Powering Laptops and Other High Current Demand

Keep your Laptop and other high current-demand electronics
working when there is no power. By Terminus © 2008 version 1.06
In order to keep a laptop, short-wave receiver functioning, all the various batteries
charged along with some portable lights in a field power situation, I decided to put
together something that was backpack-portable using the following designs and
components.
Figure 1
The battery is to let you function when there is no sunlight, or if you happen to have used
a smaller solar panel that is powerful enough to trickle-charge the battery, but not
powerful enough to provide the current requirements. . (Whether you’re in a shtf or field
situation, things will never be optimal and the trade-off will be that the charging time
required may extend too long for practical use. You have to size the battery to match your
panel and accept less capability. In other words don’t expect a 25 watt or smaller panel to
charge that 40AH battery in a reasonable amount of time if you’ve drained it in any
significant fashion. For the purposes of what I’ve found to be practical either with a 25
watt or hopefully larger panel I decided I could handle a 12AH battery weighing approx.
9lbs (Sealed Lead Acid batteries are heavier than Ni-MH or even NI-CD batteries) but
they’re rugged and can withstand more abuse.
1
Figure 2
This is a unique product in that it’s really a regulated 12vdc power
supply with a charge controller designed to be attached to a solar
panel and charge a battery (or several batteries). The three
inputs/outputs are: Solar Panel, Aux. Battery (for charging other
batteries), and 12vdc out.
Here you see a
small (10A) charge
controller attached
to the 12AH battery
itself. The charge
controller I used is
almost an exact
match in battery
size, so the battery
connections on the
charge controller
are wired directly
to the battery
terminals and then
attached to the case
with a screw, two
washers at each
corner using Velcro
strips.
Batteryspace.com
has these units
already integrated,
or you can purchase
the charge
controller
separately using
your own battery..
DC-DC converters (for laptops mostly)
The IBM ThinkPad that I use
(I love them for their
ruggedness and features)
requires 16vdc at around 3.4
amps input voltage to charge
the internal battery and
operate normally. I
recommend obtaining this
kind of adapter from a place
I’ve used several times doing
business as Powerstream,
their web site is:
http://www.powerstream.com/
Figure 3
2
For the IBM ThinkPad series, see http://www.powerstream.com/ADCIBM.htm I used their ED1060-09 model for my T23, which produces
16vdc even from as little as 10.5vdc input which is perfect for field
conditions when you may face less than optimal power conditions. For
Panasonic Toughbooks, see http://www.powerstream.com/ADCPanasonic.htm for compatible converters. For my Toughbook CF-28 I
used their ED1060-87 model which is exactly the same as the IBM
version, with a different connector.
You should look in the “High
Quality Automobile to Laptop
DC/DC Converter” section of
their site.
The Panasonic Toughbook I
use has a run-time of over 4
hours one one battery and
about 7+ hours with the
second battery pack installed
in a removable drive bay.)
I’ve tested both for use with
this solar-powered battery
system, but I prefer the cheap
unit as I only need to carry
one no matter which laptop I
happen to be using.
Figure 4
I modified the dc-dc converter input connector (removed cigarette lighter
plug and installed power-pole connectors) to obtain 12vdc power from
various sources. 1. A standard cigarette lighter plug to the power-pole
cable. 2. Attach directly to a fused output on the DC Distribution Panel.
3. Attach directly to 12vdc regulated output from charge controller &
battery system. 4. In a worst-case scenario I can attach directly to any
battery using the heavy-duty battery clip to power-pole cable.
You will see the various cable configurations I have made further within
this document.
I have alternate dc converters
for backup use. One made by
Lind for the Toughbook and
one from Powerstream for the
T23 with model-specific
connectors even though it’s
“redundant” I feel better
having them around…
3
By using a less expensive dc
converter that had a selection
of connectors (and a wide
selection of voltage outputs) I
was able to use ONE device
to power either laptop. I was
very fortunate that both the
Panasonic Toughbook and the
IBM T23 need similar voltage
levels. (having these
interchangeable tips was
useful and I only need (2)
different tips that can be
swapped as needed. The
quality and reliability of the
batteryspace.com model may
be an issue, time will tell as I
use it a lot now.
Figure 5
4
Inverters
Inverters are not really viable with a
folding solar panel and a 12AH battery and
are beyond the scope of this document.
Once again, please remember this
document was intended to address
backpack portable systems.
I don’t recommend using any AC-powered
devices as a rule unless you have massive
battery banks and huge inverters in a
stationary installation or plenty of fuel to
burn up in your vehicle.
In my experience you can get by on DC
alone if you plan on only having DC and
choose your equipment wisely.
Use devices that are powered by AA and
AAA primary batteries and then use your
standalone chargers that can be powered
from your panel and 12AH battery.
When you buy equipment look at the input
voltage first, choose 12VDC first, then if
you have to, obtain dc-dc converters that
can produce adjustable outputs in common
voltages that use 12VDC as input voltage.
It is not efficient to use an inverter driven
from a battery to convert DC to AC only to
have to convert it back to DC again to
power a laptop (or any other DC-powered
device) you lose power in the equation, and
you add unnecessary complexity and
weight by using an inverter.
The kind of DC-DC converters I use also
accept a wider range of input voltage thus
allowing me to be more flexible.
Powerstream sells many types of DC-DC
converters and I have used them for various
projects around my observatory and in my
vehicles. See
http://www.powerstream.com/dcdc.htm
for various types of dc-dc converters. You
can also check http://www.
batteryspace.com for low-cost “laptop
adapters” and selectable output (1.5v -9v)
converters for cellphones, pdas, ipod/mp3,
etc, MURS/GMRS,or 2m HT, etc… as
well.
5
If you have a high enough capacity solar
panel you don’t need the weight of the
battery but you may wish to operate your
equipment at night. Most 12vdc batteries
of the type I recommend don’t weigh that
much and can easily be adapted to fit into
small equipment pouches that can be
carried in a backpack or whatever.
Whether or not you use a gel-cell or
sealed-lead-acid battery doesn’t matter
that much with modern battery designs. If
you use a large enough laptop bag, you
could carry the battery within. My
shortwave receiver (Yaesu FRG-100) can
be powered directly from 12vdc and my
solar panel can produce up to 16vdc so I
use the battery to keep the voltage well
regulated. The radio draws less than an
amp so I can monitor news stations quite a
while just on the battery itself. Sources of
this type of battery could be any small
office/home UPS (battery backup)
replacement battery, or perhaps even
scavenge one from a bad UPS. You can
find dandy batteries that are lightweight
and still have a decent rating.
Battery (12VDC/12AH)
Figure 6
Here is a typical 12VDC 12AH SLA battery,
weighing approximately 9 lbs, is about 6 inches long,
4 inches wide, and 4 inches high.
6
Charge Controllers
Figure 7
This is a 12vdc-only 7A charge controller that was inexpensive, offering very few
features besides charging the battery from a solar panel, with some basic over-charge
protection capability built-in.
This is about as minimalist as you can get. I keep one around in case I need to charge
other batteries and as a backup. As you can see it has no “load” outputs so in this case
you’d connect any DC loads to the battery directly or via my power distribution panel.
This unit weighs about 2 oz. and you can find it at www.brunton.com and elsewhere.
I crimped on some Andersen power-pole connectors on the solar-panel terminals and now
it’s part of my modular backpack power system.
7
If you need something heavier, but still
fairly minimalist, see the ICP 21Amp
Charge Controller.
These used to be available on amazon.com
as the “ICP Solar 21 Amp Charge
Controller” but the only place I know that
still sells them is Innovation House
http://www.innovationhouse.com/products/2
1amp.html (I have not obtained this unit)
One of the things I like about this 21 amp
charge controller (besides the fact it can
handle 21 AMPS) is that it can be used with
gel-cell batteries (yes, the charging voltage
IS different!) unlike the Brunton unit which
should only be used with SLA batteries.
Figure 8
8
Folding Solar Panel
Here is the 55 watt panel sitting in the afternoon sun, gathering about 26vdc at 2 amps
according to my DVM (unloaded, when charging expect voltages to drop to about 1718vdc) Global Power P3 55 watt folding solar panel. (military version, see “SunLinq” for
their civilian models)
Figure 9
As you can see this panel hasn’t been used that much as the folds are still quite
pronounced. Each corner has sturdy grommets, so when you stretch it in the sun on 550
cord to vehicles or trees, it quickly heats up and becomes flexible. The material is not
vinyl, but a coated cordura-type fabric that is also waterproof. There is a thin protective
(transparent) layer over the CIGS cells to also seal them from moisture. In the
foreground you can see the “trailer” plug.
9
There are many sources for folding solar panels. One of my favorite vendors is
http://www.ctsolar.com they provide power systems for expeditions and sell a lot of
useful equipment. As an example, they sell a 32 watt folding solar panel for around $300
and this would work well as long as you used a battery as a “buffer” to maintain a stable
voltage even though the panel may not be able to meet the charge demand. Thus you can
use a smaller panel (nothing less than 25 watts). You can also find folding panels on
Ebay for around the same price. Sunlinq is the name brand Global Solar is selling their
“civilian” models for in case you can’t locate a reasonably priced panel. The prices have
come down a lot since I obtained my 55 watt panel as well.
Figure 10
Here you see the 55watt panel folded up, it’s quite easy to carry in a backpack, or a gear
bag, along with 100 feet of paracord, the battery and charge controller(see note), and
cables/adapters you need to keep things going.
10
I specifically didn’t specify using a charge controller because it’s not really needed, you
can get by without one. If you have multiple panels and are producing that much current
you should probably use one. There are low cost models (around $40) that can be
obtained on Ebay or at batteryspace.com. I’ve used panels to charge batteries directly
without charge controllers but you do have to be careful and understand what you’re
doing. If you happen to have a DVM (volt meter) you should disconnect the solar panel
and measure the voltage across the positive and negative terminals of the battery. If it
reads above 13 volts you’re almost fully charged. You also need to make sure that the
input voltage requirements of the device you want to directly charge with a panel won’t
be exceeded. I’ve blown up things once in awhile by not being careful. What I mean by
this is to not try to connect a 12v device when the panel may be producing 18v without
making darned sure the device can handle the increased voltage. Otherwise it’s better to
use an inexpensive charge controller 1 that has a regulated output.
Charging Batteries
You can obtain “rapid” chargers that will charge up to 10 AA/AAA batteries that are designed
to be used in an automobile. In my case, I use a 10-cell iSun “BattPak” NiMH/NiCD battery
charger that came with both an AC-adapter and automotive adapter, I discarded the AC adapter,
removed the cigarette lighter plug and installed Andersen power-pole connectors, which allows
me to either connect it to a solar panel directly (don’t do this unless you load the batteries first)
or directly to a battery that you’re also charging at the same time. I use a power distribution
panel which allows me to do more at the same time if power is available. By this, I mean use a
radio or laptop while I am charging batteries from the main battery (in this case a 12V12AH
SLA) and being charged by a solar panel hung from the tree, or tied to the top of a vehicle. I
realized that when I’m charging AA batteries this way, I can really only charge 6 cells at a time
from a 12vdc source (battery, or other power supply). If I connected the charger directly to the
solar panel, however I’m able to charge 10 AAs at the same time – because the panel is
producing about 18-27vdc open-collector, and about 16-17 vdc with a load attached.
(insert picture of my modified iSun “BattPak”
here instead)
Figure 12
Figure 11
1
See Brunton 12vdc charge controller mentioned above.
11
Most of the panels
either come with a
cigarette lighter socket
or “trailer” plugs.
Anyone with minimal
skills with crimp-on
connectors or a
soldering iron can
create adapters and
cables needed in order
to charge batteries,
power devices, or even
use multiple panels (in
parallel to increase
your current output.).
I also recommend the
use of Andersen
powerpole style
connectors. (see below)
Figure 13
12
BEFORE
Figure 14
Here is a cable I purchased at
an RV supply place for
$2.99 that I use with my
panel and a battery.
I inserted a 3 amp
automotive fuse and I am
able to protect the folding
solar panel, the battery or a
charge controller (whatever
I’m attached to the solar
panel via the “trailer plug”
connector)
The second picture shows
my modification (power pole
connectors) which allows me
to attach the panel to either
the power distribution panel
or the battery/charge
controller.
AFTER
Basically I just snipped off
the terminal lugs and
soldered/crimped on the
Andersen Power Pole
connectors.
With SAE “trailer plug”
connectors, the exposed
connector is always ground.
Figure 15
13
If you need to power
something that is less than
12vdc you could use one of
those power packs that
provide multiple voltage
outputs that hold
rechargeable batteries that
you have charged from your
backpack solar panel
Figure 16
Examples of power packs could be something like this
Carport Handheld Device Charger which would allow
you to charge the batteries with your standalone charger
then detach to be used to charge any other device that
accepts a “cigarette” lighter input. I believe you can obtain
this for about $15
There are some very expensive “power centers” that you
can also purchase, some with built-in inverters (See my
note on Inverters below). The sky is the limit I suppose, or
rather what you/and your team can carry in a backpack.
This is important to consider, just how much can you and
your team carry?
.
Once the power pack is fully
charged you then use it to
charge your gps, phone,
ipod, etc. internal batteries
by using that device’s “car
charger” … Otherwise you
can use a small, lightweight
dc-dc converter to produce
common voltages in the
range of 1.5vdc up to 9vdc
(typically selectable output
devices) such as the ones
from
http://www.batteryspace.com
... these would typically
power chargers for squadlevel communications
devices (GMRS, MURS,
etc), standalone battery
chargers (AA/AAA),
PDA’s, MP3 players, etc.
I recommend the iSun
“BattPak” which is both a
charger and a “power pack”,
it can handle direct solar
panel input (wide range of
input voltages) and can be
used as a portable battery
pack as it has a built-in
cigarette lighter socket.
14
I have used the following components so far:
(1) 12vdc 12AH SLA (Sealed Lead Acid battery) (generic UPS-style replacement)
(1) 12vdc 7.2AH SLA (Sealed Lead Acid battery)
(1) 10A Solar Charge Controller
(1) 7A Solar Charge Controller
(1) DC-DC converter (10-16 vdc to 16vdc) for both the Toughbook CF-28 as well as the
IBM T23 laptops (see both powerstream.com and batteryspace.com for these DC-DC
converters (in this case having these interchangeable tips is useful as the less expensive
versions that use these modular connectors are versatile and allow me to use ONE dc
converter for both laptops interchangeably. Their quality and reliability may be an issue
though, I have several alternate dc converters for backup use.. One made by Lind for the
Toughbook and one from Powerstream for the T23…I’ve tested both for use with this
solar-powered battery system.)
(1) 25 watt folding solar panel (Sunlinq)
(1) 55 watt folding solar panel (Global Solar)
(1) iSun “BattPak” battery charger (AA/AAA NiMH/NiCD)
(1) IBM T23 laptop (can draw up to 3.2 amps if charging internal Li-Ion battery)
(1) Panasonic Toughbook CF-28 (can draw up to 4 amps if charging internal Li-Ion
battery)
(1) Yaesu FRG-100 shortwave (draws about .8 amps, or more precisely 800ma.)
(1 pair) 12vdc 5w compact fluorescent lights (CFL)..
I no longer own cell phones so I don't much care about stepping the voltage down to
charge a phone, but you could use some of the low-cost dc-dc converter models on
batteryspace.com for smaller voltage requirements. (i.e. from 12vdc Æ1.5vdc-9vdc)
As you might guess, sun is an abundant resource in the desert southwest which is my AO,
so this solution makes sense for me, but even if you're in a less "radiated" place solar can
still be a viable energy source when you have nothing else.
Reminder, the article is about a backpack portable system and what I power with it may
be different than what you need it for. I can think of radios (re-charging squad-level
communications devices, “Shortwave” or “Ham” (i.e. 2m HT) radios , PDAs, mp3
players, battery chargers (AA/AAA), etc... Since I’m a bit of a radio person I by
shortwave I mean something more like a professional general purpose communications
receiver such as the Yaesu FRG-100.
I also realize that you may not want to cart around a 9lb battery but you can split it up
among the members of your team, and it's easy enough to make a battery pouch with
strap to carry if it's not in your backpack.
This is why I don’t use anything larger than 12AH because the weight is prohibitive…. If
you could carry larger batteries you also need more power to charge it and a folding solar
15
panel even at the largest (55watts) size would not be able to recharge larger capacity
batteries in a reasonable amount of time.
If you need more power or wish to be able to rotate charged batteries in a high demand
situation I recommend carrying multiple 12AH batteries spread among your group. This
would also work better if each team member had a folding panel and separate battery
systems but I think one or two panels and 12AH batteries among a group would be
sufficient to keep the group supplied with sufficient energy to keep their radios, gps,
whatever going on a daily basis.
Many of these sub-components should be purchased with an eye towards also using them
in your vehicle, having both solar and vehicle power sources is useful.
Here is a set of power
cables I made using
Andersen power-pole
connectors and simple
crimp-on lugs.
Connecting it all together
This cable is designed
to handle up to 40
amps.
If you are not familiar
with the Andersen
PowerPole “connector
technique” then I
highly recommend
learning about it, as
the connector system
Figure 17
is ingenious, and can
be used for extremely
high current
applications as well as
smaller applications
like this 40-amp cable.
Here is an old female
cigarette lighter plug I
scavenged from a junk
drawer after I installed
the powerpole
connectors. This will
allow me to use an
automotive charger to
16
recharge small
electronics from either
the solar panel itself
or the battery/charge
controller, or from the
power distribution
panel.
Powerpole to Clip
Leads:
If you need to attach
your solar panel to a
battery directly
If you need to
power/charge your
battery/charge
controller from a
battery directly
If you need to
connect external
power to the power
distribution panel
Figure 18
Figure 19
17
Here is a 12
vdc 3.0 amp
supply that I
salvaged from
an old
Microsoft
forcefeedback
joystick.
Shortwave Radio Dual Power
(the Yaesu FRG-100 receiver requires 12vdc @ 1Amp)
Figure 20 I cut the power cable a few inches from the potted adapter and crimped on the
Andersen power-pole connectors. This would be when I’m on commercial power or where
inverting AC is feasible This power supply was perfect for powering my Yaesu FRG-100
shortwave receiver when AC power is available.
Male
cigarette
lighter to
powerpole.
Figure 21 Because every cable created can be attached to the power distribution panel
feeding power in, or out as needed allowing us to store or produce power, or consume
power to and from the battery/charge controller package. I also wanted to power the
radio from vehicles I made a cable that I can plug into a cigarette-lighter socket. Of
course, all of these cables have multiple uses as they can be used in several different
configurations linking the battery/controller or the solar panel to whatever device needs
power, as the situation requires.
18
Finally I made a cable
to connect to the
Yaesu receiver 12vdc
input that could be
used with the wall
transformer, the
cigarette-lighter cable,
or the battery / charge
controller via the
power distribution
panel or directly in a
modular manner. I can
pick and choose how
to power the receiver
no matter what power
options I have I know
I can get it working.
Figure 22
I keep all these cables
(along with a bunch of
spare fuses for both
external and internal
replacement) with the
Yaesu FRG-100 radio
which normally lives
within a foam-padded
20mm ammo can.
Figure 23
I also keep the
receiver’s instruction
manual, the multiband antenna and 100’
of paracord to help
string the 25 foot
antenna.
Thus allowing me to use AC power or solar/vehicle sources
(any 12vdc source that had a cigarette lighter socket). As you
can see I also put an external fuse on the cable as I desperately
need to protect the receiver and it’s easier to change an external
fuse than the internal fuse within the Yaesu FRG-100. I used an
automotive-style fuse as I suspect they will be easy to come by
when you need a fuse. In this case, the fuse is 1.0 amp
19
Power Distribution on a backpack scale
Small, lightweight fused distribution panel (40A)
The entire panel weighs about
3 ounces, not including all
various adapter cables I have
fabricated..
These are Andersen powerpole chassis connectors, and
each socket is wired to the
main input line so each are
independent of the other.
Figure 24
The main input fuse of 40A is
on the left, with varying fused
connections to the right with
ranges from 30A to 1A
displayed.
The main input on the left connects to the chargecontroller output or directly to battery terminals. These
fuses are standard automotive fuses.
20
Really Portable Computing. Indefinitely.
The IBM T23 laptop, and the light are being powered by the 12VDC/12AH
battery/charge controller combination as shown.
The regulated 12vdc output of the charge controller is connected to the fused power
distribution panel which protects the charge controller output as well as providing a way
to connect independent, multiple loads to the charge controller’s output at the same time
The loose cables lying off to the side are for the solar panel charge input and the second
battery charger output.
You can connect any 12VDC source to the “solar panel charge input” and that could be
where you plug in the cigarette lighter plug into a vehicle, or even a 12VDC wall
transformer such as the one I used for the shortwave.
As you can see I have power to the laptop (which requires 16VDC, but all we have is
12VDC so we convert from 12VDC to 16VDC by using a DC-DC converter).
Figure 25
The view is with the battery and charge controller on it’s side with the power distribution
panel attached to the side of the battery using Velcro strips…
21
Here is a simplified
power configuration
using a DC-DC converter
(from batteryspace.com)
to charge a Panasonic
Toughbook, using a
cheap SLA (Sealed Lead
Acid) battery. By using a
folding solar panel to
charge the 7.2ah battery
you can keep the laptop
going under almost any
circumstances. This
Toughbook has built-in
WIFI (802.11AB), GPS
so it’s the perfect
backpack combination.
These are military-grade
rugged laptops.
Figure 26
22
Figure 27
As you can see, the receiver is powered up, and I have a 5W light running off the same supply. Everything here fits into
the padded 20mm ammo can perfectly. I hope it will protect everything from the elements and perhaps even EMP.
23
Field Lighting
I wasn’t going to
include this as the
document originally
began life as a tutorial
on how to keep your
laptop and a radio
alive in the field but
someone asked me
how I’d do it if I
needed lighting from a
backpack. I
recommend using
LED lighting but you
could also use 12vdc
fluorescent lights.
Figure 28
I used 12VDC CFL lights which are widely available. They are
very cheap and sometimes LED lights just don’t have the lumens.
These lights only consume 5 Watts each which is more than an
LED array would but these are very bright. The light sockets are
standard cheap “lamp” style sockets you can pick up anywhere,
and the lights themselves are designed to use the standard “light
bulb thread” socket. (Just remember they’re DC and do not plug
them into AC!)
24
LED Lighting
Flexible, sturdy light (Red-only LED) with 22 feet of power cord.
The sky is the limit,
you can obtain so
many variants of LED
lighting in almost any
color. For this light, I
used (1) 12vdc LED
auto signal light in
RED, about 23 feet of
14ga (2 conductor)
wiring, a 3 foot long
piece of stiff wire, a
re-cycled dishwasher
hose, 2 Andersen
powerpole housings, 2
Andersen powerpole
pins, (1) 1A fuse (not
shown) and fuse
holder (not shown),
some shrink-tubing,
about 8 small tiewraps and a bit of
solder. This light
draws less than 300ma
which means you
could power it about
20 hrs with a 7AH
battery. I chose red
because if I am using
this light, it’s at night,
and I need to help
preserve whatever
night vision I have. It
provides enough light
to read/write and to
operate equipment or
type on a laptop. I
plan on adding a
switch as soon as I can
find one sturdy
enough to become part Figure 29
of this design.
25
Details
Figure 30
This is really very simple stuff.
As you can see in the diagram (Figure 26) at point “1” the power is fed directly from the
battery instead and anything attached there will have bypassed the charge controller. You
will still be able to obtain a well conditioned 12vdc but as the battery discharges the
voltage will drop unless you’re charging it at the same time with something able to keep
up with the load.
If you connect your DC loads in this mode, you are merely using the charge controller as
a “charge regulator” only charging the battery. Which is all that most charge controllers
really do anyway.
The very inexpensive charge controller (10A max) that I used has a “load” output that
provides a regulated 12vdc @ 10A. By using the charge controllers load output (Figure
21, point “2”), we are able to offer over-discharge protection to the battery, if the battery
voltage drops to 11.1v the controller will shut off the load output of the battery but will
continue to charge the battery if the solar panel (or any other suitable source of power is
connected)
If you want to detach the solar panel and instead attach the “powerpole to clip leads”
cable directly to the charge controller you can recharge your battery in a hurry from a
26
vehicle battery (vehicle running or not) fairly rapidly. You could perhaps use a cigarette
lighter cable to attach to the charge controller and charge your battery while driving in
your vehicle.
Once again, if you always use a charge controller to handle charging your battery, you
can protect the battery from over-charging (the controller will merely stop supplying
voltage to the battery when it’s fully charged) but did you know you could use a battery
charger or even perhaps a 12vdc wall transformer instead of the solar panel and still keep
your battery fully charged when you have access to AC power. I use this method when
storing the backpack power system for long periods.
By attaching an alternate power source to the charge controller’s “solar panel inputs” you
are able to charge the battery, utilizing all the features of the charge controller including
over-voltage protection as well as automatic charging shut off having it remain in a
trickle-charge mode. Most of even the cheapest charge controllers do automatic
equalization as well as PWM.
If you don’t use a charge controller, it will pay to have a DVM with you to monitor the
battery voltage while you are charging. I am currently checking out this very interesting
unit that allows you to monitor input/output voltage, along with current (in and out), that
gets installed inline permanently as a monitor or with power-pole connectors to allow you
to use it as a diagnostic tool where ever you may need it.
Powerwerx’ Watts Up
This is one useful device, is
lightweight, powered from the line,
and draws very little current. It
measures quite a lot of information
about your power use and capacity. It
almost completely negates the need to
keep a DVM around for monitoring
your power generation and
consumption.
http://www.powerwerx.com/product.
asp?ProdID=3809
Figure 31
Features
Measures energy (Wh), charge (Ah),
power (W), current (A) and voltage
(V). Can use an optional aux. battery
for measurement down to 0vdc.
Precision: 0.01A and 0.01vdc
It measures peak Amps, peak Watts
and voltage minimum (sag)
27
This unit will handle 50A continuous
and 100A peak at 60vdc
What is also nice about this is it’s low
power usage. It draws only 7 mA
Made in USA to ISO 9001:2000
quality standards
Figure 32 If you purchase from PowerWerx you can even get it in black.
From reading the manual, it’s based on a DSP which allows the
Watts Up to have better A/D (analog to digital) resolution as well
as using differential amplifiers to improve noise immunity.
Each Watt’s Up is factory calibrated with constants stored in the
internal EEPROM to correct for component tolerance issues.
Caution: please do use a fuse on the output side of your battery, or the load side of your
charge controller.. This will help to protect your battery and charge controller from
possible disaster.
Summary
If you scrounge well, this won’t cost much. The major expenses were the solar panels, the
12V/12AH battery, and the charge controllers. Getting started using Andersen powerpole connectors can be somewhat pricey as you obtain a crimping tool, a lot of 15,30,45
amp enclosures, crimp pins, rolling pins, and connector locks. Once you’ve used
Andersen power-poles, you won’t want to use anything else!
I expect to write a similar document for powering larger systems, so please remember as
you look at this, my intent was to keep it at a backpack level. You can use these ideas as
a starting-point; the key is to come up with a modular set of cables, chargers, panels, and
adapters (dc-dc converters) to handle small power requirements when in the field that
match your equipment.
Many of these ideas can be scaled-up to provide much larger amounts of power by using
larger capacity batteries (sets of batteries), charge controllers, and more solar panels with
higher output. However this is completely beyond the scope of this document.
Best wishes to everyone, looks like the next few years are going to be critical for the
Republic, Good Luck, and God Speed! Terminus 2008-01-22
28
List of Figures
1.
2.
3.
4.
5.
6.
7.
8.
9.
Charge controller with battery and panel
Charge controller with battery and folded panel
Powerstream DC-DC Converter (laptop)
Lind DC-DC Converter (Toughbook) (12vdc to 15vdc)
Batteryspace.com DC Converter (laptop)
Typical 12V/12AH battery
Basic Charge Controller (Brunton 12vdc 7a)
ICP 21 Amp Charge Controller
Deployed 55w solar panel with charge controller and battery (charging in the
sun).
10. Folded solar panel with SAE “trailer plug” connector
11. iSun BattPak Charger/Battery Pack
12. iSun BattPak Charger/Battery Pack
13. Wide assortment of SAE “trailer plug” adapter cables.
14. RV Cable with terminal lugs attached.
15. RV Cable with Andersen powerpole connectors attached.
16. Carport Handheld Device Charger
17. 40 A power cable (Andersen powerpole)
18. Female Cigarette Lighter to Andersen powerpole
19. Andersen powerpole to Heavy-Duty clip leads.
20. 12 vdc 3A wall-supply salvaged from Microsoft Force-Feedback joystick with
Andersen powerpole.
21. Male Cigarette Lighter (Andersen powerpole)
22. Rear view of Yaesu FRG-100 communications receiver
23. Yaesu to Andersen powerpole
24. Power Distribution Panel (fused)
25. Laptop, DC-DC Converter, 12w CFL light, battery and charge controller.
26. Panasonic Toughbook CF-28 being charged by an external SLA battery.
27. Yaesu FRG-100 with 20mm Ammo can, 12w CFL light, battery and charge
controller.
28. Diagram
29. Flexible 12vdc/1w LED “Night” light.
30. 12vdc/12w CFL light with Andersen powerpole.
31. Powerwerx Watt’s Up meter detail
32. Powerwerx in black.
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