J.M.:
This got my curiosity up since I recently flew up to Big Bear, CA, and barely got my plane started the morning of our departure. I had charged it before leaving knowing that this could be a problem. It was very cold (about 35 degrees F) and I realize that a battery’s ability to source max current goes ‘way down with temperature (not to mention the oil being like molasses). My question is this. What size (peak amps) booster would be sufficient to “augment” the onboard battery, in a situation such as this? Of course the booster would have had to be kept warm, or it would be just as handicapped. Any thoughts?
Robert Lavigne:
To those of you who have asked, either here or directly, about the use of “Gel-Cell” booster packs …I apologize for being tardy in responding. I was away from my e-mail for FOUR DAYS (a truly liberating experience…try it :-))
As the principal organizer of “Project VOLONTAIRE” during the 1998 ice storm which left millions in Ontario, Quebec, New Brunswick, and large sections of northern New England without power for periods from 12 hours to 30 odd days …I have become a zealot on the subject of emergency power. (for anyone who wants to know what our airplanes can do in a “civil emergency” I will include a small paragraph at the bottom of this describing VOLONTAIRE, and if anyone would like to organize such a programme, several of the principal organizers can be contacted to give you their brutally acquired knowledge ..please contact me directly ..also ..a small number of web photos of the scale of the task are available).
GelCell Booster packs come in an expanding number of prices, sizes and capacities, and with an expanding range of accessories either “hard wired” or loose.
The most simple are compact lead-acid jelled-electrolyte filled, configured, usually, in a pair of 6.8/7.4 +/- volt batteries in series, with a simple pair of heavy gage wires ( 6-8 gauge) and moderately heavy “alligator” connectors, encased in a “non-openable” plastic case. The more elaborate have lights, larger battery capacity, compressors, a/c inverters, radios, and an increasing number of silly or valuable accessories.
I have examined and used MANY of these units and for the purposes of use in my airplane I have selected two ….one for summer use and one for winter use.
The summer one is a cute little unit, which has a 18 amp rating, weighs 7.8 lbs, is about the size of a school child’s lunch box. It has a 240 lb capacity compressor molded into its case. I typically carry a small 75 watt power inverter to plug unto one of its two 12 volt “cigar lighter” type outlets to provide a power source for things like hand held transceiver chargers, and a “double end” cable ( two cigar lighter plugs ) to either run another 12v device ..or to allow the pack to be recharged from a 12v source ..( such as a rental car outlet while in a distant port ) I haven’t yet used it to boost the plane ..but I have used it to boost several large cars ..so I know it has the “whack” to start the plane.
The winter one is a more robust unit which has the capacity to both power my pre-heater for the requisite 30 minutes ( on a typical Toronto winter morning ) and, should it be necessary, give the battery a help as the rear mounting of the battery in our airplanes precludes the warming of the battery as the engine housing warms. My winter unit also has 700 cranking amps and a light attached which is helpful in the dark nether reaches of a musketeer at 6 am on a black winter morning.
Knowing that most of the guys here are in the US ..I include this link as only a reference as to types and scope of models frequently on offer :
http://www.canadiantire.ca/assortments/browse_product.jsp?FOLDER%3C%3Efolder_id=1408474396670121&ASSORTMENT%3C%3East_id=1408474396670271&bmUID=1102162000857&assortment=primary&fromSearch=true
Any power pack you select for one of our airplanes should not only include the features and capacity you decide are correct for your needs but a satisfactory length of cable to easily reach the battery terminals while the battery pack sits in a stable position in the baggage compartment. (not many have a “comfortable” length ..so take a tape measure with you when you go shopping).
A SERIOUS consideration should be the quality and insulation arrangement on the attachment clips ( alligators ). The metal battery box in our airplanes is grounded, thus an accidental contact between the positive clamp and the box ..will offer a rather spectacular display while you have your head within inches of the source, in a dark confined space, with “no place to run” ….the least damaging outcome ..is a case of night blindness, a bumped head ..and a flight with damp shorts…the worst ..would be the explosion of gases and the attendant flash fire and acid burns …so please review the recommended practice for terminal connection of boosters of any nature. I would recommend clamps which have a plastic shielding, on the exposed area or if the model you otherwise find satisfactory doesn’t have this protection ..a roll of electrical tape ..liberally and cunningly applied should help. ( and for heavens sake ….go practice “giving yourself a boost” ..before that first frozen morning when you are trying to crank up ..while the wife and kids stare out from the frosted windows of the rental car )
Boosting your Musket would sensibly be done due to the “cold soaking ” of a battery which just doesn’t have the cold “umph ” to give your engine a fast enough crank to start ….or the dreaded ” forgotten master switch” ..but not to deal with a “dead ” battery or one which should be replaced. (Tho I have personal and close up experience in which an owner of “an other well known brand of airplane ” did remove his dead battery ..and with lavish use of electrical tape and questionable judgment did use his battery pack to get home). In winter a healthy electrical system is simply too important to be “band-aided” In general, two people, are required to properly boost a plane in this fashion. Remember, to boost one of our airplanes you have to partly dismantle the interior and remove the battery box cover, attach the booster box leads correctly, communicate with whomever is at the controls and then reverse the process while in a dark hole with a 150-200 horse power engine 12 feet away producing an arctic blast of 100 mile an hour wind trying to slam a door on your backside. If you are alone ..PLEASE don’t try to get the airplane started ..and then try to leave it running while you “dismount” and tidy up the back end ….its just not worth it ….If the you can’t get the engine running again on its own battery after 10 -20 or so minutes of standard idle ( remember to lean to prevent lead deposition ) then you have no business winter flying with that battery.
If anyone would like more info ..please contact me directly ..but I think the above covers most of the questions I was asked
RCL
( re: Operation VOLONTAIRE In the aftermath of the 1998 ice storm a group of 66 pilots and their airplanes flew relief supplies to the heart of the “Dark Triangle ” from Toronto City Centre Airport. Food, medical supplies, hospital supplies and supplies for emergency services were carried in ..and people requiring emergency and chronic care were evacuated. It was a remarkable example of the flexibility and talents of “little ” airplanes ..and the people who fly them)
Editor’s notes:
These portable power packs are terrific. They come in many sizes and accessory configurations. I have even used them as high-capacity external batteries for 12V cordless tools, with a home-made battery socket adapter.
Don’t jump-start a plane, then take off with an uncharged battery. You are inviting an in-flight power failure, as well as a trashed generator/alternator and regulator. Fully charge a weak battery first.
Don’t charge a very weak or dead battery in the plane. Get it out of the plane to a safe place first.
A fully-charged 2″W by 8″L by 6″H pack, with a lighter socket and plug, is capable of recharging a very low auto battery, enabling it to start a 351 cubic inch V8 (speaking from repeated experience). One interesting aspect of these units is that they will often read 14.3V to 14.5V when fully charged. That’s why they can transfer their power into a low battery that is much larger. I have been wondering whether their internal battery either has an extra cell, or perhaps a different electrolyte. They reach maximum capacity on their 120V recharge system, but can also be recharged from an auto power socket, as long as the regulator provides enough buss voltage for a full recharge (many don’t).
This compact type is made to recharge a low battery through a cigarette lighter connection, over a period of ten minutes or so. They are not intended for jumping a battery. The larger systems that include “jumper cables” are capable of jump-starting, but that should only be done through an external ground power receptacle (if you are determined to do it). Again, it is asking for trouble to do this with the battery in the plane. With the cost of aircraft repairs (and eyes), is it really worth the risk, to save the time of pulling a battery? How many of you have heard of, or witnessed, a battery explosion? Yup, you’ll get away with it almost every time you try it. Almost.
The compact systems with lighter connections cannot provide the instant power for starting; they are constrained by internal controls as well as small wire. There are other reasons why they are unsuitable for this in a plane. For example, the lighter socket is usually “cold” unless the Master is on. If the Master is on, the solenoid that holds the connection draws a fair bit of power all by itself. If you use the compact type, you still need an “adapter” so you can connect directly to the battery and recharge it.
A very successful use of the compact type is as a backup in-flight power supply. You can plug it in to the lighter socket, and turn off the Master (and non-essential loads). The standby battery will run the essential loads for a pretty good while; certainly long enough to reach a field and land. By turning off the Master, you eliminate a source of current consumption, and you isolate a low battery that would otherwise suck the standby dry. Caution! If you exceed the lighter’s rated power (fuse size), using a standby battery in this fashion, you’ll be right back where you started. Most of the compact standby units are internally regulated to prevent this, but you never know. Plan in advance what you’ll leave on.