slow or no charging battery

[shakazulu]

I have Force 125 89.
When in idle or on throttle multimeter shows 12.3 Volts on battery . I think it is not enough to charge the battery, is the problem in rectifier or is it old battery ? When I recharge it in my car it comes to 12 Volts . Then in boat byaliner capri goes down very fast .

 

[NetDoc]

Re: slow or no charging battery

Car batteries should have 12.6V when new and fully charged. Normal degradation {sulfation) from time and use can reduce the resting voltage a tiny bit. A functioning charging system should be able to produce in excess of 13V to almost 14.5V. Low voltage while running is a function of the alternator, however a bad battery can alter the reading somewhat. If your battery will charge off of another system, but quickly fails in your boat, then the boat is to blame. When testing a charging system, its best to charge/test the battery first and most auto part stores will be glad to do this for you at no cost. If the battery passes and your alternator is incapable of maintaining at least 13.2V, then the alternator is the problem. BTW, it makes sense with a belt driven alternator to check that tension and adjust it BEFORE you test the alternator.

 

[fucawi]

Re: slow or no charging battery

net doc got it almost right ....charge the battery fully with a mains charger and stand for 24 hrs ..it should show over 12.5v ..if it does not it is suspect. I would not trust any battery sales outlet to test your battery ....to much insentive for it to fail ...
Your charging system MUST bring it up to 14.4v to fully charge it ..nothing less will do and up to 15.3v is ok if you top it up regularly.

Check the voltage input to the rectifier or regulator ..you will have 16v or a bit more .. If that is ok and you still have a low voltage at the output then the rectifier or regulator is faulty.

 

[Jiggz]

Re: slow or no charging battery

I have the same Force 125 engine. As mentioned read the voltage across the rectifier input (AC voltage). On mine the wires are the two green/yellow wires and the voltage at around 1200 RPM is around 16VAC. Read across the rectifier output (DC voltages) with the positive on the red wire and negative to the black wire or to ground. I read around 13.2 at idle and about 14.5 at WOT. I do have a rectifier/regulator which I just recently installed. When I had my old rectifier, the output voltage is always below 13VDC. I suspected one of the diodes has probably failed since the forward-reverse resistance ratio is very low.

 

[jason32038]

Re: slow or no charging battery

Mine doesnt charge at all at idle. It reads battery voltage which is 13.something at idle. It charges when rpms are raised. If it reads 12.3 at idle and throttle you must have a bad battery, rectifier and or stator.

 

[Jiggz]

Re: slow or no charging battery

Jason must have a real very good battery if it reads 13VDC. Most batteries even when new and fully charged don't usually go above 12.75VDC! When troubleshooting and the probable causes are more than 1. Try isolating the problem by dividing the source of causes right in the middle. In your case, the rectifier is the middle position of your problem. By reading the input AC voltage from the stator and you have 15-16 VAC, it means all the wirings and components upstream of the rectifier inputs are all good. So you need to take the rectifier DC output reading. If there's no output, the rectifier is bad. If there is output, then the problem is downstream of the rectifier. And the only components downstream is basically wire, Ckt bkrs and battery.

 

[shakazulu]

Re: slow or no charging battery

It seems that battery did not charge before because + wire , red smaller wire going to battery was coroded/broken. After fixing red wire and connecting it directly to battery terminal it charges while on throttle on voltmeter 14 volts . This is with ebay rectifier

 

[fucawi]

Re: slow or no charging battery

a little higher would be better ...if 14v is all you got give it an overnight charge every 3 months or battery life will be reduced by never being fully charged ....

 

[jason32038]

Re: slow or no charging battery

Mine was reading 14volts in fast idle with the radio shack rectifier $3 or so. Also the only small wires at the battery should be going to the dash for the accessories. The red wire should go from the rectifier to the circuit breaker then to the solenoid where the big cable is connected.