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badaze · 10-01-2018, 06:30 AM

Hello,

I’ve bought a HP 19C on TAS. It came with a corroded battery pack. I cleaned the battery compartment and terminals added a brand new battery pack with fresh batteries and it works fine.
Yesterday in a flea market I, luckily, found a charger HP 82066B that would work with my calculator. As it was in a bucket with other chargers and junk I have no idea if it works or not. Of course I know it has to be plugged with the battery pack inside. My question is. As I know those devices are fragile, is there any risk to damage the calculator using the charger ?

brickviking · 10-01-2018, 08:52 AM

(10-01-2018 06:30 AM)badaze Wrote: Hello,

I’ve bought a HP 19C on TAS. It came with a corroded battery pack. I cleaned the battery compartment and terminals added a brand new battery pack with fresh batteries and it works fine.
Yesterday in a flea market I, luckily, found a charger HP 82066B that would work with my calculator. As it was in a bucket with other chargers and junk I have no idea if it works or not. Of course I know it has to be plugged with the battery pack inside. My question is. As I know those devices are fragile, is there any risk to damage the calculator using the charger ?

If possible, do you have the option of using an external charger for the batteries instead? Plenty of horror stories have been given about how precious calculators were sent to the great dumpyard in the sky just by an unseen bad connection, I'd hate yours to be yet another cautionary tale. I would no longer trust packs like this, as there's not a lot of protection for overvoltage in some of those older calculators.

(Post 293)

Leviset · 10-01-2018, 09:08 AM

There's a guy on Gumtree UK asking £500 for an HP-19c, which looking at the picture is only working off the external charger as the original battery pack will be u/s by now - good luck for him at that price!

badaze · 10-01-2018, 04:41 PM

(10-01-2018 08:52 AM)brickviking Wrote: If possible, do you have the option of using an external charger for the batteries instead? Plenty of horror stories have been given about how precious calculators were sent to the great dumpyard in the sky just by an unseen bad connection, I'd hate yours to be yet another cautionary tale. I would no longer trust packs like this, as there's not a lot of protection for overvoltage in some of those older calculators.

(Post 293)

Unfortunately I do not have an external charger. I have the external one for HP 29C and I’m pretty sure HP didn’t made one for Sting calculators.
If there is a way to charge the battery pack externaly I’m interested.

Dave Frederickson · 10-01-2018, 05:23 PM

(10-01-2018 04:41 PM)badaze Wrote: Unfortunately I do not have an external charger. I have the external one for HP 29C and I’m pretty sure HP didn’t made one for Sting calculators.
If there is a way to charge the battery pack externaly I’m interested.

I use a smart pack charger like this one for battery packs.

http://www.tenergy.com/01006?sc=59&category=38155

Contact to the battery terminals can be made with paper clips or strips of tin. Works great for charging 2225 packs, too.

Dieter · (This post was last modified: 10-01-2018 05:39 PM by Dieter.)

(10-01-2018 04:41 PM)badaze Wrote: Unfortunately I do not have an external charger. I have the external one for HP 29C and I’m pretty sure HP didn’t made one for Sting calculators.
If there is a way to charge the battery pack externaly I’m interested.

Take a look at this thread on Sting battery packs. It sounds like the original battery pack can be modified to accept four regular AA cells. There also is a link that shows such a modified battery holder. This mod seems to be quite easy to do.

Once you are able to use four individual AA cells the problem is solved: Simply get a set of four decent NiMHs (e.g. Panasonic Eneloop) and a smart charger (e.g. the ubiquitous BC-700 and its siblings). This solution provides about four times (!) the original battery capacity and reasonably fast, safe and convenient charging (due to the "intelligent" charger). Which again makes the batteries last longer.

I assume (!) it may even be possible to use (single-use) Alkaine cells. This way you can preserve the continuous memory contents while the NiMHs are charged, even if you do not have a second set of rechargeable batteries.

Dieter

burkhard · (This post was last modified: 10-02-2018 06:14 AM by burkhard.)

(10-01-2018 06:30 AM)badaze Wrote: Of course I know it has to be plugged with the battery pack inside. My question is. As I know those devices are fragile, is there any risk to damage the calculator using the charger ?

Charging the batteries while inside a Woodstock (or Sting) calculator is indeed very risky:
1. If the battery has an internal fault such that it's "open" to the charging circuit, your 19C is ruined.
2. If there's a marginal connection (crud on the connector or whatever) between the battery and the power circuit, your 19C is ruined.
3. If while it's under charge, somebody bumps it hard or it gets knocked off the desk, those couple milliseconds of "open" can mean your 19C is ruined.
4. Even though you yourself know not to attempt running the calculator w/o a battery inside, your family (and/or heirs) do not. So many nice HP calcs of this vintage get smoked because the estate sale picker plugs it in "to see if this old thing still works." It did until 50ms ago...

The safest thing you could do is never buy the OEM charger. If you "need" it for the collection, I would tag it prominently with a warning to never ever use it under any circumstance.

The charging circuit design on the Woodstocks had to be one of HP's dumbest ideas ever. Not warning people about it until page 102 (gee, thanks!) of the manual is a close second. Would a sticker inside the battery compartment (or better yet, on the back) have been so expensive?

Are the Spice series as fragile as the Woodstocks in this regard? I would assume so, but don't know that for sure.

badaze · 10-01-2018, 08:22 PM

@Dieter and @burkhard.

Thank you for your replies and advices.

badaze · 10-01-2018, 08:34 PM

(10-01-2018 05:23 PM)Dave Frederickson Wrote:
(10-01-2018 04:41 PM)badaze Wrote: Unfortunately I do not have an external charger. I have the external one for HP 29C and I’m pretty sure HP didn’t made one for Sting calculators.
If there is a way to charge the battery pack externaly I’m interested.

I use a smart pack charger like this one for battery packs.

http://www.tenergy.com/01006?sc=59&category=38155

Contact to the battery terminals can be made with paper clips or strips of tin. Works great for charging 2225 packs, too.

Thank you.