MobilePro 790 random battery bug

Huh, this is my first problem in a while now... Anyway, I keep noticing a peculiar problem with my MobilePro 790, specifically the battery indicator. Now, I usually get about 3 hours of solid use out of it from a full charge. I can usually keep it in my backpack for a week and use it lightly and it almost never runs out of juice. However, at least three times, I have gotten a fake battery warning. After using it for a bit, starting out with like 80% battery, I suddenly get a "Your main batteries are running very low" message and see that I have 20% remaining. I just think, darn that was fast, and put it away before it switches to the backup battery. But then I open it up later to check something like my schedule really quick and see that I in fact have at least 50% battery left and the messages are gone. These fake warning messages are really annoying, and because I don't ever want it to run out of juice, I just stop using my MP790 immediately. These need to stop so that I can continue my use of it unhindered. One time, I was in the car and typing an essay when this happened, so I had to do the rest when I got home and realized I had plenty of power. Is there any explanation for this, and if so, a way to fix it? Could it be that if you drain a bunch of power at once, it thinks there is none left? It just happened again today when I wanted to show my friend something, but I couldn't because my battery was "low".

EDIT: Woops, wrong forum, gotta get it moved now.

Edited by MobilePro Master 2011-03-25 8:55 PM

Might be your battery is beginning to fail....do you have another to try out in its place?

No, I don't have a spare. If it's failing, then I'm just going to run it into the ground and buy a new battery. It seems like it could be a software problem also, or maybe the sensor, because the battery does seem to have a charge but it's not being read properly. Has this ever happened to anyone before?

When batteries discharge, you've probably noticed that after they sit a while, they seem to come back to life. This is due to something they call "battery recovery effect" which essentially says that with intermittent battery discharge versus continuous battery drain, the darn things seem to come back to life.

I suspect that your battery is draining, giving you the error, then when you let it sit, it recovers to a higher state, only to repeat the process.

And it might possibly be what you said as well, something is causing an initial heavy drain to the point that the battery level software is temporarily fooled into thinking the battery is going empty....but I doubt it. I still believe your battery is simply going bad.

And you can use it till it drops...and when it does and you suddenly find yourself with a hard-reset 790, you are going to say, "Damn, wish I had went ahead and purchased another battery before now...espeically since they are so cheap!"

That's definitely a possibility. The confusing thing was that the last time it happened, I only waited about 2 minutes before I looked at it again and realized it was fine. Would that recovery effect only take 2 minutes? (20%-60%) I have noticed the effect with other devices before, but never of this degree. It wouldn't be too much of a problem if my battery went dead on me for a few reasons. I wouldn't literally run it into the ground; When I see that the battery only lasts for 10 minutes, I would buy a new one. If it spontaneously dies, the backup battery still works and so does my AC adapter (unless the current has to go through the battery like on some devices). I also back up important files to my CF card, so a hard reset would basically just do away with any personalization I had done. I haven't got that much software installed, and a hard reset would actually set me back to a clean registry. Yeah, I would probably be upset at first, but I don't think the batteries will be off the market when and if mine dies. But what the hey, I need to buy a Palm battery right now and maybe I'll just go on a battery spree!

Well, you could buy one of those AA battery adapters for the Mobilepros from Alancomputech.com and then see if the problem disappears while using AA cells. That would positively diagnose or confirm that the existing battery was the culprit.

I can't believe they still have 83 in stock. It's like they're still producing them. If I really need to figure out what's happening, I guess that would be the best choice. However, I'm running low on personal spending cash and my dad might not agree with me getting one just to test. Maybe I could use my multimeter to test the battery after I get one of those messages to see if it really is low or not. I just need to know which of the five prongs are positive and negative. I've had no success with this in the past though. I polled every combination of prongs on the LG Phenom battery after charging it with the motherboard and couldn't find the positive and negative. Any ideas?

You really can't test a battery with a multimeter. First of all, batteries need to be tested under load. Next, measuring voltage isn't an indication of current supply. Lastly, with the Mobilepro, there are current drains that have nothing to do with the operation of the unit...for instance, the rechargable internal lithium ion backup battery charges off the main battery, so it is a constant drain...albeit a minor one. Also, are you running the MC-BA9 (MP 770/780 battery) or are you actually using the MC-BA14 made for the 790? They have different capacities as well.

Someday, all the existing Mobilepro batteries will be gone...forever...and then the only thing that will work will be using the AA battery pack with rechargable batteries....to me it is a worthwhile investment...especially if you take your Mobilepro with you on vacation and don't want to sit around leaving it plugged in to recharge.

So, measuring milliamps wouldn't help either? I bought my MobilePro used, so I'm not completely sure which pack is in it (although I assume it's the original) as I've never removed it, but I'll check when I get home. And for $9, I probably will just end up buying the AA pack, but not today. How does the battery life compare to the MC-BA14 using 4x1.2v Ni-MH AAs.

Edited by MobilePro Master 2011-03-27 1:48 PM

If you use rechargable lithium ion AA batteries inside the battery pack, it is pretty decent. If you use regular AA bunny batteries, not as good...and you will go broke replacing them. But the battery pack is bulkier than a normal lion battery too since it takes 4 AA cells. I see on eBay where you can buy a MCBA14 battery for about $15 delivered....also guaranteed for 30 days...seems like a good deal to me.

Yeah, I could tell that it was bigger in the picture. There's no immediate reason to buy a battery right now though as mine still seems to hold a charge, it just lies to me about it. Did these batteries ever last for ten hours though? That's what I read, but it seems more than possible, even if you are just typing a document. If buying a new battery would get me ten hours of use, I'd do it right now. But in cash money, I only have about $60, which I would like to keep as a minimum. There were times when I would be packin $300 in my wallet, but I've been buying a lot of crap, and my primary source of income, my great grandmother, hasn't seen me in a while because of her health. I hope she gets better, but that might be unrealistic because she is losing her memory.

Oh, and I thought getting another T706 would be too painful for you... Apparently not.

No...I'm tough when it comes to pain...yeah...right...I cry at night like a baby.

Whoever was selling that last Tinybook on eBay had reposted it, so I bid $75 bucks and got it for $70.99. Lucky me. I just sold my 10.2" Wabook on eBay, well it at least has a bid of $90, so I guess I'm just trading one toy for another again...but we'll see, maybe I'll get more than $90 for it. Hardware-wise, the T706 is the finest built of any 7" CE netbook I've ever seen...it really was a quality product. The fact that it Activesyncs like a normal HPC says something of the software/hardware build as well.

I looked at the battery. It is a MC-BA14. Is the MC-BA14 the highest capacity of the 7xx batteries?

I would love to get a newer CE device like an MP900(C), Sigmarion III, Intermec 6651, Jornada 720/728, or high quality netbook, but I can't afford it and don't necessarily need it. This is another reason for my oath to only buy legacy devices under 200 MHz.

Rich, I am very happy for you! Just remember to put it under the seat the next time you leave it in the car...