Vintage Sun tachs

[G B.]

I've got an old Sun Super Tach that uses a separate sending unit. The funky 1.35 volt battery in the sending unit is dead.

I've been searching the internet for a source of new batteries, but I've struck out. I've used Williamson's in Arkansas to convert a sending unit to solid state before (for $200!). However, this time I just want to buy a darn battery. Does anyone know a vendor who sells new 1.35 volt batteries for Sun sending units? I'm not very optimistic about this search. A recent article in Street Rodder magazine says these batteries haven't been made for years.

I also want to buy a nice chrome cup for mounting this tach. They come up on eBay every now and then. The NOS versions sell for over $50! Yahoo. They must be "discontinued" as well.

My '63 convertible was converted into a full-time drag car in 1967 with 35,000 miles on it. I've restored the original FI engine to stock, but I'm leaving the vintage aftermarket chassis and interior stuff in place. Don't let it worry you; this car can always be over-restored by someone else after I'm dead.

[Mike McKown]

Re: Vintage Sun tachs

Jerry:

I went through the same thing looking for batteries. I wound up using 1.5 volt batteries and discharged them a little and stuck them in the sending unit. I can't tell you the tach is accurate but it seems to be.

I think it was Clem told me to use the rechargable kind as they are something less than 1.5 volts or maybe it was charge them to that value.

I gave up trying to find the mercury batteries or the 1.35's and I wasn't going to pay that kind of money for a changeover.

[Patrick H.]

Re: Vintage Sun tachs

Jerry,

What does the battery look like? The tach is probably older than I am, but my older Canon camera uses a similar 1.35v battery, and I have a source.

If you can get me a model number or picture of the battery...
see link below

Patrick




Battery like this????

[Duke W.]

Re: Vintage Sun tachs

FWIW, Radio Shack has a pretty good selection of weird batteries. In the last decade I found they had batteries for my old Minolta SRT-102 camera (circa '74), Seiko watch (circa '78), and Panasonic portable phone (circa '91).

The 1.35 volt sounds familiar, but you also need the correct form factor to fit the battery cavity. I recall that my Minolta required a 1.35v, but it was not available, however, the shop that rebuilt it recalibrated the light meter for a 1.5v battery that was available in a form factor that fit the battery cavity.

Duke

[Patrick H.]

Re: Vintage Sun tachs

I could have had the Canon recalibrated too, but once I found the non-mercury replacement noted above, I didn't need to go through the expense.

Patrick

[G B.]

Great ideas

Thanks for the excellent advice.

Mike, I assumed a 1.5 volt battery wouldn't work, so I didn't even try one. I will now.

Patrick, that's a great idea about using a different shape battery. The Sun batteries were small cylinders similar to maybe an AAA size. I think I could probably rig up a way to install a pill shaped 1.35 v battery, but I'm going to try the 1.5 volt cylinder type first.

There's an eBay auction for some batteries that are supposed to work, but the description is confusing to me. The auction number is 2478824170. These batteries sound like regular 1.5 volt to me.

[Mike McKown]

I believe the size is AA

I still have a set of mercury batteries for reference if you need something.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2478824170

I had a set of these in my hand (auction batteries) and for some reason would not use them. Can't remember why though. These guys sell tachometers though so they should know what they are talking about. The puzzeling part is, the tach transmitter calls for 1.35 v batteries and they are selling 1.5-1.6 v for the same application. Why buy their batteries for $25.00 plus $5.00 shipping when you can go to the drug store and get the same voltage batteries for $2.00? It would also indicate to me that the higher voltage doesn't have any detrimental effect on the performance or durability of the tac. Or does it?

[James F.]

Re: Great ideas- Jerry

Jerry,
The 1.35 mercury batteries have be legislated out of production when mercury in landfills were a No-No. I found out that common 1.5v batteries will cause your Sun to read high. I too had a vender who should have know better (and may have) tell me, "just go ahead and use a 1.5v battery, that's what we do."

The Sun mercury size is approximately 1.970 OL X .625 OD and I believe the sender unit requires two. I could not find a 1.35v battery of any type available. I had a engineer friend design and make up a little pc power board that replaced the batterys. Was small enough to fit inside he sender case. Sweet! Regards,

[William C.]

Re: I believe the size is AA

I believe the only advantage of the mercury batteries was long life. There is no "off" in the remote Sun tach transmitter, thus the drain on the bayyerys is constant. If you use a modern alkaline 1.5 volt set and remove than when the car is not going to be used, you should be just fine.

[William C.]

Re: Great ideas- Jerry *NM*

[Craig S.]

Re: Vintage Sun tachs

Duke - you are right, the Minolta is 1.35V vs 1.5V (I have an old SRT-101. The light meter can be recalibrated. The person I used to clean and adjust mine a few years ago had a source from Germany for the 1.35V batteries, so I bought a couple, probably dumb, since they are sitting and discharging, but they are mercury cells and are not marketed any more in the US due to mercury pollution on disposal....Craig

[Craig S.]

Re: Vintage Sun tachs

Patrick, that's great to know, now I have a source for a non mercury replacment for my old Minolta......Craig

[G B.]

Just shoot me

Okay, let's summarize our conclusions.

The AA size 1.5 volt drug store batteries will work, but will give inaccurate readings and won't last long unless I remove them when the car is not in use.

No one is really sure what the eBay seller is offering for $25/pair (other than very expensive batteries).

There are no 1.35 volt cylindrical mercury batteries currently available in the U.S. for environmental reasons.

No one knows of a foreign supplier of 1.35 volt cylindrical mercury batteries for this application. Footnote: Not that I would consider breaking any current or future laws of this city, county, state, or country.

I didn't mention it in my first post, but my $200 conversion to solid state in my other Sun tach transmitter gives inaccurate readings most of the time. I also get inaccurate readings from my 1-piece Sun tach that I bought new in the seventies.

All of this makes me think that I should learn to accurately guess rpm by engine sound alone.

[Chas Kingston]

Re: Just shoot me-- BANG, BANG *NM*

[William C.]

Re: Just shoot me

Jerry, Several years ago, I was able to get a Mallory replacement for the sun batteries, I believe the part number was RM-12, but don't hole me to that. Got them at an electronics supply house (industrial, not the Radio Shack variety) You might try that if there is an outlet near you. Costly, but they were available, I think a little over 12 bucks each.