Advice on Equalizing & Tackometer?
Our older Trace 3000 watt inverter/charger doesn't have the equalizing
function like newer ones. Since we're installing new Trojan 125 gulf cart
batts, we'd like to be able to equalize them. Defender has an equalizer
listed. Does anyone have advice on another product or how Defender's product
works?
Second Question: I've read about tacks not registering sometimes or starting
to register after while. What is the advice as to what is happening and how to
fix?
Third Question: We will be purchasing a new VHF radio. We'd like advice as to
a couple that are simple. We don't need to use it to talk a mile or so away.
Tks. Ted Brown, ACT II, @Columbus Marina, Columbus, Mississippi, Heading south
to Gulf when new house batteries are installed. # 2796, I think.
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<<Second Question: I've read about tacks not registering sometimes
or starting to register after while. What is the advice as to what is
happening and how to fix?>>
Ted,
With a "smart" regulator, also called 3-stage, when the bulk charge mode has timed out and the
regulator drops its voltage setting from about 14.3 to 13.4, the batteries will suddenly be
momentarily "overcharged" (holding the higher voltage for a few minutes). The regulator, sensing
this "overcharge" condition, will turn off the alternator, which means the tachometer output goes
off, too. This condition may remain for anywhere from a few seconds to an hour or more, depending
on how much current is being drawn from this battery bank, and the size of the bank.
The solution is to turn on a few amps worth of lights or something to rapidly draw this excess
charge from the batteries, so the alternator will again resume putting out a few amps.
Mark Richter, trawler-yacht Winnie the Pooh, Ortona, FL
Mark's Mobile Marine, electrical system design, installation, and repair
Wednesday, October 10, 2007, 10:50:55 AM, Helented wrote:
HB> Second Question: I've read about tacks not registering sometimes or starting
HB> to register after while. What is the advice as to what is happening and how to
HB> fix?
On most diesel engines, the tachs are driven from an output of the
alternator, and there will be no output until the alternator starts to
charge. If you start the engine at idle, the alternator will not
produce any output until the engine is sped up - my engine has to get
up to about 1100 RPM before the alternator and tach will start.
--
Peter Bennett, VE7CEI Vancouver, B.C., Canada
Ennos 31 "Honeycomb"
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
Alternative tachometer solutions:
We are currently researching solutions for our older engine, whose maximum
rpm is only 900. Alternator-driven solutions were problematic. In order to
drive our alternator to some kind of realistic output, we had to pulley it
up something like 1:3, which means that any tach driving off this would read
the alternator rpm, or three times the engine speed. Sure, we could
constantly just divide the indicated rpms by 3, but that gets old. Also,
most tachs don't recalibrate easily by such a large factor.
The "bicycle solution" is a dynamo that puts out a predictable voltage per
rpm, in this case 1 volt AC per 100 rpm. Thus, 2 volts = 200 rpm, 3 volts =
300 rpm etc. This is a great solution, if you can find the parts, and we did
(a dynamo-driven tach that reads to less than 1500 rpm, in our case, is
quite difficult to source in this day and age).
Fortunately, one tach we found works off DC as well, so it's easy to test
and calibrate. Stick a 1.5V battery on, it should read 150 rpm. A 9V battery
should read 900 RPM. We worried about "voltage drop" (it's a 35 ft wire run
from the engine room to the pilothouse, where the tach is installed), but
were told that the voltage won't drop, just the amperage.
I am told there are also optical sensor solutions for bicycles, but have not
personally laid my optics on one. Here's one for $28 (you have to provide
your own display):
http://secure.oatleyelectronics.com//product_info.php?products_id=230&osCsid
=d2745a6da3a340fe63be270e866d56bb
The motorcycle solution, also used in many cars, is a magnetic sensor, much
like those found in a gas engine spark distributor. Basically you mount a
stud on the flywheel or vibration damper, and the other is a 12V magnetic
pickup mounted directly above it. As the flywheel or damper spins, the stud
comes into proximity (close but doesn't touch) the magnetic pickup, which
senses the field and creates a pulse. The tach counts the pulses. This is
way more accurate than an alternator-type tach at low rpms.
In our case, for low rpms, we may need to use a motorcycle tach that reads
to 10,000 rpm and put ten studs, thus all we need to do is remove one zero.
You can pick up all the parts for this in any automotive junk shop.
We will probably end up with several of these and see which works best.
Rafael
Apa Ongpin nosy34@pldtdsl.net writes:
We will probably end up with several of these and see which works best.
Hi there,
There are a bunch of less-complicated solutions to this problem. I have a
1960-vintage Detroit 6-110 which has issues similar to yours. Two solutions
which I have used are:
-
Use a mechanical tachometer. My engine room tach works just fine, it's a
NOS (new old stock) Stewart Warner I picked up on eBay. I was also able to
pickup up the right angle 2:1 drive and the flex cable on eBay as well. The
drive tip was $2.50 at my local truck shop. -
Use a programmable tachometer with your alternator. I have effectively 3:1
drive on my alternators (2:1 in the engine and 1.5:1 in the belts). The VDO
makes a programmable tach (model 333-162) which you can set for any pulse
train. It takes about 10 minutes to calibrate, especially if you have a
mechanical tach to use. I also picked up a Veeder-Root hand-held digital tach
on eBay, it's great for troubleshooting all manner of mechanical devices.
Hope this helps,
Scott Welch
FirstClass Product Manager
www.firstclass.com
Those who make no mistake rarely make anything.
-----Original Message-----
From: Apa Ongpin
We are currently researching solutions for our older engine, whose maximum
rpm is only 900. Alternator-driven solutions were problematic.
snip <<<<<<<<<<<<<<<<<<<<<<<
In our case, for low rpms, we may need to use a motorcycle tach that reads
to 10,000 rpm and put ten studs, thus all we need to do is remove one zero.
You can pick up all the parts for this in any automotive junk shop.
We will probably end up with several of these and see which works best.
Rafael
REPLY
Most modern diesels and some truck engines use a pickup coil mounted close
to the flywheel.
The tachometer is programmable and counts the number of teeth on the ring
gear then divides the pulses by the correct factor to get RPM. This is s
very accurate method suitable to very slow speed diesels.
Aetna makea very good tachometer package at a reasonable price.
Arild
-----Original Message-----
From: Scott H.E. Welch
Use a programmable tachometer with your alternator.
REPLY
I would strongly urge anyone who is retro fitting an new tachometer to their
engine to avoid the ones that rely on th xpulses coming from the alternator.
If you already have a smart regulator, you wil experience the disappearing
reading efect when the regulator senses ful charge and shuts of the field
circuit.
If you laster on decide to upgrade t oa bigger better or different
alternatot with a different pole count your tacj needs recalibration.
Tach circuits are prone to sensing any spikes and electrical noise that may
get into the charge circuit. this may cause the tach to read incorrectly.
The best and most reliable tachometers read pulses directlly from some
rotating shaft on the engine.
Sensors are available to pick up gear teeth count or magnets added to a
shaft or crank pulley. some use eflective patches plus an optical sensor to
read RPM.
The more pulses per revolution the more accurate at low speed. Which is why
ring gear tooth pickups are now the norm on most computer controlled
diesels. They can even tell if the starter circuit is working normally by
the slow crank speed
Arild
"Arild Jensen" 2elnav@netbistro.com writes:
I would strongly urge anyone who is retro fitting an new tachometer to their
engine to avoid the ones that rely on th xpulses coming from the alternator.
Arild makes an excellent point. The reason I am following this thread is that
I also have the problem of "jumping tach", when my 3-stage regulator goes to
float and the alternator output drops to a level where the tach has problems
reading the frequency of the pulses.
My Detroit has a standard 7/8" - 18 threaded tach drive for mechanical tachs,
and next summer I am planning on adding a standard VDO tach sender. These
devices connect to the tach drive shaft and output 16 pulses per revolution.
Note that this is an inline device so you can still connect your mechanical
tach. At $60 seems like a good deal.
For details see the following link:
http://www.egauges.com/vdo_indS.asp?Sender=VDO_GM_speedo&PN=340-012
Scott Welch
FirstClass Product Manager
www.firstclass.com
Those who make no mistake rarely make anything.
-----Original Message-----
From: Scott H.E. Welch
My Detroit has a standard 7/8" - 18 threaded tach drive for mechanical
tachs, and next summer I am planning on adding a standard VDO tach sender.
For details see the following link:
http://www.egauges.com/vdo_indS.asp?Sender=VDO_GM_speedo&PN=340-012
REPLY
That is not exclusive to VDO. Its the identical sender I fitted to an
Aetna Tachometer. - the same one used on USCG boats and a many other yachs
and work boata I have been on. Also works on Catapillar,, big Perkins, MANN
and Lehmans.. At least I saw a mechanical take off on the engine Bob Smith
had a Poulsbo trawler fest. It puts out pulses that can trigger almost any
tachometer.
This is almost a "universal" adaptor for when your motor has a mechanical
RPM tak off.
Lacking such a mechanical take of you can use the optical sensor which
requires placing one o rmore reflective spots on a crankshaft pulley
flywhel or other externally accessed rotating part. Remember more pulses per
revolution is better.
There are no balancing problems with a reflective tape spot.
Arild