Hi

In my little world, the plan is to use a 500W modified sine wave inverter to power a couple chargers that I can't seem to find the 12V equivalent for.

One would be a regular 110V Ryobi charger and the other a 110V charger for 9 Volt Ni-MH batteries.

After getting this stuff together I read that using an transformer with a inverter is bad. What would happen? Would I fry something?

Any insight would be appreciated

TIA

Bob

After getting this stuff together I read that using an transformer with a
inverter is bad.

** Where ??

Post a link.


..... Phil

On 6/25/2012 3:57 PM, wrote:
Hi

In my little world, the plan is to use a 500W modified sine wave inverter to power a couple chargers that I can't seem to find the 12V equivalent for.

One would be a regular 110V Ryobi charger and the other a 110V charger for 9 Volt Ni-MH batteries.

After getting this stuff together I read that using an transformer with a inverter is bad. What would happen? Would I fry something?

Any insight would be appreciated

TIA

Bob

The problem is the dV/dT. The rectifiers and caps are rated for the current
you get when driven with a sine wave. Stresses on those components
can be significantly higher. But maybe they can take it.

So, my experience is that it's perfectly safe to run most anything
from an inverter...EXCEPT when it isn't.

Here's an example.
Tektronix 211 miniscope. Good company. You'd think they designed good
stuff.
Plugged on into an inverter and it quit.

Gazing at the schematic showed why. They use a series cap
and rectifier as a charge pump to charge
the batteries. The cap has a different value depending on the
market, 50 or 60 Hz.
The fast rise input waveform from the inverter blew the fuse
instantly. Could have been much worse.

Compaq laptop.
They hooked the battery thru a FET to the input socket. Relied
on the current limit in the adapter to set the charge current.
If you put voltage into the port, it smokes the FET.
But the manual did say, "Use only the recommended charger."

Bottom line is that it's a crap shoot. For most consumer devices, vendors
are more concerned about saving half a cent than whether it works
in an environment not in their spec. Clever implementations
that save cost don't necessarily enhance reliability.

thanks Mike

So the best (safest) way would be to use a full sine wave inverter rather than the modified sine wave one?

On Monday, June 25, 2012 6:57:18 PM UTC-4, wrote:
Hi

In my little world, the plan is to use a 500W modified sine wave inverter to power a couple chargers that I can't seem to find the 12V equivalent for.

One would be a regular 110V Ryobi charger and the other a 110V charger for 9 Volt Ni-MH batteries.

After getting this stuff together I read that using an transformer with a inverter is bad. What would happen? Would I fry something?

Any insight would be appreciated

TIA

Bob

** Why don't you just go drop dead?

You stinking damn troll.

On Tuesday, June 26, 2012 9:34:30 AM UTC-4, Phil Allison wrote:
** Why don't you just go drop dead?

You stinking damn troll.

Are you talking to me Phil?

On 6/26/2012 4:47 AM, wrote:
thanks Mike

So the best (safest) way would be to use a full sine wave inverter rather than the modified sine wave one?

On Monday, June 25, 2012 6:57:18 PM UTC-4, wrote:
Hi

In my little world, the plan is to use a 500W modified sine wave inverter to power a couple chargers that I can't seem to find the 12V equivalent for.

One would be a regular 110V Ryobi charger and the other a 110V charger for 9 Volt Ni-MH batteries.

After getting this stuff together I read that using an transformer with a inverter is bad. What would happen? Would I fry something?

Any insight would be appreciated

TIA

Bob

Well...the simple answer to the simple question is, YES.
Depending on the relative cost of sine and modified sine,
real sinewave is the safest.
BUT
You'll probably find that 99% of the time you'd be ok
with modified.
What's the cost of failure?

If you have a 99-cent 9V charger from China, I'd expect they're very
creative
in how it works. I'd worry more about the battery than the charger.
And if it smokes, so what?

The Ryobi is another matter. It's probably designed for abuse.
But you probably don't want to smoke a $100 charger and have it destroy
all your batteries.

First thing I'd do is call Ryobi.
Then I'd find a news group more suited to commercial guys who might use
one and ask there.

Failing that, I'd stick a current probe and oscilloscope on the power
line and look
at the peak currents with sine and inverter inputs.
If the peak current ain't too much greater, you're probably ok.

Don't forget to do the math.
If you expect to drive your truck to a remote job site and have
batteries on fast charge all day in your truck, you might have.
trouble starting the truck at the end of the day.

On Jun 26, 9:34*am, "Phil Allison" wrote:


** Why don't you just go drop dead?

* * *You stinking damn troll.

Phil, your act is really tired. Your off-the-meds rants used to be
funny, now they're just sad. Get help, and while you are, stay off
the internet.

John

"John-Delusional **** "


** Go **** a dead donk - you psycho troll.

On Mon, 25 Jun 2012 19:32:04 -0700, mike wrote:

On 6/25/2012 3:57 PM, wrote:
Hi

In my little world, the plan is to use a 500W modified sine wave inverter to power a couple chargers that I can't seem to find the 12V equivalent for.

One would be a regular 110V Ryobi charger and the other a 110V charger for 9 Volt Ni-MH batteries.

After getting this stuff together I read that using an transformer with a inverter is bad. What would happen? Would I fry something?

Any insight would be appreciated

TIA

Bob

The problem is the dV/dT. The rectifiers and caps are rated for the current
you get when driven with a sine wave. Stresses on those components
can be significantly higher. But maybe they can take it.

So, my experience is that it's perfectly safe to run most anything
from an inverter...EXCEPT when it isn't.

Here's an example.
Tektronix 211 miniscope. Good company. You'd think they designed good
stuff.
Plugged on into an inverter and it quit.

Gazing at the schematic showed why. They use a series cap
and rectifier as a charge pump to charge
the batteries. The cap has a different value depending on the
market, 50 or 60 Hz.
The fast rise input waveform from the inverter blew the fuse
instantly. Could have been much worse.

Compaq laptop.
They hooked the battery thru a FET to the input socket. Relied
on the current limit in the adapter to set the charge current.
If you put voltage into the port, it smokes the FET.
But the manual did say, "Use only the recommended charger."

Bottom line is that it's a crap shoot. For most consumer devices, vendors
are more concerned about saving half a cent than whether it works
in an environment not in their spec. Clever implementations
that save cost don't necessarily enhance reliability.

to follow up on this, if the battery charger is using a cheap cap-based
power circuit to produce consant current for fast (15 min to 1 hour) nicd
and nimh charging, you may very well get flames and smoke coming out of
your charger and/or batteries if used with a poor modified sine wave output
from a generator.

when i worked at Black & Decker, we started getting a lot of returns of for
commercial and industrial tool 1-hour chargers for just this reason. the
more expensive 15 minute charges fared much better, but also would have
occassional failures. and we were even using a Honda generator (supposedly
quit good) in the lab to do the tests to determine cause of failure.

i believe that B&D has made significant strides towards making their
chargers not blow up or massively overcharge the batteries under theses
conditions, but, as noted above, its something of a crap shoot unless you
check with the battery charger manufaturer first. (i would recommend
checking with both a power tools manufacturer's hotline as well with their
local repair outlet)

small trickle chargers, on the other hand, for 8-12 hour AA type charging
should be a lot safer IMO and experience, as their low levels of current
even if increased 3 times shouldnt hurt the cells much and ive never seen
them catch on fire.

--
dave hillstrom mhm15x4 meow

dave hillstrom wrote in
:

On Mon, 25 Jun 2012 19:32:04 -0700, mike wrote:

On 6/25/2012 3:57 PM, wrote:
Hi

In my little world, the plan is to use a 500W modified sine wave
inverter to power a couple chargers that I can't seem to find the
12V equivalent for.

One would be a regular 110V Ryobi charger and the other a 110V
charger for 9 Volt Ni-MH batteries.

After getting this stuff together I read that using an transformer
with a inverter is bad. What would happen? Would I fry something?

Any insight would be appreciated

TIA

Bob

The problem is the dV/dT. The rectifiers and caps are rated for the
current you get when driven with a sine wave. Stresses on those
components can be significantly higher. But maybe they can take it.

So, my experience is that it's perfectly safe to run most anything
from an inverter...EXCEPT when it isn't.

Here's an example.
Tektronix 211 miniscope. Good company. You'd think they designed
good stuff.

They -used- to. the TEK of today is not the TEK of the earlier years.
the 200 series was a good product,very popular with field service
people,especially the 213 with it's DMM.

Plugged on into an inverter and it quit.

Gazing at the schematic showed why. They use a series cap
and rectifier as a charge pump to charge
the batteries. The cap has a different value depending on the
market, 50 or 60 Hz.
The fast rise input waveform from the inverter blew the fuse
instantly. Could have been much worse.

Compaq laptop.
They hooked the battery thru a FET to the input socket. Relied
on the current limit in the adapter to set the charge current.
If you put voltage into the port, it smokes the FET.
But the manual did say, "Use only the recommended charger."

Bottom line is that it's a crap shoot. For most consumer devices,
vendors are more concerned about saving half a cent than whether it
works in an environment not in their spec. Clever implementations
that save cost don't necessarily enhance reliability.

to follow up on this, if the battery charger is using a cheap
cap-based power circuit to produce consant current for fast (15 min to
1 hour) nicd and nimh charging, you may very well get flames and smoke
coming out of your charger and/or batteries if used with a poor
modified sine wave output from a generator.

the TEK 211(and 212,214,and 221) is not a fast charger circuit.
in fact,TEK had to add a protection circuit and fuse the individual battery
packs to keep the scope from catching fire,literally.

One other item to watch out for on the TEK 200 series is that the PCBs are
held in place by 4 plastic pins,two on each case half. they shear off under
impacts,then the PCBs shift in relation to each other,the female pin
connectors spread open and their spring leaves fall out,shorting things
out.

--
Jim Yanik
jyanik
at
localnet
dot com

On 6/27/2012 6:32 AM, Jim Yanik wrote:


the TEK 211(and 212,214,and 221) is not a fast charger circuit.
in fact,TEK had to add a protection circuit and fuse the individual battery
packs to keep the scope from catching fire,literally.

One other item to watch out for on the TEK 200 series is that the PCBs are
held in place by 4 plastic pins,two on each case half. they shear off under
impacts,then the PCBs shift in relation to each other,the female pin
connectors spread open and their spring leaves fall out,shorting things
out.

I have a 213 that's very intermittent. The connections you mention are
a mess. Any kluge tricks for making it work better?
I thought about just soldering 'em all, but you'd never be able to
replace the battery.

On Wednesday, June 27, 2012 5:31:25 AM UTC-4, dave hillstrom wrote:
On Mon, 25 Jun 2012 19:32:04 -0700, mike wrote:

On 6/25/2012 3:57 PM, wrote:
Hi

In my little world, the plan is to use a 500W modified sine wave inverter to power a couple chargers that I can't seem to find the 12V equivalent for.

One would be a regular 110V Ryobi charger and the other a 110V charger for 9 Volt Ni-MH batteries.

After getting this stuff together I read that using an transformer with a inverter is bad. What would happen? Would I fry something?

Any insight would be appreciated

TIA

Bob

The problem is the dV/dT. The rectifiers and caps are rated for the current
you get when driven with a sine wave. Stresses on those components
can be significantly higher. But maybe they can take it.

So, my experience is that it's perfectly safe to run most anything
from an inverter...EXCEPT when it isn't.

Here's an example.
Tektronix 211 miniscope. Good company. You'd think they designed good
stuff.
Plugged on into an inverter and it quit.

Gazing at the schematic showed why. They use a series cap
and rectifier as a charge pump to charge
the batteries. The cap has a different value depending on the
market, 50 or 60 Hz.
The fast rise input waveform from the inverter blew the fuse
instantly. Could have been much worse.

Compaq laptop.
They hooked the battery thru a FET to the input socket. Relied
on the current limit in the adapter to set the charge current.
If you put voltage into the port, it smokes the FET.
But the manual did say, "Use only the recommended charger."

Bottom line is that it's a crap shoot. For most consumer devices, vendors
are more concerned about saving half a cent than whether it works
in an environment not in their spec. Clever implementations
that save cost don't necessarily enhance reliability.

to follow up on this, if the battery charger is using a cheap cap-based
power circuit to produce consant current for fast (15 min to 1 hour) nicd
and nimh charging, you may very well get flames and smoke coming out of
your charger and/or batteries if used with a poor modified sine wave output
from a generator.

when i worked at Black & Decker, we started getting a lot of returns of for
commercial and industrial tool 1-hour chargers for just this reason. the
more expensive 15 minute charges fared much better, but also would have
occassional failures. and we were even using a Honda generator (supposedly
quit good) in the lab to do the tests to determine cause of failure.

i believe that B&D has made significant strides towards making their
chargers not blow up or massively overcharge the batteries under theses
conditions, but, as noted above, its something of a crap shoot unless you
check with the battery charger manufaturer first. (i would recommend
checking with both a power tools manufacturer's hotline as well with their
local repair outlet)

small trickle chargers, on the other hand, for 8-12 hour AA type charging
should be a lot safer IMO and experience, as their low levels of current
even if increased 3 times shouldnt hurt the cells much and ive never seen
them catch on fire.

--
dave hillstrom mhm15x4 meow

Thank you too Dave for your input.