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I know there has been discussion here in the past about the charging of little used car batteries using trickle chargers that are designed to be connected to the battery for long periods without disconnecting the vehicle's positive and negative leads. Does anyone have experience of the Draper Battery Master? The reason I ask is I was considering buying one of the more expensive chargers, but my annual subscription to Practical Classics magazine is due and I see today that the latest subscription "free gift" is one of these Draper chargers!
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www.motor-world.co.uk/show_prod.php?prod_id=1691
as you will see its £17.99 to buy Ex post/p dont have personal experience of it.But you may make up your own mind on that?
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Was mech1
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Yes, I use one all the time on my car as it sits in the garage Mon to Fri whilst i use a company wagon for work.
It's very good. Does the trick for me, anyway.
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Most battery chargers, (ALL the cheaper ones and all the so called trickle chargers) provide a constant current to the battery which means that the voltage will rise as the battery is charged. If the voltage exceeds about 13.7-13.9v (depending on temperature) the battery cells will start gassing. Some of these chargers will give voltages up to 18v which can also damage vehicle electronics if they are in the live circuit.
Having said that,whilst the mini Clarke and Draper chargers are technically trickle chargers the current is so low (300mA) that, in practice, the voltage doesnt rise beyond about 13.5v and the cells do not start gassing. So whilst, theoretically, they are not suitable for permanent connection I frequently leave mine connected to the lighter socket for a week or more and the max voltage I have ever measured is 13.6v
(The mini Draper or Clarke chargers referred to above are the type that is self contained and plugs into a three pin power socket like a phone charger).
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Have used similar trickle chargers on a boat and have found that you must top up water regularly. In future, I might put the charger onto a mains timer, so it only comes on for 2 days a week.
Tim
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Victorbox
One of my friends has one of these, and has used it for keeping batteries up to charge during holidays and it's been fine. I get the impression, like others here, that it tries to continuously charge the battery, unlike the (£40) airflow, which actually monitors the voltage and only charges intermitently as required, which may be better for long term use. One of these has kept my little used Minor battery fine for a couple of years You pays your money .............
JS
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I think the Airflow is a relatively crude device. It is only voltage regulated and allows the battery to partially discharge before switching on again. There are many other more sophisticated electronically controlled chargers (for example Accumate, Gunsons) which have an algorithm charge process and will provide a continuous float charge to maintain a battery at optimum charge. One of the cheapest electronic ones I found at Argos last year for about £26
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Isn't a little current flow in both directions desirable?
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If you mean is it a good idea to cycle a battery by discharge and charge the answer, in the case of a lead acid battery, is no. The less discharge/charge the longer the battery life and the longer its ability to produce max amps and avoid sulphation. Thats why three or four stage battery chargers always have a float stage to maintain the battery in optimum condition.
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I use something called a Delfan \"battery tender\" I bought in the US some years ago for my motorbike. Which has a sealed battery anyway.Cost about $39 from Sears IIRC. Battery is into its 5th year (not bad for a bike) and I always get a full charge of power when I crank it up.
It has a red light for \"charging\" mode and a green one for \"storage\".
I swear by the thing.
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