88 spl Do i need to upgrade my charging system on my 88 spl and can i if so?

57sailplane

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Hey guys,

Last year i finally got my 19 foot 1988 Blue Fin refurbished. After 3 years of rebuilding i got to take her out last season and did rather well. The boat has an aftermarket power trim on it and all the electronics working. I have an older humminbird on the boat and just purchased a lowrance hds 8 with structure scan. I think between the two units they pull around 2 amps rms from what i can find about them. I am planning on adding an 100 lbs trolling motor in the future. so i realy need to know if i need to upgrade?

the motor is an 1988 88 spl from what i can find i think it has the 6 amp stator if someone can tell me how to find this out for sure i would appreciate it. I found these motors also come with the 9 amp stator. is it posible to change the stator to upgrade to 9 amps and if so what has to be done.

thanks Andrew K
 

F_R

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Well, to begin, let's just ignore the trolling motor. There is no way in hades that either charging system will supply enough power to run the trolling motor. Best use a separate battery for that. As for the rest of the question, from the parts list it appears that the models without factory Pt&t did come with a 6A alternator, and the models with factory Pt&t had a 9A. Since your Pt&t is aftermarket, I would assume you have a 6A. Even so, unless you use the trim & tilt an awful lot, I don't think you will have a problem.
 

steelespike

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A 100 lb motor is a 24 volt so 2 batteries connected in a series. You wouldn't be able to recharge one battery with your motor 6 or 9 amp rate let alone 2.
Obviously your 12 volt system can't charge 24 volts and if you could figure a way to charge them as individual 12 volt batteries it would take twice as long
to charge 2 batteries.
If I remember right rule of thumb 1 hour run time requires about 3 hours charge time.
Assuming a 100 amperhour battery max speed run time is 2 hours, med is 4 hours,slow is 20 hours.
The 2 hour,4 hour and 20 hour run time require about 6 hours charge.
Using shore power is the only practical way to charge those batteries either with a 24 volt charger or
​ 2 12 volt chargers. You can connect the chargers as if the batteries are standing alone.
I used to balance the 6 12 volt batteries in my electric car with 6 12 volt chargers just being careful to be sure I connected each battery correctly.
Saved a lot of time not having to do one at a time.
 

steelespike

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When selecting batteries literally the heavier the better. I like Deka group 31.It has been ten years since I sold the electric car
so I don't know how much they cost.
 

durban

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6Amp 1.5ohms +/- 0.5
9Amp 0.75ohms +/-0.2
15Amp 0.4 ohms +/- 0.4

Check your stator with meter it will tell you what you have .
 

emdsapmgr

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Trolling motors typically are recharged overnight with an on-board charger, installed by the owner. (perhaps a 20 amp, two leg charging unit.) Will have nothing to do with the main engine and it's battery. I'd agree with FR's comments on post #2. Since the engine makes it's own power for the ignition, (that is a separate system from charging the battery,) you should be ok-as long as you have a high capacity starting battery on the engine.
 

57sailplane

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So,

Man this brings up lots of questions. so is the troling motor circuit is a stand alone circuit totaly seperate from the charge circuit? If so then how do you hook the depth finder up when it hooks to the troling motor. seem this could be a problem. also in my reserch it seems that the 1988 88spl motor did not have a voltage regulator just a rectifier and on the 90hp and later models it did have one so how hard would it be to add as i realy think it would be a good idea to have constant voltage on a high end depth finder.

thanks andrew k
 

F_R

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CDI makes a combination rectifier / regulator that bolts on in place of your present rectifier. At a whole bunch of $$$$ less than the water cooled one you are considering. Sorry, I can't answer the question concerning the depth finder/trolling motor interface.

And yes, the trolling motor needs to run on it's own battery, separate from the outboard motor. Well, it doesn't HAVE to, but you don't want to be running down your starting battery. You could hand start it in an emergency, but who wants to have to do that?
 

emdsapmgr

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When we install batteries in fishing boats like yours it works this way. The engine start battery runs the engine and all normal boat accessories, including fishfinders, horn, lights, radio, etc. on a single marine start battery. On a 24V trolling motor, the two deep cycle batteries are dedicated to the trolling motor only. If you connect anything, such as a fish finder to the trolling motor batteries, you could have trolling motor interference visible on the screen of the fishfinder. An on-board separate two leg charger keeps the trolling batteries charged overnight after a day on the lake. The running of the engine should keep the starting battery charged, even with just the rectifier. Most fishfinders quit working due to under voltage (low batt voltage) that too much..
 

57sailplane

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thanks for that as i understand what you are saying. do the depth finders have an over voltage or as this was my major concern. what i think might be a problem is that with just a rectifier if the battery gets really low say anchored for hours as i most generaly do wile walleye fishing and the motor barely starts because of low battery or bad then the system could overcharge like i have read about with instances of 16 volts plus. i am not saying i run a low battery as i always keep a good charge on it. i just want to ensure i dont mess the high dollar depth finder up. just trying to cover all bad problems before they happen. so if i dont need to mess with it let me know if i do well i am more then willing to make the fixes now. what makes me curious is why most engines have the regulator?

thanks andrew k
 
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emdsapmgr

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Your fishfinder is probably sophisticated enough to protect itself from normal marine voltage ups and downs. Also, it's dedicated positive line should be individually fused with just the correct amperage to protect itself. Those 88 engines produced in your model year do not have the combination rectifier/regulator. Those 90 models do. Those 90 engines will usually limit charging voltage to around 13.5 volts or so. Your "88" engine was marketed and sold as a "low cost" model by OMC. Same as it's sister engine the 90, the 88 came without the combination rectifier/regulator, did not offer the VRO gas/oil mixing pump and power trim was offered optionally (may have been dealer installed.) That's why they were the economical product offering for those folks wanting a 90 hp engine. I'd think you could easily add the combination rectifier/regulator-see an Evinrude dealer. If you have concerns with the power capacity of your current starting battery, you may wish to upgrade to a 1010 amp battery.
 
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F_R

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There are tons of motors out there with unregulated charging systems, and yes the voltage on those can go to 16V or more. And yes there are (were?) fish finders that couldn't stand that, But I have enough faith to believe that anything made today would have built-in overvoltage protection. If not, shame on them. After all, the unregulated systems are a well known fact of life. Anyhow, either way, the new CDI regulated rectifier should take care of the problem.

EDIT: According to available information, the regulated rectifier for your motor is part number 193-3408. (The un-regulated one is 153-3408)
 
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57sailplane

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thanks guys,

if i do the rectifier it will probably be for more of piece of mind.. so i probably just need to hook up my new Depth finder when i get it then.
 

57sailplane

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well,

your never going to believe this.

i bought the heavyduty deep cycle optima battery for my starting battery. I bought an on board ******* battery charger set up for 3 batteries but only had it hooked to my optima. system worked well for 3 days wile on vacation mainly just anchored so lots of livewell use with out motor charging battery.. charger said it was charging and conditioning and all. the 4th day i was on the lake a storm rolled on us and battery was dead so dead motor did not turn. and guess what. burned up the hard drive on my lowrance hds 8... i am so ticked you cant believe it. bad battery charger, and now i have to wait to get the finder replaced. but thats another story. what do i need to do so this dose not happen again. the 2 things i can think of is definately use the low voltage alarm thats on the finder. and i am going to wire in an aux volt meeter. is there anything else that i should do... other than get rid of the piece of @#$@#% battery charger...

oh ya i never got a regulator but the motor was not runing when it went out.
 
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emdsapmgr

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You may want to reconsider the starting battery. The deep cycle batteries work best on things like trolling motors where there is a long period of discharge, then an overnight recharge of at least 10 amps per battery. Starting batteries are just that, designed to put out tons of cranking amps for 15 seconds, then get recharged immediately for a significant period of time. Some of the deep cycles will actually suffer reduced life in starting applicatons, as they just don't tolerate constant charging well. Perhaps your Optima is a deep cycle that is also approved/designed for starting applications.
 
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