Question concerning a 30amp plug charging a 230volt system

[David B]

Originally Posted by sail2bluesue

Hello,
We have a Jeanneau 43' Sun Odyssey DS and currently live aboard in Mexico. We have a 230V panel, and the shore power plug is a 30amp plug. We have two banks of batteries, and two Xantrex battery chargers. We also have solar and a generator.

The problem - We are having to replace our 8 AGM house batteries after only 4 years. We are being told that part of the problem may be that the shore power charging amps are not sufficient for the 230v system, so we have been undercharging the batteries when on shore power (which isn't too often). However since both the shore power plug and the circuit board were installed by the manufacturer, we're having a tough time processing this in our electrically challenged minds.

Does anyone have any input about whether 30amp shore power is not sufficiently charging our batteries? Should we have a higher amperage shore power for a 230v system?

Any info is appreciated!
Thanks,
Sue and Marty McDaniel
s/v Happy Dance

Seeing you are where you are, I think it safe to say you have a 110V 60Hz shore power system. The AC control panel may well be labelled 230V however. If the shore power system was inadequate capacity, then you would be tripping a breaker, not under charging your batteries. Assuming no other load, a 110V 15A system (let alone 30A), should be able to run 80A of charging capacity.

If you have 8 AGM batteries, that is four more than the normal maximum FLA service batteries fitted to such a boat. With 4 x FLA batteries, you would normally have two 40A chargers (quite likely Dolphin brand). If the capacity has been increased to eight AGM's (assuming they are not small ones), then you need more charger capacity to avoid overly long charging periods.

Do you know the capacity of your entire service battery bank (Ah or ampere hours)? Normally you would be looking at a charging capacity of around 40A per 200 - 300 Ah battery capacity max.

Another tip - if you are leaving your boat at end of season, are you turning all of the battery isolators off? In the 'off' position, the chargers should still be connected, but everything else is not - therefore no drain on the batteries other than self-discharge.

I tend to agree with other comments here - value vs capacity vs service life, it is hard to go past good quality FLA batteries. We use good quality 140Ah truck batteries, and from past experience, expect around six years or so out of them. I do give them an equalisation charge at least once a year. Other than that and ensuring they are not overly discharged, that's it.

I hope that helps.

David

[FionaJC]

You have tons of power to charge them at 30A / 230V
I am going to make this very simple (and assume 100% efficiency, linear charging, capacity at 0 and a direct VA=W)

230V x 30A=6,900W or 6.9kW. If you are able to draw all that then your interior must be nice and warm as that will dissapate as heat.

The charging system will take what it needs for example in simple terms 110A battery will need 3.7hours to charge at 30A

That means it has used 30A for that time at 12V which is 360W (assuming 100% efficiency which is impossible), assuming loads of losses and charging at 100A you would only be looking at 1200W which is miles below your available power of 6900W.

So either your powers out of wack, your batteries are toast or your charger is fried.

I had a charger delivering 35A / 19.5v and my batteries were dying. I didnt suspect the charger and changed the batteries, when they died after a fortnight on mains power I checked everything. Because im on a non mains powered pomntoon my charging was solar and engine. I changed the charger and added a battery management monitor.