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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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10th Jan 2021, 6:48 pm | #21 |
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Re: Car battery charger project.
A big zener diode was used on British motorcycles for charge regulation. It was crude but effective (just like the 'bikes) for wet cell batteries. I wouldn't bother making your own as things like these https://www.screwfix.com/c/auto-clea...rs/cat12010001 are readily available and not costly.
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10th Jan 2021, 8:52 pm | #22 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
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Re: Car battery charger project.
Hi Malc, I may have a simple cheap and cheerful ammeter (0-4A?) if you are interested
Ed |
10th Jan 2021, 9:58 pm | #23 |
Nonode
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
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Re: Car battery charger project.
I have had quite a few very old chargers over the years. Throw out the selenium rectifier and fit a modern silicon bridge. That will increase the output voltage, not a good idea, so you need to add a bit of series resistance. I usually use maybe three wire wounds, 0.5, 1.0 and 2.2 ohm, switched to control charge current.
I have recently bought a modern intelligent one, which I regularly cycle over all my lead acids used for whatever is needed including "jumping" the bike or even car. My good old 'un does have 6v, unlike the clever one, so that is useful for the 6v coil ignition I fitted to the cement mixer. Any old electrolytic connected to the output will confirm the maximum output voltage. Les. |
10th Jan 2021, 10:20 pm | #24 |
Octode
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Location: Willington, County Durham, UK.
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Re: Car battery charger project.
Ed, thanks for the offer of the meter PM sent. Just need a 0-15 volt meter now.
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Malc Scott |
10th Jan 2021, 11:58 pm | #25 |
Nonode
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Location: Cornwall, UK.
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Re: Car battery charger project.
There isn't much in older chargers, as far as my experience of seeing inside a couple to repair broken leads goes. What is the extra circuitry inside one of those 'smart' chargers one can leave connected and that 'sense' battery state? Is that easily added in to something made by the home mechanic, taking into account the behaviour in Diabolical Artificer's PDF?
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11th Jan 2021, 12:11 am | #26 |
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Re: Car battery charger project.
A reminder start mentioning vehicles engines etc will just get the thread closed, posts edited or deleted Oldcodger did warn of this early in the thread.
Cheers Mike T
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Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |
11th Jan 2021, 11:44 am | #27 | |
Nonode
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Location: Stafford, Staffs. UK.
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Re: Car battery charger project.
Quote:
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11th Jan 2021, 2:18 pm | #28 |
Hexode
Join Date: Jan 2016
Location: Ramsgate, Kent, UK.
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Re: Car battery charger project.
I replaced a selenium rectifier with a silicon one in a 12v battery charger in the distant past and this resulted in an excessive charge current due to the increased voltage. I spotted the transformer overheating and switched off quick.
I cured this by adding a few turns to the secondary winding and connecting them in anti-phase, I had to experiment with the number of turns to get the charge current right, only needed about 5 turns IIRC. I could only do that as I had enough space to get some turns on the transformer. The advantage with this method vis adding resistance is the voltage is dropped so the battery won’t overcharge.
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Andrew Illegitimi non carborundum |
11th Jan 2021, 2:44 pm | #29 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
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Re: Car battery charger project.
Hmm. Plenty of 8-16v dashmount voltmeters around, but where does Malc get a 0-15v..? (unless repurposing a more sensitive one with a series resistance)
I recall that my ancient charger shows an off-load output of around 16v on an Avo (no smoothing and a selenium rectifier)- is this a potential concern with a vehicle 45Ah battery?...and is my old meter likely to be showing the peak voltage? Dave |
11th Jan 2021, 5:10 pm | #30 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
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Re: Car battery charger project.
(My mistake, there's loads of 0-15v voltmeters available, but many are square modern lab bench type)
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11th Jan 2021, 10:11 pm | #31 |
Dekatron
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Location: Newcastle upon Tyne, Tyne & Wear, UK.
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Re: Car battery charger project.
Hi Malc, is this ammeter suitable?
A bit garish but goes up to 10A. There might be a lower current one (4A?) about but not turned it up yet, nor any similar voltmeters. Approx 2" square I do have a few 1R or so 20W resistors if you need them for current limiting, possibly even a switch to go with them. PM me with address details etc Cheers, Ed |
11th Jan 2021, 10:19 pm | #32 |
Octode
Join Date: Aug 2006
Location: Willington, County Durham, UK.
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Re: Car battery charger project.
Hi Ed, thanks for the offer but i think i will use a 0-4 or 5a I sent you a PM yesterday, Malc.
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Malc Scott |
12th Jan 2021, 10:22 pm | #33 |
Dekatron
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Location: Newcastle upon Tyne, Tyne & Wear, UK.
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Re: Car battery charger project.
Hi Malc, pictures of the 4A & 5A meters (a bit under 2" dia) as well as a square 24v voltmeter. Any use?
Ed |
13th Jan 2021, 10:56 am | #34 |
Octode
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Location: Willington, County Durham, UK.
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Re: Car battery charger project.
Hi Ed, PM sent. Cheers, Malc.
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Malc Scott |