Charging multiple batteries with 1981 Johnson OB engine

Hi All. First post on this forum.

I would like to know if it's possible to charge my 2 auxiliary deep cycle batteries in addition to the battery used for starting. Can I just connect them in parallel while underway or is there more to it? All batteries are 1 year old and have been well maintained.

Starter battery: 625 Marine Cranking Amps
Aux. Batteries: 845 Marine Cranking Amps / 122 Ampere Hours @ 1 Amp

1981 Johnson 115HP Model #J115TLCIM

Thanks!

Dan

do you have a regulator or rectifier only charging system?look on the starboard side of the engine and see if you have a rectifier about the size of a quarter mounted in the block with a terminal block near it with two yellow wires coming down from the stator..if you do it is a rectifier only system...if you dont have that then you probably have a regulator mounted on top of the block right behind the flywheel..if you have the rectifier then you probably have a 6 amp system...if a regulator it could possibly be higher..12 amps would be my guess...

there are ways to do what you want to do but i would not do it...different diode assemblies and switching systems are available...the reason i would not do it is the charging system of that engine (of the vintage especially) was designed to maintain a fully charged battery..when the boat is put in the water all batteries should be fully charged..then when you start the engine the system will maintain the charge on the starting battery...maintain is the key word here...drawing excess current places stress on the rectifier plus cause heat in the stator coils...stators dont like heat and they are a 250-300 dollar item...if the other two batteries are for a trolling motor and you run them down to the point they wont troll then you are not going to get sufficient current to charge them anyway...and if you do make a long run pulling above rated current for the charging system you are going to blow it eventually.....just my opinion...good luck and good fishing

papyson said:

do you have a regulator or rectifier only charging system?look on the starboard side of the engine and see if you have a rectifier about the size of a quarter mounted in the block with a terminal block near it with two yellow wires coming down from the stator..if you do it is a rectifier only system...if you don't have that then you probably have a regulator mounted on top of the block right behind the flywheel..if you have the rectifier then you probably have a 6 amp system...if a regulator it could possibly be higher..12 amps would be my guess...

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I've uploaded 2 images, hopefully they'll go through OK. Looks like I have rectifier system since the quarter-sized rectifier is there and nothing behind the flywheel. 6 amps would seem to be pretty marginal to handle anything other than the starting battery. Do they make a separate generator or alternator that is driven off the flywheel teeth used by the starter?

The charging system is simply not capable of producing enough current (6A) to have any meaningful effect on three batteries, assuming you are using those aux batteries for anything. And needless to say, if you are not using them, they don't need to be recharged anyway.

not to my knowledge on flywheel driven alternator etc...a solar panel will charge batteries but not at the rate you need...the bass professionals used to carry 2 sets of batteries and charge them externally at night..dont know what they do now...

Thank you both! I'm looking for additional auxiliary power for an extended trip to the Sierra Nevada mountains in CA this summer so there will be days with no 110 volt power to charge batteries. It looks like the least expensive and most flexible option would be 1 or 2 more deep cycle batteries that I can swap out and charge in the truck as I drive. I'm convinced that I shouldn't look to the OB motor or solar as a reliable source of charging power.

The amount of panels needed will break the bank!!!! Solar panels are based on their peak power production, measured in watts. The 12 volt batteries are often measured in terms of "amp hours."The formula is: Watts = Volts x Amps

So if we make a bunch of simplifying assumptions, a 12 volt, 90 amp hour battery requires 1,080 watts (or watt-hours, to be correct) of solar power to fully charge. A 85 watt panel could do the job in 12 hours, assuming optimal light and various other things that are never all true in the real world. But if you assume 3 hours of good light per day (that's very conservative in the Sierra Nevada mountains), the battery will be back to normal in 4 days. Your best bet is StaynCharge system as this is what a lot of Pros use, I sold them years ago until I became dealer for Procharger. and it uses existing wiring and charges from your tow vehicle.

Stay'NCharge Does not have to replace your AC charging unit. The AC charging unit keeps your batteries charged at very low levels while the boat is in long term storage. However once you switch it to full charge the AC charger will only charge your battery or batteries approximately 80% to 93% percent over a very, very long period of time. That is where the Stay'NCharge system comes in. The Stay'NCharge System will bring the battery or batteries up to a full charge while you drive to your destination. It will even charge your batteries while the vehicle idles. It only takes 22 minutes to bring 1 dead batteries up to a 98% charge!
One 12 volt start battery will charge in 21 minutes & 45 seconds. Three deep cell 12 volt batteries, set up as a 36 volt system (in parallel), will charge up to 98% of capacity in 2 hours 10 minutes and 15 seconds. Try that with your AC charger!
Use the Stay'NCharge system to put a full charge in your batteries and use the AC charging unit to keep your batteries charged at maintenance levels while the boat is in long term storage. Then you will never be disappointed by finding your batteries are flat or very low AFTER you get to that favorite fishing hole.
If you want to extend the life of your batteries you should start charging the batteries as soon as you finish using them and do it with a quick charge. That means as soon as the boat is loaded onto the trailer plug in Stay'NCharge and start extending the life of your batteries. By doing this your Boats batteries should last as long as your car or truck batteries.
The alternator will only feed the amps required by the batteries to charge. This is the same principal that truck and car manufacturers have used for many years. Don't take my word for it, check this out with your local area battery distributor's technical department. As soon as your done fishing and load the boat back onto the trailer you hook up the Stay'NCharge Charge system and start recharging your batteries while driving home or to your next fishing spot. This means you will never have to climb in and out of your boat again while it is on the trailer to hook up your charging system.

http://powerequipment.honda.com/generators/models/eu1000i good excuse to buy this..i have a large generator for hurricane backup for the house but my daughter has this one for camping...a good battery charger will put out 10 amps with approx 1.2 amps of generator output so you have amp capicity for other things...runs on fumes comparatively...and i think will last a life time with care and normal use...

papyson said:

http://powerequipment.honda.com/generators/models/eu1000i good excuse to buy this..i have a large generator for hurricane backup for the house but my daughter has this one for camping...a good battery charger will put out 10 amps with approx 1.2 amps of generator output so you have amp capicity for other things...runs on fumes comparatively...and i think will last a life time with care and normal use...

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I'd love to have one of these little Honda generators! They're super quiet and great for camping, etc. Just haven't been able to justify the cost yet. Dang!

I agree on the small generator. the solution is just screaming at ya !! (you also may need it if your tow vehicle battery goes dead....)