Instructions for first battery charge

[busted5mx]

Hello, I have replaced the batteries myself in a diamond mako that had non-recoverable battery problems. I bought it second hand and it did not come with manuals. It is eagerly awaiting it's first charge, but I read this in the very helpful Revo battery page at http://www.millican.info/Home/RevoBats.htm

"The first time the Revo is charged from new, or after a hard reset, the charge controller senses a chemical change in the cells. It does this by detecting a sudden thermal change in the pack which occurs at 89% of actual (84% of the indicated) capacity. This is a feature of NiMH cells. We'll call this the charge calibration point. It is absolutely crucial that you follow the Psion guidelines for the first charge so that the controller can detect this accurately."

I also read in the Revo Plus manual that I downloaded from Psion: "Note: Read the Quick Start guide FIRST, for important instructions on setting up your Revo and charging the battery."

Since the importance of proper first time charging has been thus established, can someone tell me what the official Quickstart Guide says about the first charge?

[MikeMcC]

From the Revo manual:

"We recommend that you fully charge the battery (for about 6 hours) when you first use your Revo. This is required to ensure that future battery readings are accurate."

[brianh]

Hello,

Congrats on changing the batteries. Was it difficult? Could you please post the details.

Anyway, to make sure that the charging of your device goes as planned each time, the first time you charge it may take longer than 6 hours. NiMH batteries must be conditioned (charged a long time) the first time they are used. The battery will be complete charged when the animated battery icon in the toolbar appears to "fill up" or stop moving. This can take over 6 hours the first time.

Second, follow this charge routine - allow the battery charge to go down to ~10%. Then charge with the adaptor plugged directly into the machine (not through the cradle). Keep the machine on and watch for the battery icon to stop moving (~6 - 6 1/2 hours after first starting the charge process).

Do not just charge for small bits at a time or try to keep the battery "topped up". This will cause you nothing but grief and trouble. Believe my, my cell phone has a NiMH, and when I do this it messes up the run time of the battery.

Hope this helps and keep us posted.

[busted5mx]

Thanks for the replies. I am at this moment unsure what to do- I have been charging for about 3 hours, and the battery level already reads 100%. Is it more important to leave it charging for a full 6 hours, or is it more important not to risk overcharging? It's been at 100% for about 15 minutes now, and battery icon indicates that it is still charging.

I disassembled the batteries according to Ruey Loons excellent instructions: http://www.portal-pda.com/guides/revobatt/revobatt.html

However, I have never soldered anything before so after ruining one pair of replacement batteries, I took two very small spring coils, cut them to size and inserted the leads from the former battery pack into the coils. Then I tucked the springs at either end of the battery area. I then stuck the batteries in, and taped the thermal sensor to the batteries. I am using regular off-the-shelf Energizer AAA rechargeables.

[MikeMcC]

After the initial fast charge with both red and green lights on, it goes on to a trickle charge with only the green light. This should be allowed to continue for the full 6 hours at least.

Note: You do this entirely at your own risk. The Revo batteries are not user replaceable as it is important that the charging circuitry is recalibrated for the new batteries. Psion have warned that incorrect calibration can lead to battery leakage or possible explosion.

[busted5mx]

Thanks for the warning, I hadn't read anything like that in various places where people have posted do-it-yourself battery replacement stories. I thought it was a fun lark (the mako was only $50 on ebay so if it doesn't work I won't cry) but I'll be sure and wear safety goggles while using it from now on ;) It never occured to me that the charging unit would be so fickle. Should I assume the batteries would get real hot before anything bad happens?

[MikeMcC]

Should I assume the batteries would get real hot before anything bad happens? Possibly :)

I am really just repeating the warning given many times in the newsgroups by a senior member of Psion Tech Support. He participated in the discussions in a personal capacity, not as a Psion official, and I believe it was a sincere piece of advice.

[brianh]

That's the problem that many people have. They are fooled by the battery meter. The battery level is close to 100% but must be charged via a trickle charge.

Is the charge level (mA) ~30 mA for trickle charge or is it ~400mA for fast charge?

If it is trickle charging (you can tell the mA of the battery while charging by pressing SHIFT+CTRL+P from the file view of System of by tapping on the battery icon in Today view. The second tab of the dialog has the readings on mA.

If if is low (~30) allow it to continue until the battery icon in the toolbar stops moving (6-6 1/2 hours or longer).

If it is still reading high, stop charging!

Also, you can tell charge status (fast is green & red light, trickle is green only).

Hope this helps.

[ChasenRecording]

The batteries are replaceable as you found out.

On the issue of explosive batteries:
For tests so far, the calibration unit (whatever it is) does not have to be reset if you buy batteries that have the same characteristics as the ones being replaced. If you replace the batteries with the wrong charging characteristics the machine could just keep charging and miss the "stop charging" sign that the battery gives (which in the case of NiMH batteries is a change in temperature). You are asking for trouble if you replace them with NiCD. Be VERY careful.

Buying batteries off the shelf is a bad idea because I don't beleive anyone carries the 700ma AAA (no L at the end as some do) NiMH batteries except engineering catalogues.

I am a firm beleiver in the "top off" method. Make sure you charge it overnight and never really pay attention to the battery meter almost ever. I usually charge my machine anywhere from 1-2 times a week, and sometimes when I get to one bar left on the display on the desktop. Works of advice "NEVER pay attention to the battery meter" it is so inexact becuase it is only a guess based upon what mA has been used and the output of the battery varies greatly with temperature (it lasts longer in the cold for me anyways).

You may also want to inspect the battery ribbon cable as that cable is the first to go on that machine. I have had two of those cables die on me. I am working on ordering replacement ribbon cables.

I hope this all helps.

[Calbrit]

When you find a source for replacement ribbons please can you post the link - thanks.

[ChasenRecording]

will do, but it may be a week or two.