Battery charger grille


4 May 2008
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United Kingdom
French neighbour has a rechargeable, well it was, sprayer for natures little pests. The charger made in china, mains input, 12v 1.0A IP30 output to a rechargeable lead acid 12 V 7.5Ah battery has grille itself. My question is can I connect a normal car battery charger to the battery or will it also become grille. My standing in the commune which is currently lower than a snakes testicles could become enhanced on the back of your advice, so thanks in advance.
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Using a larger battery, assuming no fault, OK. It is the charging where extreme care is required.
At 0.1A it is unlikely any battery will have a problem.
At 0.8A it can seriously damage a small battery.
Car type battery charger definitely not recommended. Provide specific details of the battery for an informed opinion on a suitable charger. Is it SLA (sealed lead acid), Ni-Cad, Ni-Mh, Lithium-Ion or some other lithium based chemistry. All of these need different charging regimes.

"Grille" should be read as "Cooked" means much the same but .....
Have just reread your text :(:(
I see you say it is lead acid.
These require charging at a constant current followed by a period at constant voltage.
I'd suggest you get a charger specifically designed for such a regime to preserve battery life.
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Four basic ways to charge a lead acid battery.
1) Constant voltage around 13.4 volt for a 12 volt battery, used where battery is a stand-by.
2) Average charge often 0.5A at around 14 volt, with instructions not to charge more than 14 hours, often found with things like hedge cutters.
3) Stage charger, typical start at 3.8A dropping to 3A, then 0.8A and then 0.1A sold by Lidi and ctek MXS 3.8 as an example, plug in and forget.
4) Pulse charger, used a lot with solar panels, designed where the battery is used at same time as being charged.

Some units are very poor, a valve regulated lead acid (VRLA) should last around 7 years, but intruder alarms, stair lifts etc often have such a poor charger lucky to get 2 years out of the battery.

Some units, like the power packs made to jump start cars are supplied with a charger which can be left connected for years, but the battery that is used as it is charged is the hard one, simply adjusting voltage between 13.2 and 13.8 according to normal load you can get away with using and charging at the same time. However where charging time is limited, as with solar panels, you want to bang in as much as possible in a short time, So charger uses pulses, and it measures the decay time to adjust pulse size, also used with narrow boats.

With a fork lift, mobility scooter, milk float, then speed is important but battery is not used at same time as being charged, so three stages, constant current until set voltage, then constant voltage quite high around 14.8 volt for a 12 volt battery, but current is measured and once it drops to set level the voltage is reduced to around 13.6 volt. So 80% of charge is very quick, and last 20% is slow.

For a 7 Ah battery I use one of these
set to under 14 Ah it charges at 0.8A to start with, then 0.1A to finish off. With over 14 Ah it goes to 3.8A. However it requires the "MODE" button to be pressed, so depends what you are using the battery for.

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