Aux battery

Without knowing specifically which model/make of AGM battery it's a bit hard to provide accurate information.

Was there a particular type you had in mind?

Dave

Seen a few with aux batts in the other front corner. That's where toyota put 'em.

locallaw,
IMO, I believe the salesperson is implying the AGM battery, being a fully sealed battery, should not be installed in a hot engine bay because they have the distinct DISadvantage of not being refillable when the engine bay heat (probably) causes the fluid, whether it be liquid or gel to evaporate, whereby if it were a wet cell battery the 'liquid' can be replaced simply by opening the 6 screw top covers and replenishing the battery fluid.

I believe he is looking after you as his statement is indeed fact, however that said, there are possibly many hundreds of AGM batteries in engine bays, to what degree the battery looses its capacity due to fluid loss may be so minimal as not to be worth mentioning, tis your battery so I am not prepared to make a decision on your behalf, when in doubt check it out!

I would not put a sealed battery in an engine bay where it will be affected by heat, as it will loose battery capacity, to some degree, due to evaporation caused by heat.
I have two 4yo sealed DC batteries and neither are in the engine bay for that same reason.

Hi Locallaw,

Mainey is right in what he says, but the biggest danger in fitting sealed batterys in the engine bay, is that they will expand to the point that they will split open. This is because they can not vent and release the pressure build up, hence they must be kept in a cool place. I have seen the square ones come out looking more like a ball.
However it is quite safe to mount them inside the car, for the same reason, as there are no gasses escaping into the cabin.

Chaz
http://members.bettanet.net.au/~conody/index.htm

Hi locallaw, do you have a specific reason for fitting an AGM type battery in the engine bay, because if there is no special purpose for it, a deep cycle will give you more capacity for the same size battery at a much lower price and a deep cycle battery will tolerate the heat of the engine bay far better than AGM type batteries.
Having said that, whether you fit a AGM or a deep cycle battery, if you fit a reflective shield between the battery and the engine E.G.. a thin stainless steel plate, you will improve the battery’s survivability dramatically.
Cheers

Gday
Whilst i dont know a great deal about these batteries, i do know a person who has had 7 years out of a starter gel cel battery in his 80 series diesel..this specific one was one of those 6 pack batteries with red top.
The good thing about the 80 series is you have a schroud around the battery, which assists in keeping radiated heat down, and allows cool air to circulate whilst moving forward.
If you havnt already, go to toyota and ask for a battery schroud for a 1990-1992 3f powered 80 series and you will get a mirror image to what you have in the passenger corner to fit to the drivers corner! They cost $120 from Yota.
The next thing you need to consider is how you will charge it...these batteries shouldnt be put in parallel with a normal battery for charging, so it would be an individual charging isolator or run two gelcels.
Andrew

More to the point, seal batteries, and infact most batteries that I know of are rated at 27deg celicius (or was that 25?), and their life is significantly reduced for every degree above that limit. When we use sealed batteries in UPS systems we generally condition the environment to increase the battery life. AGM bats may be more sensative that lead acid.