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Charging/Dead Battery Problem


Jedi Hopeful
Hey all,

Well, my 68 sprite seems to start ok for a few runs, then click...rurrr ruuurr. I can put a charger on the battery and she starts up again after a while. I started looking into the dynamo for a problem source. I searched on here and did some testing. I had the car running and it looks like 12V across the battery(although I kinda have a crappy multimeter and telling between 12 and 13 isn't that easy...but it's definately not 14+V) I also disconnect the wires to the dynamo (NY and NG, jumpered between the dynamo leads and read the multimeter between that and batter hot. It still looked like the same ~12V. I did all of these at idle and higher RPMs(not sure exactly what RPMs, my tach never goes above like 500 RPM for some reason). Still same ~12V all the time. I also have a 62 sprite that's on temporary or permanent hold, so I scavenged the dynamo from it(tach drive type..which I had already cleaned and painted years ago). I put in on, made sure it was magnetized correctly by removing the NG wire and jumping that terminal to hot on battery a few times. Started right up, but same results as for other dynamo. I also really don't know if either of the dynamos work. I've never had them tested or anything(if they can be). Inside of voltage regulator looks clean, outside spade terminals are a little dirty looking. Ignition light comes on when key is turned but not cranked. As soon as I crank/start engine, it goes out.

Also, not sure if it matters at all, but I have the crane XR-700 ignition.

Any help here would be appreciated?? Sorry for the long message, just wanted to get all the info in there.

Thanks - Drew


Jedi Hopeful
I sorta laughed when I read that since I didn't think about that and after all, it is the BATTERY that's getting drained! Oh well, brain [censored]. Although, I would think that I would get an increased voltage when the car is running regardless if the battery if taking the charge.

Thanks - I'm running out to the store now. I take the battery and have it checked.

- Drew


Jedi Hopeful
Well, glad you mentioned the battery thing. I took it to advance auto parts and it gave the beep beep of death in like 30 seconds. So, I put a new battery in today. With the 62 dynamo(one w/ tach gear drive in back) in place, I jumped between the two dynamo connectors and attached my + multimeter connector and put the negative to the - of the battery. At idle it read like 9V, but when I hit the throttle it jumped up...to like 30V....a little higher than I expected. I guess it wasn't hooked to the voltage regulator, so I really don't know what the true voltage is that the battery would see. Anyways, I take this as a victory for now.

Sound like I'm on the right track??

Thanks - Drew


Obi Wan
Country flag
Sounds good to me. When you do the generator test, the voltage should go up fairly high, as yours did, when there is no load on the generator. That's a pretty good sign that all is in order. Only thing I might add is to check the regulator--there is a simple procedure in all the shop manuals.


Jedi Hopeful
The other good news is that I already painted the 62 dynamo LBC green a few years back. Looks better than the red one that was on there. Now I have to get the fan blade and starter painted.

I picked up one of those battery isolators that you can turn the knob to disconnect the battery. Maybe that'll help long term too.

Thanks guys - educational and problem solved!



Keep an eye on that isolator, Drew. Some of the folks here have had them break right at the thinnest part. I believe all of those came from eBay, so yours may be of better quality.


Jedi Hopeful
Thanks for the heads up. I honestly can't see the benefit from buying one off of ebay. I got mine at walmart for $2.96. With that price in mind, I'll definately keep a watch!!!

- Drew


Jedi Knight
Drew...that isolater will come in handy especially during winter storage...I actually put one up under the dash on the Sprite (it always seemed to draw the battery dead over time) so it makes it easy to turn off/on and also works like a kill switch when I park it in public...
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