low charge output from SAR V3 & EMON H1??

For all issues involving the Smart Alternator Regulators, V1, V2 and V3

Re: low charge output from SAR V3 & EMON H1??

Postby mmorgan on Mon Sep 20, 2010 1:26 pm

You may have taken all the troubleshooting measurements but you haven't shared them.
MM:> what other data do you need, I have the troubleshooting worksheet I can fax to you.
Here is the set of readings from top to bottom, taken with Fluke 189 logging DVM, from house battery to reg terminals. 1st reading is engine off. 2nd reading is engine on, system running.
Note these readings show good output initially, but by the time we finished this (approx 15 minutes) output current had fallen from 323 amps to less than 100 amps.
#1 parallel: (not connected)
#2 on-off : .0005 / 14.43
#3 ground: .0004 / .0015
#4 batt +: 12.800 / 14.204
#5 field : .0010 / 6.16
#6 alt gnd: .0010 / .0020
#7 lock (not connected)
#8 batt volts: 12.794 / 14.31
#9 T- : 0.000 / .001
#10 T+ : 2.98 / 2.900
#11 ABS : 8.312 / 8.311
#12 Error lamp: 0v / 0v
#13 status lamp: off / on 1 sec, off 3 sec
#14 limit (not connected)
EQL ( not connected)

During the bulk charge cycle the field voltage output is almost equal to the voltage on the B+ input. A field voltage less than that indicates that the regulator has cut back as it should when battery voltage reaches the setpoint. Which is it in your case?
MM:> The field voltage was approx 6 ~ 8 volts, so it looks like the regulator had already cut back the field current prematurely well before reaching the absorption setpoint. During the beginning bulk charge cycle we would expect nearly batt voltage on the field, but it is much lower, why?

You have 0.6 to 0.7 Volts difference between alternator output and the batteries.
MM:> this is while charging well over 200 amps, either during the 1st few minutes before the reg cuts back, or during the full field tests. 0.7v drop at these high currents is actually pretty good.

Where is the ground wire for the regulator connected? It should be at the batteries so there should not be a voltage difference between them.
It there is then that voltage essentially make the B1V sense input higher by that amount.
MM:> the + /- regulator sense leads, and the reg power wire are connected to the main bus bars where the separate banks come together. This is the most voltage stable point in the system, and the only viable connection point in the system, as one of the banks may need to be switched off if one bank goes critical for some reason.

With the voltage drop between the alternator output and the batteries some calculations can be done to determine wiring resistance. At 0.6V and 100 Amps, the resistance is 0.006 ohms, which indicate 75 feet of #00 wire. How long are the wires?
MM:> total run for both conductors is about 25ft from alts to bus bars, then 10 more ft to the closest bank, and about 70ft from bus bars to the farthest bank.

It might be illuminating to find out where the voltage is being dropped along the circuit -- it's 60 Watts, so there must be some heat generated -- maybe in the switches?
MM:> No but the EMON shunt gets pretty hot, the fuses rose about 5 degrees over ambient.

Have you measured the difference in voltage between the alternator negative and battery negative? Is it also offset by 0.6V? Are you using a separated wire from alternator negative to battery negative, or relying on engine metal?
MM:> there is a #2/0 cable from EACH alternator negative term to the main neg bus bar. There are (2) 12"long #2/0 cables from the bus bar to the EMON shunt. Then the shunt has 2 SEPARATE #2/0 cables connecting to the battery banks, because they are in different places.
The .6v was the total difference between what we measured at the alt output terminals, and the battery terminals. Did not check drop along each part of the system, but did do thermal readings everywhere several times to make sure nothing was getting hot.

No data that you have presented indicate a regulator problem. You can send one or both regulators in for a check up, but at this time more testing of wiring is recommended.
MM:> Why is the field voltage so low, when the batteries are clearly not fully charged? Most of the time the output current drops off even before we reach the absorption setpoint? Here we can see the system had output volts at 14.3 for a few minutes, but then it falls to about 13.5 after just a short time.
M Morgan
Morgan Designs, Inc.
Morgan Marine Engineering
Corrosion & Electrolysis Inspections
Yacht Electrical Systems & Design
Posts: 6
Joined: Tue Sep 07, 2010 1:05 pm

Re: low charge output from SAR V3 & EMON H1??

Postby Coulomb on Mon Sep 20, 2010 4:59 pm

Battery voltage on Pin 8 is 14.31, indicating that the regulator is at the absorption voltage. The temperature probe indicates a rise in temperature of 8 degrees C. Based on that, the battery voltage is a little higher than what may be good for the batteries.

At this point, the regulator is operating in constant voltage mode. Current flow into the batteries is totally dependent on the absorption rate that the batteries will accept.
You might review the information here: http://www.amplepower.com/primer/full/index.html

You can disconnect the T+ wire from the regulator if you want to defeat temperature compensation. That will drive the set point up, but obviously not the best thing for the batteries.

You can break in the batteries which will increase their absorption rate. See http://www.amplepower.com/primer/break-in/index.html

The regulator is doing what it is designed to do - charge batteries properly. At the absorption set point the batteries accept what they will. That depends on their state of charge, and to a large degree, the thickness of the plates.
Site Admin
Posts: 1174
Joined: Sat Jun 06, 2009 5:11 pm


Return to Smart Alternator Regulators

Who is online

Users browsing this forum: No registered users and 2 guests