Charging House Battery from Alternators

[Tireless]

I was on the hook this weekend and needless to say I was on my house battery with periodic generator use. The house battery was charging fine while using the generator in the morning and in the evening to boost things up.

The problem I am having is charging my house battery when I am underway. My alternators charge all my batteries when I am underway. I have a hi-amp breaker under my step that is connected to the alternators line to the house battery. When the house battery is low, like after a weekend out, it appears that the breaker trips, almost like it can handle the amps coming from the alternator to charge the house battery. If the house battery voltage is slightly low, this does not occur.

I don't believe it is the battery, as it is a 2 year old 4D AGM, that charges fine on shore/genny power.

I am not sure what the issue is. Maybe a faulty hi-amp breaker?

Does anyone have an idea on what I could do to trouble shoot this issue.

Greg

[Midnightsun]

My initial thought would be the high amp breaker going bad however before you dish out for a new breaker, pull wires from both the breaker and the alternator, clean the contact area real well and reassemble as any poor contact will cause a high amp situation and will trip the breaker. If you have lots of slack in the wires, maybe cut off the last inch and skin for a like new connection.

The more a battery is drawn down the more the charging source will be taxed to input juice back to the batteries and this is why you do not see the issue when the bank is rather full. Regardless, even if the alternator/s were at max capacity the breaker is designed for this and should not trip.

Bottom line, check all connections and condition of wires first.

[bud37]

I agree with Hans, when you pull the battery/bank way down it will take quite an initial amp charge. What I have found to help me on several boats to keep track of battery banks, state of charge and charging issues is a battery monitor, like the Victron bmv series, there are a few makers but Victron is what I installed and would not have a boat without that feature.

You can watch all 12volt loads on the boat with one.

[Tireless]

Midnight Sun, I will have a look at the connects as you advised and we will see what's up. Maybe I will put a tester on the alternators as well. Is it possible that they may be putting too much out? I understand what you're saying about an increase in amps with bad connections.

Bud37, your idea is a good one to monitor the status of all batteries. In fact I installed a USB port in the dash that has the volt readout on the house, as it runs the dash. That's exactly how I was able to see what the house battery was doing, charging, or not, while I was underway. I will check out Victron BMV Series. Where would they connect to to get a read on all batteries?

Thanks guys.

[bud37]

That type on monitor has a shunt in the ground from the banks......on their site there are manuals and diagrams explaining, but it is very easy to do. The shunt allows you to also monitor amp draws out and in, whereas a volt meter just tell you the battery voltage which really is not enough for this level of boating.

[km1125]

You didn't say how large that "high-amp" breaker was. Do you know? Is there one of these for each engine, or are the engines combined somehow and that output goes though one breaker?

As a workaround, you might start the genset before the mains and recharge the battery even just a bit (10-15 minutes) so the mains don't see quite as depleted a battery when they come online.

[Tireless]

km1125

There are two breakers of similar size under the step. Only the one trips. I assumed it was the house battery only as the batteries for the engines never get too low. I have a group 31 for each engine, group 31 for the bow thruster, group 24 for the genny and there 4D for the house.I will look into that possibility.

Thanks

Greg