According to the Tandy 102 service manual, the trickle charge rate is 1.2 mA (Typ.)
On a 80 mAH battery, that’s a rate of .015C. I believe that would be safe for NiMH. Energizer says in their datasheet: “Finally a maintenance (or trickle) charge rate of less than 0.025 C (C/40) is recommended. The use of very small trickle charges is preferred to reduce the negative effects of overcharging.” Personally I think at the rate of .015C you should be ok to go with NiMH. ~George From: M100 <[email protected]> on behalf of Brian White <[email protected]> Reply-To: <[email protected]> Date: Wednesday, May 31, 2017 at 12:50 PM To: <[email protected]> Subject: Re: [M100] Oh no - think my internal nicad finally given up theghost I had given 80mah as part of the search term to use, because that is the standard capacity of the current standard drop-in replacement for the same size/shape/style as the old nicd battery. The nicd version were 50 to 60 mah. I'm not worried about overcharging because the internal battery is only charged while the main power is turned on, and by default it turns itself off when idle for 10 minutes. To overcharge the internal battery, you would have to actively use the thing for more than a day or so to get into that territory, or disable the 10 minute idle power off, and, do one of those while plugged in to the wall. Normally, either you turn it off, or it shuts itself off, or the AA batteries die long before 24 hours. I thought I read somewhere that you had the same limit with the original battery too anyway, ie that you couldn't charge that forever either. But I don't see any such admonition in the user or service manuals, and it is possible to trickle charge nicd (more or less, it's not actually harmless, just not quickly catastrophic), so, perhaps that is a valid consideration. Personally, I would not, for example, plug an M100 into the wall, issue a POWER CONT in basic, and then run it 24/7 as a server or something, even with the original battery. So, short of that, I see no difference. And, when you search for the original batteries by actual part/model number, vendors and manufacturers offer nimh's as replacements. That tells me that the new battery is expected to work in the same conditions as the old. -- bkw On May 30, 2017 10:05 PM, "Josh Malone" <[email protected]> wrote: Okay - I was looking for 80mAh for some reason. The ref manual doesn't specify the capacity, but I see the R/S part was a 50mAh originally. So, yeah, other than having to buy 4 at a time, ebay wins. I'm gonna wind up with quite a stock of 100/102 spare parts at this rate. -Josh On Tue, May 30, 2017 at 9:22 PM, Mike Stein <[email protected]> wrote: eBay 401159712873, 400826285784 etc. ----- Original Message ----- From: Josh Malone To: [email protected] Sent: Tuesday, May 30, 2017 8:31 PM Subject: Re: [M100] Oh no - think my internal nicad finally given up theghost nimh are just easier to find it seems. A quick googling finds a godzillion sources of NiMH cells in the right specs, but I can't actually find an easy supplier of nicd cells in the right specs. On Tue, May 30, 2017 at 6:31 PM, John R. Hogerhuis <[email protected]> wrote: What's wrong with NiCd? As designed... -- John.
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