Battery In Trunk = Good!

[Win]

I have three cars with trunk mounted batteries: The '04 Jaguar still has the OEM Varta it was delivered with. It has a tiny V8 that spins over pretty easy. The '08 G8 needed a battery repleacement in winter 2013. It has a tiny V6 that also spins over pretty easy.

My Xj12 has a trunk mounted battery, but it seems to be hard on them and the charging system is primitive compared to modern cars. A couple of three years is about all I seem to get from them. I imagine spinning that V12 over takes a lot of amps, as the voltage drop has to be substantial given the distance between the starter and the battery. It has a nice mechanical sound on the starter motor, though, kind of like a mini Merlin.

Do the modern cars with full cam phasing actuate the cams to release compression on initial spin up? They sure seem to turn over easier than the old cars with fixed valvetrains.

 

[artificialist]

In Florida, you can expect about 2 years and 6 months from a regular battery.
One thing that surprises me is that OEM Panasonic batteries tend to last significantly longer than that. Unfortunately, I have only seen them on cars that were built in Japan.

Having a battery in the trunk is such a huge advantage. I got 5 years from the OEM battery in the Saturn ION.

Some cars with blazing underhood temperatures had even shorter life from batteries. The 1985-1988 Nissan Maxima was such a case.

 

[hattaresguy]

Originally Posted By: Wolf359
Originally Posted By: hattaresguy
Mercedes has been putting them in the trunk or back seat since the mid 90's and their OE battery's can last up to a decade. I think the more stable temps help keep them going longer.


They also use an AGM battery which lasts longer than a regular flooded battery.


Only recently.

 

[hattaresguy]

Originally Posted By: Win
I have three cars with trunk mounted batteries: The '04 Jaguar still has the OEM Varta it was delivered with. It has a tiny V8 that spins over pretty easy. The '08 G8 needed a battery repleacement in winter 2013. It has a tiny V6 that also spins over pretty easy.

My Xj12 has a trunk mounted battery, but it seems to be hard on them and the charging system is primitive compared to modern cars. A couple of three years is about all I seem to get from them. I imagine spinning that V12 over takes a lot of amps, as the voltage drop has to be substantial given the distance between the starter and the battery. It has a nice mechanical sound on the starter motor, though, kind of like a mini Merlin.

Do the modern cars with full cam phasing actuate the cams to release compression on initial spin up? They sure seem to turn over easier than the old cars with fixed valvetrains.



A lot of modern cars have two batteries, because losing power causes all sorts of issues. I bet the new XJ's have two, the S does.

 

[weasley]

The original Mini had the battery in the trunk. The main cause of failure was that the battery tray would rust through and deposit the battery on the road.

Most cars I have had have had the battery under the hood. Exceptions were the Mini, the Mercedes B Class (it was under the floor of the cabin) and the BMW 1 Series (trunk). Oh, and the MR2 (AW11) which had the battery behind the seats... along with the motor.

The main reason for battery location is packaging - moving weight around and having space for stuff. OEMs would prefer not to put them in the trunk because the cost of a wide gauge copper cable to the front of the car is significant.

I remember when I visited the Rolls Royce assembly plant in Goodwood (UK) they explained that RRs always have two batteries, so that if you leave the lights or something else on and drain the battery, there is another (isolated) one that will always start the engine. It is not good form for a Rolls Royce to fail to start.

 

[mjoekingz28]

Originally Posted By: Nick1994
Well that sure does explain battery failures here in Arizona. Batteries last 2, MAYBE 3 years before they die, tops. Only battery lasting longer than that I know of is my great-uncle's car. He lives in Europe during the summer so the car isn't used in this heat


You need to keep up with the distilled water level more in the summer. I'd say check it every month.

 

[SHOZ]

Originally Posted By: zpinch
General rule for ANY battery chemistry: the higher the temperature, the faster it ages... the colder the temperature, the longer it will last. That goes for ANY type of battery, to a point.

Even if you are not using the battery, heat will degrade. Cold preserves.


The cold reduces effective capacity which is why people think it kills batteries. If it is already weakened, probably from heat or sitting discharged too long/too many times then they fail in the cold.

 

[artificialist]

Originally Posted By: mjoekingz28
Originally Posted By: Nick1994
Well that sure does explain battery failures here in Arizona. Batteries last 2, MAYBE 3 years before they die, tops. Only battery lasting longer than that I know of is my great-uncle's car. He lives in Europe during the summer so the car isn't used in this heat


You need to keep up with the distilled water level more in the summer. I'd say check it every month.

That sounds nice, but many batteries don't have pry-off caps.

In cars with trunk-mounted batteries, batteries need a different kind of vent, and making batteries with no caps is a must. In my ION, there were 2 batteries brands that fit, ACdelco and DEKA.

 

[SHOZ]

You need Valve Regulated Lead Acid AGM batteries. They are sealed and don't vent until a 10 lb pressure buildup in the battery.

Odyssey makes some but probably not drop in. It's what I use in my trunk mount setups.

 

[SteveSRT8]

In my battery spec all it takes is a vent tube run to the outside.

Pretty simple, but requires the battery to have a nipple on it...

 

[Bumble_guy]

Heat and undercharging is what kills batterys

 

[SHOZ]

FWIW they use silver grid alloys to combat the heat problem.

 

[HTSS_TR]

Originally Posted By: SteveSRT8
In my battery spec all it takes is a vent tube run to the outside.

Pretty simple, but requires the battery to have a nipple on it...

Not many batteries have nipple to connect the vent tube to outside the car. BCI size 49 is one of the few has nipple because it is mainly used under the rear seat or in the trunk. I think other sizes staring with "H" such as H6, H8 ... have it too.

 

[Cutehumor]

I thought of replacing my 09 cobalt battery in the trunk with over 70K miles on it, but I see people say these batteries last alot longer. I don't want an unexpected failure.

 

[artificialist]

Originally Posted By: Cutehumor
I thought of replacing my 09 cobalt battery in the trunk with over 70K miles on it, but I see people say these batteries last alot longer. I don't want an unexpected failure.

Auto parts stores will do a test on them for free. They use a Midtronics tool that determines how many CCAs your battery still has. It should be replaced if it has less than 75% remaining.