Electrical problems.

Hello all.
First time post. We are moving up the Qld coast on our 10 meter Elite cat. Left yhe Gold Coast a couple of weeks ago. Currently anchored at 1770 after coming in fromvLady Musgrave.
Im having problems with batteries getting low.
The house batteries are 2 banks made up of 2 ? 6 volt US 2200 golf cart batteries rated at 232 amo hrs. When charging they are over 13 volts. sfter charging yesterday after noon for instance they settled back to 12.2 volts. Last night we had the freezer running , anchor light and a tv for about 2 hours. This morning the batteries are at 11.1 volts. I have had these type problems since purchasing the boat 2 months ago, hence the new battery banks. The charging system has been checked ( 1 ? 80 amp alternator on each engine ) and given the all clear. For various reasons I will be here at 1770 for probably another week. Does anyone know of a marine electrician in this area. Any help and advise will be appreciated

Are you making sure they charge high enough? With solar wet batteries can get up to 14.4 to 14.7 volts. Only getting to 13 seems very low. If you are only running the engines for power the alternators may be regulating themselves back to a trickle charge.

At 11.1 volts your batteries are pretty much totally discharged. So if your alternators can put out 30 amps you have to run one motor for 230/30 = 7.6 hours to get them charged. It is worse than this as you can't charge them hard at the end of the charging cycle. Unless your alternators are fitted with smart regulators they may be backing off the charge as soon as the batteries have a surface charge. Getting to 13 volts when charging is nothing, the batteries need to get to 14.4 min volts under charge so I would be looking at the charge circuit, you are not getting enough amps in to the batteries.

At first I thought that you needed new batteries as they are behaving like dead batteries. Otherwise you may be just drawing too much and not replenishing enough. If your fridge draws 5 amps and is on a 50% duty cycle it will take 60 amp hours a day. Throw in the TV, lights, autopilot etc and you can easily get to 100 amp hours per day.

You then have to put in about 110 AH to get back because batteries are not 100% efficient. So your motors need to be putting in 50 amps for 2 hours everyday. Not many people motor that much and even if they do, the alternator has to back off the input as voltage rises or the battery overheats, so really you have to have the motor on for 3 or 4 hours. Solar is great at this topping up requirement.

If you are sure that you have new batteries and that your alternators are really putting in a heap, you have a load somewhere. Get out your multimeter and check all of your connections. Maybe a light is corroded and has high resistance. You have to find out where the extra load is coming from. Then again, if it is a load problem, turning the electrical system off at night will help solve that. Turn off the battery main switch and let the fridge get a bit warmer, it will be okay. If the battery voltage still drops from 13 to 11 overnight, your batteries are stuffed.

When you get to Gladstone, go to the marina and talk to the yachties that look like they work on their own boats. Batteries are always a source of problems and you will probably find someone who will come over and look over your system and give you a hand. A retired electrical engineer helped me a lot when I had this problem years ago - I was not charging hard enough - to 14 volts.

cheers

Phil

Well, all these replies are well qualified.
let me add a few bullet points
- charging voltage is no indication when bat. are good or half dead
- did you greased battery terminal to prevent corrosion - wrong
remove all bat. connection polish, fine sandpaper , reconnect
- after charging is your bat. voltage is 12.2 v,
from my battery capacity table,
your bat. is on 60% capacity, no wonder they are dead by morning.
-you might expirience less known bat. behaviour
- any standard lead acid bat. needs decent charge
- calcium bat. can charge with low current
-deep cycle are happy with any charge
Monitor charging - discharging current will be the answer .
Your bat. needs more charge.

Thanks guys,
From what you have all said and looking at when the batteries are at their worst, I think it is a lack of charging. Had no problem out at Musgrave but had motored a lot to get there.
So a couple more questions on the most efficient charging. I have 2 X solar panels - they seem to put out around 4 amps most of the time , most I have seen from them is 6 amps.
I also have 2.5 KVA generator. It is hooked to the system and charges via an inverter . Manual says it's a Modified Sine Wave with output power of 1000VA. It says it has a Freedom charger which they say is a 3 stage charger. Stage 1 = bulk - constant current
Stage 2 = Acceptance Charge - Constant voltage , Stage 3 = Finish "float"Charge. How long would I need to run this for to get good charge. It heats up the boat and is a bit noisy and fumey.
So having 2 diesels, when running them at anchor for charging, do I produce twice the amount of charge or only what the battery will take initially, which makes me think I only need to charge with one engine . I dont have an over ride system .Guess what I'm asking is say 2 engines X 3hrs is that less efficient than 1 engine X 6 hrs. Which option would produce the most amount of charge
Is my most efficient charging at anchor by engine or generator /Inverter .
Thanks in advance for your advice, electrics are not my best subject.

running a modern diesel under no load, is not necessarily bad for it.
and i guess the alt. will be putting a load on engine if it has to try to
keep up with your usage requirements.
totally agree with more solar panels and suggest you look into a smart
regulator for your alt. so it charges your banks efficiently and fully.

Gday

One vs two motors - I am pretty sure that running two motors won't do much more than one.

One your alternator is a voltage sensing regulator. When a battery gets charged its voltage increases quickly, but it this doesn;t mean it is charged. This extra voltage lets the regulator know that it can ease back off charging. If the alternator came off a truck or speed boat then it will not be set up to charge a deep cycle battery. You will have to dig into your regulators. Putting two motors on will get the battery voltage up quickly, then the regulators will back off charging as hard.

Better to load up the system whenever the motor is on - freezer on full, and any other optional load on to drop voltage and get the regulator to put in extra. Better than sucking out the juice later.

The generator via the inverter is going to take a long time to charge the batteries fully. When you get to the marina it will do a great job but you probably have to have in on for 8 or so hours to get to the float stage.

6 amps for solar is not much - I would be looking at upgrading. In reality you are like someone who is spending too much and not earning enough. Your income - your generating capacity - is too low. You outgoings - your electrical load - is too high. There is no magic here. You need to get some numbers on how much you are using before you can work out a system to charge properly. Get to Gladstone and get a multimeter that has an ammeter. Then check out how much your fridge, TV etc pull and multiply that by how long they are on. Your total of all electrical loads will give you an amp/hour number. Your need to get enough solar to put this back in every day with 10 % extra for battery losses. The generator will never get to float stage unless you run it for hours everyday and therefore you will sulfate your nice new batteries.

As for how long the generator /inverter has to run - it is up to the acceptance of the batteries and the charger. No one can easily tell unless we look at the setup. You may be able to learn a bit by checking the voltage when it is running. If it gets to 14.4 and stays there for an hour or so you are probably pretty well charged. Maybe.

Do the budget and get more charging capacity OR turn off the fridge. That is the cheapest option - fridges are hell on an undersized electrical system. I cruised three years with no fridge.

11.1Volts is very low - suprized your batteries are holding up after that - Also check if your multimeter is acurate. Measure at the battery terminals.