Ed Kennell 35,904 #1 Posted April 21, 2014 The 1988 520H that , with your help, we got running and charging now has another problem. The battery always did lose it's charge overnight, but I blamed that on a poor battery. Now that I have everything working and charging with the new RR, It still lost it's charge overnight. So I replaced the old battery... same result. So I started a search for the problem. I removed the Positive lead from the battery and sure enough I measured 47K ohm from the Pos lead to ground. I started unplugging connecters and wires and found the short to ground was coming through the new RR. With all wires removed from the RR I have 47K ohms from B+ to ground. This is the battery draining path when B+ wire is connected to the RR. Checked the old RR and it shows no resistance to ground, but it did not have any AC output anyway. All these checks were made with the ignition switch off. I am confused ... could the new RR be bad, but the old one drained the battery also ?? I could fix the problem by installing an on/off switch in the B+ wire . Share this post Link to post Share on other sites
Theroundhousernr 589 #2 Posted April 21, 2014 Oh man. I dont like to hear this news, I just bought one from the same place. I have not tryed it yet but the reviews seem ok though...... The resistence you are getting is from the electronic componants like the SCR and internal diodes. I could be wrong but the ignition switch should be killing the power going to the charging system when shut down. Could your problem be the ignition switch or wires hooked up to it wrong??? You could try bridging the positive terminal and the positive battery termanial with an amp meter in series to better track down your issue. I will also test my new one when I get home for you and give you some answers. I guess it could be that when you tested the old RR verses new RR you could have had the positve and negative of your meter reversed. The diode would only let electrons flow one way giving you a false reading on your older RR. I will let you know when I am home. Kyle Share this post Link to post Share on other sites
Ed Kennell 35,904 #3 Posted April 21, 2014 Kyle, I was not thinking of one way diodes when I measured the resistance , So I just measured both the old and new RRs. With the two AC leads and the B+ removed I still get 47K on the new RR, and zero on the old one. I switched leads on the ohm meter and I get the same results. The new RR is still bolted in the 520 and the old one is on the bench. I think every thing is correct on the wiring and the switch. It starts and runs and charges correctly. I guess I'll remove the new RR and see if it still has this 47K short to ground. Share this post Link to post Share on other sites
Ed Kennell 35,904 #4 Posted April 21, 2014 Kyle, I just double checked the wiring diagram for the 1988 520. The B+ wire connects the B+ RR to the battery directly only going through the 30A fuse. It does not go through the ignition switch. Share this post Link to post Share on other sites
Theroundhousernr 589 #5 Posted April 21, 2014 K thanks. I will check mine in a few minutes when i get home and let you know... Sent from my Event using Tapatalk Share this post Link to post Share on other sites
Theroundhousernr 589 #6 Posted April 21, 2014 I get 44.8 K ohms on the new one I got in the mail. The old one is still in the tractor as it charges but it is weak. I get a reading of 174 K ohms. I didnt unhook the AC leads. Maybe I should of..... I was in a rush. I still dont believe that is your problem with your tractor discharging since you said it did it before.... My old RR has 174 K ohm and it has been sitting awhile and it cranked right up.... I will have to think on this some more ... Share this post Link to post Share on other sites
Theroundhousernr 589 #7 Posted April 21, 2014 (edited) I just looked over the wiring diagram.... There is a red wire that runs from the + battery location off of the starter through the molex plug and up to the labeled battery lug on the key switch. Im sorry , I worded that kinda of funny earlier. So the key switch could be bleading power to the gauges or something dumb. I dont think it is the RR . It should not back feed to the stator even if there was a failure or if the RR is dumping current through the B+ terminal to ground I imagine that 47K would result in some kind of heat, like RR is warm to the touch. I know 47,000 ohms is alot and even with a resistor of equal value hooked right to the battery shouldnt drain it. Ever seen the danger 1,000,000 ohm sign. Its kind of a techy joke. So the switch could be powering the gas gauge , RPM gauge , really anything in the acc. loop. Hard to say , I know you said the wiring was a little butchered when you got it. Try unplugging the the B+ over night and see what happens. Pull the switch and test the functions with your ohm meter. Put your amp meter in series with one of the battery posts. The negative would be safer and start unplugging things. Pull the 10 amp accs. fuse over night. Thats all I got at the moment.... Kyle Edited April 22, 2014 by Theroundhousernr Share this post Link to post Share on other sites
Theroundhousernr 589 #8 Posted April 22, 2014 (edited) just a quick calculation 12 volts / 47,000 ohms = .0002553191 amps. Not much draw. Less then an LED by far. Average LED is .025 amps. Edited April 22, 2014 by Theroundhousernr Share this post Link to post Share on other sites
Ed Kennell 35,904 #9 Posted April 22, 2014 OK Kyle, The good news is it Sounds like the "good" RRs all have some resistance from B+ to ground. The bad one I have has none. So I think you are probably correct i.e. I am not losing battery charge thru the RR. I did also remove the RR from the tractor and with all three wires connected but the RR not touching the ground, I measured 12VDC between the RR body and battery ground. So the 12v potential is there, but I don't have a feel for the amount of current that will pass thru 47K ohm or if it would drain a battery. I am leaving early tomorrow for a few days to open our fishing camp in Delaware.... no WI FI service. But when I get back ,I will look for other battery drain sources as you suggest and report back. . I will leave the B+ disconnected while I am gone and see if the battery goes down . Thanks for your help... If you have anymore ideas...post-em up. Share this post Link to post Share on other sites
Ed Kennell 35,904 #10 Posted April 22, 2014 (edited) See you answered the question while I was typing. 0.00025amp loss thru the RR is not the problem. Edited April 22, 2014 by ekennell Share this post Link to post Share on other sites
Save Old Iron 1,563 #11 Posted April 22, 2014 ...... The resistence you are getting is from the electronic componants like the SCR and internal diodes. which means the "resistance" you measure with your meter will depend very heavily on the meter's ohm range internal test voltage - which varies considerably from different meter manufacturers. Since semiconductors are non linear devices - you will not get an exact match from meter to meter manufacture. if battery parasitic drain is suspected, insert your meter on the high mA scale in series with the negative battery wire and terminal. Start disconnecting wiring until the meter indication drops off to zero (or at least a very low current). Do not START the tractor with the meter in series with the battery leads. The high starter current will blow the meter fuse. 1 Share this post Link to post Share on other sites
Save Old Iron 1,563 #12 Posted April 22, 2014 also, be aware the hourmeter does not draw constant power from the battery, it gulps a few tenths of an amp every 20 seconds or so, just in case you use the parasitic check ans see some pulsing of current thru your meter Share this post Link to post Share on other sites
Theroundhousernr 589 #13 Posted April 28, 2014 Wondering how you are making out with the drain on the battery? I just installed my new RR last night due to the battery being really low when I pulled it out and it was not charging. I am in the green now though! Share this post Link to post Share on other sites
Ed Kennell 35,904 #14 Posted April 28, 2014 Good to hear your new RR solved your charging problem also. I was In Delaware last week working on my camp and at the Grandsons Baseball tournament over the weekend, so the WH's have not been getting much attention lately. I did work on the 520 today and the battery drain problem seems to have gone away. It has been sitting for a week with the all the wiring connected and it started right up today. I probably "fixed" the problem as I was pulling and plugging wires and connecters last week when I was checking the B+ on the new RR. The wiring definitely needs some attention and I will series the ammeter in the negative battery side and start jiggling wires as SOI instructs above and see if I can find any shorts to ground. I did manage to get the seat/ fender pan straightened and primed this morning. Then this afternoon I finished a project I have been thinking about since I got the 520 and decided to make it my snow blower. I scarfed a foot pedal and some linkage off a charger 12 parts tractor and built a foot control for the 520. I know , Maybe, If anyone is interested....., when I get it painted, I'll start a new thread on the foot control. Share this post Link to post Share on other sites
boovuc 1,090 #15 Posted April 29, 2014 Yes Ed.......we do! Share this post Link to post Share on other sites
