HP97 battery pack rebuild

[Jlouis]

Battery rebuilt succesfully.

Thanks to all for the good advises and informations.

I will post currents and time for complete charge afterwards in the respective thread.

Calculator is functining ok, altough printer motor is on all the time. As I said previously, card reader and printer are dead. I'll try to fix it, but I see the gummy wheel and a gear for the printer damaged (eroded, if it is the right word in english). I searched for parts on TAS and found only the o'rings for the card reader. I guess it will be a tough job, let's see.

Cheers,

JL

[Paul Berger (Canada)]

If the motor is running all the time and the gear is damaged, as in missing teeth it may be just trying to return to the right margin, if the print head is away from the right side, manually moving it to the right side may stop the motor. Other possible failures are the right margin sensor, transistors driving motor or the PIK chip. There is a service guide for the 97 available, with good schematics, on the MoHPC documentation memory stick.

Paul.

(02-18-2016 01:49 PM)Jlouis Wrote:  Battery rebuilt succesfully.

Thanks to all for the good advises and informations.

I will post currents and time for complete charge afterwards in the respective thread.

Calculator is functining ok, altough printer motor is on all the time. As I said previously, card reader and printer are dead. I'll try to fix it, but I see the gummy wheel and a gear for the printer damaged (eroded, if it is the right word in english). I searched for parts on TAS and found only the o'rings for the card reader. I guess it will be a tough job, let's see.

Cheers,

JL

[quantalume]

(02-18-2016 01:49 PM)Jlouis Wrote:  I searched for parts on TAS and found only the o'rings for the card reader. I guess it will be a tough job, let's see.

Many of the parts from the 82143A printer are interchangeable, and they can be had fairly cheaply if you're patient.

[Paul Berger (Canada)]

(02-18-2016 07:18 PM)quantalume Wrote:  

(02-18-2016 01:49 PM)Jlouis Wrote:  I searched for parts on TAS and found only the o'rings for the card reader. I guess it will be a tough job, let's see.

Many of the parts from the 82143A printer are interchangeable, and they can be had fairly cheaply if you're patient.

The 82143A uses a belt to drive the lead screw so it does not have the gear that is often stripped of teeth in a topcat.

[Dave Frederickson]

I received a universal smart charger today. Discharged the battery I rebuilt with 2200 mAH NICd cells in my 97 until the display went blank, except for the low battery LED. With the charger set to 1800 mA it took 1.25 hrs to recharge.

Dave

[d b]

Dave; Do you think it decreases the life of the bat pac to charge it that fast? - db

[Dieter]

(02-19-2016 07:04 AM)Den Belillo (Martinez Ca.) Wrote:  Dave; Do you think it decreases the life of the bat pac to charge it that fast? - db

I'm not Dave, but I can say that it depends on the battery type. There are completely different batteries for different purposes. Most (not all) can withstand an 1 C charge, which does not mean that battery life is not affected. Others are specially designed for higher charge rates (e.g. many batteries that are used in RC cars and power tools), here 1 C is a rather moderate charge rate. On the other hand a minimum current is required to get a significant voltage drop at full charge that can be reliably detected by the smart charger.

So as usual, it depends. Without knowing the actual battery type it is not possible to say more here.

Dieter

[Dave Frederickson]

The cells are Tenergy 2200 mAH NiCd's. The charger is also made by Tenergy and the manual highly recommends that Tenergy cells be used (of course). So far we're good. The charger includes a temperature sensor and uses the temperature and negative delta V (NDV) to detect the end of the charge cycle. The instructions state that batteries with a capacity greater than 2100 mAH should be charged at 1800 mA. If there's a concern the batteries could be charged at 900 mA. The charger is "smart" and has automatic voltage and reverse connection detection plus a number of other bells and whistles, all for less than $25 (with shipping).

So to answer Den's question, no I'm not concerned about decreasing the battery life at the higher charge current, but Dieter has some valid points which I believe could be mitigated by using the lower charging current and the temp sensor. It still beats the pants off using a Power Pack.

It should also be noted that for the NDV circuit to properly detect the end of charge the charge rate should be at least 0.5 C.

Dave