Battery Charging

[Scorcher IV]

Hi,
I have replaced the two old 120Ah Varta batteries on my B37 with new 2 new 190Ah and a new starter battery, all Varta. I have a Quick SBC 500 battery charger and a standard 115amp alternator, can anyone tell me if I have enough charging capacity with the shore power charger and the alternator when underway to adequately charge the new bank as it feels as though they discharge very quickly when sailing.
Simon

[tiger79]

Yes, you have enough charging capacity.  How quickly did the old bank discharge when sailing?

[Scorcher IV]

Hi, towards the end of the original batteries life they discharged over a day sail, these new larger don't seem to hold the charge any better despite being a lot bigger. I have not had any breakers trip so i doubt I have a short anywhere, I wonder if my panel gauge is working correctly and telling the truth.

[symphony2]

Suggest you fit a battery monitor so that you know more accurately your pattern of charging and consumption. You have more than enough potential capacity and charging.

[Diverphil1]

You will get a slightly lower reading at the gauge than if you test directly at the battery terminals. I think ours reads about 1/4 volt less at the standard gauge. I'm not sure if you can re-calibrate the gauge or not. Try and check the voltage at the battery when charging with shore power and when charging with the engine.

[Scorcher IV]

Any suggestions on a good battery monitor?

[tiger79]

Any suggestions on a good battery monitor?

For a basic monitor, look at the Victron BMV700 or 702.  If you want something more versatile with a better display, look at the Simarine Pico - I fitted one of these a few years ago and it's been great.

[SYJetzt]

The standard voltmeter doesn't show the state of charge (SOC), but only the voltage. The only way to get a correct SOC is with a battery monitor. An existing charge splitter (usually the old ones with diodes) may affect the SOC, if the alternator sensor cable isn't wired correctly. Maybe you didn't wire it correctly after changing your batteries.