Johnson charging system

[Hennysemitara]

Aloha guys i got a 1984 johnson 140 2 stroke. i went out on the water today and my battery died luckily i got to pull start it. anyways when i got in i tested the battery it was at 11.8 volts. how long would it take for this motor to charge the battery full? thanks for the help.

 

[Hennysemitara]

when i went out it was a slow crank, but she started. i figured eh by the time i get to my spot it will be charged. i guess wronged. thats why i was wondering how long the motor should be left to run in order to get it charged fully.

 

[jbuote]

Still learning charging systems on outboards, but my understanding is that they aren't really meant to "Charge" a battery..
​Rather, they're good for maintaining a charge on an already charged battery..
​Sure, it'll charge it some, but I think it takes a LONG time to charge a battery back to full from that low..

​It also depends on the battery condition.
​I think I'd probably charge the battery on a house charger so it's fully charged that way, then get the battery load tested too just to be sure the battery is ok..

​(EDIT: You may find that after charging at home, and load test shows ok, it may be fine after that with no more issue...)

​If you're running a bunch of accessories off the same battery, then that will affect how well it charges from the engine as well..

​While I don't have the info off the top of my head, I might also look up how to test my charging circuit from the engine to make sure it's really charging at all too.
If not, that'd be the first thing to fix..

I think anyway..
​NOT an expert, but that's how I understand it at this point..

​Hope it helps... At least a little..

 

[interalian]

Check all battery connections are clean and tight. 11.8V is pretty much a 'dead' battery.

 

[oldboat1]

^^agree with interalian. The battery is fully discharged. If it's a wet cell, see if it's sulfated.

You have either a 6 or 10 amp stator, and either a rectifier/regulator or a rectifier (triangular device with three wires to a terminal block.) If the battery is dead or almost dead, you risk damaging your charging system. Sandpaper all connections, but make sure the battery holds a full charge, as suggested above.

 

[Hennysemitara]

Check all battery connections are clean and tight. 11.8V is pretty much a 'dead' battery.

i checked all connections they were all good. i noticed this strange discharge has been happening recently. there are a couple things i changed with the electrical system. first i wired my chart plotter directly to the battery because the switch for the front accessories was acting up. also on late nights when we come in i run my leds coming in, and also i run them white washing the boat and when towing on the road. i figured leds dont use much of a draw on the system. theres about 16 feet total of the strip leds. i tested the battery at orilleys and they said its all good. i have a main battery switch but i have been lazy and kept it on because i could leave my boat sitting for a month and she would still crank up.

 

[Hennysemitara]

^^agree with interalian. The battery is fully discharged. If it's a wet cell, see if it's sulfated.

You have either a 6 or 10 amp stator, and either a rectifier/regulator or a rectifier (triangular device with three wires to a terminal block.) If the battery is dead or almost dead, you risk damaging your charging system. Sandpaper all connections, but make sure the battery holds a full charge, as suggested above.

i charged the battery, its now at 12.8 im gonna see how long it holds. also im gonna hook it up and see if the volts jump when the motor is started.

 

[Hennysemitara]

No Title

on a side note heres a few pictures i wanted to share with you guys, sorry for the delay LOL

 

[oldboat1]

appreciate the gorgeous location pics!

had a similar issue with navigation electronics (interference), seems to be resolved by direct connection to the house battery (pos. and neg. leads). Sounds like you may be doing something like that.

 

[Hennysemitara]

ok guys so last night after i charged the battery full it read 12.8 volts. this morning when i went to check its now at 12.5 volts. keep in mind, nothing is hooked up to the battery.

 

[Hennysemitara]

im going to try an amp draw test i seen on youtube.

 

[interalian]

We'll be on the big island in January for three weeks. Thanks for the pictures.

 

[Hennysemitara]

i did a paracitic draw test. it came out good. no draw. i turned on the leds and seen that they drew 3 amps. how long would it take for 3 amps to drain a 600 mca battery?

 

[Hennysemitara]

We'll be on the big island in January for three weeks. Thanks for the pictures.

big island hilo nice place

 

[Hennysemitara]

i looked online, my battery is rated at 90 amp hours. so if my leds draw only 3 amps, that means my battery could keep my lights on for 30 hours before draining the battery fully. is this right? at most i use it without the motor running no more then 2 hours. that leaves plenty of power.

 

[interalian]

big island hilo nice place

Yeah, 2 weeks south of Pahoa (tidepools) and a week Kona side on a rented farmstead.

Back to the post though: I'd just turn the LEDs off, but that's just me.

 

[Hennysemitara]

at idle, the battery reads from 12.4-12.6

 

[ondarvr]

The voltage at idle doesn't mean much, those low output charging systems need more RPMs to generate much voltage. It should go to 13.5V+ as the RPMs increase

 

[Hennysemitara]

The voltage at idle doesn't mean much, those low output charging systems need more RPMs to generate much voltage. It should go to 13.5V+ as the RPMs increase

i just ordered a cigarette lighter voltmeter. im gonna see if the volts jump the next time im on the water.