Ni-Cd Batteries

[surekandoo]

I'd like advice on the best way to store Ni-Cd batteries (handheld VHF etc) in the off season. When not in use is it best to store them charged, discharged, or doesn't it matter.

I know they gradually deteriorate with use (constant charge/discharge cycles) and I understand the "memory effect" common with this type of cell.

I want to maximise the life because I've just paid over £40.00 to replace the battery pack in my Icom M10 Euro.

All advice appreciated

 

[VicS]

They should not be left uncharged. As they probably don't hold their charge for very long they must be routinely dicharged ( to avoid the memory effect) and then recharged. Next time perhaps you can replace them with nickel metal hydrides. You may have to make up a battery pack youself by buying cells from Maplins, but it will be well worth the effort.

 

[alanporter]

The handbook to my handheld VHF with Ni-Cad battery says that the battery loses one percent of it's charge each day, and that it should be completely discharged before re-charging. So, if you charge it fully this week, leave it unused, and you won't need to charge it again until the end of January next year. At that time check that it is fully discharged by leaving it switched on for a day or so.

Alan Porter

 

[jfkal]

NiMH memorize as well. Only Li-Ion don't.

 

[AlanPound]

Many GPS units (and possibly hand-held radios too) have 'electronic' on/off switches, rather than real mechanical power switches. When 'off', the kit is really in some sort of hibernation state, but the electronics is really still drawing a current, however small. The trick is, when you are not using the kit for more than a few days *take the batteries out*...

In the case of Duracell dry batteries in my stand-by hand-held Garmin GPS (I keep several sets to hand in case of run-out), this makes the difference between the batteries holding their charge for years, and going from new to dead in about 3 months. (This will apply to NiCads too, although they *also* have a non-trivial self-discharge rate, and the total capacity size-for-size will be rather less for a NiCad than for a drycell).

Alan

 

[pandroid]

Nicads tend to self discharge fairly quickly (a month or so). The best bet is to give them a boost every month or so when out of commission, but I've not known any to be seriously harmed by leaving them discharged for a few months.

I had problems recently with an ICOM M1V-Euro self discharging. When I bought the unit it took about 3 months of non-use to self-discharge, (which surprised me anyway 'cos L-ion dont generally self-discharge at all). Recently the set seems to self-discharge in a week! I took the battery out of the unit and guess what? Self discharge back to normal (and, no, I didnt leave the set switched on....)

 

[rogerm]

When talking about a 'fully discharged' battery we are talking about a state prior to a full charge to prevent the memory effect. A fully discharged NiCd battery is down to 1v/cell (similar to a lead acid battery is 'fully discharged' at 1.8v/cell).

If you allow a NiCd to discharge to 0v you are likely to find that it develops an internal short which is difficullt to shift.

The best way to condition a NiCd that is to be left unused for several months is either 1/ keep the battery on trickle charge. A trickle charge is about 1/100 of the cell's rating ie a D cell might be rated at 1A so a trickle charge would be 10ma.

Or 2/ put the battery in the normal charger once/month.
In either case when you want to put it back into service fully discharge it (to 1v/cell) to clear any memory effect and then re-charge it again.
Roger

 

[Guest]

Metal Hybrides do not suffer memory .... but fail totally on shorter life ....
Lions are best .... but pricey !

I only came - cos they said there was FREE Guinness !

 

[Guest]

It is actually possible to buy a Battery cycler from a Model shop .... they have been with Nicads for years ---- flying very expensive model airplanes around by radio ....

You can get a set that you connect between charger and radio pack and it discharges the pack to safe level - NOT full discharge as that shorts it out, and then trickle charges it back up .... repeating until you disconnect. The LED's show the state of battery so that you discon at right time.

I only came - cos they said there was FREE Guinness !

 

[rbishop]

You may want to consider purchasing a device that automatically charges and discharges the batteries over time. It is my understanding that this is the best way to keep these types of batteries conditioned. May have to check out a distributor like Graybar or Grainger.

Rog

 

[Sandy.]

Nicads can be safely left to discharge in your VHF all through the winter without any ill effect. Forget memory effect, it's not an issue, unless you recharge your batteries when they do not need it, on a regular basis. NMH batteries do Not suffer from memory effect, but then again you said that you have a nicad battery.

Only lead acid batteries will suffer from being left in a discharged state. When left discharged for long periods they can sulphate and become almost impossible to recharge. This includes your starter and auxilliary battery and any sealed lead acid batteries that you may have. These batteries should be recharged every 2- 3 months to keep them in prime condition.

Good luck
Sandy

 

[chas]

One consideration when deciding to leave kit with batteries in or not is the presence of a separate memory battery which draws its charge form the power batteries.. If I leave my GPS 48 without batteries for any length of time, I get a memory battery low warning - I always store it with a fully charged set of batteries.

 

[surekandoo]

Thanks everyone