Hi All,

I've been aiming to buy a new car battery trickle charger for a while
- I've noticed that there are some very small trickle chargers that
are 500mA output and looks like a plug in power block.

Then I found I had an old adaptor from a defunct jump start unit - the
jump start was a yellow Rolson model for jump starting 12v car
batteries - but the charger that came with it is, strangely enough,
labelled 15v 500mA.

A subsequent jump starter (same yellow model, different branding) had
a charger that was labelled 12v. Both these jump starters have gone
west and I no longer have them.

Therefore could I use this little 15v/500mA charger as a trickle
charger for my car battery, like the block trickle charges I've seen?
If so I think all I would need is a couple of large crocodile clips to
put on the lead - but for charging purposes which goes on the red
positive battery terminal ?

I have a feeling that the charger's negative goes on the battery's
positive terminal and the charger's positive goes on the battery's
negative terminal. Is this right?

Thanks, Tom

"Tom" wrote in message
...
Hi All,

I've been aiming to buy a new car battery trickle charger for a
while
- I've noticed that there are some very small trickle chargers that
are 500mA output and looks like a plug in power block.

Then I found I had an old adaptor from a defunct jump start unit -
the
jump start was a yellow Rolson model for jump starting 12v car
batteries - but the charger that came with it is, strangely enough,
labelled 15v 500mA.

A subsequent jump starter (same yellow model, different branding)
had
a charger that was labelled 12v. Both these jump starters have gone
west and I no longer have them.

Therefore could I use this little 15v/500mA charger as a trickle
charger for my car battery, like the block trickle charges I've
seen?
If so I think all I would need is a couple of large crocodile clips
to
put on the lead - but for charging purposes which goes on the red
positive battery terminal ?

I have a feeling that the charger's negative goes on the battery's
positive terminal and the charger's positive goes on the battery's
negative terminal. Is this right?

Thanks, Tom

No! negative to negative and positive to positive or your wall wart
will be history pdq

AWEM

In article ,
"Andrew Mawson" writes:

"Tom" wrote in message
...
Hi All,

I've been aiming to buy a new car battery trickle charger for a
while
- I've noticed that there are some very small trickle chargers that
are 500mA output and looks like a plug in power block.

Then I found I had an old adaptor from a defunct jump start unit -
the
jump start was a yellow Rolson model for jump starting 12v car
batteries - but the charger that came with it is, strangely enough,
labelled 15v 500mA.

A subsequent jump starter (same yellow model, different branding)
had
a charger that was labelled 12v. Both these jump starters have gone
west and I no longer have them.

Therefore could I use this little 15v/500mA charger as a trickle
charger for my car battery, like the block trickle charges I've
seen?
If so I think all I would need is a couple of large crocodile clips
to
put on the lead - but for charging purposes which goes on the red
positive battery terminal ?

I have a feeling that the charger's negative goes on the battery's
positive terminal and the charger's positive goes on the battery's
negative terminal. Is this right?

Thanks, Tom

No! negative to negative and positive to positive or your wall wart
will be history pdq

Many of these wall warts do not contain any voltage regulation and
will kill a lead acid battery if connected for significantly longer
than the time to charge it. There may be a clue in the original
instructions for the jump-starter, if it says something like don't
charge for more than 24h (although absence of such a statement is
no guarantee as the voltage regulation may be in the part you're
chucked out).

A friend accidently left a jumpstarter charging for a week on one
of these, and that was the end of the battery. I have the same
model, but I used a proper voltage regulated charger and not the
wall wart which came with it, and some 6 or 7 years later, mine
still works fine.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In message , Andrew Gabriel
writes
In article ,
"Andrew Mawson" writes:

"Tom" wrote in message
...
Hi All,

I've been aiming to buy a new car battery trickle charger for a
while
- I've noticed that there are some very small trickle chargers that
are 500mA output and looks like a plug in power block.

Then I found I had an old adaptor from a defunct jump start unit -
the
jump start was a yellow Rolson model for jump starting 12v car
batteries - but the charger that came with it is, strangely enough,
labelled 15v 500mA.

A subsequent jump starter (same yellow model, different branding)
had
a charger that was labelled 12v. Both these jump starters have gone
west and I no longer have them.

Therefore could I use this little 15v/500mA charger as a trickle
charger for my car battery, like the block trickle charges I've
seen?
If so I think all I would need is a couple of large crocodile clips
to
put on the lead - but for charging purposes which goes on the red
positive battery terminal ?

I have a feeling that the charger's negative goes on the battery's
positive terminal and the charger's positive goes on the battery's
negative terminal. Is this right?

Thanks, Tom

No! negative to negative and positive to positive or your wall wart
will be history pdq

Many of these wall warts do not contain any voltage regulation and
will kill a lead acid battery if connected for significantly longer
than the time to charge it. There may be a clue in the original
instructions for the jump-starter, if it says something like don't
charge for more than 24h (although absence of such a statement is
no guarantee as the voltage regulation may be in the part you're
chucked out).

A friend accidently left a jumpstarter charging for a week on one
of these, and that was the end of the battery. I have the same
model, but I used a proper voltage regulated charger and not the
wall wart which came with it, and some 6 or 7 years later, mine
still works fine.

There's no way that a 500mA wall wart could ever deliver enough current
to kill a car battery.

The important thing would be to check what the charging current actually
was (flat battery and full battery), and see if there was enough / not
too little to be of use / not too much so that it would kill the wall
wart.
--
Ian

On Feb 20, 7:48*pm, Ian Jackson
wrote:

There's no way that a 500mA wall wart could ever deliver enough current
to kill a car battery.

It can do it if it's connected in reverse to an already-flat battery.

In message
,
Andy Dingley writes
On Feb 20, 7:48*pm, Ian Jackson
wrote:

There's no way that a 500mA wall wart could ever deliver enough current
to kill a car battery.

It can do it if it's connected in reverse to an already-flat battery.

It's unlikely that a 'flat' battery would have zero volts in it. More
likely is that one cell has dropped to zero, or even become
reverse-charged. Instead of 12V, the voltage would be 10V - or even 8V.
This is more than enough to blow a reverse-connected charger to buggery!
--
Ian

In article ,
Ian Jackson writes:
There's no way that a 500mA wall wart could ever deliver enough current
to kill a car battery.

Current, no.
Charge, yes, if there's no voltage regulation.
It just takes longer at 500mA.

The important thing would be to check what the charging current actually
was (flat battery and full battery), and see if there was enough / not
too little to be of use / not too much so that it would kill the wall
wart.

That's another issue.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 20 Feb,
Ian Jackson wrote:

There's no way that a 500mA wall wart could ever deliver enough current
to kill a car battery.

The important thing would be to check what the charging current actually
was (flat battery and full battery), and see if there was enough / not
too little to be of use / not too much so that it would kill the wall
wart.

I recently killed a battery by substituting an AC wall wart for the genuine
article. Another family member had shuffled the warts and I didn't spot it in
time. I now attempt to label all warts with their original use. It may save
other expensive mistakes.

--
B Thumbs
Change lycos to yahoo to reply

In message , writes
On 20 Feb,
Ian Jackson wrote:

There's no way that a 500mA wall wart could ever deliver enough current
to kill a car battery.

The important thing would be to check what the charging current actually
was (flat battery and full battery), and see if there was enough / not
too little to be of use / not too much so that it would kill the wall
wart.

I recently killed a battery by substituting an AC wall wart for the genuine
article. Another family member had shuffled the warts and I didn't spot it in
time. I now attempt to label all warts with their original use. It may save
other expensive mistakes.

A car battery?
--
Ian

In article
,
Tom wrote:
I've been aiming to buy a new car battery trickle charger for a while
- I've noticed that there are some very small trickle chargers that
are 500mA output and looks like a plug in power block.

They are an expensive way of doing a simple job.

Keep an eye on Lidl and Aldi. They do a proper charger - 4 amps or so -
which switches to a maintenance mode when the battery is charged. Cost
about 13 quid. They are on sale every few months.

--
*There's two theories to arguing with a woman. Neither one works *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Andrew Gabriel wrote:
A friend accidently left a jumpstarter charging for a week on one
of these, and that was the end of the battery. I have the same
model, but I used a proper voltage regulated charger and not the
wall wart which came with it, and some 6 or 7 years later, mine
still works fine.

Whether the same charger would kill a 'wet' and much larger car battery in
the same time is open to debate...

--
*You! Off my planet!

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article
,
Tom wrote:
I've been aiming to buy a new car battery trickle charger for a while
- I've noticed that there are some very small trickle chargers that
are 500mA output and looks like a plug in power block.

They are an expensive way of doing a simple job.

Keep an eye on Lidl and Aldi. They do a proper charger - 4 amps or so -
which switches to a maintenance mode when the battery is charged. Cost
about 13 quid. They are on sale every few months.


Sounds similar to my "Winfield" from Woolworths. Well over forty years
old, choice of 6 or 12 volt, High or Low charge and still works as well as
ever.
--
Tinkerer

In article ,
Tinkerer wrote:
Keep an eye on Lidl and Aldi. They do a proper charger - 4 amps or so -
which switches to a maintenance mode when the battery is charged. Cost
about 13 quid. They are on sale every few months.


Sounds similar to my "Winfield" from Woolworths. Well over forty
years old, choice of 6 or 12 volt, High or Low charge and still works
as well as ever.

Nothing like that. It is a sophisticated SMPS device which monitors the
actual battery voltage, and changes from charging to a maintenance charge
automatically so can be left on indefinitely.
Other thing is although the quoted output seems modest, it delivers that
all the time the battery is being charged (until it switches). Unlike many
which claim a much higher maximum but drop to a low figure quickly.

--
*Drugs may lead to nowhere, but at least it's the scenic route *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
"Dave Plowman (News)" writes:
In article
,
Tom wrote:
I've been aiming to buy a new car battery trickle charger for a while
- I've noticed that there are some very small trickle chargers that
are 500mA output and looks like a plug in power block.

They are an expensive way of doing a simple job.

Keep an eye on Lidl and Aldi. They do a proper charger - 4 amps or so -
which switches to a maintenance mode when the battery is charged. Cost
about 13 quid. They are on sale every few months.

and at the end of that period, I got a couple for a fiver.
They are indeed very good.

Just 2 slight gripes...

If the battery is very flat, it assumes it's a 6V one, and because
it will instantly rise to the fully charged voltage for a 6V battery,
it won't get very far. You can get around this by connecting another
12V battery (or some other 12V power source) in parallel just for a
few seconds. (OTOH, if a 12V battery is down to 6V, your chances of
charging it again are not too high anyway.)

It would be brilliant if it had some way to make it start charging
automatically after a power failure. You could then use it to build
a very cheap but effective backup power unit.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
Andrew Gabriel wrote:
It would be brilliant if it had some way to make it start charging
automatically after a power failure. You could then use it to build
a very cheap but effective backup power unit.

I agree - but suspect if would then draw current if left connected with no
mains to it. Maybe not much - but undesirable over a long period.

--
*I didn't drive my husband crazy -- I flew him there -- it was faster

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Tinkerer wrote:
Keep an eye on Lidl and Aldi. They do a proper charger - 4 amps or so -
which switches to a maintenance mode when the battery is charged. Cost
about 13 quid. They are on sale every few months.


Sounds similar to my "Winfield" from Woolworths. Well over forty
years old, choice of 6 or 12 volt, High or Low charge and still works
as well as ever.

Nothing like that. It is a sophisticated SMPS device which monitors the
actual battery voltage, and changes from charging to a maintenance charge
automatically so can be left on indefinitely.
Other thing is although the quoted output seems modest, it delivers that
all the time the battery is being charged (until it switches). Unlike many
which claim a much higher maximum but drop to a low figure quickly.


The old Woolies one has an ammeter on the front so you can momitor it.
When the battery is flat it bangs out the full 4 amps but as the charge
level in the battery increases this drops until it is half an amp or less.
I assume that is some form of what you call a maintenance charge. I have
to say that for a cheapo Woolies purchase it does seem to be very good and
certainly has longevity (better than Woolies in fact).
--
Tinkerer

In article ,
Tinkerer wrote:
The old Woolies one has an ammeter on the front so you can momitor it.
When the battery is flat it bangs out the full 4 amps but as the charge
level in the battery increases this drops until it is half an amp or
less.

Typical of a basic charger with no regulation. I have a similar Halfords
one which quotes 11 amps peak - whatever that means. It actually takes
longer to fully charge a battery than the 4 amp Lidl one.

I assume that is some form of what you call a maintenance charge.

No. The amount of current used when a charger is connected for a long time
- like say over winter or whatever - has to be carefully controlled. Yours
would be fine to leave on overnight just to make sure the battery was
fresh the next day.

I have to say that for a cheapo Woolies purchase it does seem to be
very good and certainly has longevity (better than Woolies in fact). --

Chargers of this type are pretty simple devices and no real reason why
they shouldn't last. However, the Lidl one is small enough to fit in a
pocket. Light in weight too.

--
*I'm not as think as you drunk I am.

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Tinkerer wrote:
The old Woolies one has an ammeter on the front so you can momitor it.
When the battery is flat it bangs out the full 4 amps but as the charge
level in the battery increases this drops until it is half an amp or
less.

Typical of a basic charger with no regulation. I have a similar Halfords
one which quotes 11 amps peak - whatever that means. It actually takes
longer to fully charge a battery than the 4 amp Lidl one.

I assume that is some form of what you call a maintenance charge.

No. The amount of current used when a charger is connected for a long time
- like say over winter or whatever - has to be carefully controlled. Yours
would be fine to leave on overnight just to make sure the battery was
fresh the next day.

I have to say that for a cheapo Woolies purchase it does seem to be
very good and certainly has longevity (better than Woolies in fact). --

Chargers of this type are pretty simple devices and no real reason why
they shouldn't last. However, the Lidl one is small enough to fit in a
pocket. Light in weight too.

--
*I'm not as think as you drunk I am.

Thanks for the explanations. It makes very good sense.

Here is my version of your tag line that I have used for years (and lived up
to come to think of it):
"I'm not as thunk as drinkle peep I am"

--
Tinkerer

After serious thinking Tinkerer wrote :
"Dave Plowman (News)" wrote in message
...
In article ,
Tinkerer wrote:
Keep an eye on Lidl and Aldi. They do a proper charger - 4 amps or so -
which switches to a maintenance mode when the battery is charged. Cost
about 13 quid. They are on sale every few months.


Sounds similar to my "Winfield" from Woolworths. Well over forty
years old, choice of 6 or 12 volt, High or Low charge and still works
as well as ever.

Nothing like that. It is a sophisticated SMPS device which monitors the
actual battery voltage, and changes from charging to a maintenance charge
automatically so can be left on indefinitely.
Other thing is although the quoted output seems modest, it delivers that
all the time the battery is being charged (until it switches). Unlike many
which claim a much higher maximum but drop to a low figure quickly.


The old Woolies one has an ammeter on the front so you can momitor it. When
the battery is flat it bangs out the full 4 amps but as the charge level in
the battery increases this drops until it is half an amp or less. I assume
that is some form of what you call a maintenance charge. I have to say that
for a cheapo Woolies purchase it does seem to be very good and certainly has
longevity (better than Woolies in fact).

Not all all the same thing. Your chargers output drops simply because
the voltage difference becomes less. The Lidl ones charge rate drops,
because and only because the battery is fully charged. Your charger
will eventually damage the battery, the Lidl type one will not cause
damage even if left on permanently. The latest Lidle unit is really
rather good - I bought two a month or two back.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Andrew Gabriel formulated the question :
If the battery is very flat, it assumes it's a 6V one, and because
it will instantly rise to the fully charged voltage for a 6V battery,
it won't get very far. You can get around this by connecting another
12V battery (or some other 12V power source) in parallel just for a
few seconds. (OTOH, if a 12V battery is down to 6V, your chances of
charging it again are not too high anyway.)

I built and designed for myself a rather fancy heavy duty automatic
pulse charger. That will not start to charge unless the battery voltage
is within limits, to get around it I modified it by fitting an override
button to force the charge to start.


It would be brilliant if it had some way to make it start charging
automatically after a power failure. You could then use it to build
a very cheap but effective backup power unit.

Really that is its only disadvantage, but a fairly common one on this
type of charger. I have another similar charger which does not need a
button to be pressed - its disadvantage is that if there is a power
cut, the charger will draw power from the battery and discharge it - I
use this one for my bike. Fine if it just a short power outage, but
there have been occasions when I have accidently tripped the socket
circuit in the garage and next time I go in a week later, the bike
battery is completely flat.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

In article ,
Harry Bloomfield wrote:
It would be brilliant if it had some way to make it start charging
automatically after a power failure. You could then use it to build
a very cheap but effective backup power unit.

Really that is its only disadvantage, but a fairly common one on this
type of charger. I have another similar charger which does not need a
button to be pressed - its disadvantage is that if there is a power
cut, the charger will draw power from the battery and discharge it - I
use this one for my bike. Fine if it just a short power outage, but
there have been occasions when I have accidently tripped the socket
circuit in the garage and next time I go in a week later, the bike
battery is completely flat.

Yes. The Lidl one clicks when you switch it on, so I'd guess it has a
relay and diode to prevent damage by wrong connection etc.

I have one permanently installed in the old car and can confirm it draws
no current whatsoever from the battery when not charging.

--
*Did you ever notice when you blow in a dog's face he gets mad at you? *

Dave Plowman London SW
To e-mail, change noise into sound.

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Dave Plowman (News)"
saying something like:

Yes. The Lidl one clicks when you switch it on, so I'd guess it has a
relay and diode to prevent damage by wrong connection etc.

Also spark-on-connection prevention.

In article ,
Grimly Curmudgeon wrote:
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Dave Plowman (News)"
saying something like:

Yes. The Lidl one clicks when you switch it on, so I'd guess it has a
relay and diode to prevent damage by wrong connection etc.

Also spark-on-connection prevention.

Could be - although most wouldn't connect a charger to a battery which is
already gassing.

--
*Everyone has a photographic memory. Some just don't have film*

Dave Plowman London SW
To e-mail, change noise into sound.

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Dave Plowman (News)"
saying something like:

Also spark-on-connection prevention.

Could be - although most wouldn't connect a charger to a battery which is
already gassing.

Never underestimate the stupidity of the public.

In article ,
says...
Could be - although most wouldn't connect a charger to a battery which is
already gassing.

Er - I doubt many people would be aware that it's even explosive.

--
Skipweasel - never knowingly understood.

Grimly Curmudgeon pretended :
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Dave Plowman (News)"
saying something like:

Yes. The Lidl one clicks when you switch it on, so I'd guess it has a
relay and diode to prevent damage by wrong connection etc.

Also spark-on-connection prevention.

Yes - there is no connection, until you press the button and the button
does nothing until it senses voltage from the battery.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

In article ,
Skipweasel wrote:
In article ,
says...
Could be - although most wouldn't connect a charger to a battery which
is already gassing.

Er - I doubt many people would be aware that it's even explosive.

My feeling is the risks are vastly over stated. The one explosion I know
of personally was in a garage battery charging room many years ago where a
mechanic - who should have known better - disconnected a battery still on
charge and the spark caused a bang. It was an old poorly ventilated area -
wouldn't be allowed these days.

--
*The statement below is true.

Dave Plowman London SW
To e-mail, change noise into sound.