Batteries

[The Robman]

I don't think it's a good idea to ever leave a remote plugged into a JP1 cable for any length of time. I know that the old parallel cable would run down the batteries really fast if you leave it plugged in, so I'm guessing that the flash cables might do the same.

[Tommy Tyler]

Vicky,

(1) Was everything plugged in (remote to Adapter to Interface to PC) when it popped?
(2) Had everything been plugged in for a long time?
(3) How long?
(4) Was it a 2-cell (3V) or 4-cell (6V) remote ?

Tommy

[vickyg2003]

Vicky,

(1) Was everything plugged in (remote to Adapter to Interface to PC) when it popped?

yes

(2) Had everything been plugged in for a long time?

yes

(3) How long?

probably a couple of hours sitting idle maybe longer

(4) Was it a 2-cell (3V) or 4-cell (6V) remote ?

JP1.3 Atlas 3033 2 AA batteries, I think that means 2-cell 3v.

I'm trying to remember to unplug this now. I didn't realize this was drawing power.

[Thomas]

Umm, batteries - Duracell had a period when they were trying to upgrade the power and longevity. I bought a couple 8-packs of AA size a mistake, as after a while they started leaking inside some expensive equipment. Power level was OK even while they leaked.

One other possibility, the 3V remote might have been sinking power from the 5V USB supply, enough to 'cook' the batteries until they exploded. And if the computer is off, there might be some trickle current through the adapter which would drain the batteries. Dunno, though, I have not examined the inner workings of the USB adapters.

Definitely recommended to disconnect devices when not in use!

[Tommy Tyler]

Earlier this year dolivas27 told me he had experienced a couple of battery rupture incidents when using the JP1 EEPROM Adapter for extended periods of time. I was unable to pinpoint any cause at that time. After Vicky's report I decided to do more careful tests. As Tom Carlson surmised, a 3-volt remote can draw a small amount of current from the PC's 5-volt source for USB devices. Here are some numbers, based on tests of URC-6012 (2-cell) and URC-7800 (4-cell) remotes:

In a URC-7800 the batteries discharge at about 15 uA when asleep and not connected to anything. Plugging in an Adapter increases this to 1.4 mA, and plugging in both an Adapter and interface increases it to 1.6 mA. Connecting everything to a PC does not change the measured battery current, and the batteries are always discharging, never charging.

In a URC-6012 the batteries discharge at about 5 uA when asleep and not connected to anything. Plugging in an Adapter, with or without an interface connected, increases this to 0.6 mA. But connecting everything to a PC causes reversal of current, and the batteries are charged at 0.65 mA while idle.

This is an extremely small charging current, and I am surprised that it would cook a battery. There are some published articles boasting success at recharging alkaline batteries by applying 100 mA or more overnight. Nevertheless, recharging alkaline batteries is generally frowned upon by manufacturers, and there's often a warning marked on the battery that says recharging may cause leakage or explosion. As both Rob and Tom point out, it's probably not a good idea to leave interfaces connected to remotes for extended periods of idle time, especially 2-cell remotes. If anyone has a particular need for leaving their interface plugged in for long periods of time, I will be glad to offer suggestions.

Tommy

[vickyg2003]

Nevertheless, recharging alkaline batteries is generally frowned upon by manufacturers, and there's often a warning marked on the battery that says recharging may cause leakage or explosion. As both Rob and Tom point out, it's probably not a good idea to leave interfaces connected to remotes for extended periods of idle time, especially 2-cell remotes. If anyone has a particular need for leaving their interface plugged in for long periods of time, I will be glad to offer suggestions.

I don't suppose absent-mindedness constitutes a "NEED". If I get used to disconnecting the equipment, I'll be in a better position, when I move to the laptop that won't unhibernate if I forget to disconnect my equipment.

[eferz]

I don't suppose absent-mindedness constitutes a "NEED". If I get used to disconnecting the equipment, I'll be in a better position, when I move to the laptop that won't unhibernate if I forget to disconnect my equipment.

You could always switch to rechargeable batteries.

[underquark]

You could always switch to rechargeable batteries.

Yes, but don't leave the remote plugged in to the USB indefinitely as a reverse current applied to a depleted rechargeable battery can kill it.

[Tommy Tyler]

I don't understand your point. If there's a reverse current the battery won't be depleted. It will be kept topped off by the trickle charge. Also, if a rechargeable battery becomes fully depleted, how will you ever be able to use it again without recharging it with a "reverse current"? The JP1.2/3 Interface with EEPROM Programming Adapter is not a very good battery charger because at such low current it would take forever to do the job. I'm not even sure the current level is greater than the internal self-discharge current of a rechargeable battery. But it might keep it fully charged if left plugged in indefinitely. Any battery experts among us?

[underquark]

I'm sorry, I didn't read your figures correctly. It seems that it's the plugging in of the adapter that has the greatest effect and not the plugging it into the USB. What I meant was that if pluggin in the adapter causes the batteries to discharge at a faster rate then there is a risk of one rechargeable being weaker than the others, reaching zero charge and possibly having its polarity reversed and this risk is possibly greater in a four-cell remote than in a two-cell one. I haven't actually seen it in any of my remotes but then I never leave them plugged in. I have seen it in the kids' toys but they tend to leave them switched on a lot and also shove in any old batteries. I know that some photographers keep their rechargeables in matched sets of batteries which are all recharged and used as a group to keep them as near the same charge as possible.

[zaphod7501]

Not specifically an expert but after almost 40 years in the repair business, I have seen recommendations from electronic manufacturers. I'll just throw out a bunch as I remember them. Some of these may have changed as batteries have progressed. Some of these are just interesting. Some could be considered opinion, based on observations.

Ni-Cads are never supposed to be trickle charged, it will slowly reduce their capacity. They are supposed to be charged at their output rating. A 1 amp-hour battery should be charged at a 1 amp rate. A rapid rise in temperature indicates full charge. There are probably some newer batteries specifically designed for higher or lower rates but this was the Sony statement on the Ni-Cads used in their camcorders.

A Ni-Cad can reverse polarity if a load is presented when it is discharged. A Ni-Cad cell is considered discharged when it's voltage drops to 1.0 volts. You never discharge it below 1.0 volts or it may short or reverse polarity. It may be recovered by zapping it with a charged, huge value capacitor.

A Ni-Cad will measure it's nominal voltage (1.25 volts) until it is almost fully discharged and then will drop rapidly. You cannot, therefore, determine an intermediate charge state with a voltmeter.

A Ni-Cad needs to be "Exercised" on a monthly basis. Exercising meaning discharging it to 1.0 volts, then recharging. It can last indefinitely if this is followed religiously. That's why those remote space satellites often outlast their expected lifespans - computer controlled battery exercise and disconnection of failed cells.

The use of battery packs obviously makes it difficult to observe voltage and current limits - which apply to individual cells not packs. A pack needs to be built from matched cells or it will fail early.

[CBMC]

I am definitely not a battery expert, but can tell you that .65 ma is probably not enough to keep a normal nimh battery topped off. A normal nimh discharges at about .5-1% per day. Now with a low discharge battery it might be able to keep a battery topped off, they hold about 80% after 1 year of storage. All that being said, I would not recommend the jp1 interface to charge or even trickle charge batteries, even though I am not sure how much damage .65 ma charge would do, since it is so low I highly doubt it would fry a battery, unless of course the battery was already compromised. Personally, I have the Maha C9000 Wizard One charger and really like it. It charges, discharges, analyzes, and breaks in batteries. Anything you want (and don't want) to know about batteries can be found over at the candlepower forums.

[underquark]

So, bottom line is that you shouldn't leave your remotes connected?

[vickyg2003]

So, bottom line is that you shouldn't leave your remotes connected?

That's my take on it. If I hadn't just moved my microphone right next to the battery and heard that POP, SSHHhhhhhhhh I'd still be leaving my remote in all the time. Remembering to unplug and plug is such a nuisance.

[eferz]

Now that this thread has been going for a few days. I'm starting to wonder if we're all just trying to put a Band-aid on the symptom. It seems to be the JP1 cable is either drawing power from or trickling power into the remote's battery when its not being used. Wouldn't it be better to attack the root cause of the problem?

I noticed that the JP1 USB cable uses FTDI virtual com drivers. So, I looked up their release notes and saw that they fixed unspecified power management issues on several different revisions. I wonder how difficult would it be to ask them to implement the option to shutoff the device if its not actively used for a specified amount of time, or to allow the operating system to do it.

If not, isn't it possible to use the other USB drivers and Power Options to shut it down automagically?


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