In my poking around I found this website on Battery Technology:
http://www.buchmann.ca/faq.asp
After reading this (not the most exiting read) I am starting to wonder if for very infrequent and emergency use most of us would be better off with a radio that uses throw away AA's or Hi Capacity NiMH AA's. Keep in mind that listening to NOAA is such a small current draw compared to Tx that you may have an unexpected failure it you have to Tx for an emergency.
I am sure that I will hardly every use the radio to transmit as I am not a guide and I am wondering if needed in a real emergency 3 5 years from now the battery pack included with the radio would fail. The packs are almost half the cost of a new radio. Spare AA's could be carried and replaced or recharged as needed for much less $$.
Are there any good J-7 radios that run on AA Batteries?
This from Ch 15:
The NiCd battery can be stored unattended for five years and longer. For best results, a NiCd should be fully charged, then discharged to zero volts. If this procedure is impractical, a discharge to 1V/cell is acceptable. A fully charged NiCd that is allowed to self-discharge during storage is subject to crystalline formation (memory).
[In an earlier chapter he explains that the battery looses much of its capacity in only 4 months in this situation]
Most batteries are shipped with a state-of-charge (SoC) of 40 percent. After six months storage or longer, a nickel-based battery needs to be primed before use. A slow charge, followed by one or several discharge/charge cycles, will do. Depending on the duration of storage and temperature, the battery may require two or more cycles to regain full performance. The warmer the storage temperature, the more cycles will be needed.
The Li-ion does not like prolonged storage. Irreversible capacity loss occurs after 6 to 12 months, especially if the battery is stored at full charge and at warm temperatures. It is often necessary to keep a battery fully charged as in the case of emergency response, public safety and defense. Running a laptop (or other portable device) continuously on an external power source with the battery engaged will have the same effect. Figure 15-1 illustrates the recoverable capacity after storage at different charge levels and temperatures.
The combination of a full charge condition and high temperature cannot always be avoided. Such is the case when keeping a spare battery in the car for a mobile phone. The NiMH and Li-ion chemistries are most severely affected by hot storage and operation. Among the Li-ion family, the cobalt has an advantage over the manganese (spinel) in terms of storage at elevated temperatures.
Temperature 40% charge level
(recommended storage charge level) 100% charge level
(typical user charge level)
0°C 98% after 1 year 94% after 1 year
25°C 96% after 1 year 80% after 1 year
40°C 85% after 1 year 65% after 1 year
60°C 75% after 1 year 60% after 3 months
Figure 15-1: Non-recoverable capacity loss on Li-ion batteries after storage.
High charge levels and elevated temperatures hasten the capacity loss. Improvements in chemistry have increased the storage performance of some Li-ion batteries.
From Chapter 8:
Is the Li-ion a better choice? Yes, for many applications. The Li-ion is a low maintenance battery which offers high energy, is lightweight and does not require periodic full discharge. No trickle charge is applied once the battery reaches full charge. The Li-ion battery can stay in most chargers until used. The charging process of a Li-ion is, in many ways, simpler and cleaner than that of nickel-based systems, but requires tighter tolerances. Repeated insertion into the charger or cradle does not affect the battery by inducing overcharge.
On the negative side, the Li-ion gradually loses charge acceptance as part of aging, even if not used. For this reason, Li-ion batteries should not be stored for long periods of time but be rotated like perishable food. The buyer should be aware of the manufacturing date when purchasing a replacement battery.
The Li-ion is most economical for those who use a mobile phone daily. Up to 1000 charge/discharge cycles can be expected if used within the expected service life of about two to three years. Because of the aging effect, the Li-ion does not provide an economical solution for the occasional user. If the Li-ion is the only battery choice and the equipment is seldom used, the battery should be removed from the equipment and stored in a cool place, preferably only partially charged.
Versatility & backup
I bought a Shakespear VHF because it had a NiMH battery pack but also an AA adaptor (5 batteries). I had read several horror stories about VHF battery packs losing power at critical moments that I did not want to have to rely on the NiMH pack 100%. I am always camping when I use my VHF, so being able to use alkaline AA’s as a backup is a bonus. I buy all my flashlights in AA size as well so I have a ready supply.
Jim
My Standard HX350S has a battey
adapter for AA batteries. But why not just turn your radio on once a month and leave it running in the garage so you don’t hear it. After it runs down, recharge it.
I’ve been doing that with my radio for 2 years now and the original NiCad battery works fine - both transmitting and receiving.
I know that I will almost never
Tx and you can’t do that just for battery maintenance. The problem is that while the bat indicator might show a full charge, your battery may only be able to deliver a fraction of its initial capacity.
Draining on receive is a good policy but it shows the battery only a bare fraction of the load at full power TX and will condition it in a way so that it may still fail at some point if called upon to Tx in an emergency need.
I would not choose NIMH for a
mission critical application. no complaints about Li-ion though. Seems to be working fine. When the battery goes I’ll upgrade the unit.
If you really want
to be obsessive about it, 10 bucks at Radio Shack would get you the parts you need to make a battery exerciser to allow full discharge at a controlled rate.
Seems simpler to go for a radio that uses NiMH, but also has the ability to use standard AA, and just keep some AAs with you for emergencies.
just a heads up
on the dbl. batts , if you put em in yer vhf that is submersible it is NOT once you put in the AA . Plus any moisture condensation will corrode the contacts if the AA are left in the unit . My experience w/the AA in a standard have not been acceptable to ME . And the pacs are a &(% to get open.
Thats what I thought too Peter till I
read the info on that site. The problem with Li is that they don’t like to sit idle at full charge and no matter well you treat them they only are good for about 3 years. The advantage of Li is that they carry a very dense charge and can be recharged at any point in the cycle with no ill affect.
Li are easily damaged by shock. I had a cell phone and the battery was nearly worthless after I dropped it onto a wood floor.
The best thing seems to be able to carry spare AA and use AA rechargables, or the Ni pack that ships with the radio and carry the spare AA holder after the first 2 years. That seems to be the best compromise. IMHO I hate the thought of having to buy a new radio every 3-4 years cause the battery craps out. Its an emergency device that I will not often use but want to work when needed.
Jsaults, I hope when you use
your VHF for camping you are in your kayak floating and not sitting on land!