will try this again. got cut off when trying to post this a while ago. I would like to be able to monitor amperage output of my alt.I have been having problems recharging my batteries. checked voltage with digital voltmeter and its putting out the required voltage of 13.65 but don't know amperage output. i know that it can be generating correct voltage but not putting out the amps. anyone have an inexpensive setup to monitor this. i don't want to dig out my clamp on ammeter ever time i want to check current output. i also don't want to spend 3 or 4 hundred bucks to monitor this.
want to monitor amp output of alt
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How about a simple in-line ammeter?
Old cars used to have them and I think they can still be purchased as an add-on accessory. Probably JC Whitney is a source. If you have the standard alternator, a meter that shows a center zero and +- 30 or 40 amps would suffice.
Alternatively, you could obtain and wire a low resistance current shunt in series with the battery. Typically this would be a precision 1 milli-ohm high-current device. Then you would just measure the voltage drop across it with your digital voltmeter. For every amp you would measure 1mv.
However,since you already have a clamp-on ammeter, you already have the most convenient measuring device for this task IMHO.
Old cars used to have them and I think they can still be purchased as an add-on accessory. Probably JC Whitney is a source. If you have the standard alternator, a meter that shows a center zero and +- 30 or 40 amps would suffice.
Alternatively, you could obtain and wire a low resistance current shunt in series with the battery. Typically this would be a precision 1 milli-ohm high-current device. Then you would just measure the voltage drop across it with your digital voltmeter. For every amp you would measure 1mv.
However,since you already have a clamp-on ammeter, you already have the most convenient measuring device for this task IMHO.
Depends on how big your alternator is
If it's OUTPUT is larger than 25 amps, you'll need a separate shunt with a meter. If it's less then the 25 amp Blue Seas ammeter will work. I don't recommend it, since that ammeter is very good for reading DC loads from your Distribution Panel, but too small to use with an alternator "working" to charge a depleted house bank.
Either use your clamp on, or bite the bullet and buy a real ammeter and install it (with its separate shunt). The only reason the shunts can't be built-in beyond 25 amps is that they simply get too big physically.
If it's OUTPUT is larger than 25 amps, you'll need a separate shunt with a meter. If it's less then the 25 amp Blue Seas ammeter will work. I don't recommend it, since that ammeter is very good for reading DC loads from your Distribution Panel, but too small to use with an alternator "working" to charge a depleted house bank.
Either use your clamp on, or bite the bullet and buy a real ammeter and install it (with its separate shunt). The only reason the shunts can't be built-in beyond 25 amps is that they simply get too big physically.
A Link 10 or XBM
will be some of the best money you've ever spent on your boat. I can't believe I lived without one for soooo long. I've had one installed on the last five boats and will not ever own one again without one..
will be some of the best money you've ever spent on your boat. I can't believe I lived without one for soooo long. I've had one installed on the last five boats and will not ever own one again without one..
I just did some digging!
looking in my engine manual I have a 35amp alt. it specs output should be 14.3volts +-0.3v. so since i was reading 13.65v i suspect that its going or gone south. i quess i should'nt be surprized since its the original and its a 1979 model. thanks for some very good ideas on where to find a setup.
looking in my engine manual I have a 35amp alt. it specs output should be 14.3volts +-0.3v. so since i was reading 13.65v i suspect that its going or gone south. i quess i should'nt be surprized since its the original and its a 1979 model. thanks for some very good ideas on where to find a setup.
Amp monitoring
It is not useful to monitoring the charging current as it depends on the battery and all other draws.
If the alt can pump out 14+ volts, it is working fine. If you are getting 13.6, the regulator may be shot.
It is not that expensive to replace the regulator. Most automotive electrical shop can do that inexpensively. One thing to consider is to move the voltage sensor to the battery terminal instead of the alternator output. That reduce the effect due to voltage drop of the wire. Again automotive electrical shop can do that easily.
Another thing to have a closer look is the charging indicator lamp. If due to corrosion or poor contact, the alternator will not produce output or very little. The indicator lamp is the source to "excite" the rotor winding before self-sustaining voltage can be generated. Normally the lamp acts as a resistor. It doesn't grow unless over-voltage or no-voltage.
It is not useful to monitoring the charging current as it depends on the battery and all other draws.
If the alt can pump out 14+ volts, it is working fine. If you are getting 13.6, the regulator may be shot.
It is not that expensive to replace the regulator. Most automotive electrical shop can do that inexpensively. One thing to consider is to move the voltage sensor to the battery terminal instead of the alternator output. That reduce the effect due to voltage drop of the wire. Again automotive electrical shop can do that easily.
Another thing to have a closer look is the charging indicator lamp. If due to corrosion or poor contact, the alternator will not produce output or very little. The indicator lamp is the source to "excite" the rotor winding before self-sustaining voltage can be generated. Normally the lamp acts as a resistor. It doesn't grow unless over-voltage or no-voltage.
Jim, I tried to post a reply this morning and had it get lost
A one foot long piece of number 10 wire is one milliohm of resistance. If you install such as that in the output of the alternator and measure the voltage across it, one millivolt will equal one amp of current flow. With a good digital V-O-M that is do able.
A one foot long piece of number 10 wire is one milliohm of resistance. If you install such as that in the output of the alternator and measure the voltage across it, one millivolt will equal one amp of current flow. With a good digital V-O-M that is do able.
I think my plan of action at this point!
I have a spare alt that needs a new regulator. there's a local alt/starter shop that said they could rebuild it for about $75. my local parts dist said he can order me either a 30 or 60 amp add on gage for about $15. this would be a truck gage that is 2" in dia. and this is all i need.
thanks all.
I have a spare alt that needs a new regulator. there's a local alt/starter shop that said they could rebuild it for about $75. my local parts dist said he can order me either a 30 or 60 amp add on gage for about $15. this would be a truck gage that is 2" in dia. and this is all i need.
thanks all.
Jim be careful..
wiring in an amp meter without an external shunt. Most truck ameters interrupt the charging circuit so your entire load to your battery may have a 10, 12, 15 or even 30 foot run of wire before it gets to your batteries.
Many early Universal and Westerbeke panels came wired this way and most owners very quickly ripped out that circuit in place of a more direct path.
You alt sounds to me like it may be working just fine. It all depends on where and how you measure the voltage. 13.65 is well within the voltage drop range.
wiring in an amp meter without an external shunt. Most truck ameters interrupt the charging circuit so your entire load to your battery may have a 10, 12, 15 or even 30 foot run of wire before it gets to your batteries.
Many early Universal and Westerbeke panels came wired this way and most owners very quickly ripped out that circuit in place of a more direct path.
You alt sounds to me like it may be working just fine. It all depends on where and how you measure the voltage. 13.65 is well within the voltage drop range.
1 Foot of number ten wire is an external shunt.
Ann analog meter movements are either micro amp or milli amp meters adapted to read what ever you need. Volt meters just have a resistor in series with the movement and amp meters have a shunt in parallel with them. You can buy 0-10 micro amp movements.
Ann analog meter movements are either micro amp or milli amp meters adapted to read what ever you need. Volt meters just have a resistor in series with the movement and amp meters have a shunt in parallel with them. You can buy 0-10 micro amp movements.
Capt Jim, remember it will read 13.65v (or less) if your batteries are not full
If you ran your batteries down or they are just old weak batteries it may take a long time before the Alternator puts out a full 14+ volts. I am assuming there is a simple (3 stage?) internal regulator in you alternator like my old original alternator had.
Some questions. How big is your battery bank? Were these batteries fully charged before you ran the engine or did you run the batteries down? How old are the batteries?
Also I bet you would be lock to get very much more than 20-25 amps out of a stock 35A rated alternator even when the batteries were all the way down.
PS. I also highly recommend a Link 2 battery monitor (or equivalent) its one of the best things I put on my boat and will be on any of my future boats if I go cruising.
If you ran your batteries down or they are just old weak batteries it may take a long time before the Alternator puts out a full 14+ volts. I am assuming there is a simple (3 stage?) internal regulator in you alternator like my old original alternator had.
Some questions. How big is your battery bank? Were these batteries fully charged before you ran the engine or did you run the batteries down? How old are the batteries?
Also I bet you would be lock to get very much more than 20-25 amps out of a stock 35A rated alternator even when the batteries were all the way down.
PS. I also highly recommend a Link 2 battery monitor (or equivalent) its one of the best things I put on my boat and will be on any of my future boats if I go cruising.
Unfortunately..
Quote: "PS. I also highly recommend a Link 2 battery monitor (or equivalent) its one of the best things I put on my boat and will be on any of my future boats if I go cruising."
Unfortunately you can't explain the benefits of a Link or an XBM successfully to a would be buyer. I've tried several times..
Once someone see's one, and plays with it, they are SOLD. I have had three people try mine and play with the parameters and then buy one within a few days.
Quote: "PS. I also highly recommend a Link 2 battery monitor (or equivalent) its one of the best things I put on my boat and will be on any of my future boats if I go cruising."
Unfortunately you can't explain the benefits of a Link or an XBM successfully to a would be buyer. I've tried several times..
Once someone see's one, and plays with it, they are SOLD. I have had three people try mine and play with the parameters and then buy one within a few days.
A 35A auto-type alternator will only put out.....
about 2/3 of that nameplate 35A rating. This is due to the industry practice of specifying the output as PEAK amps and not RMS (or average) amps. Given an alternating current waveform inside the alternator, the internal bank of six rectifying diodes will deliver the rectified DC output. However the average or more correctly the Root-Mean-Square (RMS) value of that current will be only about 2/3 of the peak. Hence, 2/3 of 35A is about 23.3A of DC current.
AND, that maximum value will only be observed if the alternator is running flat out (otherwise known as full-fielded). If the internal regulator is throttling back the alternator you will see less current.
To put this in the real-world perspective, suppose you have a battery bank of two group 24 deep cycle batteries. I think these have about 90-100AH of capacity each. In parallel you would have about 180-200AH. At a 50% discharge you would be trying to replace about 90AH into the batteries. If your alternator could run at max output (and it can't BTW), it would take over four hours of engine running to recharge fully. Don't forget that due to charging inefficiencies you need to replace about 5% more AH than you took out.
In short, you may have a perfectly good alternator but realistically under-sized for your recharging task.
Any decent auto electrical shop can test your alternator in a few minutes and tell you what if anything is deficient. Beyond that, I think your solution will be a larger alternator that is designed for continuous high output, and MORE importantly, an external regulator that is actually designed to recharge deep-cycle batteries.
about 2/3 of that nameplate 35A rating. This is due to the industry practice of specifying the output as PEAK amps and not RMS (or average) amps. Given an alternating current waveform inside the alternator, the internal bank of six rectifying diodes will deliver the rectified DC output. However the average or more correctly the Root-Mean-Square (RMS) value of that current will be only about 2/3 of the peak. Hence, 2/3 of 35A is about 23.3A of DC current.
AND, that maximum value will only be observed if the alternator is running flat out (otherwise known as full-fielded). If the internal regulator is throttling back the alternator you will see less current.
To put this in the real-world perspective, suppose you have a battery bank of two group 24 deep cycle batteries. I think these have about 90-100AH of capacity each. In parallel you would have about 180-200AH. At a 50% discharge you would be trying to replace about 90AH into the batteries. If your alternator could run at max output (and it can't BTW), it would take over four hours of engine running to recharge fully. Don't forget that due to charging inefficiencies you need to replace about 5% more AH than you took out.
In short, you may have a perfectly good alternator but realistically under-sized for your recharging task.
Any decent auto electrical shop can test your alternator in a few minutes and tell you what if anything is deficient. Beyond that, I think your solution will be a larger alternator that is designed for continuous high output, and MORE importantly, an external regulator that is actually designed to recharge deep-cycle batteries.
Battery Monitors
I agree with Maine Sail's Reply #13. I actually did everything backwards, myself. Left the Link 2000 to the very last.
What I learned:
1. My energy budget numbers are almost exactly on target (see my post on that earlier) for amps being taken OUT
2. My energy budget for RECHARGING was WAY, WAY OFF. It takes much longer to charge, even with a shorepower charger, than I had thought. This is IMPORTANT to know for REALLY extended cruising. The “steadily diminishing law of returns” from my earlier post on that subject goes like this:
See the whole discussion at the link.
I agree with Maine Sail's Reply #13. I actually did everything backwards, myself. Left the Link 2000 to the very last.
What I learned:
1. My energy budget numbers are almost exactly on target (see my post on that earlier) for amps being taken OUT
2. My energy budget for RECHARGING was WAY, WAY OFF. It takes much longer to charge, even with a shorepower charger, than I had thought. This is IMPORTANT to know for REALLY extended cruising. The “steadily diminishing law of returns” from my earlier post on that subject goes like this:
See the whole discussion at the link.
cruising without a battery monitor...
...is like sailing without telltales on your jib. It can be done, but why?
I've either been hanging on the hook or sailing for three of the past four weeks, and I haven't referenced a single gauge during that time more than the battery monitor. With my current solar panel/wind turbine combination I've discovered that I'm able to anchor indefinitely in 90 degree heat if I run the fridge but not the freezer. Next year I'll be able to keep the freezer online as well because I know how much more wattage I need to generate each day thanks to the battery monitor. (Adding a single 123-watt panel will do it.) The monitor takes a lot of the guesswork out of energy budgeting that you end up doing with just a voltage meter.
I used a Link 1000 on the last boat, but have been able to do just fine with a Link 10 on the new boat. I don't miss any of the "extra" features the Link 1000 gave me, because I can access all those through my charger console.
...is like sailing without telltales on your jib. It can be done, but why?
I've either been hanging on the hook or sailing for three of the past four weeks, and I haven't referenced a single gauge during that time more than the battery monitor. With my current solar panel/wind turbine combination I've discovered that I'm able to anchor indefinitely in 90 degree heat if I run the fridge but not the freezer. Next year I'll be able to keep the freezer online as well because I know how much more wattage I need to generate each day thanks to the battery monitor. (Adding a single 123-watt panel will do it.) The monitor takes a lot of the guesswork out of energy budgeting that you end up doing with just a voltage meter.
I used a Link 1000 on the last boat, but have been able to do just fine with a Link 10 on the new boat. I don't miss any of the "extra" features the Link 1000 gave me, because I can access all those through my charger console.
A battery monitor might be a nice toy!
I have had this boat for 18 years and until now have never had any problems. my power demands on this boat are very minimal. needs are battery to start the motor,lights,wind instruments,depth sounder and bilge pump, oh and cellphone charger.
I have a new grp27 house battery, a very old, (10yrs) grp24 starting battery, that i know is toast. it now won't keep a charge. i have been using my house battery to start the last few weeks.
while i think that a monitor would be nice, i don't think its a necessity for me. i feel a more prudent spending of the money would be a solar panel to keep the batteries topped off.
I completely forgot about the fact that alt are rated at peak output as opposed to rms.
I have no worries about voltage lose to the batteries as my cables are way over sized.
right now my biggest problem has been the damn bilge pump running to much. but i pretty much have that cured by rerouting it to discharge into the galley sink drain line. it was routed to a discharge in the stern before and the back flow after it shut off from the long run of hose just had it starting right up again in a few minutes. I have an extremely flat and shallow bilge so 1 qt of water kicks the pump on.
I think i have that solved now as when we got to the boat this weekend i had a completely dry bilge.not one drop of water in it, and this was after not being used for 3 weeks.
I have had this boat for 18 years and until now have never had any problems. my power demands on this boat are very minimal. needs are battery to start the motor,lights,wind instruments,depth sounder and bilge pump, oh and cellphone charger.
I have a new grp27 house battery, a very old, (10yrs) grp24 starting battery, that i know is toast. it now won't keep a charge. i have been using my house battery to start the last few weeks.
while i think that a monitor would be nice, i don't think its a necessity for me. i feel a more prudent spending of the money would be a solar panel to keep the batteries topped off.
I completely forgot about the fact that alt are rated at peak output as opposed to rms.
I have no worries about voltage lose to the batteries as my cables are way over sized.
right now my biggest problem has been the damn bilge pump running to much. but i pretty much have that cured by rerouting it to discharge into the galley sink drain line. it was routed to a discharge in the stern before and the back flow after it shut off from the long run of hose just had it starting right up again in a few minutes. I have an extremely flat and shallow bilge so 1 qt of water kicks the pump on.
I think i have that solved now as when we got to the boat this weekend i had a completely dry bilge.not one drop of water in it, and this was after not being used for 3 weeks.
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