charging jump battery using car

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I just found out that this is a more logical technique to use a battery to jump a car. A battery will tend to have more juice than a typical jump box. I like to know if it is possible to leave a car running for about 5 minutes to recharge the battery used as jumper so that it can be reused on the same trip with full confident. It would be much better than having to carry a battery charger and find a place to recharge it. Thank you for your help.
 
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I don't think it would recharge in 5 minutes. Depending on size it will probably start the vehicle several times before it needs recharged, however.
 
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^ what he said. If you get the $4.99 digital voltmeter from harbor freight you can see state-of-charge, below 12.6 volts at room temp means you should leave the jumper cables on for a while. Going from 80% charge to 90% charge happens much faster than the last little bit, because the battery internal resistance will be less. A slightly higher idle, 1800 RPM or so, will help too, especially since your car battery will be very flat with all the problems you're having.
 
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Agreed. You could just hook up a battery charger to it every now and then. I'd keep it in the trunk, than hook up a charger to it once or 2x a week.
 
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When I use my jump starter, I typically leave it connected for a couple of minutes. I figure this is enough to replenish some of the charge. I've also heard that (for nearly dead ones) battery degradation can be reduced by keeping the initial charging current down a bit; keeping it connected will suck up some of the current. You might also be able to rig a charging circuit from the lighter adapter. Still - I'm not too keen on keeping a spare unsealed battery around, just in case it leaks.
 
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Bad idea to charge a battery from a battery except in a real emergency. For preference you want to charge a battery at no more than 10 AMP to not reduce its life. I like a taper charger overnight or until the charge has tapered to less that 1 Amp.
 

M1Accord

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I guess this is why a good jump box is as expensive as a battery and much more expensive for the high end industrial grade one. I still can't determine if the Chicago Electric Power Tools jump box I got from Harbor Freight Tools is good. The shop manager that just helped me fix my starting problem thinks highly of it but he's a nice person and may not have want to say bad things about stuffs. Anyone with experience on them or Harbor Freight Tools in general? Is this a good brand and is the store a place to buy real tool unlike Wally and Dollar Tree.
 
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Well, fill us in on how you fixed the starting problem. I assume this is the the same problem you mentioned in your previous thread, concerning your battery running down.
 
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 Originally Posted By: Eddie
Bad idea to charge a battery from a battery except in a real emergency. For preference you want to charge a battery at no more than 10 AMP to not reduce its life. I like a taper charger overnight or until the charge has tapered to less that 1 Amp.
That's not what I believe anyone is proposing here. The idea is to charge the battery off of the alternator. However - there are some portable battery starting kits that do work by slowly recharging a drained battery with a charged one. Some can even do it via the lighter accessory plug. The general idea is to put enough charge into the drained battery to allow it to start. The "donor" battery doesn't even have to be very powerful. However - it's difficult to judge how long it needs to remain connected. I've heard 10-15 minutes. I have a couple of male-male lighter plug cords for recharging a portable jump starter. One of them has a built-in 10 amp fuse at one of the lighter plug ends. Something similar could be rigged to connect to a pair of battery clamps, but my worry would be if the battery or the clamps get shorted.
 
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 Originally Posted By: M1Accord
I guess this is why a good jump box is as expensive as a battery and much more expensive for the high end industrial grade one. I still can't determine if the Chicago Electric Power Tools jump box I got from Harbor Freight Tools is good. The shop manager that just helped me fix my starting problem thinks highly of it but he's a nice person and may not have want to say bad things about stuffs. Anyone with experience on them or Harbor Freight Tools in general? Is this a good brand and is the store a place to buy real tool unlike Wally and Dollar Tree.
Again - looking at the photo, this wouldn't be at the top of my list. For myself, Schumacher Electric is at the top of my recommendation list because they design the products they sell, own the factories where their products are made, and keep tight quality control. However - of primary importance is whether or not this thing will start your car with a severely depleted battery. Sounds to me like it's got a 24 amp-hour battery. Even if the 600/1200 amp rating is generous, this thing should be able to start pretty much any passenger car with a depleted battery. It might even start a small car without a battery. My first encounter with one of these jump starters was when I intentionally left on my parking lights on my WRX 3+ years ago. I figured it would help with visibility just in case someone was driving or biking in the lot at night. The manager of the hostel I was staying in said something about it, but I thought the battery should be able to last. By the morning, the power locks barely worked and the dome light was extremely dim. I asked the manager for help and he went to his car and pulled out a jump starter; apparently his van had electrical problems and he kept it around just in case his battery got depleted. It was one of those bright yellow ones with toy-like plastic - similar to yours but probably not as heavy. It may not have been made out of the best materials, but it worked. Your best bet would be simply to try it out when you need it. I could understand where one of the smaller ones may be borderline; they may barely work depending on how much charge is left in the main battery. I don't think there's really much of a problem with the charging circuit of that B&D jump starter you mentioned in another thread. It's simply a very, very weak unit compared to others on the market. However - the one you got from Harbor Freight is so big that I think will either work or it won't.
 

M1Accord

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I see Schumacher Electric jump box at AAP but it doesn't seem to have much amp output and is quite light. The price is around 100-150 dollars. I didn't look inside to see how good its construction is. Yes, the yellowish color does make certain thing toy like but the B&D is made of the same exterior material, just in black color. I know the B&D I have, although brand new in appearance, is absolutely junk. I may just take my other for the trip and buy a Snap-On jump box when I get back. The shop manager here has the Maco connection and can order me one. I may have to go with that route.
 
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Dunno about Schumacher quality. I once bought a Schumacher handheld battery load tester (cheese grater type) because it was low priced and when I tested it, found it only put a 50 amp load on the battery when most of the handheld units put a 100 amp load. Took it back to the store and got my money back. What was disappointing was that nowhere did Schumacher mention that it only puts out a 50 amp load. They made the usual claims about being able to test batteries up to 1000 CCA. Heck, I could put a 10 ohm power resistor in a case and claim that it tests batteries up to 1000 CCA. I have never looked at Schumacher since that bad experience.
 
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 Originally Posted By: George7941
Dunno about Schumacher quality. I once bought a Schumacher handheld battery load tester (cheese grater type) because it was low priced and when I tested it, found it only put a 50 amp load on the battery when most of the handheld units put a 100 amp load. Took it back to the store and got my money back. What was disappointing was that nowhere did Schumacher mention that it only puts out a 50 amp load. They made the usual claims about being able to test batteries up to 1000 CCA. Heck, I could put a 10 ohm power resistor in a case and claim that it tests batteries up to 1000 CCA. I have never looked at Schumacher since that bad experience.
Was it this one? If it is, the specs are clearly stated on their own sales page. http://store.schumachermart.com/bt-100.html
 Quote:
BT-100 - 100 amp Battery Load Tester For everyday do-it-yourself use. Easy to operate. Test load, battery condition, starter motor draw and complete charging system diagnosis. Works on 6 and 12 volt batteries. • 100 amp load test – for 6 volt batteries. • 50 amp load test – for 12 volt batteries. • Tests 6 and 12 volt batteries – up to 1000 CCA.
Perhaps you had some disappointment with some of their basic products. They also have a wide range of more professional-line stuff. However, what was getting at is that they've got a real business with real engineers, technicians, and customer support staff. Their customer support phone number is right on the labels of their products. Their products are designed in-house. They own their own factories in Mexico/China and supervise them directly. I've read reviews of their products where the customer thought there was a defect, and they sent out a replacement product promptly. They're not like the brand that the OP has (Chicago Electric Power Tools) which seems to just order from a generic manufacturer in China and where you can't seem to find any information about the company selling the product. I would unequivocally recommend any version of the Mighty-Mite jump starter. I also couldn't figure out the whole thing about different Vector Manufacturing jump starters - especially the difference between the black/orange Black & Decker relabeled versions and the ones only carrying the Vector name. I looked it up and apparently Vector was bought out by B&D three years ago. http://www.vectormfg.com
 
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That was probably the tester I bought. I am not sure since this goes back about seven years. Nowhere on the tester, packaging or instruction sheet did it mention 50 amps, I had to hook it up to my truck battery and measure the current. I think I did it in the parking lot of Princess Auto, where I bought it, and I took it right back to the 'Returns' counter and got my money back.
 
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