AGM Battery Under Bonet v6 120 Series

[brooksy78 Member Find all posts View Profile Close brooksy78]

Try ABR Sidewinder either via ebay or their web store and shoot Derek an email.

He was really helpful and I'm putting together my own dual battery system, inverter for the rear and accessory plugs. Supplies exactly what you need and if you're not sure he can provide you with advice.

I didnt see the need to go DCDC (adds a bit in cost), just went the ABR isolator with monitor and put a quasi sine wave inverter in the back so I can charge all our battery devices like laptops, phones and the odd tool (never leave home without the cordless drill!). Didnt need a diode, my voltage was close enough to 14V. And I've to a 2003 V6.

I'm going to fit an AGM mainly to minimise weight over the front of the car. I've been told they last about as long as a wet cell battery in the engine bay. So main reason is really to avoid too much strain on the battery mount.

Cheers

Brooksy

[Anth120playdo Banned Find all posts View Profile Close Anth120playdo]

Totally agree, you need to check the voltage first but chances are that you don't get above 14V on the Prado.

I don't know Ctek D250s so I cant comment on how it works or reacts on an increased voltage
I am using a simple voltage sensing relay which connects both batteries as soon as I get above 13v and disconnect with ignition off.
For my simple mind a simple high power relay is working well ;-)

I take from you post that you have some background knowledge so I skip the details but the function of the diode is not too complicated:
If sitting in the voltage sensing cable of the regulator and (if working in the correct orientation) the voltage drop is fooling the regulator to increase the charging voltage by approx 0.7 volts.

You most probably know that get a diode at Jaycar for a few cents (from memory I am using a 1A diode) or you can get a modified fuse for the fusebox for around $35.
There is a fellow from Pradopoint selling them on fleebay but I cant remember the name.
Search for voltage booster.

Regards
Michael

I use a simple voltage relay also. Hyperstart, connects at 13.3 disconnects at 12.8. the kit was $129 at supercheap.
my 2003 alternator does it easy. for an optima 34 yellow.
get a diesel the battery fits right in.... hahahha.....

[Anth120playdo Banned Find all posts View Profile Close Anth120playdo]

double post urggg

[Anth120playdo Banned Find all posts View Profile Close Anth120playdo]

how many batteries can we run? is more batteries over-loading the alternator? or just takes longer to charge them?
im toying with the idea of 3 batteries

[Wombat1 Junior Member Find all posts View Profile Close Wombat1]

Hi Lad or Ladies,

Please be reminded this is for a v6 2003 120 series Prado.

It seems would seem that the Outback Accessories Australia item that was supplied by Oops lockers was for a diesel and thus the trouble, when originally mounted. (Power Steering Position)

The previous post was exactly what I have been talking about. The idea of this forum was highlight originally was, whether you could mount a AGM battery under the bonnet. It would seem from feedback, that it was not impossible, but still no certainty.
Secondly it was whether the CTKE D250S would work under bonnet efficiently, considering the temperatures. Surely someone else has tried this before, have they not?

The diode method would seem to be a good solution for standard charging of the main battery, by increasing the input/voltage (Remember do not over load the type of battery you have)

The reason for running a second battery would surely, be for the use of running auxiliary items e.g. fridge lights etc. And third battery in the back of, say a trailer, camper trailer, boat (charging the battery), caravan etc.

Also on this topic, is there going to be massive voltage drop running 8bs cable if the battery was mounted to the rear and the third battery from there, or should you run 6/4 bs cable?

I look forward to your responses and your assistance would be grateful.

Get it right the 1st time and you do not look back is my opinion.

[Wombat1 Junior Member Find all posts View Profile Close Wombat1]

Hi Lads or Ladetts,

It would seem that this thread has gone cold. Only want correct feedback, not dis-crediting the previous feedback, but surely others would like an answer or solution to their potential build up. Not advertising any specific product. It is what I have got and previously had, pictures would be greatfull to assit me and also other in the future. ( If I have to go this alone, I will, and post pictures and results as necessary and be factual)

By the way this was not a double post, but simply a request for help, with formal opions??? Urrggg.

If previous threads show or highlight the solution would love to know where to find them. Probably sound like a novice

I Look forward to your responses.

[drivesafe Senior Member Find all posts View Profile Close drivesafe]

Hi Wombat and while 8B&S ( 7.9mm2 ) is fine for wiring up two batteries under the bonnet, but if you are planning to mount a battery in the rear or in a caravan or camper trailer then you need 6B&S ( 13.5mm2 ) twin or 16mm2 twin.

You do not need to remove all voltage drop but if you use the thinner 8B&S cable for the rear battery, it will cause far too much voltage drop when the rear battery is in a low state of charge.

As to charging house batteries in a camper or caravan, there is a better option than DC/DC devices.

I do not what to go into too much detail here as it WILL amount to spamming but DC/DC devices are a single use appliance and if you use an inverter ( fitted with new safety devices ) and a battery charger, you can get multiple uses that can not only charge a battery bank but power a 3 way fridges at the same time from a single power supply cable from the tow vehicle.

Just some suggestions.

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

I actually think the answer to your questions are already here in the forum just hard to track down in a single place.

There are several of us who successfully run AGM batteries under the bonnet. There are a few people who haven't but wouldn't because of the temperature. The only issue I have had was my own stupid fault running the AGM down too low and that would have killed any battery and a conventional battery very quickly. I still got 4 years service out of that battery. My fridge now cuts off at a safe level for the battery, the old fridge had no such setting.

There are numerous opinions on what is the best way to charge an auxiliary battery.

There are several options regardless of opinion:

DC-DC charger, solenoid isolator and boost diode (D4D only?), solar panel, AC charger (mains and/or generator), one of the other types of isolator.

I am not sure what drivesafe is suggesting as I don't have a camper. But what I do know is that if you have AC available then the best option for all your batteries is an AC smart charger. I top up all my AGM batteries (one 120 AH under the bonnet, one 120 AH sitting in a jerry can holder in the non camper trailer and a 20AH battery that runs a pump for the hot water system) with an AC charger before I go away. I have a Rotronics smart isolator that I wouldn't recommend. I have a solar panel that I do recommend.

I find that given usual weather conditions the solar panel can pretty much keep up with the output on the car mounted AGM which is only running a fridge and occasional compressor. A few town runs also helps. The second auxiliary only provides a couple of LED lights in the camp and charges phones. It usually doesn't need a top up. The 20AH battery is also usually ok but if needed I just plug it into the solar panel for a day. The solar panel also takes a considerable heat load off the interior of the Prado despite it being parked in the sun and that in turn reduces the load on the fridge and battery so the solar panel provides a dual benefit. I also use sun blinds front and rear and have the darkest legal tint on the windows.

Despite the negative press on here I would be inclinded to go DC - DC charger instead of the Rotronics next time. The Rotronics unit cost two arms, one leg and a naughty bit and doesn't perform as well as I expected. I would go the DC - DC charger because then I know I can provide the 14 odd volts that the AGM likes and it treats the AGM independently to the main starter battery as per the diagram from ABR reproduced earlier. I have already posted my experience with a Piranha isolator and conventional battery plus AGM and it wasn't pretty. As to the DC - DC chargers with all the frills and smart charging I haven't done enough research to decide if that is worth the effort or not for the extra $.

I think you need to ask specifics about particular set ups people have rather than the generic question that has already yielded 3 pages of opinion here and lots elsewhere on the forum. And let people know what you intend to do and what you have available. By the way I also know of one set up that uses a wind turbine to top up batteries. Noisy bloody thing it is too as well as expensive.

Michael

[Anth120playdo Banned Find all posts View Profile Close Anth120playdo]

I have seen agm batteries under the bonnet look heat affected, really distorted, from memory thats on the big v6 maybe with gas.
I use one under my 120diesel it seems very happy. Mine seems to stay pretty cool under there.

[drivesafe Senior Member Find all posts View Profile Close drivesafe]

It’s the actual location of the battery that makes an under bonnet dual battery feasible or a risk.

If the auxiliary battery can be mounted at the front of the engine bay then there is every chance it will be fine.

If the battery is mounted further back in the engine bay then there is a real risk of heat damage and this is not just limited to AGMs.

The are a number of vehicle makes, not just Toyotas, that because of space constraints, have the battery mounted away from the front of the engine bay and in most cases, it results in very short battery life spans.