battery

[philcasino1973]

hello,, asking for a bit of advice
am doing a restoration on a li125 special and want to fit a pair of pathfinder lights ...what battery do i need ..its a non battery frame with a 12litre long range tank going in
any info advice will be very helpful as i have no experience on the spotlight conversion
willbe running 12v ac but with bgm reg that has a dc output

regards
phil

[Muppet]

me thinks your goin to have t think about this a little more than you have; bgm dc=20 watts ish pathfinders=100 watts ish orthereabouts and small batteries hold little charge

[Chris in Margate]

2 x55 watt spots will draw just under 10 amps.
On a 12 Volt 5 ampere battery theoretically you could run them both for 30 mins. However that is in a perfect no loss circuit so you should expect less. Keeping the battery trickle charged whilst running will help but you won't get much charge if headlamp is drawing the power.
The simple caculation is battery capacity divided by current draw.
3 ampere battery about 18 mins.
4 ampere battery about 24 mins.
5 ampere battery about 30 mins and so on.

Problem is siting the battery as above 4 amperes they start to get big and then you've got to find somewhere within the limited space of your Lambretta.

It goes without saying: good cabling; switches and of course a fused circuit.

[holty]

what type of bulbs are in your spotlamps, it may be possible to convert them to leds which will consume a lot less amps
and will not drain the battery flat. they are used a lot on boats to save power, other option would be bigger battery, or two batteries, i fitted my battery in one of the oil bottle carriers for sale on ebay, might be an option.
holty

[philcasino1973]

thanks for the replies lads ...was thinking of putting battery in a oil carrier as you have said
are they wet or sealed batteries? who sells them and lastly will the bgm reg trickle charge it with the dc output?
sorry for the questions just on a learning curve with this!!!!!!!!!!!!!!!!!
regards
phil

[Nerdy Norm]

Have a look on this chart and get the biggest one you can fit in the oil carrier. You'll probably be able to fit an NP7-12 (7 amp) battery in there, perhaps even a bigger one:
http://www.yuasabatteries.com/pdfs/NP_4 ... ctList.pdf

They are sealed batteries, designed for burglar alarm systems. They can be fitted at any angle, and have regular spade connector terminals. The 12V DC output from your regulator will charge the battery (but not as fast as the spotlights will drain it, as has already been pointed out).

Check Ebay for prices, the 7 amp battery is around £13.

[GeorgeS]

Screwfix sell something very similar, i've got one in my vespa smallframe side bubble which powers the sip speedo. I think it was about 12 quid plus a fiver for an inline fuse holder from Halfords. Charged from a vedspatronic and all good do far.