brute force 750 battery

[Hailey04]

I have an 05 brute force 750. rus great but when i turn on lights of use the winch it quickly drain the battery of all charge and will die.. It will also drain the battery and die if the cooling fan runs for any period of time.. Any thoughts and mabe "how to" would be much appreciated

[bigpig750]

Sounds like your generator is out or getting week. does the battery hold a charge?
If not change it because that is hard on the generator.

[Hailey04]

The battery does hold a charge as long as nothing else is running or pulling any power

[Hayashi]

There are 3 components to be checked:
> Stator AC output check
> Regulator/Rectifier DC output check
> Battery load test

Let me know what dc voltage you get from the battery terminal while revving the engine at about 1/2 throttle.

[Hailey04]

12.24 V

[Hayashi]

That's way too low. My 750 puts out 13+ VDC at that rpm.
Now you have to do the AC output voltage check as outlined in the SM.

[Hailey04]

Thats sucks. I bought it used and he had lost the SM

[ruetheday69]

Just had this happen to my new 2008 750 EFI. However, I am stumped as to why a low or weak battery would cause a quad run for say 10 mins and then die. I can understand not having enough juice to start it or maybe enough to turn it over but not enough to fire it up but can anyone educate me on why an EFI quad dies once the battery gets weak? I took this back to the stealer and had them fix it, not realizing that the battery was the issue. So, doesnt the quad produce enough power when it is running to keep the bike up?? Does the fuel and computer system run off clean power, aka the battery and is this why a no charging battery, producing lower than required juice would cause the bike to quit?

This happened while running a plow, with a winch...and after replacing the battery..life is good. So does anyone have a good technical description on why this would be the case. I am new to these EFI quads and stumped on any logic as to why this would be the case. The stealer also told me that basically these new quads, wont charge a weak battery but will maintain it, I find that to be a hard comment to swallow, assuming a battery will take a charge...why would a running quad not charge it??

Anyways, sorry to ramble but if some smart person could educate me on this I would appreciate it, thank you in advance and when I reference the stealer I really mean the dealer [img]i/expressions/face-icon-small-smile.gif[/img]

[ruetheday69]

I think I might have come to a theory as to what would cause this. Suppose the battery is weak..but has enough to fire the bike up.. So the bike is running...and I engage the winch...the winch would draw power from the battery to avoide pulling it from the VDC being produced by the engine, simply because the engine needs that VDC to keep the EFI working and bike firing. So..in the case of a weak battery..it cannot provide enough VDC to the winch..so the winch ... when engaged..steals VDC output from the engine..thus robbing the juice from the EFI..causing the bike to die. After charging or letting the bike sit..enough juice is provided back to restart the bike..which will run fine until the winch is used again..and the same problem manifests itself.

Is this a decent theory? Is it correct to assume that the quad does charge a battery, assuming it can accept a charge? I put a battery attender on the bike to keep the new battery topped off and I think that should work for now. However, if I ever haven an issue on the trail..if I jump the quad due to a dead battery..will the bike produce enough VDC to keep it running .. with a dead battery...assuming I dont use the winch etc?

Sorry for all the questions but that is a theory that makes some sense to me...anyone else?