Marine Priority Start for single battery single engine????

wakeup

wakeup

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Anyone fitted one of these Marine Priority start devices to their batteries. Do they work?

I am thinking of fitting one of these to errrr my friends boat after he had an embarassing experience with a flat battery out in the Bristol channel last weekend, I errr I mean he spent 3 hours at anchor waiting for rescue last weekend after a flattened battery....

Seems to me though that it would cost me the same to fit a second battery and add a dual switch???

Can you do this easilly on a Mercu 5.0 or would I have to change the alternator???

Any advice greatfully received for my friend of course /forums/images/graemlins/confused.gif
 
Can't find a good picture but here is what the text says
"This automatic computerized on/off switching system monitors your battery level and disconnects the battery when voltage drains below 11.9 volts. When you're ready to start the boat, PriorityStart® automatically reconnects the battery when the ignition key, running lights, or other electrical device is turned on. Handles 1000 starting amps. Installs in minutes with three easy steps."

It is a small yellow box that straps to the side of the battery with a cuple of large wires connected between battery and boat.
 
I've just looked at the website http://www.prioritystart.com/ and it looks to be a straightforward product which must comprise of a heavy duty relay and some electronic voltage and current sensors. It seems that below 11.9v the relay will only come in under heavy load ie the starter motor. I guess the price of $99 is realistic because they won't sell thousands.
Nothing to do with the alternator so no problems there and installation should be a few minutes.
Although a second battery and switch would be cheaper its far more hastle to fit and you will have to remember to switch across to charge both batteries.
 
It sounds like a variation on a couple of units we have manufactured since the early 80's.
The problem is that if you are using power, then the voltage of the battery will vary with the load drawn, the size of the battery and the age of the battery. Add to this how much reserve you want for starting, depends on engine type and starter motor, you have many variables to cover. Of load you need to be looking at a minimum battery volts of around 12.2, but if your pulling around 10% of battery capacity as a load, you need around 11.8 volt. the problem comes were you are pulling a small load, 1/2 amps, you can then drain a battery nearly flat before you get to 11.8 volt.

Would prefer to see a small starter battery and split charge relay.

I prefer to see power-lockout / reserve power systems on service batteries were it is critical.

BRian
 
Errr ok thanks for that, but in laymans terms or should I say batteries for dummies terms what should I do to improve my battery , should I fit a second battery with a switch (space might be a problem) and if so how do I wire the battery switch (what do I do about charging them etc) or should I fit one of these gadgets or do I do both???
 
I think you actually have 3 choices
1. Fit the Priority Start which will be quick and will work under most circumstances (ref halcyon's thread and I respectfully acknowledge that he knows far more about this than me...have you seen his website?)
2. Fit another battery and simple isolator switch so that you can have either battery on its own but you have to remember to switch from one to the other. (cheapest solution)
3. The proper battery management solution which I guess is what halcyon would recommend which will be the best and most expensive solution.
The choice is yours
David
 
Thanks very much for the info guys, i'll go and do somethinking...... /forums/images/graemlins/confused.gif

Do you have Halcyon's web site url???
 
The problem is that we are starting with only a car battery, if you assume lockout , depending on load is between 25 and 50% capacity, you have around 10 - 20 amp hour available. I would not like to rely on that to start a V8 in all circumstances in the Bristol Channel.
If you fit a second car battery, Hella type isolator switch, and a split charge relay from a caravan dealer, it's not going to cost £50. You have twice the battery capacity for starting, twice the capacity for services, have spent no more money, and have a spare starter battery.
The end of the day it's horses for courses, he has a simple installation, he needs a simple system, if he wants a more comprehensive system I can help him.

Brian
 
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