smart alt/reg v3 over charging

[gil waller]

Hi

My v3 seems to have gone crazy with overcharge. House bank is fine, fully charged but starting battery is getting instantly killed with something like 70 plus amps and starts boiling instantly - using conventional lead acid batteries. I changed the dip switches from all off to all on (for gel battery) and it started and worked perfectly. Next time I started the boat and moved out with 'full confidence' I started to smell gas, went and checked and the starting battery was boiling and blowing acid out the vents. Since then I've tried nearly every combination, disconnected the temp sensor, disconnected the parrallel wire, nothing seems to help at all. As soon as I start the motor and bring up a few revs, the voltage goes off the dial - 18 volts plus. Can you help?

Gil

[Coulomb]

Do you have a 1-2-both switch for battery selection?

[gil waller]

Yes I do, but have always run with just house bank turned on, should I try running them together? I seem to remember at least once I tried with both and still overcharged but not certain.

By the way I am in an isolated area in the far north of Australia so may have some delay in replying at times

Many thanks
Gil

[Coulomb]

There are a few reasons that a 1-2-both switch should not be used. See this URL for the #1 reason:
http://www.amplepower.com/apps/burnt_sw/index.html.

The starter battery can't be charged unless the switch is at the starter battery position or the switch is in the both position.
If it is the starter battery position only, then you will have the symptoms you describe, because the regulator is sensing the house battery.

Please look at our wiring diagrams and convert you wiring such that the switch is only a parallel switch. See this URL for an example:
http://www.amplepower.com/primer/retro/index.html

[gil waller]

Isn't having both on a parallell?

I always run with only the house switched on and Starter battery off. Will try with heat and parallell wires re-connected and both batteries on, and report back

Thank you
Gil

[Coulomb]

In that case, how does the starter battery get charged? And how does it get overcharged when the house battery isn't?

Answer: The selector switch was on the starter battery but the regulator was sensing the house bank.

[gil waller]

I understood the regulator could charge both banks independently but with only one on to draw power from like my 240 volt Baintech charger.

You suggestion has worked, with both banks switched on the charging seems to be working perfectly. Only odd thing, and I don't know enough to know whether it is important, the starter bank has 2 heavy duty wires on the positive, one shows say 6.5 amps of power and the other says perhaps -5.7 amps. What worries me a little is that the house bank at the same time reads a minus of maybe 5 or 6 amps, does that mean it is discharging and not charging?

Also, when the 240 charger is running and the v3 is off, the amperage readings at the starter battery are the other way around, the wire that showed positive amps, now shows negative amps and the second wire reads the positive. Is this indicative of a possible wiring problem or is it likely that it doesn't matter? As far as I can tell, everything seems to be ending up about right now.

Appreciate your help so much
Many thanks
Gil

[Coulomb]

The current measurements are suspicious, but without a wiring diagram no conclusion can be drawn.