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Early 1978 battery recommendation/ and what is this connection?
I have a '78 US#412 with a very large battery box and I need a new Battery. My battery shows 12.4 volts but only 345 amps and i have been having a warm starting issue. I assume from the increased resistance from heat or expanding gaps in the starter or alternator. Those things aside I want to get a NEW battery.
I am a little confused on the "Group sizes". I see H8, H9, 48, 49 and other codes for sizing used. It seems it would be good to get a smaller( because it's lighter) battery if possible, but I am not sure if my car has any hold down at all for the battery so a smaller one might cause it to move around. I know the current battery shows cranking amps at 850 but I am unsure of the RC / reserve capacity rating. I see some battery's that websites say fit my car (I take that with a grain of salt) and they are like 50-60 lbs! I there something folks recommend in their OB's?
The 'correct' battery for '78 is a group 49, but it's interesting- the pic of the battery on page 57 of the 78 owner's manual is a much smaller battery, there must be 4-5" of space behind it. AFAIK there's no provision for a hold-down in '78. The WSM specs two battery capacities, 66Ah and 88Ah, and there's an option code for the stronger battery used worldwide from '80 through '81. No idea whether they were specifically called out in '78-79, nor whether the two different batteries were different physical dimensions.
Just a WAG, but I bet that extra connection is related to the automatic and is unused on a 5-speed. And I think that plunger switch hanging next to your ground cable is for the rear hatch light switch, which is an early car (78 only?) thing.
I think the Group 49 was spec'd for single-exhaust cars. The shorter Group 48 (same as H6) battery is needed for the dual-exhaust cars, since the crossover pipe passes between the battery box and the rear differential cover. Group 49 was used in many Mercedes models, some VW models, and I'm sure others that slip my mind right now.
I'm trying to remember if that cover is metal or plastic. If you need a hold-down, it wouldn't be too tough to adapt a generic H/crossbar hold-down for the early cars, particularly the first OB series where the battery box is bolted to the back of the gearbox rather than being part of the rear tub.
So I went with this from walmart https://www.walmart.com/ip/16782701 800 cranking, 650 cold cranking. not sure of the RC though (reserve capacity) considerably smaller and lighter than what was in there. I guess it will work fine. It got good reviews, we'll see.
Last edited by crushingday; 08-25-2016 at 11:24 PM.
What's your plan for a hold-down for the baby-sized battery?
Full disclosure:
I have the Wal-Mart "premium" H6 battery in my S4 going on four years now, with ZERO issues. It lives most of the time with a 'smart' charger/maintainer plugged in. It easily passed the specific-gravity test in the spring after it's second winter storage, something the previous parts-store battery had trouble with. The first two years with this battery, it was in a "regularly driven all year" situation before the relocation to a four-seasons location.
What's your plan for a hold-down for the baby-sized battery?
Full disclosure:
I have the Wal-Mart "premium" H6 battery in my S4 going on four years now, with ZERO issues. It lives most of the time with a 'smart' charger/maintainer plugged in. It easily passed the specific-gravity test in the spring after it's second winter storage, something the previous parts-store battery had trouble with. The first two years with this battery, it was in a "regularly driven all year" situation before the relocation to a four-seasons location.
I am not sure really.. Drive slowly? I understand it is best to have one but is it really necessary?
Perhaps I can find the appropriate material i.e. an old plastic cutting board, a storage container lid etc. and fit that to it. I am not sure
I am not sure really.. Drive slowly? I understand it is best to have one but is it really necessary?
Perhaps I can find the appropriate material i.e. an old plastic cutting board, a storage container lid etc. and fit that to it. I am not sure
Did you look at the H8 battery? That's the size you really need to fill the well and such. The factory-fitted cables are long enough for the bigger battery, but may be too short to reach the terminals on the shorter battery.
As far as the hold-downs, they are critical. The battery will literally rattle/bounce around in the well. With no hold-down, the real (and well-documented...) risk is that the positive post and connection will contact the lid, and weld itself there in a fraction of a second. A hard short-circuit like that will cause the car to immediately stop running as ignition and fuel pump power are shunted to ground through the lid. There's a very real risk of battery explosion, typically contained within the battery case fortunately. Now the lid is welded to the battery and there's no easy way to disconnect it, not that you'd really want to mess with it immediately. With the cables helping maintain the battery position fore-and-aft as well as vertically, battery movement will loosen the connections or break the cables, sooner or later.
You can make spacer blocks out of wood to limit fore-and-aft movement in the box. Adding a clamp and/or a rubber mat on top of the battery can help with the short-circuit risk, but only the clamp will hold the battery in place.
So I went with this from walmart https://www.walmart.com/ip/16782701 800 cranking, 650 cold cranking. not sure of the RC though (reserve capacity) considerably smaller and lighter than what was in there. I guess it will work fine. It got good reviews, we'll see.
CCA is pretty meaningless unless you are AK or Canada eh. The battery you got will have a lower amp-hour rating than the group 49. This is important for older cars where there is a longer crank time, as you've noticed with hot start issues. The smaller battery will heat up faster, and not dissipate the cranking load as fast as the big group 49 battery. I think the 49 batt is rated at 92Ah, and a 41 is prolly more like 60Ah. So, don't crank your starter a long time, as it will tend to over heat the battery in summer, and maybe boil off some of the electrolyte, or warp a plate. When that happens, the battery is basically dead.
A V8 engine about 5L or so, with a high C/R requires a pretty decent battery, which is why the 928 came with that big dude we have in there. Also, 928s are harsh on batteries anyway, and the newer the car, the harder they are on batteries. I'm sure you'll get away with the smaller battery for a time, but it's not going to last very long if you continue to have hot start problems. I would take it back, and find the group 49 or H8, or whatever it is, and let the larger mass of the plates and electrolyte dissipate the cranking power needed.
If you doubt me, touch the side of the batt after having run the starter for 30 seconds. It'll be plenty warm.
Wal Mart did carry the group 49 batteries? I have a 79 - 928- ROW ---I got mine from Autozone -Platinum Series- $174.98 - it has a guarantee. Has held up well - again, I highly recommend an alternator upgrade - it has made a world of difference in performance of all of the electrical components on the car.
Warranty is one reason for going with Walmart - their warranty is good at any store. The Advance system means that the store in BF Egypt doesn't know you or have a record of your purchase. The store of original purchase should still have the record, or if you buy it online (by far the best way) you will have your own record. Whether you will have it with you is another question.
08-24-2016, 05:33 PM
Early 1978 battery recommendation/ and what is this connection?
