How to retro-fit a bigger capacity battery to a Mk7 Golf

pokeyjoe said:

I believe the opposite is true. Heat kills batteries. I've even had cars with grill vents directed at the battery to cool them. Audi puts batteries in an area outside of the actual engine compartment to keep them away from the heat. Mini has them next to the air intake for the cabin. The battery in a Golf is subject to a lot of heat under the hood thanks to the turbo. You should have something there to protect it.

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Black fabric absorbs heat & does not reflect it away....basic thermal dynamics..

To reflect radiant heat from the engine away from the battery you need to wrap the battery in a shiny metal foil...DEI do plenty for this purpose & all well proven.

Faceman said:

I wonder if removing the weatherstripping at the base of the hood would help keep the battery cooler. If so, what negatives would there be besides increased noise?

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You may also get loads more road spray etc in also wind lift as more air under the bonnet which could cause that edge of the bonnet to ripple...

Just get a DEI battery blanket/wrap

golfdave said:

Black fabric absorbs heat & does not reflect it away....basic thermal dynamics..

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Black objects absorb incoming radiation in the visible range. I don't think there is much visible radiation under the hood of a car.

I stand by my previous remarks. I don't want to clutter an excellent DIY thread with some silly debate.

pokeyjoe said:

Black objects absorb incoming radiation in the visible range. I don't think there is much visible radiation under the hood of a car.

I stand by my previous remarks. I don't want to clutter an excellent DIY thread with some silly debate.

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I do know that re black etc..just trying to get to basics...as the battery wrap is mainly a cold insulator.

Metal foils even in a dark engine bay will protect against heat...due to smaller surface area as the flat smooth surface is smaller than the fluffy rough fabric surface area which can capture more radiant heat given off by the engine. (again basic explanation)

I'd keep the wrap but put a metal foil layer under it...as metal foil layers do protect and are used in buildings in the walls/roof where there is no visible light.

BTW Audi etc putting batteries in the boot or behind the scuttle panel ...space constraints that's why, can't get it in the engine bay (why they fit in the boot)...& our scuttle panel is to small for the battery so it had to go in the engine bay.

Ok slightly off topic but relevant to the battery.

I did Technical Architecture at University instead of opting for an Honours Degree in Electrical or Mechanical engineering...

So thermal design & heat transmission etc is part of the remit...

Heat will flow in an object/solid/liquid/gas until the temperature is the same (equilibrium). The transfer of heat will be by either conduction, convection or radiation.

So battery in engine bay, engine emits (radiates) heat to heat up the air around it to reach the same temp as the engine. The air in the engine bay will then heat up any object in the engine bay, by convection. Anything that is in direct touch/contact with the engine will heat up by conduction.

Radiation, most people just think of sunlight & thus an engine bay is not in direct sunlight so this does not apply. Wrong! Sunlight is short wave length....as very high temps, lower temps including red heat from metal are long wavelength radiation & are what is called "far infra-red" which is why we can see this "invisible" heat from a hot engine in a thermal imaging camera! So the engine will radiate heat to heat up any item in the engine bay, even if in dark garage!

There is then the whole "thermal resistance" of the materials to consider. i.e. does the material present resistance to the flow of heat from one side of the material to the other side?

A good example of this is the bulkhead in your engine bay, black felt to provide sound insulation & some thermal properties when cold. However it has a silver coloured corrugated aluminium foil on top to stop this black felt from gaining heat from the turbo etc...& this is in a dark engine bay..so no visible radiation...so why??

Basically shiny metallic surfaces have a low emissivity in both the visible heat radiation & the invisible far infrared heat spectrums...& they can work in both direction..ie wrap the battery, & it can stop the battery emitting heat...& also stop the battery gaining heat from the surrounding air.

Low emissivity materials are concerned with the heat absorbed & radiated by the material & this can have NOTHING to do with sunlight or visible radiation! which is why you have aluminium foils inside building walls etc. as "low-e"..same applies to engine bays... wrap the items you want to protect from heat in polished silver or gold foils...not a black fabric...

I could write a whole thesis on this if you want but a good webpage on wiki here:-

https://en.wikipedia.org/wiki/Thermal_radiation

& the specifics on Low emissivity materials are here-

https://en.wikipedia.org/wiki/Low_emissivity

If you put metal foil around the battery isn't that just going to have the battery hold heat just as well? So maybe foil under that battery and the side that is closest to the engine? keep the other side and top un-foiled?

ITGUY said:

If you put metal foil around the battery isn't that just going to have the battery hold heat just as well? So maybe foil under that battery and the side that is closest to the engine? keep the other side and top un-foiled?

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My earlier quote:-

""Basically shiny metallic surfaces have a low emissivity in both the visible radiation & the invisible far infrared spectrums...& they can work in both direction..ie wrap the battery, & it can stop the battery emitting heat...& also stop the battery gaining heat from the surrounding air."""


So the correct low-e material will stop a heat producing item emitting heat i.e. trap the heat next to the item..batteries should not produce as much heat as the heat from the engine...so wrapping the battery in low-e material will protect the battery from the engine heat...

Doing the sides facing the heat source will protect more from the direct radiation...doing the whole thing will provide total protection for really hot environs..

If you are worried about the battery self cooking if totally wrapped then just do the side nearest the engine to provide the most direct path protection.

This is just basic thermal management & why there are companies such as DEI & Zircoflex & Cool-it etc...its not all BS or snake oil, its actually based on scientific facts...

I'm using DEI reflectagold to wrap my ignition coil wires as I don't want to suffer the same fate as the old MK4 1.8T engines...heat making the wires go brittle resulting in failures & in a new ignition coil loom!!

I will also be looking into a foil for the battery..as I have now blanked off the slam panel air duct to direct more cold ait to air intake..so engine bay hotter..

Duracell 48(H6)AGM from Sam's Club or Batteries Plus. Think this is assembled in USA by East Penn (DEKA).

George Ab said:

Thanks again Dave! Wanted to say thanks and bump this thread.

Been waiting awhile to perform this upgrade. Battery only had three years, but I was having to throw a charger on it more often than I would like. Proper fitting battery blanket finally arrived along with my new properly hinged windshield wiper reservoir cap http://www.golfmk7.com/forums/showthread.php?t=26076 (thanks for that also). Adaptations made in CAN Gateway and away I go.

That’s not a battery, now this is a battery!

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I just replaced the original battery in my 2015 NAR Golf TDI. I chose the Interstate fitment#29 from Costco because it was only $113 and has the larger capacity. This is the larger battery with a 70Ah rating. It fits, but it is tight in my TDI, especially since the Interstate version from Costco does not come with handles on top. I kept the red plastic cover that came with the new battery and thanks to Dave the rubber cap (VW #7N0 915-429-A, $1.04) to help insulate the positive terminal. I also transferred the little plastic plug that was in the vent from the old to the new battery. It was originally on the positive side. Also, with the bigger battery cover (VW # 5Q0-915-411-H, $34.50) installed it looks factory. Thanks again Dave for the original post and references.

moonlite said:

I just replaced the original battery in my 2015 NAR Golf TDI. I chose the Interstate fitment#29 from Costco because it was only $113 and has the larger capacity. This is the larger battery with a 70Ah rating. It fits, but it is tight in my TDI, especially since the Interstate version from Costco does not come with handles on top. I kept the red plastic cover that came with the new battery and thanks to Dave the rubber cap (VW #7N0 915-429-A, $1.04) to help insulate the positive terminal. I also transferred the little plastic plug that was in the vent from the old to the new battery. It was originally on the positive side. Also, with the bigger battery cover (VW # 5Q0-915-411-H, $34.50) installed it looks factory. Thanks again Dave for the original post and references.

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Those nice little VW covers make all the difference to those of use paranoid about bare main terminals..


& glad you did it all ok.....

Travis9935 said:

I've been thinking about this battery..

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Did you end up getting this battery and if so did you like it? It seems to be about the same specs as AGM batteries from Auto Zone and Advance Auto Parts but for about $35 less.Thanks

I still don't think I understand the purpose of this mod. You said you have a lot of electronics, but all cars have a lot of electronics. What's the underlying reason? More available amperage, or more capacity? Why would you need either if the stock battery already works?

jcw122 said:

I still don't think I understand the purpose of this mod. You said you have a lot of electronics, but all cars have a lot of electronics. What's the underlying reason? More available amperage, or more capacity? Why would you need either if the stock battery already works?

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Many threads on this forum & other VAG car forums...MQB platform cars failing with dead batteries...stop/start functions killing the batteries also....

VAG have fitted the smallest possible size to each car that they can get away with....I stated that in the first posts along with loads of other info...

jcw122 said:

I still don't think I understand the purpose of this mod. You said you have a lot of electronics, but all cars have a lot of electronics. What's the underlying reason? More available amperage, or more capacity? Why would you need either if the stock battery already works?

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Why doesn't VW fit all of our cars with the 1.4, too?

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In

jcw122 said:

I still don't think I understand the purpose of this mod. You said you have a lot of electronics, but all cars have a lot of electronics. What's the underlying reason? More available amperage, or more capacity? Why would you need either if the stock battery already works?

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I guess it depends on the individual. My battery was three and a half years old and I notice it was cranking slower than usual and I drained it, headlights on while using obdeleven, are we charging on my charger in the car started but it was still slow. So it was eight degrees out yesterday to give you an idea how cold it can get where I'm at outside Philly so I put in the larger AGM battery. It turned over quickly, I'm not going to go into all the reasons an AGM battery is better because I'm sure there's threads on it

Thanks GolfDave again for the detailed DIY., my standard 56ah battery, was its way out (3 yrs old)., with difficulty starting and occasional no enough power to start.

After researching with 70ah AGM Batteries (Interstate, Duracell and Duralast Autozone battery)., settled with the Duralast with 3yr replacement warranty one.

Fits perfectly on the craddle/base. Had a fibre/felt battery cover that did not fit (since the new duralast is bigger)., but was able to modify the sleeve (cut and reattached it to make it bigger.

Even the VCDS coding was very straight forward-
Battery Type
Battery Capacity
Serial Number.

Attached is the duralast battery model and spec, in case if someone is looking for it.