Question for Prado experts

chartrock

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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

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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 ....
 

Drover

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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

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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.
 

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DRW

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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
 

Boots in Action

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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.
 
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Drover

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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

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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

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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...............
 
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Boots in Action

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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

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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 .............
 
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Gero

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Next door neighbour is preparing for annual trip to Broome and after last trip decided to keep the power connected ito his Silverline van on all the time. Resulting in bulging batteries which I assume where agms. However the interesting part is the inline fuse didnt play its part as the controller was totally stuffed needing a new one. A lesson to be learnt here I guess.
 

Boots in Action

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Next door neighbour is preparing for annual trip to Broome and after last trip decided to keep the power connected ito his Silverline van on all the time. Resulting in bulging batteries which I assume where agms. However the interesting part is the inline fuse didnt play its part as the controller was totally stuffed needing a new one. A lesson to be learnt here I guess.
Hi @Gero, this is not one for Prado "experts", but one for electrical experts. Fuses are only in line to protect wiring/equipment downline from the fuse. And they only blow to cut off power if there is sufficient rush of current flow to burn out (overload) fuze wire. If this does not happen, then a lesser current will continue to flow to loads on that line. In the case of batteries bulging and getting hot, if the batteries on charge do not reach the required voltage level when connected to tug, the controller will continue to pass current (be it high or low current!) to try to achieve the cutoff voltage before reducing charging current (even to "float level") and still not blow the fuse. Batteries that are severely sulphated as a result of not being regularly charged (or just getting old) do not accept charge very well and get all hot and bothered and internal gases cause bulging in sealed AGMs. Unlike bench charging with a multistage "smart" charger, it is difficult to monitor the charging process when connected to a tug when you have to rely on a somewhat simple charging arrangement without actually being able to monitor what is happening. However, even if there is an internal short in the battery, this may still not be enough to cause fuse to blow. but "smart" chargers will cut off the power or stop charging automatically.

The lesson to be learnt here is not to allow battery to become sulphated by leaving it in a rundown or partially discharged state, but on the other hand do not leave fully charged AGMs on continuous "float" charge as this corrodes the positive plates. Discharge battery a little (10% to 30%) and recharge again promptly for only as long as necessary to regain FULL capacity. Frequent short/small discharging and follow up charging cycles will prolong battery life. And heat kills batteries too. Attached is list of other things that destroy batteries.
 

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Drover

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Next door neighbour is preparing for annual trip to Broome and after last trip decided to keep the power connected ito his Silverline van on all the time. Resulting in bulging batteries which I assume where agms. However the interesting part is the inline fuse didnt play its part as the controller was totally stuffed needing a new one. A lesson to be learnt here I guess.

They certainly would have been AGM's and I would guess since the controller is cactus as well it was possibly the cause of the battery fail, not uncommon actually............ As Boots said the fuse will protect the wiring but in this case the charge to destroy the battery wouldn't be anywhere near whats needed to let the fuse go, the controller could have malfunctioned and just shunted 15v or so into the battery to cook it , not unheard of, if the battery dropped a cell and cooked it shouldn't have killed the controller but could be a combination of both .. lost a GEL that way once, I was suss about the controller but it checked out okay later so dropped cell likely but I kept an eye on things so discovered it before anything else happened, caught it as it was in melt down .............

Calcium/acid will go Boom, AGM/GELs will melt down, LiPo4 will melt down as well but no fire, while Lithium Ion will become a fire ball.

The van when parked up should have everything shut down, then if you plug in for battery charging just the charger fired up and looked at regularly along with the battery, some chargers shouldn't be left on all the time as they are not really trust worthy I have found and led light display jobs don't tell you anything so shouldn't be left on forever I reckon but thats for AGM/GELS, Lithium once you park up if they are near full charge just shut them down and leave them, mine is very happy shut down at 70-80% and gets a boost just before we head off, never kept at 100%, they don't like it.... water pumps should be shut down as well or it could run dry....

I don't trust these auto selection types they can get it wrong ...........................
 

Boots in Action

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They certainly would have been AGM's and I would guess since the controller is cactus as well it was possibly the cause of the battery fail, not uncommon actually............ As Boots said the fuse will protect the wiring but in this case the charge to destroy the battery wouldn't be anywhere near whats needed to let the fuse go, the controller could have malfunctioned and just shunted 15v or so into the battery to cook it , not unheard of, if the battery dropped a cell and cooked it shouldn't have killed the controller but could be a combination of both .. lost a GEL that way once, I was suss about the controller but it checked out okay later so dropped cell likely but I kept an eye on things so discovered it before anything else happened, caught it as it was in melt down .............

Calcium/acid will go Boom, AGM/GELs will melt down, LiPo4 will melt down as well but no fire, while Lithium Ion will become a fire ball.

The van when parked up should have everything shut down, then if you plug in for battery charging just the charger fired up and looked at regularly along with the battery, some chargers shouldn't be left on all the time as they are not really trust worthy I have found and led light display jobs don't tell you anything so shouldn't be left on forever I reckon but thats for AGM/GELS, Lithium once you park up if they are near full charge just shut them down and leave them, mine is very happy shut down at 70-80% and gets a boost just before we head off, never kept at 100%, they don't like it.... water pumps should be shut down as well or it could run dry....

I don't trust these auto selection types they can get it wrong ...........................
I remember reading in a caravan magazine some time ago about battery charging in a Silverline van. From memory, the article said that battery charging for Silverline vans has a few problems. Because of the long distance from the in house charger to the battery/ies, the voltage drop is considerable with the existing original wiring. The figure quoted was a total of over 14 metres (7 metres to and from) and this introduced the problem of undercharging resulting in battery sulphation. Also, the charging device (probably the old Setec Series II or III ST35) which only had a max charge voltage of 14.0 volts, or charging from tug alternator, you never had enough voltage (especially for AGMs) to overcome the long distance let alone charge two batteries in parallel which I believe was the norm. No doubt some Silverline owners will deny this potential as they never had that problem, but the article was by a caravan builder with considerable experience with problems he had seen with those particular vans? His solution was to upgrade charger and wiring as battery position could not be changed successfully or provide a plug in point for an outside "smart" charger direct to battery/ies and just let the Setec be the distribution point for all devices after disconnecting the Setec charger. No doubt this situation has been remedied in later Silverline models??
 
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