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MicroVAX TOD batteries - good seller

Terri Kennedy

Experienced Member
Joined
Jul 7, 2017
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New York
Ni-Cd batteries for things like the VAX 4000 series of CPUs are becoming harder and harder to find. I've ended up with NiMH ones, ones that don't even say what cell technology they use, and ones with AA instead of AAA size cells.

This eBay listing: https://www.ebay.com/itm/310432371314 is for batteries which are actually a drop-in replacement for both the 2-slot cover on the VAX 4000-200 and the 5-slot cover on other BA4x0 MicroVAX systems. They should also work on any other systems that use 3,6V Ni-Cd batteries in the 3 x AAA form factor.

The connectors on these are not the right ones, so you'll have to splice the leads or have your own pins/crimper (and optionally connector body if you don't want to re-use the existing connector).

I expect that once these are gone, there won't be any more made, at least not in pre-packaged assemblies like these. So at this point you should probably treat this as a "last lifetime buy" and stock up if you ever think you might need some in the future. Shelf life in storage seems to be excellent (there's no date code on these, but an earlier order from 1999 was still good when installed in a VAX 4000-705A). It is important to disconnect the battery if your system won't be used for an extended period, because once you run these down to 0V they're gone forever. That's easy on the 5-slot front cover and a real PITA on the 2-slot cover, so I hide an on/off switch under the cover on the 2-slot version so I can disconnect the battery if the system is going to be stored for an extended period.
 
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I wish I'd known this 2 weeks ago. lol I bought a pack for my MV3100 M95 from Ebay but got a "Best Offer" of $45 (instead of $49.95) https://www.ebay.com/itm/302015244803 😞

I guess I should have looked better.
Well, for some people having the correct connector on them already is worth the extra cost.

Per that listing, those packs are nearly 7 years old so that would be a bit of a concern for me. Although to be honest I didn't cut the shrink wrap on the battery I listed above, so the cell dates (if they have dates) are unknown. I did run the system for 24 hours, powered it down for 24 hours, and it came back up with language, boot device and restart mode remembered, so they do seem to work, at least short term. If I were going to leave the system off for more than a week or two, I'd definitely hit the hidden disconnect switch I put under the console cover.
 
A few years ago I have designed a battery replacement board for MicroVAX II/III machines that can also work for any other mainboard that needs a 3.6V backup battery.
It can easily give several months of backup time on a MicroVAX (50-100uA driving a MC146818), much better than a NiCad pack.
You are welcome to build as many as you like:
https://github.com/microvax2/KA630-TOY-Battery-Replacement-Board

-Alon.
 
A few years ago I have designed a battery replacement board for MicroVAX II/III machines that can also work for any other mainboard that needs a 3.6V backup battery.
It can easily give several months of backup time on a MicroVAX (50-100uA driving a MC146818), much better than a NiCad pack.
You are welcome to build as many as you like:
https://github.com/microvax2/KA630-TOY-Battery-Replacement-Board

-Alon.
Interesting. I don't think it will work in a MV3100 setting though. It doesn't have the front panel like a MV II/III in a BA23/BA123/BA21x. It just has a clip to hold the battery pack and a 2-pin connection.
 
Well, for some people having the correct connector on them already is worth the extra cost.

Per that listing, those packs are nearly 7 years old so that would be a bit of a concern for me. Although to be honest I didn't cut the shrink wrap on the battery I listed above, so the cell dates (if they have dates) are unknown. I did run the system for 24 hours, powered it down for 24 hours, and it came back up with language, boot device and restart mode remembered, so they do seem to work, at least short term. If I were going to leave the system off for more than a week or two, I'd definitely hit the hidden disconnect switch I put under the console cover.
I have 2 MV3100 M95's. I bought that pack originally 2 years ago and it's been in my first MV since and working well. I replaced a home built pack that worked so-so because it was the wrong size cells (AA instead of AAA) and didn't fit the battery clip so was just in the case loose. That system has been down at times for a month or more (Texas heat issues in the summer) and come back with all the data and TOY still set. I just bought the second MV3100 a month ago and wish I'd looked around before buying another of the same (expensive) pack. I have no problem changing the plugs. I have crimping tools and parts up to my armpits. lol
 
Would either of those eBay NiCad batteries be a good match for the RK05 'emergency retract' battery?
 
Interesting. I don't think it will work in a MV3100 setting though. It doesn't have the front panel like a MV II/III in a BA23/BA123/BA21x. It just has a clip to hold the battery pack and a 2-pin connection.
This board should work as all it needs is a standard "disk drive" 4-pin molex (for the charging IC) and a 2-pin connection going to the main board, similar to the one all battery packs from that era were using (100 mil pitch, Molex KK series).

-Alon.
 

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This board should work as all it needs is a standard "disk drive" 4-pin molex (for the charging IC) and a 2-pin connection going to the main board, similar to the one all battery packs from that era were using (100 mil pitch, Molex KK series).

-Alon.
Ah. Just ignore the other connections then. That's good to know. I will have to estimate if it will fit someplace in the MV3100 empty spaces. I've got plenty of disk drive connections open for charging since I replaced the drives with ZuluSCSI.
 
Would either of those eBay NiCad batteries be a good match for the RK05 'emergency retract' battery?
I don't recall what the RK05 (or RK06/7) used. If you can post clear pictures of the top/bottom/connector of the battery pack, I'll see if I can come up with something.
 
A few years ago I have designed a battery replacement board for MicroVAX II/III machines that can also work for any other mainboard that needs a 3.6V backup battery.
It can easily give several months of backup time on a MicroVAX (50-100uA driving a MC146818), much better than a NiCad pack.
You are welcome to build as many as you like:
https://github.com/microvax2/KA630-TOY-Battery-Replacement-Board

-Alon.
That's great for BA12/123 type boxes. There is very little space in the BA4x00type chassis VAXen - pretty much just room for the cells themselves.
 
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