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emon h1a/acs/sarv2/agm batteries

PostPosted: Tue Mar 02, 2010 11:22 am
by Neil
working on a customers boat with above setup. initial call was for overvoltage charging. initial investigation found ~50% of crimp connections were bad - wires almost fell out. repaired all crimps and got error message of bad battery temp sensor. replaced sensor and checked out alternator - all charging & seemed Ok.

Called back - still overcharging. More investigation of wiring compared to drawing AT9401262 showed that someone had added a ground wire connection to TB2-3 on SARv2 without removing the connection to EMON 1-1 (Vref). Measuring the output of EMON 1-1 shows 0V (actually ~10mV but this is likely noise).
Question - if EMON 1-1 is shorted to ground will it cook the internal Vref of EMON? What should I see on 1-1? My understanding would be 1/10th of target voltage set on EMON.
fyi TB1-3 is 0.14V, TB2-2 is 9.26V, TB2-3 is 0V

Removed connection. Noticed that with-out TB2-4 grounded the SARv2 responds only to internal regulation. In this mode SARv2 from turn-on steps up through float to 14.9V - seems high.
Connect gel to gnd & voltage is reduced to 14.7V - seems high but better
connect lock to +ve voltage is reduced to 13.6V - this seems correct
connect remote to gnd - voltage goes to 13.2 - but no field voltage (0.23V) which makes sense to me when TB2-3 is 0
Question - why is charge voltage so high when not in lock? can it be adjusted?
Observation - link to SARv2 data seems to be inaccessible - old manuals link takes me to current manuals

Re: emon h1a/acs/sarv2/agm batteries

PostPosted: Wed Mar 03, 2010 12:52 am
by Coulomb
The regulator appears to be working - it went down when gel was grounded. What's the battery temperature? You can disconnect the T+ terminal from the regulator to see what the voltage goes to - it assumes temperature is 25C without the temp. connection.

The Emon probably has a shorted amplifier that produces Vref after being shorted to ground.

The SAR V2 was last made in about 1993. Isn't it about time to upgrade to a V3?

Re: emon h1a/acs/sarv2/agm batteries

PostPosted: Thu Mar 04, 2010 3:18 pm
by Neil
Removed T+ on SARv2 and found charge voltage drops to 14.2V (gel mode). What is the voltage rise per degree C drop below 25C?

In a move towards a new V3 for the customer, I suggest removing EMON and ACS wires to VREF, IREF and ISENSE on SARv2 - do you agree?

How long does SARv2 and SARv3 stay in absorption mode before moving to float? Is it strictly time or is it related to field output volts?


Re: emon h1a/acs/sarv2/agm batteries

PostPosted: Thu Mar 04, 2010 7:09 pm
by Coulomb
Temperature compensation isn't linear, but over a small range it is about 0.005 Volts per 2-V cell.

The SARV3 doesn't use the Vref and Iref signals.

Absorption time is fixed on the V2, but on the V3 an algorithm is used to limit absorption time when the battery doesn't need it.