Hello Group

My latest conundrum. I gave up on my starter on my 1992 907ie and took it to a shop. After now replacing my thermostat and tossing my old starter and replacing with a Ducati starter and thermostat, now my battery will be almost dead after sitting for 2 days, so I am keeping it on a battery tender and that is working for now. The shop said that my charging systems works fine when the motor is running, but causes the battery to drain when sitting idle. And they say my rectifier is on it's way out. Is This a likely scenario? Has anyone else had this problem?

I was reading up on charging issues and one thread recommends installing the Roadstercycle SH775 R/R units. Upon looking on his site he subsequently recommends a SH847 r/r Kit.

Does this solution fit my problem? Or what is the consensus on a battery draining completely in 2 days just sitting Idle? Neither I nor the shop can find any shorts that can be causing the battery drain. Or would changing the R/R unit have any effect on idiopathic battery drain?

The SH775 and SH847 are both series regulators and will give your alternator an easier time. If you are changing the regulator one of these would be a good option.
Regarding the battery draining. Remove the 30A fuse between the R/R and the battery. With the ignition switched to OFF connect a multimeter set to read DC current across the fuse socket terminals. If it reads less than 5mA the drain shouldn't really be much of a problem. If it is more than 10mA the regulator definitely need replacing.
You can check for parasitic drains from other circuits by connecting the meter in the same way in place of each of the 15A fuses in turn. The RH fuse supplies the clock, fan and ignition switch and the clock will consume some current and help drain the battery. If I'm laying my bike up for more than a week or so I pull out the RH 15A fuse so that the clock won't pull the battery down.
Of course it could be the battery itself which is faulty. Does it maintain it's voltage if disconnected from the bike?

The battery is fine if disconnected. It's a fairly new battery (3 mos.) and is a Deka brand. Both me and the bike shop looked for voltage drops and couldn't find any. Doesn't mean there are none though. Let me do some more poking around. Maybe there is something I missed. I'll also check the voltage drop across the 30 amp fuse.

Thanks

when the engine is running do you read at least 2V more when measuring over the battery as when the engine is off?

I'll also check the voltage while running

Thanks

Just my 2 cents, my feeling is the regulator, however never dismiss other opytions such as the Dash and in particular the CLOCK.

those buggers tend to become very HUNGRY with age and you would never think they drain so much the battery until you test them. In My wife's Alfa Duetto the battery won't last 1 week and the same goes on my old Fiat X1/9 , for both I ended disconnecting the clocks.

My 907ie I always disconnect the battery unless I use it every day... now they do kits for bike so that you can disconnect the battery with a "twist" of a knob, very convenient if you do not use it every day.

One last thing, never assume the battery is good, my last battery for the 907 lasted 2 months despite being kept charged alt all times, now it is only good as a door stopper .

I'm 98% sure the battery is Ok. My old old battery lasted 2 years. Never had a problem until I changed batteries. I'm never buying a battery off of EBay again. I bought a Motobatt. A big heavy battery that was supposed to last 5 years. It wouldn't stay charges long at all. I burned up my starter cranking it with a low battery. Then after 3 starter rebuilds and one more ebay battery, I bought an Odessa battery, another Super battery. It would drain also. Then after getting a New Ducati starter my starter problems are cured, but now I am stuck with batteries draining after a couple of days. I have a Deka battery now and when left on a battery maintainer it seems like a pretty hot battery. I have been thinking about leaving it on the charger or disconnecting the battery wires if going to let it sit up for a while which letting it sit up for six months I think was the beginning of my problems. I have 5 bikes and keeping the 3 that I ride all doing well is a chore, but I love them all. I will just have to get in the habit of regularly rotating their use so they all stay running well and everything working well. I may just learn to live with the battery maintainer on the Ducati and my Yamaha Roadstar Warrior. And the 6 volt trickle charger on my 1938 Zundapp K800. Keeping a battery in good shape is just a fact of life with bikes and 3 of them is just something I will have to do.
Russell

Just pull out the 30A fuse when you lay the bike up. If the battery is OK after a day or two then you know that the problem lies with the regulator, in which case replace it. Why continue to struggle with the problem?