I hate that plural. The purist lurking in me suggests Lithia, but the chemist says that lithia would be an oxide
Anyway: while visiting a UK Toys R Us I notice that another manufacturer is making disposable lithium batteries (same type and chemistry as the Energiser Lithium) and selling them for about GBP5 for four cells.
AAA and AA are the same price, and they also had the larger C, D cells and a PP3 shape
Sorry - I have forgotten the manufacturers name - might have been Kodak or Hitachi.
This will hopefully pull the general price level of Lithiums down - they are a good bet for Footys and the ONLY choice for cameras using AAs
andrew
I was at our pond this last Saturday and talked to a couple of fellows testing some fast electrics. I discussed Li-Po rechargeables with them, and was shown one ‘battery pack’ (several cells in a sealed package), which cost CAN $250.00 each!- and was capable of 60 Amp draw current, for about 4 minutes. The guy suggested using the Lithiums from Energizer, (which are not rechargeable), but (he claimed) would last a whole season in your transmitter, and probably the same length of time as boat batteries in a Soling.
He emphasized most strongly that Li-Po rechargeables required a LiPo charger, and that he charged only on a concrete slab or in a metal tub, in case of fire.
I would be most reluctant to go into ‘charging’ for Footys, and Lithium Energizers in the boat have the problem that you wont know when your batteries are going to die, unless you keep a record of hours of use, as I understand they give little warning of their impending exhaustion.
If someone has extensive experience with Li in-hull batteries over a season, I would like to have his/her opinion of all this.
We missed an opportunity - I have just passed through Ont. on business and managed to meet some footy notables. Next Time?
The throwaway lithiums are excellent.
it is possible to detect their state of charge (capacity left) by measuring the voltage (under load if one is being a purist) and estimating how much energy is left. (I have never heard of anyone doing this, for any type of throwaway battery)
The energiser Lithiums lasted Firstfooty for a racing season - I believe that he, like me, soldered them up into a fit and forget pack.
I had a seasons use in Razor from mine.
They would indeed be ideal in a Tx. I get a year’s use out of ordinary alkaline cells in my Txs (watching the voltmeter sensibly)
Lipos are quite different kettle of fish, and perfectly usable in a footy.
I believe it should be possible to race on one cell (1S) as that is over 4V when full. I just feed my 27 receiver with 2S (8V) and it still has the full complement of smoke (it has a BEC)
As your racers said it is ESSENTIAL to use a Lithium charger and quite a sensible precaution to charge in full view on a safe surface.
HOWEVER - you don’t, and I don’t (when charging our cellphones/computers/bluetooth headsets/home drills/screwdrivers)
No need to be worried about them or any other lithium chemistry they need no more care or understanding than Ni batteries or Lead ones
Here is a pack I have just wired up - total weight 22.5gms, capacity 500mAh: LiIon single cell, switch jack and lead to receiver.
It replaced a 4 x AAA NiMh of 900mAh capacity weighing 57gms,
Which in turn replaced a 4 x 500 mAh NiCad at 113gms…
The LiIon pack cost me less than $5 new surplus. It charges with a standard phone charger in a couple of hours, and at 100mAh average consumption (good practice on the sail servo to avoid stalling - maximum movement lanyard etc.) will allow 4- 5 hrs sailing. It’s condition can be monitored through the switch jack with a simple multimeter, but in practice will be charged before each outing and will maintain it’s charge with little loss over time. It drives my servos and receiver well on the test bench, good range and torque.
I will not be charging it in a fire proof container or worrying about it any more than I do my cell phone. If it gets wet and shorts out, it’s still only a few bucks for another from the surplus or cell phone store.
I made the change because of cost more than anything but it now means I can put a 10 ounce bulb on the keel that was designed for 8. Now I know I can loose another 2 ounces by getting a more modern sail servo to replace my standard 40 gm one, and a small 5gm fm or $15 2.4Ghz receiver, but that will cost and, like most Footys, this boat was designed for a 450gm displacement.
How many are sailing new-generation boats optimized for radio setups now cheaply possible of less than 40 gms?
What is the amount of warning that you would get about the imminent exhaustion of a Lithium Energizer cell while in use as the in-hull battery of a Footy–or in a Soling 1M?
My understanding has been that most people moved to Ni-Cds and then to NiMHs because they could be recharged prior to each trip to the pond, and so avoid the embarrassment of dead batteries while the boat is far out on the water.
My transmitter has a voltmeter, which I can see at the pond, but my in-hull batteries are assessed only by the voltage decrease, (after 14 hrs charging) seen on the meter of my charger back home. I have noticed, with my Soling, after 3-4 hours of sailing in heavier winds, that I cannot steer while sheeting in the sails–I assume this is some function of the BEC with which the receiver is equipped.
I note also that my transmitter for my Soling runs on 8 x 1300mAhr cells, but they show a noticeable voltage drop after 4 hours of sailing. Would Lithium Energizers be capable of a whole season’s use under the same conditions?
I’ve been mentioned in dispatches by “The Addict” - so I must comment.
I ran a set of Energiser AA Lithiums in Mistralette last year and got 25 hours running out of them.
I have since reverted to rechargable AAAs because what I didn’t like about the Lithiums was the way that they gave up the ghost very very quickly at the end of their life. For the majority of their life the measured residual voltage was pretty constant with only something like 0.1V fall after a 4 hour sailing session.
After starting out at about 6.9V measured when new I set out one day measuring 6.5V and within 2 hours they died completely and measured 3.4V while still in the boat.
In hindsight this is quite reasonable since they are quoted as having a 3000mAh capacity which at 120 mA usage rate is just 25 hours.
Perhaps if I had done the job properly and measured voltages on load I would have had a more accurate measure of residual capacity, but I’m not that rigorous. So I now run the 800mAh AAA Ni-Mh rechargables and just charge them before each day’s sailing.
I don’t think 2 cell 7.4V Li-Pos are worth the hassle since their weight and capacities are not much different to the AAA Ni-Mhs and Footys just don’t need their discharge capabilities.
(when charging our cellphones/computers/bluetooth headsets/home drills/screwdrivers)