Battery charging circuit

[Damn Dan]

I've been working on a project that would recharge the battery of my Honda
Insight (a hybrid vehicle) while I'm parked at work using a solar panel.
The Insight's battery pack averages around 165V during usage. Currently I
have the solar panel constantly charging a 12V battery with an appropriate
charge controller. The battery is then connected to a 12Vdc to 120Vac
inverter, which is connected to a 120Vac to 220Vac converter, which is in
turn rectified to 220Vdc. I actually only get 200Vdc in the end, I guess
just due to inefficiencies.

I'm trying to design a current limiter that would only allow as much power
into the 165V battery as is coming in from the solar panel. The panel is
80W, so after it's been stepped up to 200V, the output current is 0.4Amps
(200V * .4A = 80W). Thus, I want to implement a current limiter that will
only allow 0.4A into the 165V battery.

The main issue I'm dealing with right now is understanding how two power
sources interact with each other in the same circuit. Specifically, I have
a 200V source charging a 165V battery with 0.4Ohms internal resistance. So
is that exactly equivelent to setting up a circuit with a 35V source
(200V-165V = 35V) and a 0.4Ohm resistor? I set that circuit up in PSpice,
but it doesn't seem to account for the two DC sources interacting with each
other. Any thoughts?

 

[mike]

Damn Dan wrote:

I've been working on a project that would recharge the battery of my Honda
Insight (a hybrid vehicle) while I'm parked at work using a solar panel.
The Insight's battery pack averages around 165V during usage. Currently I
have the solar panel constantly charging a 12V battery with an appropriate
charge controller. The battery is then connected to a 12Vdc to 120Vac
inverter, which is connected to a 120Vac to 220Vac converter, which is in
turn rectified to 220Vdc. I actually only get 200Vdc in the end, I guess
just due to inefficiencies.

I'm trying to design a current limiter that would only allow as much power
into the 165V battery as is coming in from the solar panel. The panel is
80W, so after it's been stepped up to 200V, the output current is 0.4Amps
(200V * .4A = 80W). Thus, I want to implement a current limiter that will
only allow 0.4A into the 165V battery.

The main issue I'm dealing with right now is understanding how two power
sources interact with each other in the same circuit. Specifically, I have
a 200V source charging a 165V battery with 0.4Ohms internal resistance. So
is that exactly equivelent to setting up a circuit with a 35V source
(200V-165V = 35V) and a 0.4Ohm resistor? I set that circuit up in PSpice,
but it doesn't seem to account for the two DC sources interacting with each
other. Any thoughts?

I'm fascinated by all this.
Over 8-hours, you get at most 640WH. Depending on where you live and
what season it is and the weather and...and...and...maybe MUCH less.
About how much gas will this save you per day??
How much gas does it cost you to haul around all this extra weight?
What's the cost of a new set of batteries when your controller fries
'em? What's the cost of
the remote alarm system you'll need to let you know when someone stole
the panel?

Where are you gonna park it? Complete address please ;-)

....fascinating...
mike

--
Return address is VALID.
500MHz Tek DSOscilloscope TDS520
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Bunch of stuff For Sale and Wanted at the link below.
http://www.geocities.com/SiliconValley/Monitor/4710/

 

[Damn Dan]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:10n7f92rkhicha4@corp.supernews.com...

"Ross Herbert" <rherber1SPAMEX@bigpond.net.au> wrote in message
newstr6n0hbnfpbro61itov63eqrupmuc6nnr@4ax.com...
You are starting from the wrong end...

You need to determine the charging requirements of the 165V battery
itself before anything else. Only then can you determine what is
required of your charging circuitry and design it accordingly. The
fact that you want to use a 12V (nominal), 80W solar panel as the
charging source simply because that is what you have on hand is not
the way to go about the problem. Once you know what the charging
requirements of the battery are you can then determine how many solar
panels you will require in order to charge a 12V,24V or 48V battery to
power a suitable dc - ac inverter/rectifier/charging arrangement.

I don't buy that at all. Firs off, he doesn't need to know the charging
requuirements of the 165V battery because it can charge at anywhere up
to hundreds of amps for short periods. And he will never be able to buy
enough solar cells to do that, let alone the next problem.

And the next problem is that the solar cells will put out anywhere from
max to min to zero depending on the time of day, and the weather,
cloudy, overcast, etc. So he needs a converter that can handle a large
variation in input power. Why should he need an intermediate battery,
12V, etc. to charge? That's just a waste of efficiecny.

What he needs is a converter that monitors the input voltage to see if
it drops below a threshold, as long as it stays at about 12V, pull as
much current from the solar cells as it can. Then monitor the output
voltage to make sure it doesn't go much above 200V, so that if the
converter is not plugged into the battery, it shuts down.

What I would do is start with a standard Dc-Dc converter like those used
for running tube equipment off 12V. Add an overvoltage monitor to the
output, and under voltage to the input. And fuses, of course.

And he can put a large capacitor across the solar cell, to hold enough
charge to run the converter for a second or two. If the converter
charges in spurts, that's okay, too.

Right, getting enough panels to produce that much voltage would be
financially and physically impossible. The second problem you mentioned is
actually the very reason I went for the 12V battery as a middle-man.
Originally I wanted to hook the panel directly to the 165V battery through
the converter. But my main constraint is that I'm trying to do this El
Cheapo style. I did a bit of research but found no reasonably cheap (i.e.
less than $50) 12V-200V DC-DC converters. If you happen to know of one,
please let me know! The inexpensive solution I have come to is using a
regular car inverter that you plug into your cigarette lighter. That gives
me 120Vac. I step that up with a international power converter that you can
buy at any Radio Shack. The 200 or so volts out of that gets rectified to
DC. All in all, it cost just over $50. So now the reason I'm attaching the
car inverter to the 12V battery is all car inverters have safety mechanisms
that shut off power if the inverter detects a "weird" voltage input. The
solar panel outputs between 15V and 20V, which it considers "weird", so it
doesn't work. The 12V battery keeps the voltage at an unweird level. It
also accomodates for any variation that the solar panel will give due to
weather conditions and time of day. Plus, it keeps a steady, predictable
current into the 165V battery. But like I said, if you know of any
off-the-shelf, cheap converters that would accomplish the same goal, I'm all
ears.

 

[Damn Dan]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:10n97eie5jc4l42@corp.supernews.com...

"Ross Herbert" <rherber1SPAMEX@bigpond.net.au> wrote in message
news:nu19n0hkadrrcm56omeave8g1rqp5jkavu@4ax.com...

[snip]

Yep, this would work. However, what do you do when you desperately
must have the 165V battery charged right now and the weather is such
that only brief periods of sunshine were available during the daytime?

You start the engine. THis is a h-y-b-r-i-d vehicle!

At least with a panel storage battery already fully charged you could
dump most of the stored capacity into the 165V battery via the
charging converter.

I know who's system would work best and it wouldn't be yours.

An intermediate battery would be just a waste of efficiency. Leave it
out.

If I may peacefully chime in here.

I wanted to clarify that I only use a fraction of the usable 3.8Ah of the
battery. At most I would need to recharge a 1/10th of that capacity, which
by my elementary calculations shouldn't take too long, even after
considering in substantional ineffiencies.

Watson, I looked inside of my inverter... and basically forget about it.
It's way too complicated. It's a double-sided printed board and the little
bit of multimeter probing I did returned nothing I was able to understand.
Unfortunately my electronics abilities are far inferior to start
reverse-engineering that thing. Although even if I was able to get the
inverter to give me 200V, I still have the inverter's "safety" feature to
contend with, which is why I am including the battery. The solar panel puts
out a voltage that is above the inverter's tolerance range. Thus far,
introducing a 12V battery, however inefficient, is the only solution I've
come up with.

Ross, my philosphy with this project is basically "get whatever I can get in
8 hours at work". I'm going to feed the battery a mere trickle-charge that
could not possibly charge the whole battery in a day. Instead, I hope to
simply recover the loss I accrued while driving to work, which is very small
compared to the capacity of the battery. During the 6 mile drive, I almost
recover the charge I use through regenerative braking, but not quite, so
there's a slight net loss.

-Dan

 

[Watson A.Name - \"Watt Su]

"Damn Dan" <a@a.com> wrote in message
news:%rndd.93528$Lo6.13671@fed1read03...
[snip]

Honda's "charge controller" for the Insight battery is not a typical
controller in the usual sense of the word. A computer monitors the
state of
the battery using temperature sensors and voltmeters. It also
actively
keeps track of all current going in and out of the battery. Using
that
data, it makes an estimation about the state of the battery and
informs the
electric engine about its condition. The electric engine then sends
power
to the battery (to recharge it, if it is ok to charge) or receives
power
from the battery (during assist mode, if it is ok to load) based on
the
state of the battery. So really its the electric motor that acts as
the
"charge controller".

THe scary thought here is that what if the Honda can't account for the
extra charge you're putting in? In other words, it thinks the battery
is discharged when actually it has been topped off by your solar panels.
And then it tries to charge the battery even more.

 

[Damn Dan]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:10nee03n0c7fk30@corp.supernews.com...

"Damn Dan" <a@a.com> wrote in message
news:%rndd.93528$Lo6.13671@fed1read03...
[snip]

Honda's "charge controller" for the Insight battery is not a typical
controller in the usual sense of the word. A computer monitors the
state of
the battery using temperature sensors and voltmeters. It also
actively
keeps track of all current going in and out of the battery. Using
that
data, it makes an estimation about the state of the battery and
informs the
electric engine about its condition. The electric engine then sends
power
to the battery (to recharge it, if it is ok to charge) or receives
power
from the battery (during assist mode, if it is ok to load) based on
the
state of the battery. So really its the electric motor that acts as
the
"charge controller".

THe scary thought here is that what if the Honda can't account for the
extra charge you're putting in? In other words, it thinks the battery
is discharged when actually it has been topped off by your solar panels.
And then it tries to charge the battery even more.

Good point. I'm definitely going on faith that the many onboard sensors
(serveral voltage, current, and temperature sensors) will pick up the change
and react accordingly. Granted, the current sensors are useless unless I
power them while I'm charging. I'll keep that in mind, though.

I guess I'm being an optimist and imagining that I'll turn the car on after
charging it and voila, the SOC indicator will accurately reflect the
increased capacity. That sure would make me happy .

 

[Clarence]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote in
message news:10nes2jj0srpo7c@corp.supernews.com...

"Florian" <petafrog@evilemail.com> wrote in message
news:m34qko4rip.fsf@tiainen.domain.invalid...
"Damn Dan" <a@a.com> writes:

(snip)

I'd be nice if Honda did provide some kind of solar device or at
least
an external charger... that'd make my life a lot easier.

Wouldn't an external charger be the way to go in any case? In other
posts you've mentioned that 1) driving to work consumes 10% of the
battery charge, and 2) when the battery goes below 50%, the car starts
recharging it, reducing your gas mileage. From this, it seems the
solar
panel is an unnecessary complication -- if you can make a round trip
commute to work with only 80% loss, you're not triggering the recharge
cycle, so why not just top off the battery at home every night from a
wall socket and forget about fickle and expensive solar panel?

From what I've read, the all electric vehicles have to have a massive,
special charger installed at your home. That's not cheap, something
like $5k, plus you then have to pay for the electricity.

(snip)

Really?
Why so much?
A 200 Amp 12 Volt Charger can be bought new for $120.00

 

[Clarence]

<William P.N. Smith> wrote in message
news:spdfn0pdabp0h5skavjijrqulfcabqtpsk@4ax.com...

"Clarence" <no@No.com> wrote:
A 200 Amp 12 Volt Charger can be bought new for $120.00

Really, where? Or are we talking about a battery booster at the local
gas station to dump some uncontrolled charge into the battery?

I did a Google search, there were many hits and the one I priced as an example
was a 'three level' charger with a 500 Amp "booster" mode for starting.

There were 47,800 hits for a 200 Amp Charger and many were duplicates.
I am sure that many were the gas station variety.
The one I priced was among the cheapest, but there were MANY more to choose
from.

 

[Clarence]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote in
message news:10ni1iasis93u20@corp.supernews.com...

"Clarence" <no@No.com> wrote in message
news:U6Sdd.16988$nj.8537@newssvr13.news.prodigy.com...

William P.N. Smith> wrote in message
news:spdfn0pdabp0h5skavjijrqulfcabqtpsk@4ax.com...
"Clarence" <no@No.com> wrote:
A 200 Amp 12 Volt Charger can be bought new for $120.00

Really, where? Or are we talking about a battery booster at the
local
gas station to dump some uncontrolled charge into the battery?


I did a Google search, there were many hits and the one I priced as an
example
was a 'three level' charger with a 500 Amp "booster" mode for
starting.

There were 47,800 hits for a 200 Amp Charger and many were duplicates.
I am sure that many were the gas station variety.
The one I priced was among the cheapest, but there were MANY more to
choose
from.

We had an electric vehicle "golf cart" at work for a year, and I read
the manual for it. They esxplained <typo?> that the three pronged plug had
one
pin for the onboard computer to control the charger. This was for a
48VDC lead acid system. So the trend today seems to be towards more
intelligent chargers, and hence the higher prices.

Interestingly, the book also explained that when the yellow "low
battery" light on the dash lit up, you had two hours or 36 holes of
golf left(!) )

Having designed some chargers for Golf carts and fork lift trucks, I can tell
you that More intelligent does not mean more expensive. My last design was one
third the cost to build for the simple single control unit it replaced.

 

"Watson A.Name - \"Watt Sun, the Dark Remover\""
<NOSPAM@dslextreme.com> wrote:

We had an electric vehicle "golf cart" at work for a year, and I read
the manual for it. They esxplained that the three pronged plug had one
pin for the onboard computer to control the charger. This was for a
48VDC lead acid system. So the trend today seems to be towards more
intelligent chargers, and hence the higher prices.

I've got two 48V Club Car golf carts, and the "intelligence" in the
charger is the relay on the end of that third pin. The onboard
computer on the golf cart watches battery voltage and current {into,
out of} the battery pack, and adjusts the "automatic" charge cycle
accordingly.

Strangely, the price of these 48V, 20A chargers (transformer,
half-wave bridge, 'magnetic' ammeter, connectors) is on the order of a
buck a watt! Unfortunately, the 200A, 12V charger isn't real...

 

[Watson A.Name - \"Watt Su]

"Clarence" <no@No.com> wrote in message
news:uI7ed.33522$QJ3.11413@newssvr21.news.prodigy.com...

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com
wrote in
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"Clarence" <no@No.com> wrote in message
news:U6Sdd.16988$nj.8537@newssvr13.news.prodigy.com...

William P.N. Smith> wrote in message
news:spdfn0pdabp0h5skavjijrqulfcabqtpsk@4ax.com...
"Clarence" <no@No.com> wrote:
A 200 Amp 12 Volt Charger can be bought new for $120.00

Really, where? Or are we talking about a battery booster at the
local
gas station to dump some uncontrolled charge into the battery?


I did a Google search, there were many hits and the one I priced
as an
example
was a 'three level' charger with a 500 Amp "booster" mode for
starting.

There were 47,800 hits for a 200 Amp Charger and many were
duplicates.
I am sure that many were the gas station variety.
The one I priced was among the cheapest, but there were MANY more
to
choose
from.

We had an electric vehicle "golf cart" at work for a year, and I
read
the manual for it. They esxplained <typo?> that the three pronged
plug had
one
pin for the onboard computer to control the charger. This was for a
48VDC lead acid system. So the trend today seems to be towards more
intelligent chargers, and hence the higher prices.

Interestingly, the book also explained that when the yellow "low
battery" light on the dash lit up, you had two hours or 36 holes of
golf left(!) )


Having designed some chargers for Golf carts and fork lift trucks, I
can tell
you that More intelligent does not mean more expensive. My last
design was one
third the cost to build for the simple single control unit it
replaced.

More silicon and less iron? In other words, a switch mode power
supply..

 

[Watson A.Name - \"Watt Su]

<William P.N. Smith> wrote in message
news:4pfjn05p8553cfonde2h7gpirft90aekl0@4ax.com...

"Watson A.Name - \"Watt Sun, the Dark Remover\""
NOSPAM@dslextreme.com> wrote:
We had an electric vehicle "golf cart" at work for a year, and I read
the manual for it. They esxplained that the three pronged plug had
one
pin for the onboard computer to control the charger. This was for a
48VDC lead acid system. So the trend today seems to be towards more
intelligent chargers, and hence the higher prices.

I've got two 48V Club Car golf carts, and the "intelligence" in the
charger is the relay on the end of that third pin. The onboard
computer on the golf cart watches battery voltage and current {into,
out of} the battery pack, and adjusts the "automatic" charge cycle
accordingly.

Strangely, the price of these 48V, 20A chargers (transformer,
half-wave bridge, 'magnetic' ammeter, connectors) is on the order of a
buck a watt! Unfortunately, the 200A, 12V charger isn't real...

Our cart sat for a few weeks w/o being used. We tried to use it, but it
was completely dead. The transpo guy got it towed over to his shop, and
got a field tech to check it out. Turned out that the battery voltage
dropped so low that the 'intelligent' charging system thought that the
batteries were disconnected and refused to turn on. All it took was a
good charge to get it up and running again. (From an external charger,
of course.)

The reason why the damn thing was seldom used was that one couldn't put
a computer or monitor in the tiny space in the back where the golf clubs
were supposed to go. It had to go on the passenger seat, and even
strapping it in with the seat belt wouldn't secure it adequately.

 

[Watson A.Name - \"Watt Su]

"Clarence" <no@No.com> wrote in message
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"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com
wrote in
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"Clarence" <no@No.com> wrote in message
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"Watson A.Name - "Watt Sun, the Dark Remover""
NOSPAM@dslextreme.com
wrote in
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"Clarence" <no@No.com> wrote in message
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William P.N. Smith> wrote in message
news:spdfn0pdabp0h5skavjijrqulfcabqtpsk@4ax.com...
"Clarence" <no@No.com> wrote:
A 200 Amp 12 Volt Charger can be bought new for $120.00

Really, where? Or are we talking about a battery booster at the
local gas station to dump some uncontrolled charge into the
battery?

I did a Google search, there were many hits and the one I
priced
as an example
was a 'three level' charger with a 500 Amp "booster" mode for
starting.

There were 47,800 hits for a 200 Amp Charger and many were
duplicates.
I am sure that many were the gas station variety.
The one I priced was among the cheapest, but there were MANY
more
to choose from.

We had an electric vehicle "golf cart" at work for a year, and I
read
the manual for it. They esxplained <typo?> that the three
pronged
plug had
one
pin for the onboard computer to control the charger. This was
for a
48VDC lead acid system. So the trend today seems to be towards
more
intelligent chargers, and hence the higher prices.

Interestingly, the book also explained that when the yellow "low
battery" light on the dash lit up, you had two hours or 36
holes of
golf left(!) )


Having designed some chargers for Golf carts and fork lift trucks,
I
can tell
you that More intelligent does not mean more expensive. My last
design was one
third the cost to build for the simple single control unit it
replaced.

More silicon and less iron? In other words, a switch mode power
supply..

That too. Let the Chargers be built into the Cart instead of lining
up at one
station.

Well, the one we had was heavy, and had a good-sized transformer. I
would guess they left it off the cart because of the weight penalty,
having to haul another 20 pounds around all the time. But a person
could carry it around with the cart if he wanted to.

The Taylor-Dunn electric carts that the maintenance dept uses have sheet
steel for the body, and must weigh an awful lot. Some of those have the
charger built-in. They use 36V and the old nichrome ribbon resistors
for the speed control. Big waste of power.

Someone should develop a braking system for these that pumps all that
wasted energy back into the battery. Probably increase the range
dramatically.