battery drain

[knrhodes]

I am finding about once every month my battery is drained and wont have enough juice to crank - I hook up a trickle charger and its good for another month (I'm pretty much a daily rider) but didnt have this problem with my other magna - I recently replaced the battery (within the last 12 months) and dont remember the last one doing this - but could be wrong - any ideas???

[lragan]

Is the bike stock, or do you have accessories that use electric power?  If you have excessive power drain, the regulator/rectifier will not keep up with the demand.

I have two '96 Magnas, and I keep a charger on both of them whenever they are parked at home.  I don't ride as much as you do, though.

It is also possible, although not likely, that the regulator/rectifier has lost one of its three rectifying diodes, and is not putting out the rated current while running. 

The regulator rectifier really doesn't do much below about 3000 rpm, so if most of your riding is done at low engine speed, this could also cause inadequate charge.

Lots of guessing and speculation here, hope it helps somehow....

[TLRam1]

Check to make sure the regulator is charging the battery.

[knrhodes]

stock so no extra drain - stupid question - how would one check the regulator?

[walc]

Why don't you use a battery tender, such as Battery Tender Jr., when you aren't riding?
http://batterytender.com/

[lragan]

First, to check if the battery is being charged, one needs a voltmeter of some sort.  Harbor Freight sells a small one that is quite adequate for <$10 (<$5 on sale!). 

The "nominal" battery voltage on a charged battery should be about 12.6 volts.  When it is charging, you should read at least 14V across the terminals.  An old battery will read higher during charge, a brand new one closer to 14V.  You will need to remove the seat to access the top of the battery. 

The "battery tender" devices I use were purchased from Wal-Mart for around $10.  They have worked well.  About the size of a small brick.  They came with leads which I attached to the battery terminals and fed out from under the seat on the left side, that have mating connectors for the charger/monitor ("battery tender").  They produce a small amount of heat (never very warm) which is enough to keep moisture from condensing under the covers I use in my carport, so they serve two purposes.  When I park the bikes, I simply plug them in and set them on the seat or saddle bag.  There are lights on the front that tell the status of the battery.

If you ride daily, it is unlikely that your regulator/rectifier is not charging at all.  I rather doubt that the battery would last a month without charge under regular use.

[knrhodes]

Why don't you use a battery tender, such as Battery Tender Jr., when you aren't riding?
http://batterytender.com/

I do - but being a daily rider its sometimes a pain to take off the seats, etc - now if I installed a "quick release" for the seats of maybe wire leads so I didnt have to take off the seats it would be as much of a pain

[dgc67]

I do - but being a daily rider its sometimes a pain to take off the seats, etc - now if I installed a "quick release" for the seats of maybe wire leads so I didnt have to take off the seats it would be as much of a pain

So, a dead battery is less pain than pulling the seats after a ride?

[TLRam1]

Better to check and eliminate the easy stuff.

No particular order for the first two.

1. Check battery voltage to see what it is from a resting state, after 24 hours of being charged.
         (even a new battery can be bummed, not often but can be)

2. Check output voltage as Lawrence described with the motor running at various RPM's, what are your readings on the voltmeter.

3. Load Test - With a charged battery and maybe when you first start your bike (prefer the bike not start up immediately) put a voltmeter across the battery terminals and hit the starter, watch the voltmeter and what is the reading, should be around 10 volts. If it's dropping in the 8 volt range with a load your battery is not well.

4. If all the above is good, you could have a leg of the regulator out and not putting out the amps needed (volts might be affected if this is the case) or you have a constant drain on the battery.

This should cover 99 percent of what may be your problem, if not there is Lake Worth you can ride it off in. 

[Troystg]

Why don't you use a battery tender, such as Battery Tender Jr., when you aren't riding?
http://batterytender.com/

I do - but being a daily rider its sometimes a pain to take off the seats, etc - now if I installed a "quick release" for the seats of maybe wire leads so I didnt have to take off the seats it would be as much of a pain

"Most" of the battery tenders do have quick connect plugs to leave a permanent connection under the seat.

[dgc67]

"Most" of the battery tenders do have quick connect plugs to leave a permanent connection under the seat.

He doesn't want to remove the seat.  Seems like you could locate the quick connector somewhere you can get to it without removing the seat.

[walc]

"Most" of the battery tenders do have quick connect plugs to leave a permanent connection under the seat.

He doesn't want to remove the seat.  Seems like you could locate the quick connector somewhere you can get to it without removing the seat.

The connector plug isn't under the seat.

[Magniac]

Mine is under the right side cover. One lead is about a foot long to reach the left battery terminal, and of course the other is shorter.

[walc]

Mine is under the right side cover. One lead is about a foot long to reach the left battery terminal, and of course the other is shorter.

I installed mine so the connector plug hangs out, from under the seat, for easy access.
It has an attached cover, so no water gets in.
http://batterytender.com/

[drkngas]

I had the same problem with my Magna.  I had great charging voltage at 4500rpm but if I just putted around it did seem to run dead after three to four weeks.  In the summer with the cooling fan running more, I would just leave the battery on the trickle charger.  In the cooler months I could go longer.  I ran wire up to the handle bars and put my battery tender plug up there.  I carried a solar charger while out traveling or camping. Bike was sold over the summer so I never fixed the problem.