battery question

I am after some advice regarding fitting a second battery in the engine bay of the troopy.
The location is over the turbo, probably the hottest place in the engine bay, I have been offered to options, 1 a century marine pro 720 and 2 an optima yellow top at about twice the price.
My question is, is the optima worth the extra outlay and would putting a rubber mat under the batteries help absorb some of the vibration and protect them in the long term.
Any advice will be appreciated.

Thanks
Rick
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Reply By: GT Campers - Monday, May 07, 2012 at 18:18

Monday, May 07, 2012 at 18:18
what Troopy is it? All those that I have seen have the battery(s) against the near-side/passenger edge of the engine bay..?
AnswerID: 485220

Follow Up By: Rick and Kerrie - Tuesday, May 08, 2012 at 07:32

Tuesday, May 08, 2012 at 07:32
It's a 2010 VDJ78, the batteries are where you say and the turbo is on the same side at the back end of the motor.
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Follow Up By: Member - Howard (ACT) - Tuesday, May 08, 2012 at 16:46

Tuesday, May 08, 2012 at 16:46
Hi Rick & Kerrie
cannot see any issues with 2nd battery mounted behind start battery on Passenger side
My 2009 VDJ79R (ute not troopy but same engine /engine bay)has had the battery there since i got it and no issues with either heat or vibration.
this is pretty std setup on the post 2007 landcruisers.
while the turbo on the V8 motor is on passenger side it is down low just
behind engine mount.
cheers
Howard
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Reply By: Member - Serendipity(WA) - Monday, May 07, 2012 at 18:21

Monday, May 07, 2012 at 18:21
My second battery is located above the turbo and I have used a Century Marine Pro 720. It has been there 3 years now no problems.

I have used Century Marine Pros before for many years in previous cars and had a really good run. I like that they are built with protection for the rough pounding a boat will take on the water and have the same regard for rough tracks in my 4x4.

Have not tried the optima so no opinion.

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AnswerID: 485221

Reply By: Ross M - Monday, May 07, 2012 at 18:33

Monday, May 07, 2012 at 18:33
G'day Rick and Kerrie

I think the rubber map will help with some vibration depending on how tight you fasten the battery down. Tighter = less vibe absorbtion.

The Optima is a good battery but it isn't really a storage type battery if that is what you are after. It is a starting battery and even the biggest of these is far smaller in capacity than others. Great for starting and general use but not suited to running the fridge etc. I can't justify the price for what I get in charge storage ability v the dollars.
The position above the turbo is the worst possible place to have a battery and despite fitting generous amounts of thermal insulation it will most likely over heat and ruin the battery because of the radiant heat it will receive.
You would be far better to fit a battery elsewhere or under the body.

The only way it might survive is to feed it air via a dedicated hose from the front of the engine bay and have it feed with a computer fan to run after the engine is switched off so a large amount of cool down of the area is provided to combat the heat sink effect form the engine and turbo which occurs after the engine is shutdown.

Ross M
AnswerID: 485224

Reply By: Ron N - Monday, May 07, 2012 at 21:36

Monday, May 07, 2012 at 21:36
After a lengthy high speed run on a warm night, pull up and open your bonnet quickly and you'll see why mounting a battery over a turbo or exhaust manifold is a bad idea.

Your turbo housing and manifold will be glowing a dull red after running at about 600 degrees for a couple of hours. This will happen to nearly all vehicles. My old 6 cyl Holden ute manifolds would glow after a high speed run.

Even my old 4 cyl Landrover would get the manifold glowing after a decent high speed highway dash (that was sitting on 90-95kmh!).

Cheers - Ron.
AnswerID: 485247

Reply By: Rick and Kerrie - Tuesday, May 08, 2012 at 07:39

Tuesday, May 08, 2012 at 07:39
Thanks for your responses, I should have added that I have a 100AH AGM that I will probably put in the back for the fridge, camping lights etc and the second battery under the bonnet will be a backup for both the starter and the AGM.

Rick.
AnswerID: 485264

Follow Up By: Charlie B2 - Tuesday, May 08, 2012 at 13:19

Tuesday, May 08, 2012 at 13:19
Hi everyone,

Apart from the heat issue, there are another couple of possible concerns you might like to take into consideration with Optima batteries under the bonnet. Whatever your final decision, remember that Optimas themselves are very tall batteries and often have even taller terminals.

If you think I'm just being super-critical, please understand that I bought an Optima red-top, with every intention of fitting it under my bonnet on the 100 series 'Cruiser, to replace a wet-cell deep cycle. In fact, it was fitted (in a tray that hadn't been designed for it, admittedly), but, thankfully, I must have sensed something amiss because I closed the bonnet very carefully. When I discovered that it wouldn't close, I looked at the situation a little more critically. All I can say is, "Thank goodness for Mr Toyota's good underbonnet insulation!" It's clearly insulated electrically as well as thermally.

Let me give you a strong tip: a poor choice of battery and battery tray could result in an interesting experience for all concerned when closing the bonnet for the first time! Tall terminals biting into the bonnet metal wouldn't be a good look, even if there wasn't 75 amp-hours of current all trying to get out at once!

You mention you've already got a 100AH AGM. Why not try it the other way around if you have to put one of them under the bonnet? I'd probably drop the 100AH under there, and leave the Optima in the rear of the vehicle.

Clearly , it's your call, but my Optima now rides in my Jayco Eagle!

Regards,


Charlie

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FollowupID: 760531

Reply By: GT Campers - Tuesday, May 08, 2012 at 09:21

Tuesday, May 08, 2012 at 09:21
You could try installing flexible alloy exhaust heat shield (from a car parts shop or exhaust mob) and enclose the battery in a vented box (take a look at any 1990s Ford falcon for the basic idea).

Best of all is to install the battery elsewhere, if you have the space down the back!
AnswerID: 485273

Reply By: The Bantam - Tuesday, May 08, 2012 at 12:03

Tuesday, May 08, 2012 at 12:03
Firstly let me say that I am very much in favour of the use of marine batteries in 4wds....My personall choice is the supercharge seamaster gold, they have a very solid following in boating circles....no vested interest.

Marine batteries are a rugged construction battery.
Some manufacturers market a "marine" battery, "4WD" battery and some an earthmoving battery..... generally they are identical appart from their colour and the sticker.....but you will often get a better deal on the marine item.

As for vibration.....there is a whole pile of....um.....er......"misinformation and misunderstanding" arround.

Firtsly lets seperate the idea of vibration and shock.

Unless you are going to install a complicated and bulky system you will do bugger all about shock and vibration that originates from the vehicle, you have to rely on your suspension and this is why you buy a rugged construction battery.

A lot of other vibtarion comes from things not being firmly mounted and properly restrained

Putting rubber under your battery will not absorb any vibration, not a single bit......remember you battery strap is still rigid......... what it will do is give the bottom of the battery traction on the battery tray and it will also give the battery clamp something to compress to maintain its tension.

Before I put rubber under the cranking battery in the factory battery tray, I could not get enough tension on the factory battery clamp to properly restrain the battery......the battery would move arround.......a far more sreious issue that any vibration.

One thing on my list and everybody should consider, is upgrading the factory battery tray and battery clamp.....many trays don't fully support the bottom of the battery and many battery clamps are simply too weak to hold the battery in place.
ALL batteries should be held down firmly, if you can push your battery around in the tray or if it moves at all in operation of the vehicle, it is not properly restrained

As far as heat goes......heat is the #1 enemy of lead acid batteries, raise the operating temperature of a battery from 25C to 45C and you reduce its life expectencay by at least half, some sealed AGM style batteries it will reduce the expected life span from 5 years to under 1.
And the battery will perform poorer in every way.

The best thing you can do for any lead acid battery is to get it out from under your bonnet......unfortunately lots of us cant.

Managing heat under your bonnet.

Firstly a bit of rubber is going to provide no effective insulation for your battery.

we need to understand there is aconsiderable airflow under the bonnet of most vehicles......there is a trucking big fan behind the radiator.....that air might not be all that cool, but at least it is flowing and cooler than most of the engine components, certainly cooler than the exhaust & the turbo.

look arround under the bonnet of most moder cars and there are heat shields all over the place....their job is to be an obsticle to radiant heat.

Under the bonnet radiant heat is about the only heat we can do anything about......so the idea is to place something between the heat source and the sensitive item and allow airflow past it.

Mostly this is just a sheet of metal......it don't have to be fancy to work..look at the top of your catlictic converter for example.

putting a steel sheet heat shield mounted on the turbo will probably do the most.

there are foil jackets you can get for batteries too and i have seen all sort of attempts.....but I can't see them being all that effective.

Remember insulation and heat barriers only slow down the passage of heat.....you need airflow or other cooling, or the cool side of the insulation will get just as hot as the hot side gven time.

cheers
AnswerID: 485280

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