Voltage with Optima AND an EVR

Barry in St.Paul

Barry in St.Paul

Senior Member
hi guys,
I'm running a stock generator, except with Tom's EVR, and also an Optima battery. I had noticed my horn didn't have any 'oomph" unless I was running, and then only when the EVR decided to 'charge', but thought it was just my horn ground (which WAS extremely high, and has now been corrected by scraping paint away and down to <0.2ohms).
So, expected the horn to work 'normally', but still no horn unless generator is charging. I got out the Fluke, and I have about 5.95 volts "cold", which cranks the starter just fine and the engine is running in just one or two revolutions, always. But the EVR does not kick in it seems, until the voltage is much less than 6V (didn't have the Fluke on it when it finally kicked in and started charging). When charging, I'm picking up almost 8V at the generator, and >6V at the starter/battery. While driving my little 12 mile 'loop' here, the EVR kicked in for maybe 2/3 of the drive, sometimes maxing out at 20amp, or sometimes down near 0 (but I was driving with lights on). After 12 miles and back home, I turned her off, and again, no horn. Re-checked battery voltage, and about 6.05 (hot).
I talked to Tom about it last weekend in St.Could at the swap meet, he builds these based on "standard" batteries and isn't sure if there is some odd interaction with the Optima. Anyone out there had a similar experience, and/or a fix, without getting rid of either the EVR or the Optima, both which I like? :-) If the horn would spin at <6V I'd probably ignore it, everything else works great. (I rebuilt horn, oiled it, and have about 0.2ohms ground resistance, and you can see the ammeter dip when horn button is pushed but "no spin" unless generator is charging...... and then it sounds GREAT!
Ideas? I don't understand the Optima's, and guessing there is something there that doesn't feedback to Tom's EVR like a standard battery does.... Thanks!
 
Buy the little horn relay kit that installs inside horn cover---it shortens the distance of horn current travel by at least 6 feet.
 
Normally, a fully charged wet cell voltage is 2.1 volts, so a 6 volt battery would read 6.3 volts. Therefore yours is not fully charged. Usual charging voltage for a 6 volt system is about 7.2 volts. I'm not sure if Optimas have different specs, but my experience has been that they can last a long time but many die an early death and do weird things to the electrical system. Try borrowing a good normal 6 volt battery and see what happens.
 
thanks. (Hi Tom!! was great to see you and the phaeton in St.Cloud!)
First, re: ground, I was measuring between the horn motor base and the radiator shell screws (convenience, and the resistance between the shell screws and the unpainted engineblock head studs was almost zero... maybe 0.2ohms or less).
Measuring between there and the horn motor mount (ie: the base where the windings and the two 'arms' that connect to the horn 'base' ) was initially MEGA ohms, and I thought "ahhhh! foolish me, I never scraped the paint on the horn bracket or the bolts connecting it to the horn. After taking it apart and doing THAT, I had 0.2ohms between the radiator shell bolts (or effectively from engine block) to the horn motor mount). By coincidence, when I tried it again, the EVR had kicked in and the horn sounded great (sitting at an idle; this is when I talked to you in St.Cloud Tom and thought I'd fixed it)

Now to address horn tightness, that was my first thought too. But, I can back the adjustment screw off until the commutator will spin free (no sound) by hand, but it STILL doesn't turn electrically unless the generator is charging. I tried this again yesterday. To reinforce the problem as I see it, having the "generator charging" appears to simply be what it takes to have the Optima keep the battery >6V, and the EVR doesn't kick in to allow the generator to charge until the batter voltage is at least less than 5.8V (at some point after measuring 5.8V I was back to the interior of the car, and I noticed the ammeter needle kick over and I ran back to the Fluke again and now had 6.4V or something on the batter, measured at the starter post to head-stud, and 7.8V from generator post to head-stud.
As far as Optima being 'bad" I've had it in there for a year, and has always acted the same way. Works perfectly in all regards (starts car IMMEDIATLEY, cranks one or two turns and vroom!), and I usually drive with headlights on here in the metro for safety. I have just over a 1000 miles on her now, and since I don't "do" parades unles absolutely necessary (I grew up with a Dad with several old cars and spent the better part of my teenage weekends hauling politicians and beauty queens around every local Minnesota town's local festival!! ) I've never had occasion to bother honking the horn at low rpm until recently or really bother with it since I put the Optima in. I did have the standard battery when first putting things back together and when checking my horn rebuild out. So, I am prone to think the Optima is the root of the dilemma, Tom's EVR, if at all, is only involved in perhaps the different type of signal it is giving the EVR vs what he designed it for (and how nice it is to be able to polarize across and EVR, which you can do with Tom's unit!!! Thanks again Tom for providing these great units!).
I was just wondering if anyone else had had the problem. I brought my "good" standard batter up to the farm for Dad to use in the '28 Stude or '28 AA gas truck this summer, so don't have it here to test, but sounds like that is the best 'next step' to try, maybe after I go up next time and get cars put away for the winter and take the battery out, I'll just bring one of them back home again with me. Would rather run a standard batter than be without Tom's genius EVR.
This simply might be an Optima charactristic as it interfaces with the EVR...I'm a mechanical engineer, never got into those little electrons any more than necessary. :- )
 
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The horn body is grounded by design, but the horn circuit doesn't use that ground. The motor windings are entirely insulated from the horn body and motor frame. The ONLY ground needed is through the horn button and steering column to the chassis.

Try jumping a ground wire from the horn contact to a head nut and see if the horn blows like it should. Vince's horn was whimpy until I held some fine sandpaper against the commutator while it was spinning. After a few seconds it started picking up speed and now blows great. It's improtant to have a clean armature.
 
I think Tom has you on the right track but you provided the key clue. If your horn does not spin with no load and close to 6 volts you either have a bad horn, switch, or connection. Bypass the switch with a straight connection or just try the relay. Did you bench test the horn? When the system is charging the slightly higher voltage is simply compensating for the problem you are trying to track down.
 
I don't believe your problem is related to the Optima or the EVR. I run one car with a EVR and an Optima battery. The ammeter shows a slight charge at all times not any different than it would with a wet cell. Sounds like you have a bad connection some place in the system and should be looking for that. I think you are going in the wrong direction chasing the EVR and the battery. The fact that the car starts fine means the battery is good and that you can run with lights means the generator is working. Look where the problem is not at the parts that seem to be working. I would start by checking the horn for voltage not ground.

For reference the Optima is fully charged no load at 6.4 volts and the recommended charge voltage is 6.65 to 7.50 volts. It is not recommended to run an Optima without a regulator as they are very sensitive to over charging.
 
thanks all. Good food for thought; not sure if I'll get to it today (modern car winter-prep on Labor Day up here, on vehicle #2 oil and filter and air filter change right now...) Will post any new results.
thanks again.
 
UPDATE: after considering the layout of the horn button, and viewing a nice article that showed the button, bezel, spring and lever all apart, I remembered how it really worked and simply "rotated" the horn button back and forth several times, kind of 'grinding' it against the contact surface inside, to get a better ground (the horn rod is literally the only piece of the entire car I did NOT disassemble and 'restore' !!!! was scared of breaking off those little tabs, so left it alone besides polishing the aluminum lever housing)
Sure enough, the horn now spins over without the car running. Voltage at starter measures only 5.93V, but again, the Optima seems to always be just less than 6V when sitting, and still functions well, so maybe that is just what it is when it sits on my particular unit.
Thanks for the reminders on how the horn is wired up Tom!
Barry
 
Barry, I have the same problem on my Huckster. I have just an common 6V battery. I have taken the horn off the car, put the two leads to a extra battery I have sitting around, and the horn works great. I put it back on the car, push the horn button and nothing except I see the amp meter goes down when the button is pushed but not even a spin of the horn motor when I back off the adjustment.

So, maybe I need to do what you did-rotate the horn button! I put in an after market horn button and shaft when I restored the rig-maybe that is the problem. I will have to get out and rotating the button but think I will wait for evening-it is about 100 degrees here in dear old rainy Oregon.
 
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