atrax27407 Posted December 22, 2014 Share Posted December 22, 2014 Most of the RAMdisks (not the HRD16) are powered by rechargeable Ni-Cad batteries (usually AA size) when the P-Box is turned off. That used to be the only rechargeable battery available. I wonder if you could substitute a rechargeable Ni-Mh battery of a comparable size in place of the Ni-Cads. OK, hardware gurus, have at it! Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted December 22, 2014 Share Posted December 22, 2014 My two cents. Take with a grain of salt... I spoke with a Varta tech rep a while back about replacing the rechargeable batteries in old Amiga systems and was given their blessing. I was told that the charging circuits are essentially the same for NiCd and NiMH and they often sell NiMH as viable replacements. That said, if you specifically want NiCd batteries you can still obtain NiCd AA batteries from your garden center. Those batteries for the solar lights are almost always NiCd. And for FWIW, I have replaced said NiCd batteries with NiMH with nothing bad happening. This is, of course, uneducated layman experience, possibly the same kind which tells you it is just find to use an HD floppy in a DD drive. Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted December 22, 2014 Author Share Posted December 22, 2014 The only real question becomes: Since the Ni-Cads are generally 1000MaH and the Ni-Mh are a higher value (sometimes 3000MaH), would there be a problem? Quote Link to comment Share on other sites More sharing options...
Omega-TI Posted December 22, 2014 Share Posted December 22, 2014 The only real question becomes: Since the Ni-Cads are generally 1000MaH and the Ni-Mh are a higher value (sometimes 3000MaH), would there be a problem? I cannot imagine why the storage capacity would have any effect, other than taking longer to charge. It's the (E)lectromotive force or the higher voltage of the charging device which charges the battery. Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted December 22, 2014 Author Share Posted December 22, 2014 Thanks all - got 8 AA Ni-Mh batteries and a charger on the way. Quote Link to comment Share on other sites More sharing options...
+Lee Stewart Posted December 22, 2014 Share Posted December 22, 2014 The rated operating voltage is the same for both NiCd and NiMH. I agree with what Kevan said. The only other difference might be a different optimum over-voltage for the charger's deciding when to quit charging the battery or a different optimum charging rate. ...lee Quote Link to comment Share on other sites More sharing options...
+Lee Stewart Posted December 22, 2014 Share Posted December 22, 2014 Does the RAMdisk charge the batteries in place? ...lee Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted December 22, 2014 Author Share Posted December 22, 2014 Yes, as long as the P-Box is turned on. Since a lot of the chargers that I see are rated for both Ni-Cad and Ni-Mh batteries, the charging circuit in the RAMdisk should work for either, I think. Quote Link to comment Share on other sites More sharing options...
Gary from OPA Posted December 22, 2014 Share Posted December 22, 2014 (edited) The only problem with Horizon design, is NO SHUT DOWN. it just keeps charging the batteries (not that bad as the current going is very low, trickle charger), for those that never turn off their PE-BOX, it can end up being a problem after a while. Edited December 22, 2014 by Gary from OPA Quote Link to comment Share on other sites More sharing options...
Omega-TI Posted December 22, 2014 Share Posted December 22, 2014 The only problem with Horizon design, is NO SHUT DOWN. I curious, what is the charging voltage? Some designs I've seen for things have the charging voltage set low enough to just "float the battery" at a pre-determined maximum, meaning at a certain point the voltages equalize and it simply cannot charge past a certain point. Could that be the case here? Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted December 23, 2014 Author Share Posted December 23, 2014 Unless you are running one of the two remaining BBS's, why would you leave your PEB turned on 24/7? Quote Link to comment Share on other sites More sharing options...
+Lee Stewart Posted December 23, 2014 Share Posted December 23, 2014 Thanks all - got 8 AA Ni-Mh batteries and a charger on the way. Bob, I just checked the manuals for RAMdisk 2000, 3000 and 4000 and they are using AAA batteries, NOT AA. You might want to change your order! ...lee Quote Link to comment Share on other sites More sharing options...
+Lee Stewart Posted December 23, 2014 Share Posted December 23, 2014 The three AAA batteries are connected in series for 3.6 volts and are connected to +5 volts. Gary is right—they will charge at 1.4 V over-voltage total or 0.47 V per battery, which is probably not good for a constant-on condition. That's 40 % over-voltage. I don't really know whether that's good or bad; but, I would say that it's more than a trickle. ...lee 1 Quote Link to comment Share on other sites More sharing options...
jstimson Posted December 23, 2014 Share Posted December 23, 2014 I've been using the same set of Ni-Mh batteries for years with no issues. And since I don't get on my TI as much as I would like, it can sit for months between charges with no loss of memory. 1 Quote Link to comment Share on other sites More sharing options...
Gazoo Posted December 23, 2014 Share Posted December 23, 2014 If you put a diode (in the correct polarity of course) on one of the ends of the battery connections, it will prevent the charging circuit from working. Then you can use alkaline or lithium batteries. I've found that they keep the card contents intact for three to five years, and you don't have to worry about turning on the computer to keep the batteries charged. If you want to get fancy, you can run 2 wires and take the batteries off-board and use some D cells in holders. You might get a few more years extra for taking that approach. Since I hardly ever change the contents of my Horizons, I'd like to replace the Sram chips with Eproms or EEproms. If I could find a way to dump the individual Srams on the board, I would already have this in place. Unfortunately I don't have the skill-set to do this. Maybe someone here does. Gazoo Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted December 23, 2014 Author Share Posted December 23, 2014 The Horizon (probably a M. Becker clone) is labelled "Solid State Disk Drive" and definitely has three AA batteries . I've had it running but the Ni-Cads that I got from (ugh!) China won't hold a charge or even charge properly. The 3 - 512K Quest RAMdisks that I have do use AAA batteries.. Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted December 23, 2014 Share Posted December 23, 2014 You just made life easier from a space standpoint, Atrax--I actually shoehorned 3-AA batteries into the space reserved for the battery pack on the new layout for those Quest boards. . . Quote Link to comment Share on other sites More sharing options...
+Lee Stewart Posted December 23, 2014 Share Posted December 23, 2014 Bob... I can't argue with the card in front of you; but, I was reading Horizon manuals from Bud Mills Services. On another note—along with what Tony suggested, you could use a single 3.6 V (or however they come) lithium battery with the diode. ...lee Quote Link to comment Share on other sites More sharing options...
senior_falcon Posted December 23, 2014 Share Posted December 23, 2014 (edited) The three AAA batteries are connected in series for 3.6 volts and are connected to +5 volts. Gary is right—they will charge at 1.4 V over-voltage total or 0.47 V per battery, which is probably not good for a constant-on condition. That's 40 % over-voltage. I don't really know whether that's good or bad; but, I would say that it's more than a trickle. ...lee A couple of points about NiCad and NiMH batteries: A very standard way of charging them is to charge at a rate of c/10 for 14 hours. That is, a 600 mah battery would be charged at 60 milliamps which is c/10. NiCad can handle c/10 for 90 days (!) although obviously that is not recommended. NiMH is less tolerant of such abuse. Batteries will self discharge over time and often there is a "trickle" charge that can be applied indefinitely to hold them in a fully charged state. Trickle charge for NiCad is c/20 or less; for NiMH it is around c/40. In a simple charger such as in the HRD, a voltage is applied to the battery with a resistor in series to limit the current. The charger could put out 100 volts and the right choice of resistor would still allow you to trickle charge. Ohms law is V=IR, so the resistor can be found with R=V/I. If I wanted to put 20 milliamps to the battery it would be 100v/.020amp giving a value of 5K. (Technically it would be (100-3.6)/.020) The 1.2 volts refers to the voltage at the middle of the discharge curve. When a NiCad or NiMH battery is fully charged the voltage is 1.4v or even higher. The interesting thing about charging the battery with 5 volts is that the current will go down to almost zero as the battery gets closer to a full charge, so it will automatically go into trickle charge mode. Another cool thing is that NiMH batteries have a higher capacity, which automatically gives a lower rate of charge relative to the capacity of the batteries. If you are charging a NiCad at c/20 the larger capacity of the NiMH will automatically drop that to around c/40. So the bottom line is that any rechargeable whether NiCad or NiMH should work. (But don't charge lithium batteries this way!!!) The battery holder on my HRD 4000 is aluminum and the contacts are riveted to a solder tab. That connection corrodes over time, and no matter how clean the contacts are at the battery there is no connection due to the corrosion. Check this. If they have corroded you may need to replace the battery holder. And for what it's worth, my HRD takes AAA size batteries. Edited December 23, 2014 by senior_falcon 1 Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted December 23, 2014 Author Share Posted December 23, 2014 Here are a couple of photos of my Horizon-type RAMdisk. I suspect that it is a prototype (Michael Becker?). It is clearly marked with "Solid State Floppy Drive on both sides. 1 Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted December 23, 2014 Share Posted December 23, 2014 That one doesn't look like Michael's work Atrax--it is definitely not his soldering job, and he was not one to let bare boards out of his Magic Basement. The layout isn't his style either, it looks more like something that came out of one of the user's groups as a kit card. It may not have come from Germany even, as I never saw or heard of this one while I was over there. Is it possibly a development from one of the Australian groups, similar to the Quest boards? It definitely has a lot of HRD 1000 DNA in it. . . Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted December 23, 2014 Author Share Posted December 23, 2014 I'm not aware of any RAMdisk development from Australia except for the Quest RD200 which WAS marketed. I'm not sure how many of them were sold but, at one time, I had accumulated 5 of them. I don't remember where the board came from but, since I acquired a couple of Michael's projects at about the same time, I assumed that the board at least (but not the soldering) came from him or a sinilar source in Deutschland. My next project when the facility becomes available (hint!hint!nudge!nudge! Jim) for me to once again run two P-Boxes simultaneously is to get all of my RAMdisks running and add a second RS232 card and move my Speech Synthesizer into the second P-Box. I found my RAVE Speech card so I'm good to go as soon as I order some AAA Ni-Mh batteries. Quote Link to comment Share on other sites More sharing options...
Shift838 Posted December 27, 2014 Share Posted December 27, 2014 I have replaced my original batteries on both of my HRDs with NiMH batteries and they work like champs. Chris Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted December 27, 2014 Author Share Posted December 27, 2014 I wonder if the Horizon would charge alone in a P-Box without the Interface card - I have a spare P-Box or two . . . Quote Link to comment Share on other sites More sharing options...
Gary from OPA Posted December 27, 2014 Share Posted December 27, 2014 I wonder if the Horizon would charge alone in a P-Box without the Interface card - I have a spare P-Box or two . . . I see no reason why it would not. the charging circuit just needs some power. All tho earlier HRD, the very first models and some of 3000/4000 models were a bit qlitchly on memory loss, when removing the card and moving it between systems, the switch-over circuit from power to battery was not perfect, but that was fixed on most cards, and ones that were home-built mods were published on how to improved it Quote Link to comment Share on other sites More sharing options...
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