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1985 suzuki dt140 not charging battery

J

jflat

New member
Hey all, i have a question for anyone who may have an answer or some helpful advice. I have a 1985 suzuki dt140 it sat for a long time, but i now have it running and it runs good... however, it doesn't charge anything... i have replaced the rectifier, the stator, battery cables. I don't know everything about the electrical on these motors so i'm all ears for anyone who has a possible solution. Thanks all
 
Did you test the old components ?? did you test the replacement components ??---------------------------You have replaced everything to do with battery charging on the motor -----------How about the battery itself , been tested ?.
 
Visually inspected all the wiring, the old rectifier did have a burnt spot on it. The battery tests fine, I even switched it out with another battery just for the heck of it. Only thing i have not tried is testing the new rectifier, and the only reason i have not checked the stator is because i picked up a used stator for a great price so i just tried switching them. It is pretty cold here right now haha, but i will try to get out and run a few tests on the different items.
 
well... i have tested everything, all seems to be in working order. continuity in the rectifier is good, amp output from the stator is good, and if i test ac voltage directly comming out of the stator by unhooking the red and brown wires and testing there i'm getting some good ac current comming out of the stator... however somewhere down the line of wiring something isn't working out quite right... not sure what it is i'm knee deep in this repair manual right now...
 
Stator and rectifier can be tested with the motor not running.---------------Improper testing with the motor running can do damage.
 
well i'm going by the book... as much as possible. the one test the book has for the stator is checking the amps between the fuse and battery... is the test your talking about an ohms test? if so i have not done this test yet. So far what i have coming out of the white wire from the rectifier (which i believe to be the wire supplying the battery with charging current?) is about 9 volts at idle, increasing to 15-16 with throttle, however when the white wire is plugged back into the system the battery shows no charging... that is what i have as of now...
 
Test the stator with motor stopped ( ohms ) -test rectifier ( on the work bench )with ohmmeter , rectifiers typically show infinity one way and continuity the other way.-------------Should be outlined in a manual.
 
I tested the rectifier in that manner with good results, continuity one way and nothing the other, I will test the stator ohms tomorrow with the engine off and see if its within acceptable parameters.
 
well... everything tests out good, the resistance testing on the stator is withing limits according to the book i have tested about everything every way it could be tested. what should the battery read when the engine is at ide? my thought is 14.something, however i am only getting 12, when i increase the throttle it bumps up a bit to 13 maybe a little over and with any sort of load on the battery besides the engine it goes way down. unless i am misunderstanding something (which is very possible) then there has to be something else wrong? so if any of this info helps you out with suggestions or whatnot there you have it haha.
 
The charging system consists of stator coils / windings and a rectifier.--------------The parts book does not show a voltage regulator.-----------Most motors show 13 volts at idle and up to 15 volts at full throttle.
 
yeah i have been looking at that, charging system on my specific motor has a non serviceable stator with high and low speed charging coils. which sends ac power to the rectifier which converts the ac to dc and sends it back to the battery, no voltage regulator only the equipment that i have listed... I get 13 volts at idle, however if you put any sort of load on the battery it goes down and does not go back up to 13 for quite a while, i also get the same reading from my battery weather the battery is just sitting or running idle, which leads me to believe it isn't charging at all idle?? it does increase a little when running higher rpm, but no where near 15, unless i have to have it WOT to see results like that... so i dunno, maybe i'm just retarded which could also be the case haha. Well if you can think of anything else that may be worth looking into let me know. Thanks
 
The stator has charge coils for the cd ignition ( high and low speeds perhaps ) and coils that do nothing but provide power to charge the battery.-------------Thus 2 seperate systems.
 
Im just plain confused, did everything by the book as much as i could. I changed batteries out a couple of times during this process to make sure it wasn't a specific battery going bad or whatever. Well i had been using deep cycle marine batteries about the size of an ordinary car battery (not sure if there is a specific name) i decided to try the bigger sized deep cycle batteries like on a camp trailer, and it charges those fine. I know there are cranking amp differences... but it charged both the larger sized marine batteries find at 13-14 vlt idle, and right up to 15 volts with rpm increase. When i would try the smaller sized batteries, the most i could get was 13... i dunno, i tested the batteries and specific gravites and whatnot... am i missing some "duh" kind of thing here?
 
I have used the engine in saltwater before but not much, mostly fresh water, it sat in an open field for 15 years, and before that it was down in texas so i'm not sure what kind of water it was previously used in. Battery cables are brand new, terminals are all clean. I have cleaned every connection within the engines wiring that i can see and added anti corrosion spray.
 
you need a volt meter
put it on the battery
start motor
run motor up to 1500 rpm
the voltage should be at least 12.8v - 14.7v
now turn the volt meter to a/c volts
if you measure over .7 you have a bad regulator/rectifier

you might have a charging coil n that modsel
 
In cold weather, it is not unusual to have 13 volts at the battery at idle. Below freezing, a fully charged battery will only check out at 12.5 volts, not the 12.6-12.8 volts in the summer. The charging systems on these older two strokes are nowhere close to what is in an automobile. Running all of the electronics on boats these days, such as a depthfinder, GPS, VHF radio, Stereos, and whatever lights are needed in total asking the charging system probably more than it is able to provide, especially at lower RPM's. The newer four strokes have much more robust charging systems, making this almost a nonissue.
 
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