Question for Prado experts

[chartrock]

My daughter and SiL have a 2013 Prado and this has 2 batteries under the bonnet. Are these batteries just paralleled up for starting or are they one cranking and one just a second battery for accessopries. The second one has just died, reading 0.34 v even after starting the car which started no problems. They were on holidays with a van and one of two batteries in the van died as well, bulging, smelling and getting hot.
SiL has bought two new batteries and wants help replacing them but I know nothing about Prado electrical systems.
Anything I should be particularly aware of?

 

[Drover]

Sounds like it has a Stop/Start system, hence the 2 batteries, just replace the dud with the correct battery and hook up the cables ... Since the main starter works just get it tested but stop/start batteries can get a flogging on short traffic runs as the engine will shut down when stopped and restart when foot lifted off brake .......... The starter and stop/start batteries are the same type of battery calcium usually especially if under the bonnet ................. if its not a stop/start model Prado it may be an aux battery, if it and van battery died at same time it would seem like a charging issue and a full check of the charging profile would need to be carried out.... though if the van is an AGM or Gel then the one under the bonnet wouldn't be charging from the same unit.

The van if it went like your old AGM could have had a a cell fail or been cooked by the charger so a check of the charger if the battery has been idle off charger for long periods, over 6 years old it more than likely just died but check that the charger is selected to the battery type, wrong selection can melt them ....

 

[chartrock]

Thanks, @Drover, the Prado is not stop/start battery (it is a diesel) so I can rule that one out. I have to go up to Brissie on Thursday so will see what I can find.

 

[Drover]

Been doing some reading, if its a grey import from Japan, Europe and cold places they have 2 batteries as crankers to make sure they fire up, known as a winter pack with the 2 batteries wired in parallel so they crank okay in the Cold........ Australian diesel just have a single cranker but since they seem to come with the rack it may be an aux battery fitting, follow the cables and see what goes...

Diesels have been coming out with stop/start systems, what a stupid thing....................

 

[Boots in Action]

Been doing some reading, if its a grey import from Japan, Europe and cold places they have 2 batteries as crankers to make sure they fire up, known as a winter pack with the 2 batteries wired in parallel so they crank okay in the Cold........ Australian diesel just have a single cranker but since they seem to come with the rack it may be an aux battery fitting, follow the cables and see what goes...

Diesels have been coming out with stop/start systems, what a stupid thing....................

Hi @chartrock and @Drover, according to the info I have been able to provide on earlier on this forum, the alternator charging on that model Prado is a Temperature Compensated Regulated type. When cold, the alternator charges at 14.0 volts , but when the engine is warm, the alternator reduces the charge voltage to just 13.2 volts. This is just suitable to keep the starting battery at a reasonable charge, definitely NOT suitable to charge up a flat/low/auxiliary battery to full capacity. While GEL type only need approx 14.2 volts to reach full capacity, AGMs need 14.7 volts. In addition, both types (AGMs and Calcium) need higher voltages again to provide "equalization charge" to bring ALL cells up to max capacity - AGMs to around 15.0 volts and Calcium type up to 15.3 volts. Once you start having additional batteries (especially different types under the bonnet), just connecting in parallel is going to cause problems and when one is used as an auxiliary battery or the charging system is connected to another battery in a van, then the need for specialized wiring including a DC to DC charger becomes necessary for best results and battery life. See attached.

 

[DRW]

However if you run a dc to dc charger the alternator senses the battery draw on the start battery from the dc to dc and compensates for that draw and hence charges the second battery

 

[chartrock]

Thanks for all that, @Drover , @Boots in Action and @DRW. Lots to ponder over and maybe leaving to experts. Thursday is the day.

 

[Boots in Action]

However if you run a dc to dc charger the alternator senses the battery draw on the start battery from the dc to dc and compensates for that draw and hence charges the second battery

True @DRW . But not necessarily if a third battery is involved, either the second battery in the tug (auxiliary) or the AGM in the van, each with their own individual chemistry and charge requirements.

 

[Drover]

Let us know what you find out about the set up in this Prado Paul, as it always handy information ................. but follow the cable if its a aux it will be a Deep Cycle anyway ........

 

[chartrock]

Well, definitely a deep cycle AGM (try lifting a 120 ah one them over the guard into the engine bay). I tried to see where the wires went but they disappeared into a conduit and then into another then vanished into the bowels of the beast. At least there did not appear to be ant short circuits. The van one was 3cms bigger than the original so would not fit into the opening provided under the seat. It was a 120 ah so we took it back and swapped it for a 105 ah which was the correct one. No faults were found so we assume they were both original (8-10 years old). We will just wait and see, they are going away again in about 3 weeks.

 

[Drover]

AGM under the bonnet and lasted that long, thats pretty good really................. if it all works then alls good.....leave well enough alone I reckon...............

 

[DRW]

I put a AGM under the bonnet of my new Everest the lead acid deep cycle century only lasted a year, the main battery from factory is an AGM as well. From experience these usually last well.

 

[Boots in Action]

I put a AGM under the bonnet of my new Everest the lead acid deep cycle century only lasted a year, the main battery from factory is an AGM as well. From experience these usually last well.

A lot of battery outlets do not recommend AGM batteries for under bonnet work. In fact, some sellers will invalidate any warranty claims if used thar way. However, I have noticed that some car manufacturers have a well ventilated spot away from primary heat sources for any type (especially for AGM) of battery. Some even have a sort of insulating material around battery space so direct heat is prevented from reaching the battery itself, especially when engine is turned off after a long hot run. No battery, whatever the type, handles heat very well. I guess there is the potential for lots of air movement when vehicle moving on highway so not a problem at that time.

 

[Drover]

I have seen batteries in an insulted box with an air draft vent form outside to stop the battery cooking ................. mines an AGM, bigg Hooaa lives under my seat so is airconditioned, the price of the bluddy thing .............