battery and reserve power

Could someone explain to me or point me in the direction of a thread which will explain how xj's run on battery reserve power at idle? If you were to keep the bike idling (theoretically) for hours on end, would the battery die?


Thanks in advance.
Marshall

 

The charging system doesn't begin to produce electricity until you get to 2,000 rpm. So, anything below that you are running off the battery.

Yes. It won't idle for hours on end. When I sold mine it was to a new rider. He managed to run the battery dead in a few blocks because he wasn't getting the revs up (I did have some extra lights too).

Most motorcycle charging systems produce little at idle. When I'm tuning a bike I always put a charger on it, otherwise I'm likely to get ignition issues from low voltage.

 

Thats the response I was looking for, thanks very much. I do a lot of city driving and I am dealing with ignition issues. I guess I will have to adopt more of a "start it and go" type of technique as well as a little more throttle blipping at red lights. For the longest time I thought I had a fuel issue. Live and learn (hopefully). Should I rely solely on the bike to keep the battery up to charge (alternator reads to spec) or should I charge the battery periodically?

Thanks again MiCarl.

 

Id invest in a battery tender. I got one at Wal*Mart for $20, connected the included connector to the battery and only have to plug it in when I need to tend.

 

how often do you need to tend? Each night, only when there will be a few or more days until you ride again?

Thanks

 

I never had a problem with a traffic light, even with the extra lights.

If you're having power issues at a light, and the charging system is putting out 14 volts at 2K rpm I'd guess it's time for a new battery.

I only use a tender for extended parked periods - when I don't ride for a couple weeks or more.

 

I have to agree with MiCarl. Unless you are running most of your time under 2k rpm on your entire ride you should get charging.

You should at least check your charging system.

 

how often do you need to tend? Each night, only when there will be a few or more days until you ride again?

Thanks[/quote]

I put it on when I know its going to be more than a couple days between rides.

 

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If the battery drained within a few blocks either the battery was bad or you had landing beacons from a 747 mounted on that thing. Cause there is no way it could drain the battery that fast. I don't buy the whole runs off the battery till 2,000rpms though. I have personally sat in stop/go traffic for an hour and a half with my bike never revving over 1500rpm and had absolutely no problems. I even shut the bike off a couple times and it fired right up. I believe that optimum charging system output isn't reached until 2,000 or so but it has to be putting out something.

 

If you are going to be tuning for awhile, disable the headlight. the bike seems to generate enough power at idle to run w/o using the battery, if you disable the headlight.

I base this on improved idle and blinkers actually blinking at idle.

 

I just replaced the battery. After a 20 minute ride through Baltimore (40 mph max) the bike stumbled a little after getting it up into the yard of my rowhome (not an easy task...ramp, steep grade, narrow etc.). At this point the battery (at idle) was reading 11.8 to 11.9 or so and reads 12.35 when the bike is not running. The battery is from Battery Warehouse, (not sure if it is local/national outfit), and is sealed; all gel. I think I remember reading a post a while back about some aftermarket headlights drawing too much power? The voltage above 2k is to spec. It seems as though the problem is going to be hard to find. Ground, fuses?


I appreciate all the input.

 

Are you actually riding below 2K rpms? The motor doesn't like that either, regardless of low road speed I'm never below 3 grand on my 550 it simply won't pull from that low (although it will "trickle along".) I agree you need to take a look at your charging system; test it per the book, take a look inside the alternator for the wear length on the brushes and crud buildup. It doesn't sound "normal."

 

I think the battery was showing it's age. I knocked a few $$ off to cover a new one for him.

 

No I'm not riding below 2k. I cleaned the alternator and brushes look good. Not sure how I would test the spring tension but they feel ok to me too. Going to go for a chilly ride today, I'll let you know how it turns out...

Thanks.

 

[quote="MiCarl]The charging system doesn't begin to produce electricity until you get to 2,000 rpm. So, anything below that you are running off the battery.[/quote]

This is a very interesting topic to me because not charging at idle was one of my main concerns after converting to fuel injection. I didn't realize that not charging at idle was considered normal.

This was one of the main reasons I converted to LED lighting. At idle, in neutral, I'd guess I'm saving about 50W with the LED's, but, on the other hand, I have the extra 4.4A load of the fuel pump, the unknown loads of the idle air valve and O2 sensor, and the 1A or so drawn by the ECU itself.

I may be saving a bit of power from the coils, over stock, since the ECU has better control of dwell time than TCI does, but I can't believe that would account for much.

Yet, when I just measured my battery voltage before start (12.571V) and after starting and idling for about 10 mins (fluctuating around 12.65V), I don't find the battery getting discharged. My idle is a bit high (1450 or so), but the whole time was under 2K. I suppose it's possible that the PO upgraded the alternator, but I don't think it's terribly likely, as he didn't do much else to the bike and it only had 14K miles on it when I got it.

And, yes, this was with the headlight connected and illuminated.

YMMV.

Cheers,
Paul

 

This is a very interesting topic to me because not charging at idle was one of my main concerns after converting to fuel injection. I didn't realize that not charging at idle was considered normal.

This was one of the main reasons I converted to LED lighting. At idle, in neutral, I'd guess I'm saving about 50W with the LED's, but, on the other hand, I have the extra 4.4A load of the fuel pump, the unknown loads of the idle air valve and O2 sensor, and the 1A or so drawn by the ECU itself.

I may be saving a bit of power from the coils, over stock, since the ECU has better control of dwell time than TCI does, but I can't believe that would account for much.

Yet, when I just measured my battery voltage before start (12.571V) and after starting and idling for about 10 mins (fluctuating around 12.65V), I don't find the battery getting discharged. My idle is a bit high (1450 or so), but the whole time was under 2K. I suppose it's possible that the PO upgraded the alternator, but I don't think it's terribly likely, as he didn't do much else to the bike and it only had 14K miles on it when I got it.

And, yes, this was with the headlight connected and illuminated.

YMMV.

Cheers,
Paul[/quote]

Ok, what I initially said about producing electricity is technically incorrect. The alternator produces electricity any time it is turning and the rotor is energized.

My point was that the at a 1,100rpm idle the alternator does not reliably produce enough power to keep the motorcycle running indefinitely.

Charging voltage for a 12V lead acid battery is generally 13.8V or more. The spec for XJ alternators is 14V at 2,000rpm.

 

And my point is that, if the battery voltage holds steady or rises slghtly during idling, then the alternator IS producing enough power to keep the bike running indefinitley (or rather, until it runs out of fuel or overheats).

It may not bring the battery to a true full charge, but what I was seeing was that a) the after idling voltage was higher than the initial voltage (which was key off, bike having been sitting for a couple of days), and b) the 12.65 voltage was still rising slowly.

So, regardless of whether it would eventually reach full charge or instead level out somewhere between 12.65 and 14, the battery in my bike was at least being charged slowly and was already at sufficient voltage for the engine to run. I.e. the alternator was producing more current than the electrical system was drawing.

Now, the down side of this that I can see is, if the battery were to have run down for some reason, and I jump started the bike, the alternator probably wouldn't be producing enough power at that point to both charge the drained battery and run the elecrical system. Getting the engine up to 3500 RPM or so (IIRC, the point where the alternator hits its rated 19A) would then be neccessary to keep the engine running.

 

I took the route that SQLGuy took and converted several of my lights over to led. I cleaned my alternator brushes picked up a new battery and actually took the time to charge it correctly (overnight). After pretty much any ride I take now a quick check of the battery when I get home shows 13.2 volts and after a couple of hours drops back to 12.8 or so.

Something for you to think about is this. By switching the cluster lights, brake lights and license plate light to led's should net roughly a 2amp savings!

 

fully charged battery is 12.6 volts

 

So this thread was referenced the other day and since it is not conclusive I thought I would add to it. The bike is a 750 Seca with an AGM battery that is close to three years old.


The setup:









Some info about the video:


1. The sum of the two current meters is the total current.

2. A positive indication indicates drain on the battery, a negative indicates the AC Generator is producing enough power to run the electrical load plus charge the battery.

3. At ignition on 3 to 5 sec the power up current is high for a couple of seconds as the TCI drives one coil and then switches to a standby state.

4. At 5 seconds the current settles to approximately 4.5 amps - the tail 1156 bulbs and the AC generator rotor consume most of this.

5. At approximately 11 seconds at idle the generator is producing enough power to run the headlight and all the other electrics with just a minimal loss of approximately 1.8 amps. The Generator output would roughly be the 4.5 amps noted earlier plus the headlight, so a total output of close to 8 amps at idle.

6. At 28 seconds the brake is applied, net current loss is close to 5 amps at idle - 1157 bulbs x2 are current hogs.

7. At 37 seconds rpm slowly raised and net loss of zero with brake applied occurs at about 1250 to 1500 rpm





So, the conclusion is a very minimal drain occurs to the battery at lower rpm. Worst case is idle, brake light illuminated, and then adding flasher a net loss of approximately 8 amps would exist. With the typical XJ battery rated at 14 AH it would take approximately 2 hours of worst case condition to discharge a serviceable battery when also considering the 50% duty cycle of the flashers.


Note also that the charging voltage is slightly low in the beginning of the video with the rpm raised, and higher later in the video as the rpm is raised. The lower voltage is a result of a battery that is not fully charged – but very close. The higher voltage at the end of the video depicts the charging system of a battery near full charge. This is why when evaluating the charging system it is important to start with a fully charged battery. A discharged or defective battery because of its low impedance will effectively reduce the measured voltage at the battery when evaluating the charging system.

 

Rooster, that is awesome! Thank you for sharing that!

 

Rooster's posts are so over my head, they have to look down to see the sky!

 

I made my old (new at the time) scooter be able to charge the battery at idle by swiching to LED taillamps (I was compnsating for some accessories. charging at idle only occured when the accessories were turned offf). Unfortunately there would be a warning light issue on the bikes with the ATARI.