Verifying Alternator Output

[Gary Wyngarden]

Well I completed the installation of a new Balmar 110 amp alternator and a Xantrex three stage regulator yesterday. The alternator turns. There's no belt slippage. The voltage regulator lights up and appears to go through the various stages ok.But it would be nice to verify the charge that the alternator is putting out. My multimeter has a 10 amp limit. Anyone have any ideas on testing the alternator output? Thanks for your help.Gary WyngardenS/V Wanderlust H37.5

 

[Miles8313]

Get yourself a Link 10 (or 20)...

It's really nice to see how much current is flowing in or out of the batteries. Also shows voltage and estimated time remaining. Pretty handy.You could also check the battery voltage with your multimeter and see if it's at the appropriate level for the stage of charge the regulator is in. That would imply some current flow at least. You could load it down by turning on everything on the boat.I've got the same setup and on mine the you can hear the alternator and engine change tones as the regulator ramps up and load increases. It would tell you that something is happening but not any hard number of course.

 

[Derek Rowell]

Measure the battery voltage

Gary, A simple check is to monitor the battery voltage while charging. It should rise from the resting voltage to about 14.6 (or so - depending on the settings) during the bulk charge phase, then settle to a lower voltage during the absorption phase and about 13.6 volts in the float phase. The actual current flowing will depend on the state of your batteries. Don't expect to see 70 amps just because you have a 70 amp alternator. If the batteries are already charged you will see a much lower current, even in the bulk phase. In other words, just because you don't see a high charging current doesn't mean that the regulator isn't working.Derek

 

[Fred Ficarra]

Miles has the most accurate method and Derek

has a very practical and cost effective method. I use it. But I would caution against 14.6 volts for the acceptance stage. We blew two rectifiers this summer using that setting. Read all about it on photo #53 on my web site.

 

[Gary Wyngarden]

Thanks, Guys

I think Derek's method will provide the check I'm looking for.Gary WyngardenS/V Wanderlust H37.5

 

[Seattle Scott]

Gary, I had this question

for different reason. See thread on link for ways to measure your amps.

 

[Don12364]

Clip On Meter

Gary,The problem of inserting an ammeter in circuit is that the small volt drop across it will completely upset the charging current and this will reduce considerably. The workaround is to put the battery sense lead directly on the battery terminal.Or use a clip on meter. Its a handy thing to have anywayI bought a cheap plastic clip on ammeter from an auto supplies store. It is a bit rough and ready but is probably accurate to better than a few amps.Turn everything on, including the inverter & microwave - if you have one - then run the engine at about 2000 rpm and clip the meter on to the lead from alternator to battery. The alternator should attempt to compensate for the high battery drain and you should see it doing its best.

 

[Gord May]

Elect. Testing Help

Some great on-line resources from ‘FLUKE’:“Beat The Book” Testing Electrical Systems with a Digital Multimeterhttp://assets.fluke.com/appnotes/automotive/beatbook.pdfAutomotive electrical diagnosis. Better diagnosis, faster repairhttp://fluke.ma.informationstore.net/pubstore/a/10054-eng-01-a.pdfFrom ‘METERMAN’:1643518 - Boat Electrical http://assets.metermantesttools.com/howto/1643518-boat_Electrical.pdfandhttp://assets.metermantesttools.com/howto/1643507-Auto_Electrical.pdf

 

[Mike VanderVaart]

Amperage and voltage

Keep in mind that amperage is the amount of current and voltage is the push. You can have voltage with little current flow. The current and voltage will change with the state of charge of the battery. The best indicator is current or amperage if you can do it.

 

[jmcclain]

Verifying Alternator output!

I have the same basic setup in our boat, plus a Link 10 monitor. Based on your description, you have the all information that you need to determine if alternator is functioning. Your alternator will not advance beyond bulk charge stage unless there is a change in battery charge state. The fact that your alternator advances to a float stage indicates to me that there is a positive change in battery charge state. That can only occur in the presence of alternator output in excess of the circuit load. If you need to know exactly how much current is being generated you will have to measure output with a suitable ammeter. An ammeter that will accurately measure currents in excess of 10 amps usually requires the installation of a shunt similar to the one provided with the Link 10 monitor. You can hardwire a high current ammeter w/shunt, or better yet, install a Link 10 or Link 20 monitor. At the risk of overstating the obvious, did you remember to increase the alternator output cable to handle the increased output? Very important!Jons/v Beneteau 321