Why bypassing the ammeter is a GOOD idea!

[RRDon]

Here's a well written article on this subject that may be of interest.

http://madelectrical.com/electricaltech/amp-gauges.shtml

Excellent article! Thanks much. I have same issue with my 68 RR. Will do the mod.

 

[JimKueneman]

Guess what ? a fully discharged batt won't suck more than 40 amps ever. Chemicals inside are not able to be so fast to get the electrochemical balance back, so a 40 amps ammeter is quite enough. Of course is not safe to get running that load for long time on a car, but still ammeter is able to handle it. Still if you get a full charge or discharge reading for some time something is really wrong on the car, and a 40 amps gaue will tell you that. Then it's up to you if you decide still work on that stage, but don't blame the ammeter.

6 months ago I would have agreed. I bought a Deka battery for my Coronet. I was working on it with the doors open for much of the day and discharged the battery quite a bit. I fired it up and the alternator pegged out on the dash charging. I looked at the voltage on the battery and it was 12V. I thought my alternator or regulator died. I looked at the output of the alternator on the post and it was 13.5V... mmmm.... Looked at the back of the ammeter and it was in the mid 12V on one side and almost 1V drop across it.... that scared me, way to much power being dissipated in the meter. I pulled the alternator and pulled it apart, diodes were fine, nothing looked wrong. Put it back on and looked at the field winding voltage/current. About right, regulator working. I finally said what if the battery could accept more current than the charging system could produce, if that were true all the things I was seeing could occur. I pulled the battery and put it on my battery charger. I hit it with fast charge (65A) and the voltage across it BARELY MOVED. That Deka could take over 65A and not developed much of a drop across it at all. I put it back to normal charge and let it charge for 6 hours. Put it back in the car and the charging system worked as expected. Lesson some the new newer high quality batteries can now take all the charge that an old system can deliver. I would be really nervous with a 100A alternator in that condition as that battery could likely cause it to be moving 100A through the harness. Not a big fan of that. Also learned I really need to be careful about discharging the battery too far, it can really abuse the wiring system with the high currents that can be developed.

Jim

 

[Nacho-RT74]

well the amm was telling you something was wrong... It was up to you if decided to run like that, but don't blame the alt or the ammeter for that. If you had a voltmeter you never advertised that

 

[67belvedere/225]

I installed a fm alternator on mine
Self exiting (npi) one wire direct to battery and I fused it
Put Ina volt gauge 95 amp is plenty for my car

 

[RRDon]

Excellent article! Thanks much. I have same issue with my 68 RR. Will do the mod.

Yes, mod worked out great. No more smoking wire connections at firewall.

 

[Crackedback]

The Madelectric article is OK. I suggest doing most of that except leave the black oem wire connected to the alternator. As long as you are pulling stock loads through the line, it should be OK if in good shape at bulkhead. When the loads go up, that line should be addressed or run a secondary bus point for high amp items inside the car.

Whether the ammeter failed or components associated with it, fiber gaskets, it's the point of origin for the issue. I'm not a fan of ammeters, run them if you like. If they aren't there, the risk of failure is gone as well.

 

[wagonman]

The English make crappy cars..

Boy You aint kidding. Lucas electronics were the worst. My buddy bought a brand spanking new Triumph GT6-Plus in 71 and it burned to the ground the day after he got it due to an electrical fire. I wonder if it was the Amp Meter? I have had my fill of Brit cars and will never ever touch one again ( 69 XKE ) was the last one, what a POS.

 

[Derwud]

Boy You aint kidding. Lucas electronics were the worst. My buddy bought a brand spanking new Triumph GT6-Plus in 71 and it burned to the ground the day after he got it due to an electrical fire. I wonder if it was the Amp Meter? I have had my fill of Brit cars and will never ever touch one again ( 69 XKE ) was the last one, what a POS.

Yep...

 

[Wietse]

I've just finished the bypass as well, crimped and soldered the amp gauge connections together and covered them with shrinking tube.
After i have run a heavy wire direct from the alternator to the battery terminal to provide direct charging power and power for the additional electrical equipment that is separate hooked up to the battery.
I've replaced all my wiring harnesses in the car, so the terminals and bulk head connectors are good for use on the standard equipment where it was made for.
This survived almost 50 years and will do another 50 from now on.

 

[Glenwood]

I decided to put my ammeter back in service now that I've upsized the alternator wiring and bypassed the bulkhead terminals. It's a good tool to have in addition to the new voltmeter I recently added to monitor the charging system.

 

[Wietse]

If you have a volt meter it's all you need, even better is to hook up an additional meter with alarm which kicks in at a set voltage.
Once alarm you know the alternator is giving trouble....or the belt is broken which also means your cooling water pump and fan are not spinning.

 

[Nacho-RT74]

If you have a volt meter it's all you need, even better is to hook up an additional meter with alarm which kicks in at a set voltage.
Once alarm you know the alternator is giving trouble....or the belt is broken which also means your cooling water pump and fan are not spinning.

Not if AC

 

[Wietse]

Not if AC

Mine is a non A/C so don't know any better

 

[wyrmrider]

X2 on the Jag Lucas I had an early 60's Isky cams, kept loosing the clutch so I put a C4 in it (I know Iknow but the early Jag 4 speed was a crash box in low and the faster you went in low the longer it took to shift to second- C4 was actually quicker- but that's another story
I bought one of Ak Millers flatheads when he went Oldsmobile in his Mexican Road Race hot rod. LUCAS IGNITION- I wonder what he was thinking
I asked him about the cam- which he (copied- re ground) ground on a converted bench grinder- he only said it had lots of lift AND lots of duration
I had it in a 54 business coupe with 4.11s and a t85 with OD (T85 was the basis of the T10 speed but also a non synchro low) I could dust off a certain 57 chevy fulie 4 speed. Les Ritchie had a T85 in a blown 57 Ford Ranchero- he busted his knuckles on the dash shifting the darn thing- next week he had a floor shift and we protested that it was not stock.Later we put two 4bbl manifold on the Factory blown car- ran for quite a while before we got protested- all the parts were factory...
..Les would go up in smoke with the Right Rear smoking- no posi- we showed him how to jack the left front and right rear till he got even rubber
something I always did before putting in a posi. YOu want both tires pushing the same and let the posi cover little differneces
RIP LES, Akton-- thanks for listening

 

[mopar73dge]

As previous stated and my two cents when new all is well, usually all theses cars last over 100,000 miles with out a problem, good and tight connections are needed, just like all the parts of your old cars, everything needs a refresh always the electrical at the most critical area's especially. The battery post connections are the most neglected area under the hood. I see this all the time at the car shows, most people do not understand electrical theory and miss how important a good connection is for high amp draws, battery post are beaten, loose and corroded, that's why your car wont start, a nice engine bay has old worn cables and connectors for the battery, I will never understand that. Many new cars driven daily have the same problem poor connections and no one seems to clean and re-grease this even when you have your oil changed at the shop. The mechanics miss this I have always taken care of this and never have a starting issue with a 4- 5 year old battery in my drivers. So everyone should take care of these issues and ensure you have clean tight connections.