| Home-made
Battery Pack |
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| After tripping many times on the power cord
between my scope setup and my car as well as dragging out a power supply
and extension cord in my backyard, I decided that I needed a compact
self-contained power supply. The supply needed to provide
enough power for at least 8 hours of use. The setup has the following
power requirements:
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| Losmandy G11 mount:
500 mA |
| SBIG ST-4 CCD autoguider:
1 A |
| Kendricks Dew controller
+ one 5" and one 3" dew heater: 1 A at 50% setting |
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| Total power = 2.5A |
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| In addition, I sometimes bring a friend that
has a Meade LX6 scope and he uses my power as well. For 8 hours of
use, I would need about 24 Amp hours. This rules out all
of the car emergency starters that are around 17 AH and leaves the
Kendricks 34 AH packs. One look at the price and I was sure I could
make one much cheaper. Here's what you need: |
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| Battery Pak |
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| I wanted a battery that did not leak, need any
maintenance and was reasonable in price. This ruled out standard
lead acid batteries for cars. I finally settled on a 32 AH GelCell
battery that I bought at a local automotive parts supply store.
WalMart also sells these batteries at around $100 CDN. |
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| You will also need the
following parts: |
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| 3 automotive style 12V cigarette sockets, panel mount |
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| 3 10A inline fuses |
| 6 Crimp connectors |
| Toolbox |
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| I bought all of the these parts at WalMart for
a cost of around $70 CDN for a total of $170 CDN. Compare this
to the price of the Kendricks system which costs around $400 CDN.
Sure it doesn't have a voltmeter and uses circuit breakers instead of
fuses, but its easy enough to bring a VTM with you. The voltage on a
Gel Cell will range between 13V fully charged and 12 V discharged. |
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| Here is the finished
product |
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| Charging the battery |
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| Do not use a standard automotive battery
charger for charging Gel Cells! It will lead to a damaged
battery. You will need to buy a "Float Charger" that has a
lower voltage. Kendricks sells a 6A unit that will charge the
battery in about 8 hours. Alternatively, you can buy this charger
from Schumacher |
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| All images and contents are © Copyright 2000 by Tom
Blahovici. All rights reserved. The images and contents may not be reproduced, published,
copied or transmitted in any form without written permission of the author. |
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