Evil Elvis Posted October 24, 2008 Report Share Posted October 24, 2008 I have a 12v lamp battery for my deben lamp, its a good lamp but Ive been spoilt by using bobs lightforce 170.So I have bought one with no battery. It will fit my deben battery, but I was thinking of getting another one. When they say 12v 3.3ah/20 hour What does it mean? and if i buy a: 12v 7.2ah will it last longer? the better ah the heavier they are, if i bought another 3.3ah and wired them together will it last longer or drain them both simultaneously? maplins hav 7.2ah for 25.99 and screwfix have 7.0ah for £15.99 Are any of the above any good or can someone recommend better ones? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
Evil Elvis Posted October 24, 2008 Author Report Share Posted October 24, 2008 These seem reasonable: batteries but 2 of these would be lighter: batteries Quote Link to comment Share on other sites More sharing options...
JohnGalway Posted October 24, 2008 Report Share Posted October 24, 2008 (edited) Neither of those links work for me. The more amps the longer it'll last. I've used Ama, Yuasa and debens batteries. So long as they're sealed lead acid rechargeables or those gel ones you'll be fine. Can't remember if I was using a 75W or 100W bulb but I would usually get 2 hours good light and 30 minutes going downhill from an 18amp battery running the light continiously. The more amps, the heavier it gets. My 20 amp will last me something over three hours. No idea what those figures they quoted you mean, you're not going to get 20 hours light from any decent lamping bulb. I'm no electrician but if I was to join up two batteries I'd join two of equal amps. Edited October 24, 2008 by JohnGalway Quote Link to comment Share on other sites More sharing options...
Evil Elvis Posted October 24, 2008 Author Report Share Posted October 24, 2008 :yp: tHANKS JOHN, I DID MEAN JOIN UP THE SAME AMPS, IF YOU DID X2 7.2AMPS WOULD THEY LST TWICE AS LONG? Quote Link to comment Share on other sites More sharing options...
JohnGalway Posted October 24, 2008 Report Share Posted October 24, 2008 I'd imagine so, but I'm no expert on it. You're doubling the amps, which is from what I know like putting twice the amount of petrol in your car. Quote Link to comment Share on other sites More sharing options...
markbivvy Posted October 24, 2008 Report Share Posted October 24, 2008 (edited) :yp: tHANKS JOHN, I DID MEAN JOIN UP THE SAME AMPS, IF YOU DID X2 7.2AMPS WOULD THEY LST TWICE AS LONG? yes. I use a 12v/12amp battery and cant flatten it in 1 night with a lightforce 170. Edited October 24, 2008 by markbivvy Quote Link to comment Share on other sites More sharing options...
Evil Elvis Posted October 24, 2008 Author Report Share Posted October 24, 2008 Soooooooo...if I wire 2 7.2 together it will be the equivalent of having a 14.4ah? :yp: Quote Link to comment Share on other sites More sharing options...
markbivvy Posted October 24, 2008 Report Share Posted October 24, 2008 Soooooooo...if I wire 2 7.2 together it will be the equivalent of having a 14.4ah? :yp: yes. Quote Link to comment Share on other sites More sharing options...
Evil Elvis Posted October 24, 2008 Author Report Share Posted October 24, 2008 Thank you!!! :yp: Quote Link to comment Share on other sites More sharing options...
markbivvy Posted October 24, 2008 Report Share Posted October 24, 2008 Thank you!!! :yp: just remember to keep ammo and battery's separate. Quote Link to comment Share on other sites More sharing options...
Evil Elvis Posted October 24, 2008 Author Report Share Posted October 24, 2008 :yp: I do what can happen then? Ive dropped rimmie ammo into my battery pack before.................. Quote Link to comment Share on other sites More sharing options...
JohnGalway Posted October 24, 2008 Report Share Posted October 24, 2008 just remember to keep ammo and battery's separate. :yp: Do I remember a thread from many moons ago that involved a very narrow escape in those circumstances? Quote Link to comment Share on other sites More sharing options...
HW682 Posted October 24, 2008 Report Share Posted October 24, 2008 (edited) Evil, I am not an expert on batteries, but as an electrical/electronic engineer I know the basics. So here goes... a 12V 3.3ah battery. First bit is easy, it means it is a 12V battery. second bit is the capacity in amphours or amps x hours. So for example a 3.3ah battery should give out 3.3 amps for 1 hour. Or 6.6 amps for 1/2 hour, or 1.65amps for 2 hours. Now take Johns 100W lamp. 100W is the power which is volts x amps. So a 100W lamp will draw a current of approx 100 divided by 12 = 8.3 amps. So in two hours it will have consumed approx 16.6 amphours. This will more or less flatten a 18ah battery but with a bit left. If you connect two 3.3ah in parallel (ie + to + and - to -) you will in theory get a 12v battery with 6.6ah capacity. If you connect them in series (ie + of one to - of other) you will get a 24V battery with 3.3ah capacity. I would be tempted not connect two in parallel because unless they are very close in performance (ie same brand, same age, same state of charge etc) you will get reduced performance. Remember that 12v is only the nominal output voltage. When just charged they might be nearer 13V. If you connect a healthy 13V battery to a sick 11V battery, then the good battery is going to waste some of its performance by trying to charge up the bad one. Personally I would use one larger battery. For what its worth Yuasa is a well known quality battery. In fact, just having a quick look through the Deben catalogue no 8 (da2590) is listed as 18ah but the picture looks like a yuasa 17ah with the yuasa logo missing. see link to datasheet http://docs-europe.electrocomponents.com/w...66b80c1b2e7.pdf Hope this helps. HW682 Edited October 24, 2008 by HW682 Quote Link to comment Share on other sites More sharing options...
JohnGalway Posted October 24, 2008 Report Share Posted October 24, 2008 Very interesting reading there HW :yp: Quote Link to comment Share on other sites More sharing options...
Evil Elvis Posted October 24, 2008 Author Report Share Posted October 24, 2008 :yp: Despite copious quantities of etoh Im with you...thanks!! Quote Link to comment Share on other sites More sharing options...
HW682 Posted October 25, 2008 Report Share Posted October 25, 2008 Glad to be able to help and put a bit back into the forum. HW682 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.