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Batteries?BenzBoy
@benzboy
Club Retro Rides Member 7
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Jan 24, 2007 16:47:28 GMT
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I need a new one for my Merc. Being a bit of an electronics dunderhead, I'm getting confused. The one fitted is 70Ah, but the alternator kicks out 55Ah. Why does it require such a big battery? I'm looking to source one from a scrapyard to keep costs down, but what would happen if I was to fit a less powerful battery to the car (for instance, my girlfriends one off her Golf when she's not looking...)?
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bxer
Part of things
Posts: 457
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Jan 24, 2007 16:53:36 GMT
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You've got bit mixed up between Ah and Amps....
Ah gives an idea of how much juice a battery holds, ie a 70Ah battery will drain in 7 hours with a load of 10 amps, 10 hours with 7 amps etc...
The alternator supplies 55 amps, which is used to charge the battery and run the electrics.
You could steal the Golf battery, but it might struggle to start it if much cranking is involved, or you do a lot of short journeys...
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Batteries?BenzBoy
@benzboy
Club Retro Rides Member 7
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Jan 24, 2007 17:39:43 GMT
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Thanks for the explanation bxer. See, I told you I'm an electronics dunce! ;D I will try and get the beefiest battery I can find down the scrappers. With the car not being started for a few months it might take some cranking, so it'll need to be up to the job!
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Jan 24, 2007 17:42:03 GMT
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if you get a battery thats too big it wont get charged!
on something like that, stick close enough to what the battery in it says. i think my 525 has a 75ah, 280 or 300A should be close enough i'd reckon
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Batteries?BenzBoy
@benzboy
Club Retro Rides Member 7
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Jan 24, 2007 17:53:08 GMT
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if you get a battery thats too big it wont get charged! Good point. I'll look for something similar sized in that case.
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Jan 24, 2007 18:45:57 GMT
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ive got a 2.5 tranny Di battery on my benz. original spec one couldnt handle the ice system.
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Batteries?bazza2541
@GUEST
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Jan 24, 2007 18:49:45 GMT
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don't buy one that has been sitting on concrete.
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bxer
Part of things
Posts: 457
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Jan 24, 2007 22:05:01 GMT
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if you get a battery thats too big it wont get charged! on something like that, stick close enough to what the battery in it says. I think my 525 has a 75ah, 280 or 300A should be close enough i'd reckon Don't worry, it'll still get charged If it's really run down, it'll take longer to get to a full charge, but once it's up to strength, as it'll be using less of it's capacity starting, it'll need less to recharge, so it shouldn't matter... Make sure they've got a tester there (looks like two big skewers and a meter), so you make sure you don't get a dud 'un
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Jan 24, 2007 23:00:53 GMT
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i've known batteries to constantly go flat due to under-charging.
but yeah, not in every case but as long as he doesn't fit a w12 phaeton one in he should be alright anyway lol.
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Batteries?BenzBoy
@benzboy
Club Retro Rides Member 7
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Jan 24, 2007 23:48:15 GMT
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don't buy one that has been sitting on concrete. Why's this? I'll see what the scrap dude has. Last time I bought one he fired up the car it was on to see if it was OK. Not scientific but it worked alright on my Volvo. For a fiver I'll risk it ;D
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Batteries?bazza2541
@GUEST
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Jan 25, 2007 11:01:30 GMT
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Something to do with setting up a reaction that fubars the battery.
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Jan 25, 2007 11:36:37 GMT
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I'm not sure if thats an old wifes tale or not. After all battery cases are very good insulators...
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1941 Wolseley Not Rod - 1956 Humber Hawk - 1957 Daimler Conquest - 1966 Buick LeSabre - 1968 Plymouth Sport Fury - 1968 Ford Galaxie - 1969 Ford Country Squire - 1969 Mercury Marquis - 1970 Morris Minor - 1970 Buick Skylark - 1970 Ford Galaxie - 1971 Ford Galaxie - 1976 Continental Mark IV - 1976 Ford Capri - 1994 Ford Fiesta
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bxer
Part of things
Posts: 457
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Jan 25, 2007 11:51:28 GMT
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don't buy one that has been sitting on concrete. Something to do with setting up a reaction that fubars the battery. This had me intrigued... a quick search found this, which also has loads of other useful info about batteries... From the page, it looks like you've gone uber-retro ;D "In the early 1900s, when battery cases were made of porous materials such as tar-lined wood boxes, storing batteries on concrete floor would accelerate their natural self-discharge due to external leakage. Modern battery cases are made of polypropylene or hard rubber. These cases are sealed better, so external leakage-causing discharge is no longer a problem, provided the top of the battery is clean and free from wet or dried electrolyte and the same temperature as the floor."
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Last Edit: Jan 25, 2007 11:54:23 GMT by bxer
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Batteries?bazza2541
@GUEST
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Jan 25, 2007 12:09:59 GMT
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I don't know about the science (read magic) behind it, but I do know that it happens, even yet. If you don't believe me try it on a good battery, for about a fortnight and then see if it will hold a charge.
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Jan 25, 2007 12:20:28 GMT
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I often have that exact same problem when fitting them in my car...
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1941 Wolseley Not Rod - 1956 Humber Hawk - 1957 Daimler Conquest - 1966 Buick LeSabre - 1968 Plymouth Sport Fury - 1968 Ford Galaxie - 1969 Ford Country Squire - 1969 Mercury Marquis - 1970 Morris Minor - 1970 Buick Skylark - 1970 Ford Galaxie - 1971 Ford Galaxie - 1976 Continental Mark IV - 1976 Ford Capri - 1994 Ford Fiesta
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