battery/charging problem

[cleatus]

hi all.

before I spend £60 on a new reg/rec, can I ask for your advice please.

a few weeks ago the battery went flat on my cbr929. It wasn't very old (10 months) but it was a cheap chinese one so I assumed it had just packed up and bought a new Varta battery. I charged the new battery, fitted it and all was well again. since then i've been out about three times and today. half way home i stopped for petrol and when i went to start again the battery barely turned the engine over. got home luckily, but when i put the bike away, tried to start it again and the battery was flat. i had noticed also that the headlight goes a bit dimmer when the bike is idling, been like that for a while.

i'm just guessing that it's the reg/rec because i don't know what else it ciuld be.

is this problem most likely the reg/rec or will i be wasting my money? is there any way i can test the reg/rec?

any advice appreciated,

Dan

[lorenzo]

First post I came accross (and it's by me too, gotta be a good 'un). However, if you're on your 2nd battery in a few weeks I'd say you've certainly got charging issues and by a long way the most common issue is the reg/rec on hondas of this era. Get an aftermarket one rather than a genuine one, get as many fins on it as possible, and if you're really swish, buy some cpu heatsink paste from a computer shop and splodge it on the back to help dissipate the heat.

[cleatus]

i've charged the (chinese) battery ovenight. After trying to melt my new multimeter, i find that it is giving 13.5v this morning off the bike. i'll check out what it's like on the bike later.

thanks both for the advice

dan

[kwakbiker]

If you do need a reg/rec then try a company called electrex, do good quality pattern parts

[trumpetman21]

Buy a testmate mini from M&P (£15) - great little bit of kit, you can plug it into your optimate lead to check the battery whenever you like.

[cleatus]

I've put the battery back on, warmed the bike up and put the test meter on as you advised.

when idling, the voltage goes up slowly (.01v at a time) to between 13v and 14v, with the headlight on dip the voltage steadily dropped to about 12v before i turned off.

with the bike revved up the voltage goes up quickly, but still comes down (more slowly) with the headlight on.

does that mean the reg/rec is shagged?

I'm going to order an electrex one (thanks kwakbiker) tommorrow, if its not that at least i'll have ruled it out.

thanks again

dan

[lorenzo]

I'd say, and I'm kinda on the edge of my knowledge here, that you could have one of two problems: Firstly, your reg/rec could be goosed and is simply not passing enough through to the battery to get it charged with your lights on. If it's holding the voltage down, which it is, I'd say this is pretty unusual. More often than not they'll work or won't work, that is, they'll either pass a regulated charge through OK or it'll just go off the scale by the time you hit about 8000 rpm. The other thing it could be is the actual alternator. There's usually 3 sets of windings, each giving a sequence of voltage humps which the reg/rec will smooth between to get one steady output. If one of these windings is knackered then you'll only be getting 2/3rds of the normal output to the reg/rec, which in turn means it could be struggling to cope when there's higher current drains. If you've got a haynes or something there's most likely a bit in there where it tells you how to check your alternator, get your multimeter out!

[cleatus]

I'd say, and I'm kinda on the edge of my knowledge here, that you could have one of two problems: Firstly, your reg/rec could be goosed and is simply not passing enough through to the battery to get it charged with your lights on. If it's holding the voltage down, which it is, I'd say this is pretty unusual. More often than not they'll work or won't work, that is, they'll either pass a regulated charge through OK or it'll just go off the scale by the time you hit about 8000 rpm. The other thing it could be is the actual alternator. There's usually 3 sets of windings, each giving a sequence of voltage humps which the reg/rec will smooth between to get one steady output. If one of these windings is knackered then you'll only be getting 2/3rds of the normal output to the reg/rec, which in turn means it could be struggling to cope when there's higher current drains. If you've got a haynes or something there's most likely a bit in there where it tells you how to check your alternator, get your multimeter out!

I called electrex and they pointed out some diagnostic instructions on their web site, so i'll try those tonight. I had a quick look at the instructions on my break and yes, you're right it does seem bit wierd that it seems to be holding the current back rather than the other way round. Makes me wonder if it might be the generator. I had an off about a year ago and when the bike went down it smashed the generator cover. I bought a new one and fitted it and never had any problems till now. Maybe the generator was damaged then. It was untouched as far as I could see, just the cover broken. Any how, electrex give instructions for testing the reg/rec off the bike, so I should know tonight. Thanks again.

Dan

[cleatus]

A quick update.

I got hold of a new reg/rec from electrex and fitted it, but it hasn't made any difference. From what I have been told, I'm reasonably confident it must be the generator. Someone told me it has probably lost a phase, which would make sense ,as there is excess voltage getting to the battery, but as soon as the lights go on it plummets at any revs. I went for a long ride yesterday and didn't use the headlight, when I got back there was still 12v in the battery. It will have to stay like that for now until I get round to sorting a new generator.

or in other words, what Lorenzo said

I've learned a lot of new stuff so far, so it's all good.

thanks again

dan

[lorenzo]

You say phase, I say voltage humps. It's all the same stuff....