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Quick battery disconnect question

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jimmaki

jimmaki

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It seems the battery in my SeaDoo holds its charge better when infrequently used if I disconnect the battery after the last ride of the day. This is no big deal but a pain to reconnect the battery since the female threads on the battery posts "float" and are not always easy to re-engage. While working on some VTS issues on my boat I traced the power from the battery's positive lead going into the rear electronics box (on a 98 XPS 787) and it goes to the starter solenoid and splits to two fuses, one to the VTS and the other to the MPEM. Of course the other side of the solenoid goes to the starter but that is normally not hot unless starting the motor. So ... where am I going with this ? .... I am pretty sure it is the same as disconnecting the battery if the square connector on the top of the box is pulled.

Can anyone think of a reason this would be not such a good idea? Chance of blowing expensive electronics? I dunno, but thought I'd ask if anyone else tried this a paid a price in blown electronics for the convenience of just pulling the plug. Is the MPEM engaged as long as the start timer isn't triggered?

My other thought was to just get a waterproof boat battery switch. But so far I haven't found one that looks easy to mount in an SPX SeaDoo. I guess it could be mounted on the dash but that means two long heavy gauge battery cables chafing from their supports all the way from the rear of the Doo to the dash. I guess it could be mounted to the transome somehow or ... hmmm, what? Idears anyone? I've seen switches for car batteries that mount on the battery post itself but I haven't seen any that would work with a PWC type battery "post".
 
I think it's a great idea, anything you can do to make these small batteries last longer is a plus. A disconnect located at or near the battery would be best. There are battery disconnect switches made for motorcycles that should work fine, use it on the neg. post.

Lou
 
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Good idea, should be no problem. I think you could also mount a 10~15 Amp toggle switch in that line if you wanted, eliminating the need for a heavy-duty battery switch capable of handling starter current.
 
But if you have your heart set on a large battery switch you can probably epoxy it to the inside of the bilge somewhere using JB-Weld, use a block of treated wood epoxied somewhere to mount it on using screws.
 
For the little battery nuts insert some small tubing like the 3/32" oil injection line under them and it will hold them up so the bolts thread in easier and the nuts don't fall into the bilge.
 
Or install wire ties around the terminal once you put the floating nut in the terminal.


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curious, how is it that it "seems" to hold a better charge when disconnected ? (although logic would agree)

I have no issues with disconnecting if it makes you feel better, but a $25 tender jr. with the quick connect would solve the problem with less hassle, install the quick connect and zip tie it up near the seat and toss the tender on. (this assumes garage storage not back yard, easier to plug in a tender when your in the garage)

I recently had a $120 battery go dead after sitting 5 weeks with no tender, but it was entering its 4th season anyway so I just snagged a new one and never thought about it. Its possible that it might have still been ok if I had disconnected or tendered it during that longer than usual lapse in riding but my theory was that it did me a favor by going dead, forced me to get a replacement that I might have decided was good for one more year...

Being as it was already 36 months old I feel better about a new one anyway, I have a 120 mile range on a full tank and have been known to get 45 miles+ away from the ramp pretty often so I don't want to trust an old battery when we take a break, nobody wants to tow me 45 miles... I was towed 35 miles once and it sucks, (blew top end) but I don't' want to get towed because my battery was questionable when I left.
 
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Most skis have the ability to use power even when the lanyard is not attached. The MPEM always has power as it is feed from the HOT side of the solenoid for example. Many skis require you to hit the START/STOP button to wake it up. It is a small amount of draw, but it does exist. If things are good, they could sit two months and have no issue.
 
There are parasitic power losses involved with keeping the MPEM in sleep while monitoring the lanyard and stop button for activity but I suspect in some cases the losses are aggravated by a leaky surge protection diode, perhaps.

I question the quality of those avalanche diodes b/c they're supposed to be able to handle more than 5Amps reverse biased and not supposed to avalanche until well over 20 volts?

Those auto-test bilge pumps will constantly nurse off the battery as well.
 
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Thanks. I already shoved some closed cell foam under the nuts. When the screw theads in it makes a hole in the foam and keeps it in there. I'm thinking silicone might work better.
 
My ski sat for three years, but I didn't know that would be the case when I rode it the last time three years ago. Didn't think to go down and disconnect the battery during those three years. Well, ok, I did think about it ... just didn't do anything about it.
 
My battery sat three years and was two years old three years ago. When we moved in here I ran power all the way down to the dock to run the irrigation pump and to have lights and charge the water toys. I got some Guest chargers, I think they are maintainers and not just trickle charges, but I'll have to check. Even put quick disconnects on all the boats. But for some reason I quit using them. I think the batteries were drying out faster and I don't have distilled water faucets down at the dock. :-) Oh, wait, yeah, another reason might be I pulled out of the lift with the boat still plugged in to the 110v outlet. ooops!
 
If you're saying the battery is five years old, it's time to replace it. I feel lucky if I can get three seasons out of a battery.

Lou
 
Wonder why Guess or Perko doesn't come out with a battery switch for pwc water craft...or have they already?
I always disconnect my battery after getting back home from the lake, especially the DI's.
When winterizing I pull my batteries and fully charge them, unhook them from the charger and let set all winter in the garage. When I de winterize the batteries are usually fully charged and ready to go.
 
LouDoo said:
If you're saying the battery is five years old, it's time to replace it. I feel lucky if I can get three seasons out of a battery.

Lou
Click to expand...

Yeah, five years old. But I only used it two. :-) It sat for three without any attention from me and probably died from a lonely heart.
 
I believe they're rated both in current and voltage as far as what they'll handle in either direction. With mechanical devices voltage is largely irrelevant if the current rating is known, but with solid state devices both V and I are relevant.
 
Same here, I searched on PWC battery switch and got zip. I did find a knife switch that will mount directly to the negative battery post of a PWC battery.

knife switch.jpg
 
There are small profile switches from Blue-Sea, Perko, Marinco, etc.

The MC-10 from Marinco is pretty sweet, and could easily be bonded to the inside of the hull using some 3M 5200 or equivalent.

http://www.bepmarine.com/
 
Thanks, I'll take a look. I found a switch that is meant to be mounted on side terminal car batteries using just the terminal screw that looks like it will work on the small PWC battery posts.

sidemount battery switch.jpg
 
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