Guest Posted September 29, 2008 Share Posted September 29, 2008 hello i used a 18 v battery off a drill which worked very well for my motor but i think i have over charged it so am wantin to make a new one and i am wondering about laptop battery? would anyone have any ideas? Quote Link to comment Share on other sites More sharing options...
Phil_P Posted September 29, 2008 Share Posted September 29, 2008 Laptop battery's would be great BUT and it's a big one, they are VERY sensitive to poor charging technique. They are lithium based (Lithium Ion usually) and will burn to the point of exploding if mishandled. In a laptop, the charging circuit usually includes a sophisticated charging circuit with current and thermal cut-outs. If you are running 'total loss' electrics, ie not using inflight charging, it's not such an issue, as you can charge carefully on the ground. I am about to use a pair of radio control Lithium polymer batteries (2 x 7.4 v wired in series) for my avionics. These are again sensitive to charging, but good suitable chargers are easy to come by in the R/C model world. Many of these batteries are rated for a discharge of 30 times their rated capacity, so for example, a 7.4v 3000mAh battery can be discharged at 90 amps continuously till flat. This rating is given as a 'C' value if you purchase such packs. Loads to be found on a well known auction site direct from HK, or for twice the price from your local model shop (even WITH postal charges). Despite having a suitable charger, I will charge outdoors, underneath a metal bucket. Worst case scenario for a lithium battery would be an inflight short circuit! If you would consider Lead acid technology, the Hawker Odyssey absorbed glass mat are some of the best you can buy, You can mount them any way up except fully inverted and can recharge them VERY fast. For example, you could recharge a 10 Ah battery in half an hour with a suitable charger. In fact they thrive on hard charging. They also tolerate cold conditions and deep discharge very well. Quote Link to comment Share on other sites More sharing options...
Farmer_Dave Posted September 30, 2008 Share Posted September 30, 2008 Lee I do have a spare Flat-Top Li-Ion 16-8 volt battery. You would need a smart charger, as Phil explained, and NOT charge inflight. I fly alot and tend to remember to charge it fortnightly. It turns the Simonini 200 engine really fast, so your fingers not on the button long. Theory is that more volts saves your starter motor from overheating and therefor burning brushes. Starter failure isn't completely unknown on the Flat-Top though. Just less frequent. Checked the spare recently. It was 16-8 volts in early June, it's 16-7 volts now. pretty good charge retention. Dave Quote Link to comment Share on other sites More sharing options...
Guest Posted September 30, 2008 Share Posted September 30, 2008 yes il have it off you if you are selling it i dont have the inflight charger so thats a good thing for these i guess i did make up a battery off a drill but also made a charger which i think boiled it so it aint got a lot of kick now , but yes if your parting with it i will have it Quote Link to comment Share on other sites More sharing options...
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