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Author Topic:   Marine Priority Start draining battery
djreichenbach posted 02-11-2008 09:06 AM ET (US)   Profile for djreichenbach   Send Email to djreichenbach  
I recently replaced the entire electrical system on my '75 Montauk. I tried to keep it relatively simple. Decided to go with one battery system since I have very few accessories that draw power and I never had a problem with battery discharge or starting in the past. My current system in a nutshell:

New dual purpose battery connected to engine for cranking and power trim.

House power going to 40 amp breaker, then to fuse block, then to console for fish finder, 12 volt outlet on console, 3 position switch for nav. lights and that's it.

I decided to buy a "Marine Priority Start" device from West Marine to protect from discharging the battery to the point of not having enough juice to crank the engine, i.e. if I was fishing, running the depthfinder, had a radio plugged into the outlet, etc... and ran the battery down, the device is designed to sense the charge left in the battery and disconnect if it gets to a certain point to always allow enough to let you crank the engine. This way, your protected if you have a single battery system.

Sounded good to me. Everything seemed to be working well, but when the boat sat for a month or so without being run, my battery was too low to crank the engine. This happened once, so I recharged it, checked the connections and the next time I tripped the master breaker to be sure something wasn't draining the power slowly (although if that were the case, the Priority Start should have protected me). It happened again and this time the battery was completely DEAD. After fully recharging (new battery), things ran fine. Used a voltmeter to see if battery was charging while engine running and it was. There did not appear to be a draw on the battery from the engine while not running either. I decided it must be the Priority Start that is somehow drawing a small amount of power off of the battery to monitor the charge, which eventually over enough time, drains the charge off the battery. Seems to me that this defeats the purpose of having the device in the first place. I took it out of the circuit and so far, no problems. Has anyone used a Priority Start before? Experienced the same problem? Is my device defective and in need of replacing? Any thoughts would be appreciated (except suggesting getting a second battery for cranking, I already thought of that).


Casco Bay Outrage posted 02-11-2008 10:13 AM ET (US)     Profile for Casco Bay Outrage  Send Email to Casco Bay Outrage     
Dan -

In looking at the item on West Marine's site, I see it is a tool for sensing battery drain.In theory a device like this should work well since it will stop any device draining the battery. At $80, it is pricey.

If you are running a vhf, gps and radio, I would guess you would have 4 hrs of power before it would affect the starting of the motor.

I would agree that if the boat sits, the Priority Start may be draining the battery.

If you really want the Priority Start feature to warn you while using the boat, I would suggest you add a simple and effective master battery switch to prevent drain while the boat is not in use. These run $35 and is a simple on/off. Example: http:/ / www. boatersworld. com/ product/ 196970792. htm?bct=t13046503%3 Bcielectrical-boat%3Bcibattery-systems%3Bcibattery-switches-isolators

My opinion - You are not running many accessories so I would ditch the Priority Start and install the master switch. Assuming your battery is correctly sized, just remember how much time you are running the accessories. KIS principle.


Jerry Townsend posted 02-11-2008 01:30 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Dan - the suggestions by Cisco Bay are good. If you go this route - place the master switch between the battery and your protection device.

Now - for yourself and others - similar protection is easily and automatically provided and a bit cheaper by using a simple solenoid (a starter solenoid works well) between the two batteries with one battery used for starting and the other used for all other loads. The second battery is then connected in parallel to the main starting battery. The solenoid is powered by the alternator. Then the two batteries are connected via the solenoid - only when the alternator is operating. When the engine is not operating, the solenoid is open and the batteries are isolated. It has been a long time since I bought a starter solenoid - but they should be in the range of $15 - $30. ---- Jerry/Idaho

Jerry Townsend posted 02-11-2008 03:23 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Another note I should have included above - the alternator is only connected to the main (starting) battery and the coil on the solenoid. The secondary battery is simply charged via the main battery - when the engine is operating. ---- Jerry/Idaho
Chuck Tribolet posted 02-11-2008 03:53 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
VHF, FF, and GPS will run for several days on a battery.
Together, they are less than an amp (as long as you aren't
transmitting on the VHF). Typical battery is 60 AH. So
at least 60 hours.


Bella con23 posted 02-11-2008 06:13 PM ET (US)     Profile for Bella con23  Send Email to Bella con23     
I like the concept Jerry, however I would question the ability of the solenoid to stay energized for any length of time. I was always under the impression that a starter solenoid was designed for non-continuous use.

Have you used this setup with success? It would be cost saving compared to the various microprocessor controlled electronic switches available.

Chuck Tribolet posted 02-11-2008 06:40 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
ON the solenoid, not
THROUGH the solenoid.

The alternator's +12V wire typically runs to the big lug on
the solenoid where the battery's big +12V wire attaches. But
there's no requirement for that, it could run straight to the
battery instead, but it's usually cheaper for the manufacturer
and less work for the rigger to run it to the solenoid.


Chuck Tribolet posted 02-11-2008 06:58 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
I just took some measurements on my '97ish Montauk.

Engine, ignition on but not running: .4A
Anchor Light: .6A
VHF+GPS+FF: .9A (most of that is the VHF)
Running Lights (including Anchor light) 2.25A

Net: remember to turn off your lights.


Jerry Townsend posted 02-11-2008 10:32 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Bella - I use the solenoid technique a lot of time - in my camper - where the camper battery is paralleled from the vehicle battery via a solenoid. I only have one battery in the boat ('96 17 Outrage), but if I were to install a second battery - there would be a solenoid in place. I only have one battery in the boat because of the facts that Chuck points out - the drain from the GPS and radio are of no significance - a no-never-mind.

Thanks Bella - because I forgot to mention another point - get a solenoid rated for continuous operation. ---- Jerry/Idaho

andygere posted 02-12-2008 04:34 PM ET (US)     Profile for andygere  Send Email to andygere     
Jerry's solution is clever, but it has the limitation that the second battery can not be used to start the outboard without using jumper cables. This is kind of a poor man's voltage sensing relay system. Off the shelf units are available with integral battery switches, and these really work well. They cost a few buck more, but are still a lot cheaper than a tow.
davej14 posted 02-12-2008 05:50 PM ET (US)     Profile for davej14  Send Email to davej14     
In the first paragraph of the original post it is clearly stated that this is a one battery system.
Jerry Townsend posted 02-12-2008 06:36 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Andygere is correct - the solenoid does not provide an immediate switch to the second battery for starting the engine. To use the second battery for starting purposes requires one jumper cable for the positive lead - as the grounds (negatives) are common.

But, for those using multiple battery setups - the solenoid provides a typically fault-free, automatic isolation system.

And my apologies for digressing from the single battery originating post - as davej14 points out. Thanks Dave --- Jerry/Idaho

djreichenbach posted 03-14-2008 07:20 AM ET (US)     Profile for djreichenbach  Send Email to djreichenbach     
Lots of interesting info. I think the take home point for me is to get rid of the Priority Start and not worry about it. The whole point of installing is was as a safety measure on a one battery system to prevent running down my cranking battery and getting stranded. The bottom line is, I never had a problem with this for the last 10 years and now with the device in place, I'm getting battery drain! I think there is a lot to be said for keeping things simple. Anybody want to buy a slightly used Marine Priority Start device?

Ferdinando posted 03-14-2008 10:56 AM ET (US)     Profile for Ferdinando  Send Email to Ferdinando     
I also installed a Priority Start and it left me high & dry, I dumped mine in the trash and will go to 2 batteries as soon as my new boat arrives.


bigjohn1 posted 03-15-2008 06:44 AM ET (US)     Profile for bigjohn1  Send Email to bigjohn1     
Some will disagree with this but it has worked wonderfully for me and several fishermen I know on multiple boats. This assumes you have no need for a trolling motor battery.

Keep it simple and stay with ONE BATTERY. By a quality AGM and have it load tested once per year whether you think it needs it or not. This way, you have confidence in your battery and know it won't leave you stranded. Think back to the times a battery has left you (or someone you know) stranded. Almost with exception, those occurances were the result of accidentally leaving something on, a bad connections, bad wiring, or not keeping up on the condition of your battery (i.e. not laod testing it periodically).

Sure, there is the odd battery which on the very rare ocasion die all at once with no indication but that is a very rare situation to say the least with a quality battery. This is not a 38' Sportfisher, its a 17' Montauk.

Ed R posted 04-18-2008 11:41 AM ET (US)     Profile for Ed R  Send Email to Ed R     
Hello. I am a sales representative from BLI - the manufacturer of the PriorityStart. I want to clarify two things I read about our product.

1. Our unit has a 8-12mA draw - depending on if it is in a disconnected or reconnected position. Our product is not meant for boats in long term storage. Sometimes a trickle charger in addition to our product would be useful in that type of scenario.

2. West Marine discontinued our product some time ago (things could always change in the future) and they are selling models that were being sold between 2003-2005. There have been many improvements since this time. Our #1 Marine distributor is Overton's ( They should be carrying the newest of the model. (As of 04/2008).

Our product has been on the market for over ten years, so it has proven to work many times. We do have an extensive troubleshooting guide on our official website.

Thank you.

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