridge while the car is parked up.
The button might be to jump start your car off the second battery if your main battery goes flat. Is it a push in button that springs back when you let go?


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[ben29150]

Dumb Question but...

So let me start off by saying I have no electronical knowledge at all so this will most likely be a dumb question but... I had ARB install a duel battery system in my new prado but they didn't really explain how to use it... Question 1: Does the ignition need to be on to use the second battery or is it on all the time? Question 2: I have attached a pic of a button that ARB installed and have no idea what it does...

Sorry in advance for my cluelessness.

[MelbournePark]

My son took the 90 series (circa 1996) to Philip Island for some concert thing.

I had removed the wiring for the fridge, but I bought him wire and fuse and let him do it himself. NO back up except for jumper leads though ....

He ran the motor during the weekend too ...

Of course, the motor wouldn't start! The battery was dead ...

He jumpered it - no problems. Then went to his girlfriend's parents spare place in Warragul area ... and it wouldn't start!!

No RACV coverage on that vehicle either ... no red light in the dash (hence alternator should be OK) ... no swollen battery (an 18 month old 66 AH Optima so still under warranty), and the casing appeared fine ...

Thanks to this thread, I thought it through and suggested he check how tight the wiring was ... it was a bit loose, and when tightened, the motor started fine!!

Glad I got him to do it ... he learn't something I reckon ...

[AJ120]

Yes they give off gas but the caps have vents.

Cheers Andrew

[ttmx83]

I hook the charger up to the rear Anderson plug. Charges the auxiliary battery then the isolator clicks in and charges the main. I give no care that one is calcium and one is gel. I like to live on the edge but with fully charged batteries!

Cheers Brad.

[fido666]

I presume you mean when charging with a 240v charger?

Yes, charging off 240v.

once the voltage allows the isolator to connect the second battery that gets a charge as well. I've done this heaps of times no problems at all.

OK, so I can just hook the charger up to the main battery and let the isolator switch to the aux? No need to disconnect the battery cables?

I never remove the caps, you don't remove them when the alternator charges you battery when driving so cant see the point.

The instructions do say to refit the vent caps after topping up with distilled water, was just checking as I do know that lead acid batteries may produce gases.

[AJ120]

When charging batteries in a dual battery system linked by an electronic isolator should the batteries be charged separately? Also should vent caps be on or off (batteries are wet cell)?

I presume you mean when charging with a 240v charger?

When preparing for a trip I will regularly hook a battery charger up to my camper trailer battery, that feeds directly to the crank battery through the Anderson plug, once the voltage allows the isolator to connect the second battery that gets a charge as well. I've done this heaps of times no problems at all.

I never remove the caps, you don't remove them when the alternator charges you battery when driving so cant see the point.

Cheers Andrew

[fido666]

When charging batteries in a dual battery system linked by an electronic isolator should the batteries be charged separately? Also should vent caps be on or off (batteries are wet cell)?

[drivesafe]

Hi Ben and if you are mounting a battery in the rear of your vehicle, no matter what type of battery it is, the battery’s internal resistance combined wire the cabling resistance and length, will act as a quasi voltage/current regulator and you will never cook a battery while charging from your alternator.

It’s actually quite a safe way to charge any battery, even when alternator voltages can be in the mid 15v in some makes of vehicles.

So just fit and forget.

[Ben80]

Not mounted under bonnet rather in a box at the rear so only subject to ambient temps, thanks for the replies.

[LeighW]

No problems, maybe others with a VRLA can comment, generally though when a manufacture is talking "float" he is referring to float charging 24/7 and float voltages under these conditions can become critical for VRLA batteries as the pressure builds up due to constant trickle charging, your battery is cycling. I would be more worried about temperature, make sure the battery can handle under bonnet temps.

[Ben80]

Thanks Leigh,

Its actually a vrla, the starter battery still tests up fine and its the 5 year old original panasonic so I figured it had no problem with a higher voltage. All information I have found shows the vrla likes a lowish float, thought I would see if anybody had damaged a battery from a higher voltage

[LeighW]

Ben80,

Voltage is fine, manufactures generally state that maintaining continuous normal charge voltages for up to 24 hours will not harm the battery. The starter battery sits there at these voltages day in day out.

One point that has been raised above though AGM stands for Absorbent Glass Matt, lots of different types of batteries are now using AGM, just the use of AGM does not make a true AGM battery as most think of it.

Symo,

For your use it would be ok, but keep in mind some go touring for 3 to 6 months a year cycling their batteries daily.

[Symo]

I'm confused - if a battery is discharged fully like the optima (but any AGM battery in general) and you get 300 cycles at this rate, surely at that is enough for anyone?

I mean I discharge my battery fully 2-3 times a year, do you really think my battery will last 100 years?

So all this arguing about how much to discharge a battery is all a pissing contest and pointless given that the average user is not 'consuming' their battery as a whole fast enough to out pace the general life of the battery which is only 5-10 years under PERFECT conditions.

Use the thing for what its designed for, spend less time hyper-analysing the voltage in your battery and more time enjoying life/camping/boating/fishing/ prado-ing! Cross the dead battery bridge when you get to it! just like 99.9% of every starter battery out there...