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ContinuousWave: Small Boat Electrical
Emergency Start Battery Jump Pack
|Author||Topic: Emergency Start Battery Jump Pack|
posted 03-12-2006 01:02 PM ET (US)
I am thinking of buying a starter pack as an emergency start for a Mercury 90-HP two-stroke. Will it start? I believe [the jump start pack] is fitted with a 17.5 ampere-hour sealed lead acid cell.
posted 03-12-2006 01:10 PM ET (US)
I have used mine to start several large V8's but luckily have not had the opportunity to use it for starting my outboard yet.
I'm sure it would have no problem starting your 90 HP motor.
posted 03-12-2006 02:33 PM ET (US)
A 90-HP Mercury two-stroke is only a three cylinder motor, and the compression ratio is not particularly high. If the jump start can turn over a V8 automobile engine, it ought to crank your outboard. Now how long it takes to start your outboard and how much cranking--those are other questions.
|Tom W Clark||
posted 03-13-2006 09:41 AM ET (US)
The short length of robe that is already under the motor's cowl weighs a lot less than a jump pack and takes up far less space in a 16SL.
I can't see the need for a jump pack and I wouldn't bother with one.
posted 03-13-2006 10:51 AM ET (US)
Jump packs are great. I have lent mine to numerous stranded cars,suvs and it has always started them on the first or second crank. Much easier and safer than jumper cables which I no longer carry. The jump pack goes in the boat and would be easy to pass to another boat. I think it is very important to get one that has an on/off switch so there is no danger of sparks when attaching the cables.
Also very cost effective for single battery boats that really don't need two batteries to install and maintain.
posted 03-13-2006 01:49 PM ET (US)
I bought one as insurance and though I have never needed it myself, I have helped 2 other boaters on our canal get started so I know it works.
posted 03-13-2006 10:53 PM ET (US)
I'd use the battery to power the ignition system with the key in the run position, then use a rope to pull start the motor. A 90hp 2 stroke is started pretty easily with a rope. That way, you get many more start attemps without risk of totally draining your backup source battery. BillS
posted 03-14-2006 01:44 AM ET (US)
Does THAT Merc 90 have an option of a rope start? In that
HP range, some do, some don't.
I've seen a jump start pack get a boat in that range going,
|JOHN W MAYO||
posted 03-14-2006 07:34 AM ET (US)
I assume you are talking about the Jumstart battery pack that comes with 2 short jumper cabes.
I have carried one of those jumpers for several years. They work excellent, especially at the the begining of boating season and to help others who have not maintained there batteries during the winter months. At the lakes, more than the ocean, I probably have started 5-10 boats a year.
It is good backup for yourself and your trucks battery also.
Look for one with the hightest Amperage. Mine two are 1000 amp and 800 amp. I like the highter reserve power, I see a lot at 400 amp,
posted 03-15-2006 09:53 PM ET (US)
All Merc two stokes have notches in the flywheel for Ropestarting up to the small block V6s. Maybe the bog blocks too, I never checked those. I've rope started a Merc 175 and 135 Opti just to prove I could do it. I don't think a 90 would be a problem. You may need to pop off the flywheel shield to access the top of the flywheel. My 175 even came with a little pocket inside the cowl to hold the rope. Bills
posted 03-17-2006 03:25 PM ET (US)
Many thanks guys I don't currently have a rope start under the cowl so ill make one up, but as I am one armed I think the power pack is good insurance. I believe its rated at 900 amps peak.
posted 03-18-2006 12:32 AM ET (US)
bsmotril, the Optimax may have notches in the flywheel for rope starting but you need a fully charged battery to rope start it. Doesn't really make sense to have a rope and notched flywheel when it will not start with a dead battery.
posted 03-18-2006 07:51 PM ET (US)
Well, since this discussion thread started with the premise of a backup battery pack, I made my rope starting suggestion to save the current draw on the starter motor and rope start it so the backup pack can power the rest of the electrical goodies under the cowl. In my case, there were two motors as well as two batteries. I don't make a habit of ropestarting any engine unless there is no other choice. If some day you may have to exercise that option, why not test it before you need to do it 20 miles offshore?
posted 03-20-2006 01:37 PM ET (US)
I picked up an emergency battery jumper from Home Depot as a backup. With a dead battery, the jumper would start my 1986 150HP Yamaha with no problem.
I continued to have intemittent problems even after I charged both batteries so I needed to do some trouble shooting.
I finally replaced the off-1-both-2 battery switch and this solved the immediate problem. I have since replaced both batteries and everything works great.
Lesson: If your battery keeps failing check the condition of the battery. It may be time to replace. If your battery is fine then check the load to make sure you don't have soemthing draining the battery.
PS-- I tried the solar panel route, but I think it was draining the battery when the sun went down. If you go this route make sure you get a panel with a blocking diode so that the voltage does not drop after sundown.
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