Saturday, Feb 28, 2004 at 17:25
In the 11 years I was fitting 4wd accessories that would have been one of the most asked question.
Just looking at the replies so far and the photos of the vehicles, most are late model and could have some form of electronic engine management system. Fuel injection is one example (petrol). Electrical plugs that are pluged in the air cleaner chamber or in the air pipes from the air cleaner to the manifold are another give away that you have some thing thinking for you.
With a simple methiod, when the motor starts the alternator will try and charge both batteries at the same time. If one battery is low, below 10.5 volts it will try and charge it up quick. This is were a power spike could come from.
A alternator will stop charging a battery when it sences it is fully charged and will then free wheel until required, just like the air con compressor, with a good isolating system instead of the alternator free wheeling it will charge the second battery and when that is fully chareged it will then free wheel.
Once a spike goes through the system, that is when on board computer system goes down.
If one of the batteries drops a cell the alternator keeps on charging and will over charge the good battery.
You are also asking a alternator to charge two batteries at one time when it is only made to charge one at a time.
If a deep cycle battery is fitted the alternator can not sence this and tries to charge it at a cranking battery rate. The deep cycle battery will soon die.
You are going to have to put some form of isolating system in the set up or both batteries could go flat if running acessories when the motor is stopped.
I have always fitted the Piranha dual battery isolator for the following reasons
1 Spike protection built in
2 Charges the second battery (deep cycle) at a slower rate
3 Printed circuit, no moving parts or diodes to build up heat or create voltage drop
4 Simple to install, one x150amp cable to the main battery, one x150 amp cable to the second battery, one 2mm wire to earth and one 2mm wire to turn the system on.
5 The system once installed is maintiance free and there are no switches for the driver to forget to flick.
One of the replies to this thread mention the cost of recovery from the desert because of battery failure add to that the cost of blown engine management system which would not be covered by warrenty and the amount of down time and I for one can not see the value in a simple setup.
Piranha also do a system if you are running two cranking batteries, works the same but has the option of joining both batteries to gether, via a button on the in cabin controll box. The controll box also has led lights to show volts in each battery and the amount of charge is put out by the alternator.
I hope this will explain why on a average I would fit 2 of these units a week.
WayneAlways Out'N About
AnswerID:
48540
Follow Up By: Rosco - Bris. - Saturday, Feb 28, 2004 at 19:20
Saturday, Feb 28, 2004 at 19:20
Well said Wayne
I also preferred the KISS principle ..... until the issue of spikes etc was explained to me.Fidei defensor
Rosco
FollowupID:
310374
Follow Up By: Mad Dog Morgan (Geelong) - Saturday, Feb 28, 2004 at 20:03
Saturday, Feb 28, 2004 at 20:03
Every time a relay collapses or a contact is broken damaging transients and high voltage spikes can result so it's not only the dual battery system we need to be concerned about. Ideally we should all have an antizap device installed at the battery to protect the vehicle and our expensive toys...cheap insurance
BEAM ME UP SCOTTY
Hooroo
Ray
FollowupID:
310381
Follow Up By: Wayne (NSW) - Saturday, Feb 28, 2004 at 20:46
Saturday, Feb 28, 2004 at 20:46
Ray,
The Piranha has that spike protection built in. Spikes could harm any device connected to the batteries,GPS, Mobile Phones,Fridges,UHF and HF radioes
WayneAlways Out'N About
FollowupID:
310385