Solar Battery Charger??

[Goo]

I left my bike for a week and was surprised to find the battery flat when I came back. My BMW dealer tells me this is normal. So...

I am looking for a battery charger for it that does not require mains power - My bike is kept in my front garden and I wouldn't be able to leave it connected to the mains overnight)

Am I right in thinking that a solar charger is my only option?

Can someone please recommend me a suitable charger?

Is it possible to use this charger connected via the auxiliary socket
on the bike or would I have to connect directly to the battery? (and therefore have to unscrew the centre trim panel each time)

Any thoughts much appreciated.

Thanks!

 

[Grey Beard]

I don't think it is normal to flatten a battery within a week when left standing. It should last four weeks anyway. I take it you are not leaving something like a Garmin connected to the bike permanently?

I don't know much about solar chargers and always thought they were pretty low powered, really for computers, cameras,etc. but maybe bigger ones are available now. If you can get a 12V battery solar charger, I don't see why you can't plug it into the auxiliary socket on the bike, rather than direct to the battery. I don't know what would happen at night when the solar cell would stop charging. I guess the CAN-Bus, if fitted, may automatically switch off the charge system and it wouldn't charge again the next morning until reset? Some tests would be required.

However, if you are going to leave a solar charger outside, is there not a risk you will have it stolen. What is wrong with a mains power battery charger? Is it you don't have a mains socket outside and would have to leave a window or door open for the cable or are you worried about theft?

Grey Beard

 

[Goo]

Thanks for that Grey Beard.

The dealer (BMW Park Lane) told me that a new battery should hold its' charge for about 2 weeks but mine because it is 2.5 years old would more likely last only a week. The bike had only just come back from an annual service and the battery had passed their tests no problem. I did have a cable for my garmin attached but not the actual unit. But anyway, the accessory socket is supposed to cut off power 15mins after the ignition is turned off. I also had the alarm on but again, it goes into sleep mode after 20 mins and is not supposed to drain the battery appreciably.

When I talked to them about buying a charger, the person serving me said that he personally used a solar charger for his bike and that it only cost £12 or whatever from eBay. Like me he lives in a flat in London and the bike is in the front garden. I'm on the first floor so a cable out of the window overnight is not really practical.

I am concerned about theft but I figure I can probably hid a solar charger away from view of the street behind the bike. Or maybe I will be able to figure out a way to lock it to the bike.

I know the BMW charger can be connected to the accessory socket and switches off when the battery achieves full charge. Also, I know there are solar chargers out there that won't overcharge a battery and that have a diode to prevent discharging overnight.

I'm just wondering if I can connect one to the accessory socket and have it work.

Guy

 

[Goo]

...and also, the dealer told me that it's pretty hard to fully-charge the battery by riding alone. The lights and ABS use enough current to mostly counteract the alternator (which only cuts in above 3000 revs apparently)

 

[karlp]

...and also, the dealer told me that it's pretty hard to fully-charge the battery by riding alone. The lights and ABS use enough current to mostly counteract the alternator (which only cuts in above 3000 revs apparently)

I have never heard such utter crap (unless of course you have the alarm on)

I never put my bike on an optimate.
Have left it for 2 months and it started first press of the button.
Ride with (sometimes) everything on and still starts ok.

Maybe best to clarify by informing us what bike it is

 

[Dave Ett]

Your dealer talks sh*te!

I have run the lights, aux lights, heated grips, heated jacket, GPS, and autocom throughout the winter and the battery is perfectly fine.

A battery in good condition will last months without a drain, even one a couple of years old should be good for a couple.

I suspect the battery is probably past it's best, especially if you only ride at low speed round London. You need to get out at least once a week for a good half hour run to fully restore the battery - it takes at least 5 minutes to restor what starting it takes out.

Your best & cheapest option is to wire in a dedicated socket for connecting things to the battery - I have mine running to the rear of the bike with either the battery charger or a cigarette lighter socket. This way you can bypass the stupid BMW timer!

Maplin do solar chargers which simply plug into the cigarette socket, and my brother uses one to keep his lorry battery topped up. How you'd secure this to the bike is up to you - if it's off the road then perhaps you could screw it to the wall? A post?

 

[Goo]

The bike is 2009 F650GS twin.

I did have the alarm on.... According to the alarm manual, it's supposed to switch off after a couple of days for this very reason. And that same dealer told me that there was no way the alarm would have flattened the battery. Maybe he is full of shite though...?

Would it be easy enough to wire the existing accessory socket directly to the battery (with a fuse I guess) and thereby use it as a connection for a solar charger. In this case would it charge OK or would the rest of the bikes' electronics being connected in parallel be a problem? ie would I have to disconnect the battery from the other circuits when charging?

Do you suppose I need to get a new battery?? Is there a way to test it?

Sorry for my ignorance! I'm pretty new to all this stuff.

PS - what is an 'optimate'?

 

[Grey Beard]

The bike is 2009 F650GS twin.

I did have the alarm on.... According to the alarm manual, it's supposed to switch off after a couple of days for this very reason. And that same dealer told me that there was no way the alarm would have flattened the battery. Maybe he is full of shite though...?

Would it be easy enough to wire the existing accessory socket directly to the battery (with a fuse I guess) and thereby use it as a connection for a solar charger. In this case would it charge OK or would the rest of the bikes' electronics being connected in parallel be a problem? ie would I have to disconnect the battery from the other circuits when charging?

Do you suppose I need to get a new battery?? Is there a way to test it?

Sorry for my ignorance! I'm pretty new to all this stuff.

PS - what is an 'optimate'?

Hi Goo

The Optimate is a (non BMW) battery charger, which can now be supplied with an adapter to charge via the BMW CAN-Bus socket. It is slightly cheaper (not much, but more flexible) than the BMW charger.

I think I would install a standard cigarette lighter socket (though PopEye of this parish told me they were very unreliable - corrosion issues) or install a cable with a suitable loose socket and in-line fuse direct to the battery. Then plug in your solar charger to the socket.

I don't think your Garmin will do any discharging since it is not connected. The CAN-Bus socket will usually switch off one minute after the ignition. If you have a charger on it, then it will continue to accept the charge. The BMW charger will go through the charging, desulphatisation and trickle routine until it is happy that the battery is fully charged. At that point it will drop back to and maintain a trickle charge.

Not heard that the battery will only be charged from 3000 rpm - possible, but seen nothing in the manuals about that. (I know that the newer BMW car saloons do not charge the battery if you are accelerating hard, in order to maximise the engine power to the wheels when accelerating, but that is fairly new technology I think.

I don't know about gel batteries, but I once had a standard heavy duty lead acid battery load tested at a battery/exhaust type shop, so maybe the dealer can do that for you also. But your battery shouldn't be clapped out already. Do you know if it was charged regularly over the winter if the bike was not used? Cold doesn't do much for a lead acid battery!

The other thing that people have mentioned is a fault on the CAN-Bus, which does not shut it down after one minute or a fault on the alarm, which is drawing too much power.

I find that even a leisurely one hour ride will give the battery quite a good charge.

Grey Beard

 

[(RIP) Tunneruk]

Without wanting to jump in like a vulture ........

I'm just about to put a solar charger up for sale on here. It's bloody ACE.
My MV Agusta would only last about 5 days before going flat, I bought this solar panel and it completely kept it topped up!

My Shed is 200ft away from the house so it was perfect. I'm just about to move to a place with a nice powered garage.

PM me if you'd like to know more.

Cheers, Chris.