battery charging

[Sue Larrington]

A few months ago, Graham fitted a pair of 55w lights to my 2004 GS, I love them and use them alot of the time. However the alternator is not keeping up with the demand and the (new) battery has to be recharged every two or three runs (600-800 miles. I wondered if anyone has had the same problem. sue

 

[Summer]

Sue, when Nick fitted extra lights to his 1150 he had to also fit a 30amp - I think it was 30amp relay as well so as not to have this problem. Not sure if this is similar or any help

 

[Womble]

The 30 amp relay is an electronic switch that you turn on through the existing wiring but which connects the new bulbs via wiring that runs directly to the battery, so as not to burn out the existing wires.

The problem mentioned sounds like the battery is on the way out. However, it could be dirty connections, or a problem with the charging circuit.

Did the bike come with heated grips? If I remember correctly, bikes without heated grips don't have high output alternators, which could also cause this problem.

 

[Summer]

There you go sue, I knew some kind member would come along and help you out unlike me, well, I am female

 

[Womble]

Don't worry Little Beemer, your description was spot on.

Sue - have you got a chance of using a charger such as an Optimate between rides? Keeping the battery topped up is better for it than cycling it from full to empty, with it stored partially charged in between.

If you've got a garage but no electricity, it is still possible to use solar panels for charging. However, I'm not sure how well that would work in Scotland in the Winter, particularly once you start factoring in extra headlamp usage as well.

 

[talltony]

The alternator is well able to cope with the extra lights so assuming you're not using other things such as heated grips and/or clothing the problem is probably down to running at relatively low RPMs.
You need to be around 4000rpm+ to get close to maximum output.If you do much town riding,that could be hard to achieve.Turning off the auxilliary lights a half hour or so before the end of the ride can allow the battery to charge up properly.

Tony

 

[brassmonkey001]

I have Hella Micro DEs on mine and when the engine is idling the alternator output is insufficient to charge the battery (I have a voltage monitor fitted) when the DEs are on. So I converted them to HID which brought their drain down from 55w to 35w and increased their light output significantly. My rear light is LED which reduces drain as well.

 

[komatias]

If you do go down the route of changing your battery, I would suggest you swap the original battery for a sealed battery like the westco. I have been running it for about two years now with no problems of cold starting, lack of oomf. It alls behaves better in an off because the acid doesnt leak out burning the electircal cables.

 

[Sue Larrington]

Thanks guys, the battery is new and we do use an Optimate charger, the bike has heated grips and I do use a heated waistcoat (needs about 4 1/2 watts). BMW say the alternator output is 29amps @ just over 7000rpm and Graham recons the bike takes about 22amps with everything on, ie main beam, indicators, stop light ect, and about 17 amps for normal running with the extra lights on. The addition of 2 x 55w lamps almost doubles the power requirement. Due to my work I only get out twice a month or so, but my runs are never less than 2-300 miles, Ive already done nearly 6000 miles this season, so Graham suspects that we are expecting too much and I will need to use the lights only when visibility is an issue and as suggested switch them off for the last few miles to let it recover. Does seem strange you
can buy off the shelf lights for this bike if it wont keep up. sue

 

[alimey4u2]

Tis a conundrum for manufacturers to make an alternator that has ample output with minimum weight, weight (lack of it) sells bikes not wattage I'm afraid.....
If the load is greater than the supply the system will eventually come to a grinding halt when the battery (no matter how large or efficient) becomes depleted.
Either research a more powerful alternator (if available) or look at reducing the load (converting to 35 watt HIDs as an example.)

 

[Womble]

Are you actually leaving the bike attached to the Optimate all the time when it's not in use? This is the best way of keeping the bike battery charged and the Optimate is designed specifically for that sort of usage. Don't worry it won't hurt the battery at all - I've been using them for over 10 years and using them has saved me loads in battery costs.

The heated vest which draws 4.5 Amps is equivalent to another 55W bulb. Using the vest and the lamps will draw 13.5 amps from the system, and if the alternator can't cope, the battery gets drained. Another thing to bear in mind is that the alternator won't be up to full output at lower revs, so riding through town at 2000 rpm with everything on is very likely to drain the battery, which is the sort of thing that you're seeing. There is a slight chance that the charging circuit is slightly dodgy, but I'd not worry about that just right now.

Why do BMW sell lights that allow the battery to be drained? I suspect that they're sold as fog lights, and therefore aren't expected to be for continuous use.

Apart from keeping the bike on charge all the time when not in use - by far and away the cheapest solution for you, the only other solutions are to drain less power or fit a higher output alternator.

To lower the power, you either have to switch things off, or make them use less power.

You might want to consider using lower wattage bulbs instead of the 55W ones that you have now, but it all depends on your riding conditions.

Alternatively, you can look at HID conversions for some or all of the bulbs. 35W HIDs are a lot brighter than 55W standard bulbs. By putting 35W HIDs in the lamps and on the dipped beam, you would decrease the total current required by 5A. Fitting HIDs costs about £50 per bulb, just for the parts, and is a bit of a pig of a job on 650s, so it's not the simplest of solutions.

 

[Sue Larrington]

Hi again, you misread my letter slightly, heated waistcoats need about 4.5watts, about .375 amps so will make little difference, however it all adds up. The Optimate is not permanently connected, it is used between both bikes and goes on mine after a run now, and then again a few days prior to going out. This is ok until we go away for a few days. You are quite right about the alternator output, BMW quote max at 7000rpm, almost flat out, a bit stupid really, Grahams Varadero gives 36 amps @ 5000rpm, just over half revs and so at road speeds my bikes output will be well below the quoted figure and in town losing ground fast (all the places you need to be more visible are going to be at a slower pace). I think the advice earlier on fitting a volt meter is probably the answer for now when at least I can see whats going on. sue

 

[alimey4u2]

With all due respect, an ampmeter would give you the earliest warning & tell you when you are going negative well before a voltmeter. More tedious to wire though....

 

[Womble]

I think you need to check the figures on heated waistcoats as they do tend to be in the 3.5A and upwards range. If I had a heated waistcoat that used that little power, I'd be looking to get a bigger one anyway And that's not because I need a diet

Going back to ammeters and voltmeters, it's true that an ammeter in the battery circuit can tell you whether the power is going into the battery or out, but I haven't seen one on anything since my 1970s Land Rover, probably because wiring faults can be interesting

I'd start with a voltmeter - when you use it, the important thing to watch is the engine RPM when the voltage gets above about 13.5V - that's the point when the battery starts to charge. If the voltage is too low, try riding in a slightly lower gear and see if that helps. If you haven't already got a voltmeter, I wouldn't bother with a vehicle meter, just get a cheapo meter from Maplins, Rapid Electronics or Halfords. Some wire and a couple of banana plugs and you'll be well set to check the voltage, but you'll be able to use it for so much more.

If the voltage doesn't reach 13.5V by the time you get to 2500 RPM, or if it goes over 14.5V, you may have a faulty charging circuit.

Other things to bear in mind are to make sure that the connections to and from the battery and the starter motor and the earth are all in good condition - dodgy connections can give a healthy voltage, but with no push behind it.

There's another thing to bear in mind which is wearing the heated vest as close to your body as possible, with extra layers on top. If you do that, you stay toasty warm but you can afford to turn it off more often. Also, don't assume that a heat controller on heated clothing will decrease the amount of power used, some of the cheaper controllers just move the heat from the vest to the controller, and the current drain remains pretty much the same.

 

[Sue Larrington]

My sincere apologies, Graham just looked and Giali say our waistcoats do indeed use 4.5 amps and this problem has occurred before Ive started using it this year. Its very easy to open your mouth and put in both of your feet. Now, Grahams going to run it down the road with his voltmeter connected and see what the reading is, we will then know if the small amp age saving with HID lamps will be enough. sue

 

[Womble]

Hi Sue.

If the problem was there before you started using the heated waistcoat, adding HIDs will help but the heated waistcoat will take you back to the limit again, so you will still need to be careful.

Once you and Graham have checked the connections, then you need to make sure that the battery is in tip-top condition all the time and that there aren't any other electrical faults on the bike.

If you're feeling brave, check out the thread on DRZ-400 charging - the principles are the same but some of the figures might be a bit different.

 

[Der Lustenauer]

I wondered if anyone has had the same problem. sue

I had a pair of Wunderlich fog lights (twice 55 Watts) on my 2000 F650 GS and had the same problem (no heated vest, but had the grips on sometimes).
Found out during a trip to the Alps, lots of revs on the motorway down and I keep them normally above 4000 when going up mountain passes.

The lights got professionally installed with the Wunderlich cables, switch and so on by BMW Battersea.

 

[Sue Larrington]

Had a good run out last weekend (some 400 miles) with a fully charged battery, but only used the driving lights when needed, making sure they were off for the last 40 miles and the battery was fully charged. I am still going to fit a Heads up voltage monitor so I can see whats happening and I think that will end the problem. sue

 

[alimey4u2]

Had a good run out last weekend (some 400 miles) with a fully charged battery, but only used the driving lights when needed, making sure they were off for the last 40 miles and the battery was fully charged. I am still going to fit a Heads up voltage monitor so I can see whats happening and I think that will end the problem. sue

Gnus....