Dead Battery

[Countdown]

Does any one know why a WR450 will not run with a low battery? One would think that the (CDI) ignition system is independent of the battery system.

[jbrooks26]

I don't own a 450, but I don't believe that there would be any reason that it wouldn't run without the battery installed. The lights and other accessories would not work, but the bike should still run. Someone please correct me if I am wrong.

Josh

[odonnks]

The WR should run without a battery installed. With a (very) dead one installed it may be too much of a load for the charging circuit. Batteries can actually short between cells. This problem could cause it to not run.

Pull it out and try it.

[25year2stroker]

My 05 450 would not run without the battery,I kicked for over an hour and got nothing.We ended up jumping the batt leads with a quad and it fired right up.Ran fine just don't shut it off or stall it.

[Frank_z28]

My wr battery is really low and it still run . Sometimes in the wood i have to kick start it, he always start and run. They're another post with a guys explaining well how "electricity circuit" work for those bike.

[PBDBLUE]

The '03 manual contains this note:

NOTE:

If the indicator light will not light up with the

main switch “ON”, it shows a lack of the battery

voltage. Recharge the battery. If the engine is

kick started, turn off the light switch.

Kind of intereting. The WR450 (in stock form) has a charging magneto and a lighting magneto. The ignition runs off the charging coil so I'm not sure why they are recommending turning off the headlight. '04 and newer WR's don't have a light switch so I'm not sure what you're supposed to do in that case. I've never had a problem kick starting either of my WR's even with a dead battery. By any chance did the bike have a dual sport kit with a modified stator (ala Baja Designs)? BD modifies the stator so that the entire bike runs off DC only. In that case it may be that there is not enough DC output without the battery to energize the ignition and all the other loads (i.e. headlight).

[Countdown]

I have a hard time believing that CDI runs on AC stock system and DC with a BD kit?

The '03 manual contains this note:

NOTE:

If the indicator light will not light up with the

main switch “ON”, it shows a lack of the battery

voltage. Recharge the battery. If the engine is

kick started, turn off the light switch.

Kind of intereting. The WR450 (in stock form) has a charging magneto and a lighting magneto. The ignition runs off the charging coil so I'm not sure why they are recommending turning off the headlight. '04 and newer WR's don't have a light switch so I'm not sure what you're supposed to do in that case. I've never had a problem kick starting either of my WR's even with a dead battery. By any chance did the bike have a dual sport kit with a modified stator (ala Baja Designs)? BD modifies the stator so that the entire bike runs off DC only. In that case it may be that there is not enough DC output without the battery to energize the ignition and all the other loads (i.e. headlight).

[odonnks]

The 06 actually does have three separate charging windings.

[PBDBLUE]

I have a hard time believing that CDI runs on AC stock system and DC with a BD kit?

Actually sort of. There are two power connections to the CDI. From the schematic it looks like the main CDI power comes from the AC side of the charge magneto ahead of the rectifier/regulator. There is also a DC input that comes from the ignition switch which I think is nothing more than a control input to turn the ignition system on but it must have 12 volts dc on it to get spark. In the factory wiring there are no other loads on the DC side other than the ignition switch and the battery. All the lighting is run off a seperate "lighting" magneto (similar to the KTM's and the CRFX's). In the BD scheme they rewire the two magneto coils together to provide one output for everything - lights, ignition switch, battery, etc - so there are a lot more loads on the DC side. I'm not sure if that will be a problem for dead battery starting or not but maybe? My '03 is DS wired so that the headlight runs off the lighting magneto and everything else (LED tailight, turn signals, brake light) run off the battery. As I mentioned in the other post on this subject I went out to the garage yesterday, disconnected the battery and it kickstarted no problem. I'm not really sure what the cause of the problem you were experiencing was but it was just a thought.

[PBDBLUE]

The 06 actually does have three separate charging windings.

Are you sure about that? I believe the '06 is the same as the '03 - '05's. I think you may be confusing the trigger coil for a magneto. The third coil is the trigger coil which signals the CDI to fire the plug but does not supply any power.

[BajaFool]

PBDBLUE,

Now that the discussion has included Baja Designs kits, does this mean that we need to revisit the discussion on the other thread that was about starting the bike with a dead battery? One of the situations I described was if the rectifier fails on a bike (2005WR) with a Baja Designs dualsport kit installed, will the bike start with the kick starter if the ignition is turned on. Also, does the Baja Designs kit replace the stock rectifier?

[PBDBLUE]

My guess is that the bike will not start if the regulator/rectifier is blown and the battery is dead regardless of whether it's stock or aftermarket since the CDI box requires 12 volts DC from the ignition switch to operate. And yes the BD kit replaces the stock regulator. I have not heard of any widespread problem with the stock regulators going out though it is always a possibility. The stock regulator circuit provides about 25 watts. I think as long as you keep the loads within those guidelines you should be ok. That's one of the reasons I went with an LED taillight bulb. Remember the more current you draw through the regulator the more heat it will have to dissipate and heat is the number one enemy of electronics.