monster 796 battery woes

[mgrover]

So I put in a brand new Yuasa battery, this is the batterys states

off -> 12.9v
ignition on -> 12.1-12.3
running -> 14v
freshly turned off -> 12.2/12.5

But if I leave it overnight it seems to drop to something along the lines of 12.0 or less.

I haven't added any extra gizmos to the bike, recently my ignition coil seems to be getting wet so that could cause a problem in starting, but when dry I still have this issue. So could I of nicked an important wire or is something else causing this issue?

A lot of people have said alternator or rectifier/regulator. But if the battery charges fine when running then it shouldnt be an issue?

cheers

martin

[Ron1000]

your battery states look good to me.

and it's charging ok too, maybe check the connections at the battery. Have you maybe got a drain somewhere or not tightened something down properly.

Is the 796 under the tank like the 1100? it's a PITA to get to.

[mgrover]

yeah the battery is under the tank, I'll have to open her up again and take a look since am off for a ride in the lake district in a couple of weeks and I don't fancy getting stuck there

[Mr Gazza]

You do seem to have a very slight current drain there somewhere. Does it continue to drain below 12 volts if left longer?

Your upper figures look normal... Healthy even.

The lower figure after just turning off might just be that the engine has not run long enough after the start up to charge the battery back up?

14 volts running shows a healthy charge.

Reg/Recs have a lot of diodes in them, which control the direction in which current flows.
The battery and reg/rec are permanently connected and not switched, so the diodes stop the current getting past the reg/rec from the battery, but allows it to the battery when running.... They are one way valves.
When they fail they can allow some current past in the wrong direction. I just had this on a car. The drain was 5amp hours, so quite significant but not a dead short you see..

I am sorry I can't suggest how to test if it is a diode in the reg/rec, but someone on here might be able to.

Some moisture in the wrong place might do it too, or any number of weird ways to leech current away... Suggest you remove one fuse at a time to try and narrow the cause down.

[mgrover]

Never let it get too far past 12, but I should check, usually when the weekend comes up I'll check for it. Now I have to take it out every lunch time for a quick half hour blast to make sure it starts at teh end of the day...although not complaining about that too much :P

I'll strip her down on saturday and see wtf is going on. Reg/rec seems the easiest to replace but the only ones I can find are 20quid ones from amazon that seem like there from china and not too reliable. is there any decent after market reg/rec?

[Mr Gazza]

I wouldn't write the reg/rec off just yet. Disconnect it and see if the current still drains.

I also wonder if the battery is simply under-performing due to the cold?

[utopia]

I'm no electrics expert but could you not connect an ammeter in the various circuits to check for any current flow (ie drain) when everything is switched off ?

[mgrover]

it could be the cold tbh, since its around -1 here and shes outside.

utopia next thing am going to do, check if theres any pull on the battery, then start removing fuses till it stops

[Flip]

Firstly, I'm not much of a fan of recent Yuasa batteries- my original one lasted twelve years ('97-'09) the second only two before I bought a Motobatt which has been trouble free since fitting.

Getting a battery to show volts is really only part of the story- it needs a load to test it properly. Therefore it is quite possible to be showing all happy (even on an Optimate type charger) but have a dead cell which when you demand the kind of load the starter circuit wants the battery huffs and puffs and conks out. I even had this on a new Motobatt on my race bike which caused me a DNF- luckily it was under warranty and was replaced free of charge by the dealer I bought it from (unfortunately my race entry fee wasn't though!!).

I am inclined to agree with Mr G not to write off your RR or alternator just yet as it would be more likely that the bike dies while riding with your lights on etc. if the battery wasn't being charged- plus if the battery isn't getting cooked leans towards the RR being ok in controlling the voltage getting through to the battery.

As Utopia says- could well be a current drain somewhere- dodgy ground point on the frame or such but get the battery checked for taking a load first then work onto the more tricky tests.

Before you can really establish a cause you will need a multimeter to perform a few simple tests- do you have one?

[Tosh]

I agree with testing with a multimeter. If you don't have one a simple test is to disconnect the earth lead. Make sure the key is off. Then turn out the garage lights, and very slowly touch the earth back on the battery. There should be no spark. If there is then you have a drain and will need further investigation .
Good luck. Tosh

[mgrover]

Am getting another ignition coil(different annoying problem) next week, so I'll strip her down then hopefully its just something loose.

Firstly, I'm not much of a fan of recent Yuasa batteries- my original one lasted twelve years ('97-'09) the second only two before I bought a Motobatt which has been trouble free since fitting.

...

Before you can really establish a cause you will need a multimeter to perform a few simple tests- do you have one?

I do indeed have a multimeter.

[Flip]

I do indeed have a multimeter.

Excellent now you can have some fun!!!

If I am not teaching the sucking of eggs, an easy D.I.Y. drop test for the battery is to disconnect it and rig up a 55w headlight bulb across the terminals and depending upon the amperage of the battery you can work out how long it should stay lit for and try it (if the battery is shot it will usually dim pretty quick).

Power (Watts) = I (Current- Amps) x V (Voltage)

So a 55w bulb consumes 4.58 amps so divide that by the Ah rating of your battery to give you a time (this is not actually the real time for a number of reasons as the battery depletes but it's a good enough guide for this test). If the battery is shot it won't stay lit very long.

Obviously it is worth checking that the charging system is doing it's job as well by putting a multimeter across the battery terminals with the engine running to make sure it is getting something around 14v which you have already confirmed to be the case.

So here's a couple of pretty good links to doing some other electrical drop tests on the wiring:

http://www.aa1car.com/library/voltage_drop_testing.htm

http://www.fluke.com/fluke/uses/comu...agnosevoltdrop

[mgrover]

so...its raining today. and am there ****ing about with my ignition coils cause bike won't start, so I take the one from the top cylinder off and while holding it(i know am an idiot) I hit the ignition, and low and behold I get a slight electric shock. So am like hmm, what a great way to diagnose, so plug the sucker back in and do the same for the bottom cylinder, I get no shock nothing, thankfully the ignition coil i ordered has arrived.

is it safe to say there isnt a decent spark from the lower coil, or atleast i shouldnt of been electrocuted since its rubber

[mgrover]

a quick update, swapped out the coil that was meh and bikes running lovely, took tank off and one of tje insulators on something the red lead gets plugged into was exposed so shoved that back in its plqce and.just waiting on a good thunderstorm to give it a good test