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15th May 2014, 07:56 | #21 | |
I really should get out more.......
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From what I read in your text, it would seem that this system wouldn't get close to any of the on-board computers, but can only work with the key on (at least) accessoires. Otherwise the relays don't get powered and the electricity can't reach the battery. However, I do have an aux socket in the boot that's directly connected to the car battery, without any circuitry in between (only a fuse). That should work in any case. But since it's in the boot I'd still need to get out of the car .
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15th May 2014, 08:06 | #22 | |
Doesn't do things by halves
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Simon
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15th May 2014, 08:20 | #23 | |
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Try this simple experiment.... Connect one flat and one fully charged battery together, via an ammeter. You will get a small initial current flow as the voltage on the two batteries equalise, then there will be no further flow at all, nothing at all, zilch. The reason being that their is no voltage differential between the batteries to make the current flow from one to the other. If you have a bank of batteries connected in parallel, standard practice is to do what is called an equalising charge occasionally. The batteries are left on charge for an extended period, to ensure all of the batteries are brought up to a fully charged state. The reason for that equalising charge is that the low batteries cannot be charged from the fully charged batteries, because they lack the voltage to transfer their charge. Once again - batteries are not buckets, nor do they behave like buckets! The public are being fooled by the sellers of these items and if you doubt that you only need read the many reviews which confirm they do not work.
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15th May 2014, 08:27 | #24 |
This is my second home
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That would work fine, to keep a battery topped up in the boot, to a full charge. I have done that myself. The small size of the wiring and the resistance helps prevent large currents flowing back to the main battery, yet it will be big enough to allow the battery to be restored to a full charge. I would suggest adding an extra fuse, very close to the battery.
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Harry How To's and items I offer for free, or just to cover the cost of my expenses... http://www.the75andztclub.co.uk/foru...40#post1764540 Fix a poor handbrake; DIY ABS diagnostic unit; Loan of the spanner needed to change the CDT belts; free OBD diagnostics +MAF; Correct Bosch MAF cheap; DVB-T install in an ex-hi-line system; DD install with a HK amp; FBH servicing. I've taken a vow of poverty. To annoy me, send money. |
15th May 2014, 08:31 | #25 | |
I really should get out more.......
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I just bought a double 12v socket from Conrad and pulled the wires through the car into the boot. Apart from it giving power to whatever you want, I use 1 socket to power my sub in the boot. (I replaced the screws for smaller black ones)
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15th May 2014, 08:42 | #26 | |
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Simon
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15th May 2014, 12:11 | #27 |
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If the battery just did not have quite enough power by the time you connected that useless thing and waited 15 minutes you could have got a push from some passers by anb be home but only if its a manual
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15th May 2014, 13:13 | #28 | |
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If you would care to go and verify that from any graph depicting charge vs voltage, you could perhaps go and look at the link in the previous post? It is perfectly sensible to expect two batteries connected together to equalize their charges, and that is indeed what happens. What would be unreasonable, is to expect the one battery to charge the other fully, and I have never claimed that. What I have claimed, and what is indeed true, is that if you connect another battery, that is charged to your discharged car battery, that a flow will go from the charged battery into the uncharged battery and that will persist, until the voltage difference is nil. So the case is, in this story, it will help to connect any other battery with a higher charge to your car battery. |
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15th May 2014, 13:32 | #29 | ||
I really should get out more.......
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15th May 2014, 13:36 | #30 |
I really should get out more.......
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It might be helpfull for the discussion if you mention voltage, ampere or watts when you say 'charge'. Not 100% about English, but in the Dutch language 'charge' can mean either voltage, ampere or watts.
(for the smartypants; I know power is voltage x ampere ).
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