Battery Sizing

[TurboJ]

So. I would like to hear about people's experiences for battery sizing.

Most part programmes recommend a 64 Ah or 70 Ah battery for a Mk2 with 1.6D or TD engine.
Maximum starting power is recommended to be at least 600 A.

I'm wondering since those recommendations are for winter use, how much less you could get away with if you only drive in the summer. My point is of course to lose every possible LBS possible, keeping the total weight of the car down.

I also have a 1.9 head that's been slightly reshaped, so my combustion ratio should be about 20 instead of 23 of a standard engine.

Tell me how small batteries have you guys used and how it has worked out.

Thank you!!

[Fredrikkk]

I'm using a 71 Ah Sonnak battery and that really does its work. When I bought my car it had a really small 50 Ah battery, and it worked fine, but if I cranked it for a longer time it would run out.

[theman53]

I am using a 1000ca battery that is traditional acid. Optima has one that is like a taller motorcycle battery that IIRC is still 1000ca and much lighter.

[DJPyro]

^ Same, mine is over 1000CCA, and people laugh when I pop my hood because my battery looks like it came out of a truck... I'll likely switch to an Optima (750ish CCA I think), or some other sealed type when I relocate the battery to the trunk.

My 1000CCA lead-acid starts my car with no problems down below -15C, two glow cycles, no block heater after sitting at work for 4h. Never left me stranded. (knock on wood)

[fatmobile]

Interstate MTP 91,..
 for a MK2

An '84 Rabbit can actually fit a MTP 93
 Megatron plus = MTP

[mystery3]

These guys have a good reputation and very lightweight batteries http://www.braillebattery.com/

The only question I have is pulse cranking amps vs. cold cranking amps?

[VWCaddy]

I'm running an Odyssey PC1200 in my '82 w/ 1.9D engine:
- http://www.odysseybatteries.com/battery/pc1200series.htm



It does fairly well, have upgraded to heavy gauge (1/0) battery cables + new clamps and that has helped cold cranking speed.  Not sure how it would do below about 40F though, about the coldest I have started in.

I run a pair of PC925s in my Toyota 4Runner and find with one battery, cranking speed is noticeable slower than a typical size battery (the 925 is about 380CCA and 24 lbs).  With both batteries in parallel, it cranks over at least twice what a normal battery does, it'll start it in gear in 1st.

[mystery3]

I'd rather keep a high amp battery, ride the bicycle a few more places and lose the pounds from myself.   

If I lost the 20lbs you can shave by switching to a lightweight battery I'd be 112-115lbs, not a healthy weight. If you've done everything else this may be one of the last areas with potential for real savings.
 

[TurboJ]

Same here, not a lot of fat left to shave

I have thought about weight for everything, so obviously the battery sizing also needs to be optimized...
And the VW's factory recommendations should be higher than necessery for a summer car as they have been set for year-round use.

Thanks for the input, guys! I guess I'll take some batteries onto scales when I have my next working day.