A forum for owners of Yamaha TTR250 trail and enduro bikes!

Stupat · Newbie

Battery discharging when bike not in use.

Paul13 · Veteran Member

http://www.ebay.co.uk/sch/i.html?_odkw=yamaha+ttr+250&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0&_nkw=yamaha+ttr+250+rectifier&_sacat=0

try the above, so do not know if you are in the uk

TT-R250M · Super Guru

It does not necessarily mean that the rectifier is at fault, it may be a grounded power wire. I could also mean the battery is on the way out.

If it charges well when running then the charging circuit should be good so I would check that your battery is not grounding on the positive terminal and the fuse and fuse wire is in good condition. Another good thing to check would be that the starter relay positive terminal is not grounding anywhere on the frame.

Don't forget to turn the ignition off after using (obvious).

Jarrah

yamalama · Veteran Member

Hi Stupat,

It might well be the rectifier/regulator leaking current. I have had experience of this on another bike in the past. You can check for this if you have a multimeter that will read hundreds of milliamps (mA). With the ignition turned off disconnect the ground (Black) lead from the battery and connect the multimeter, set up to measure hundreds of mA between the battery groung terminal and the end of the ground lead. Assuming you have no accessories connected directly to the battery the meter should show no current flowing.

If you see any current flowing, try unplugging the wiring from the regulator. If the reading falls to 0mA then the Rec/rec is faulty. If you still have current flowing and you are positive that there are no accessories connected on the battery side of the ignition switch, you have a problem with a partial short on the small amount of wiring going from the battery positive to the ignition switch, or possibly the switch itself (although I have never heard of this happening).

If your initial current reading is 0mA, your problem might well be the battery itself. You could try charging it disconnected from the bike, leave it disconnected for the length of time that it is going flat on the bike, connect it to bike and see if it goes flat. I could tell you other ways to test the battery, but I suspect that that is enough for now.

Good luck with sorting it out

Lama

TTRfan · Super Guru

Stupat wrote:
Is this likely to be the rectifier unit and, if so, where and how much for a new one?

Good information on the reg/rec - not heard that before but a nice simple check wink

Does your TTR have a digital speedo? These have been known to put a drain on the battery when the ignition is switched off. It takes a small current to keep the time correct. If you disconnect a digital speedo you have to reset the time - or at least that's the case in my experience!

Brian

Lostboyscout · Veteran Member

Good info guys , a good test as part of service ....

Many thanks

TTRfan · Super Guru

TT-R250M wrote:
The rectifiers job is to convert the AC power generated from the AC magneto into DC power and also regulate the power (lower it to 12V). The power from the battery does not go through the rectifier, it simply joins to the 12V charging curcuit after the regulator. If your charging circuit was at fault the battery would not charge properly. If the power was leaking through the voltage regulator/ ressistor, it would touch DC power to AC and would burn out the wiring completely (been there done that, not a pretty sight lol). So by rights Lama's test for the ''current flowing'' will not work (no offence to Lama). Also the black earth wire that Lama suggested to test is actually to ground the AC power, not DC (it is part of the trigger circuit that tells the ignition coil when to fire).
To test your rectifier (charging curcuit)- Dissconnect the battery (the red terminal or both), connect a multimeter to the red wire coming out from the rectifier (you can test this at the fuse), use the kickstarter (or put it in top gear with back wheel raised and spin the wheel). Earth the black mutimeter terminal to the frame or motor. Now- is there constant 12-V coming out of the rectifier. If it is fluctuating under or over 12V or there is no power- your rectifier/regulator or AC magneto is at fault.
If it is not the charging circuit you need to find where in the ignition/lighting system is earthed or crossed. Check all lighting components are working as they should and that the wires are not crossed or earthed. This includes your ignition switch, light switch, off/on switch and all lighting components.

Very thorough Jarrah!

brindabella · Senior Member

coming back to the original question, the battery is apparently discharging when NOT in use, although of course this would be more noticeable if the charging system was not working well.

Hopefully the battery terminal screws are nice and tight and all appears clean and tidy.

But if we are looking at the rectifier/regulator unit, Yamaha (in the service manual) say "charging circuit is good" when the measured battery voltage is between 13v and 15V with the battery connected and the bike running at about 3000rpm.

The battery manufacturer recommends charging voltage of 14.0V to 14.8V by the way, so Yamaha are being generous.

On my own TTR with a good standard (ie VRLA maintenance free type) battery in a good state of charge, the measured battery voltage while the engine is running at a fast idle is 14.3V and it stays at that figure at higher revs too. After waiting an hour, the battery voltage when NOT running is 13.1V. So I guess that is a normal "known good" benchmark comparison figure.

Anyway, supposing a decent voltage at 3000rpm the engine would be recharging the battery, so the battery losing charge while not in use is either a dud battery (my bet), or some kind of small constant current drain.

These batteries need charging when the charge drops by 25% (and the measured voltage is 12.8V).

At a normal temperature, just sitting in an unridden bike, a fully charged VRLA battery will lose 5% per month as "self-discharge". A 1mA drain would drain 11% of battery capacity per month.

A dud or draining battery might be recognised by comparing the voltages 30 minutes after stopping from a ride, and then a few days later (preferably at the same outside temperature).

If the was no significant voltage drop, then it still could be a dud battery failing under the load of starting.

If the voltage dropped significantly after a few days, you could go for a decent length ride (to recharge the battery), then disconnect the the battery after stopping, and see if the voltage dropped by the same amount after another few days- if it did, that confirms that the battery is the problem, whereas if the voltage only dropped while connected to the bike, you clearly have a current drain problem.

A current drain could be confirmed by inserting a milliammeter between the battery terminal and the battery wire, eg as suggested by yamalama. Probably a good test to do straight away as it is quick and the standard ttr (unlike some fancy bikes with dashboard clocks etc) should normally have a zero current drain on the battery when switched off.

If there is a current drain, the cause is most likely one of the things Jarrah and others suggested to check in the wiring.

However it COULD also be the rectifier part of the rectifier/regulator - its inner circuitry is NOT shown in Yamaha manuals, but it will have 6 silicon diodes, and these diodes normally have negligible reverse current flow, however one or more failing rectifier diodes can allow a small current drain from the battery (and CAN do so while the bike runs well but of course with a slightly reduced charging ability). As yamalama suggested, this possibility can be eliminated as a hypothesis simply by temporarily disconnecting the rectifier/regulator (the thing with cooling fins under the tank) and seeing if the re-measured current goes to near zero. Don't try to do this while the engine is running (that could cause damaging voltage transients due to inductive load) and make sure it is properly connected again before starting the engine.

NOTE 1: unless you have added hard wired electrical equipment (or a yamaha digital speedo?) the normal measured current will be very small, definitely much LESS than 1 milliamp unless there are problems. The reason to be a little suspicious of the rectifier/regulator unit is that it is the only item normally remaining connected across the battery terminals when the bike is switched off (and they are known to fail or partially fail due to heat and other causes including bad connections).

NOTE 2: to measure drain, the bike should be switched off, your meter should be set to read current. the battery NEGATIVE terminal bolt (safer and easier) should be unscrewed from the battery and the lead that was attached moved aside to separate it from touching the battery terminal. maybe put a bit of cardboard in there temporarily to keep the terminal and lead apart while measuring. you touch one meter probe to the negative battery terminal and one to the end of the lead that you just unbolted from it, completing the circuit from battery positive to the rectifier/regulator and back to the battery negative via your meter.

-- Edited by brindabella on Friday 21st of June 2013 03:18:30 AM

Nickj_UK · Member

Anyone reading the above should remember that the battery will get a charging voltage of anything between 12.8 to 14.4 volts or there about.
If you meter a low or a high voltage the regulators probably dead.
I the battery self discharges it may be shot, it should meter out at about 12.8 - 13.2 ish is good, under 12 bad

TTRfan · Super Guru

Well, Stuart hasn't accessed the forum since 23rd May so all your good work may have been in vain guys

Perhaps he has absconded to the ThumperTalk forum wink

He didn't answer a key question as to whether his TTR has the digital speedo fitted. These take some current to keep the clock going but have been known to drain more battery than they really ought to....

Where did you go Stuart confuse

TTRfan · Super Guru

Before going off to the States I thought I would disconnect the earth lead from the battery on my TTR with the digital speedo.

Just for interest I thought I would put check if there was any current flowing between the disconnected wire and the battery terminal on my multi-meter.

On all three "A" settings it took the needle off the scale! Haven't got time to be more scientific on the measurement but my bet is the battery will be good to start the bike in a month's time wink

Will tell you more when I get back and do a proper leak check.

Brian

Paul13 · Veteran Member

This is all way over my head.

biggrin

TTRfan · Super Guru

TT-R250M wrote:
If that is too hard for anyone to do or understand,

Mea culpa disbelief

No excuse.......

I will follow the advice carefully when I get back to Blighty wink

Brian

TT-R250M · Super Guru

Here is a test that anyone can do...Set your multimeter to DC 20-V range, connect the red probe to the red battery terminal, connect the other black probe to the black battery terminal, now- if it is reading in the minus's or significantly lower than the battery when a terminal is disconnected, you have a wire crossed or the rectifier is earthing to ground (not likely).

Just like testing a battery.

Just a reminder- you can damage your multimeter or electrical components. This thread has been confused BIG TIME so it would be easy to make a mistake. I have deleted my posts for this reason.

Quite frankly- if the rectifier is charging properly it is not going to be the problem.

I take no responsibilty for damaged goods.

Jarrah

brindabella · Senior Member

welcome to the amazing shrinking and morphing thread

as Jarrah has deleted some posts, I had to delete some posts also (as they made little sense out of context).
PLUS, I made some relevant electrical measurements on my own bike and report on them in my heavily edited remaining post above.

Maniot · Veteran Member

I have been having this problem here in Greece with the Open Enduro (with the digital speedo) I look after for an absent client. I recently changed the battery and fitted another Yuasa, my battery of choice. After fully charging (via Optimate charger) and fitting I returned ten days later to find the battery flat. I put it in on charge again and returned the next day. All fine and bike started first try. With the ignition switched off I measured the voltage between the negative terminal and the negative feed wire and got 12.5v....letting it sit for a number of minutes I noticed this reading dropping to 12.2 then 12.1 and so on.....so clearly some problem. Measuring with the ignition on I read 13.2v.

Battery voltage alone reading 13-14v. Any advice? Next step check the rectifier? Thanks.....

TTRfan · Super Guru

Try disconnecting the digital speedo and see if that solves the problem confuse

Maniot · Veteran Member

TTRfan wrote:
Try disconnecting the digital speedo and see if that solves the problem

Thanks ....will try that....some time ago I fitted a GPS speedometer that is easily detached from velcro pads on top of the digital speedo. So it wouldn't make any odds if permanently isolated! This was the second digital speedometer along with a new sender unit which hasn't worked so got fed up with it and got the GPS....

ttboof · Super Guru

If it was the rectifier or a pos lead touching it would be pretty obvious.

Sounds like a leak / Constant draw or a battery

Easy check like you have found disconnect the speedo . Next step disconnect the battery after riding reconnect when you next use it should go if a leak is the problem

JOHNYBOY · Super Guru

what i do is disconnect the live wire fron the battery put a small wattage bulb on to the battery & one to the lead if it lights up you are drawing power from your battery with nothing switched on uncouple various components to find out which one is the problem if it drains the battery over a long period you will have to do this with a miliampmeter

ttboof · Super Guru

Spot on

Maniot · Veteran Member

Great advice all...thanks!