On Board Battery Charger

First, if you are running down your house battery until things start to beep then you are probably running it down too far. I think for the items you are running you should have 2 house batteries.

How long are you running the generator and charger for to charge the battery? A run down battery can take several hours to charge.

How many amp hours is your house battery? Remember, you can only use half of a batteries amp hours if you want the battery to last. So if you have a 100 amp hour battery you should only use 50 before charging. Running 2 fridges along with other items will eat up 50 amp hours in 8-10 hours or so. That will depend on how efficient your fridges are.

On a recent 6 day outing we did the following. We have 2- 100 amp hour batteries in parallel. 2 fridges, stereo, toilet, water pump etc. we woulld run the generator for around 3 hours each evening to change the batteries, use the AC, and grill. At around the 3 hour mark the batteries were fully charged and the charger went into standby.

Correct, I have gone 21 hrs between charging. That is with 2- 100 amp hour deep cycle batteries. At some point I plan to install a wireless battery monitor system like this one

www.amazon.com/Bluetooth-Battery-Monitor-Power-Meter/dp/B075828HGS

We have 2 batteries on our 28 Express (1 engine, 1 house) with no built in generator. When we stay on our mooring ball 2-3 nights at a time we run the fridge the whole time and run the stereo during the day, charge phones etc. I run the boats engine about 3 times a day for a about 15 minutes each and we stay charged up. It helped tremendously when I changed ALL of the lights on the boat to LED. Made a huge difference in power consumption. I do carry a portable 2200 generator and will sometimes turn on the battery charger after running the cooktop, microwave or coffee. But running the boat is a little quieter and heats up the water tank!

Hi

I have a 2016 28 Express with no gensest as well. I've switched the  two batteries to AGM types and the house battery is a group 31 at 100 amps. I've added a 3rd group 31 100 amp AGM centered over where the gensest would be and it's wired into a 1 KW sine-wave inverter which feeds one side of a transfer switch in the cabin. I have 2 high resolution voltmeters in the electrical panel area to monitor the house and inverter batteries voltage readings.

My charger is a Pro-Nautic 40 amp ( 3 outputs) so all 3 batteries are being charged when on shore power. On the water, I currently have one 100 watt flexible solar panel which can provide about 5 to 6 amps to help offset the current drawn by my 2 refrigerators, stereo, chart plotter use, etc. by charging the house battery (or the inverter battery). Optimally, I'd like to add a 2nd 100 watt panel so that I can charge both the house and inverter batteries simultaneously, or by paralleling the outputs, one or the other.

Biggest problem is the solar panels on top of the bimini - the bimini canvas needs protection from even these light-weight flexible panels - I'll probably get pouches made to hold them in place permanently.

I notice that your charger is pegged off-scale so assume you're showing it at maximum output (ie: 30 amps or so)?

Rick

I have a 2003 2665 commodore and like several boaters here, we have no genset and operate on a 2 battery system hooked up to an onboard charger. I replaced the original batteries with AGM and they are still running strong after 5 years. With the selector switch, either one can be used as a starter/house battery. Every outing I will alternate which battery is being used for the weekend. As stated earlier, changing all the lights to LED most definitely cut down on power usage when we are on the hook. The biggest user of juice is the amped up stereo system but normally, we will be moving from spot to spot during the day so the batt will recharge during that period. To date, I have never had a low/dead batt when waking up in the am and cranking up the engine. In an emergency, we have a Honda 1000 portable on board.