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Trickle charging

4K views 21 replies 15 participants last post by  paintergirl 
#1 ·
How long on a normal charge?

Is it safe to leave it overnight?
 
#6 ·
I don't like leaving mine on overnight because I monitor the charge every hour, so I end up charging from flat over two days.
My 10A charger takes somewhere around 24-hours I think.
 
#9 ·
You can't over-charge a battery if you run a small current through it. When the battery is fully charged the resistance of the electrolyte increases and it becomes too much for the small current to flow across it. It's how those battery conditioners that are designed to be plugged in permanently, while the vehicle is stored, work.

If you have a charger with an amp reader, you'll see that the current rate drops as the battery becomes more charged.

Use 2 or 3 Amps and the beast won't ever brew up.. though for a completely flat 65 amp-hour battery you would be looking at 20 hours to fully re-charge it. :D A typical flat battery still has plenty of juice in it, so 8 hours (overnight) should be fine.

You can use a higher rate to give your flat battery a quick boost but 5 or 6 amps should be the max and don't run it like that for very long or you'll heat up the plates too much which may cause them to warp, touch each other, internally short-circuit the cells and lead to an early battery death. A slow charge at the lowest ampage that your charger will support is the best way...

Before you charge it, top up the electrolyte to the "Max" mark with distilled water, since that keeps the cells cool (especially if the level dropped and exposed the tops of the plates) and if you add water after the charge, you're diluting the electrolyte and making the battery marginally less charged.


Ralf S.
 
#10 ·
I too use a solar charger on the dashboard.
On the p2 cars the cigarette lighter is ignition switch operated, and the stereo is permanent live. One of the main flat battery culprits is an after market stereo that is on permanent live.

So on my car I wired the stereo power from the switched live from the lighter, and used the permanent live that was going to the stereo to mount an accessory socket discretely in the footwell to plug my solar charger into.

If I know the car wont be used for a while, I plug the charger in and leave on the seat or the dash.
 
#11 ·
One of the main flat battery culprits is an after market stereo that is on permanent live.
That's a bit of a sweeping statement.

Mine uses less than 5mA when off. 5mA would take 200 hours just to take 1A out of the battery and that alone would take months to make the car unstartable. 5mA is so low it can be ignored.

To put that in perspective, the Scorpion alarm fitted to P1s takes 13mA when armed.

Before blaming the radio, check it's standby current.
 
#13 ·
You guys don't use smart chargers?
I have a Ctek charger.www.ctek.com
I have one which I use when needed ( not very much these days though ).

Not quite fit and forget if you don't have a sealed battery. With an unsealed battery you will get a loss of electrolyte venting to the atmosphere so you need to check the electrolyte and top it up as necessary.

The other benefit of the cTek is its desulphation system.
 
#16 ·
Oh and back on track... I trickle charge my car, overnight is no issue and inside or outside and in rain I would just cover the charger and lift it off the ground, either under the bonnet or under a bucket. your call if doing that as you want to be sure it wont get wet.

I use an old optimate from the late 90s I bought for my bikes, some other one I got free with an elise I bought new in 2001 (lotus sticker peeled off on its own long ago LOL) and also an aldi unit. best one? the aldi one I would say, its the newest.
 
#17 ·
I got my Aldi battery charger last year for £9.99. Great value and ideal for trickle charging.

The Aldi battery charger was a special buy at £13.99 earlier this month, a newer version with an LCD display
 
#19 ·
From your description the battery probably needs replacing. How old is it? If its likely to be more than four or five years I would replace it with a Bosch or Varta battery. (Search AO for recommendations.)

Do you have a separate voltmeter to check the voltage after charging? It should be 12.5v minimum to an average 13.5v fully charged. However a more professional check would be necessary to find its voltage under starting conditions (cold cranking load). If you have any doubt change it now.
 
#21 ·
I too have a CTEK and they are OK to leave connected, no danger of damaging the battery.

Having once had to leave a building in a hurry due to a big hot orangey smelly burny thing (or fire as some would know it) I am rather paranoid about anything being left on when asleep so mine is used during the day only!
 
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