Battery Switch, battery or something is wronf

[smac999]

Originally Posted by TrailerCruiser

Thanks a lot guys for help here. Here is what I found out today

I did the load test as suggested. With my 8d AGM battery totally disconnected I measure the voltage with a voltmetter from the + (plus) to the - (Minus) post on the battery. The voltage read 12.85 with nothing attached. I then hooked a LED flood light to directly to the battery. The LED light eliminated. With the LED light running I read the voltage again with my voltmeter. Now it reads 6.92 volts with the flood light running. Based on earlier discussion someone said this meant the battery was dead. But is it really dead, or does it need a good charge? I hooked up my battery charger to the battery and put it in AGM mode. I then turned on the charger. The charger ran for a little while and then shutoff. I assume this means the battery is too low to take a charge. Is there any way to bring this AGM battery back to life or is it really dead and needs to be replace. Thoughts?

12.85v is a full battery.

The charger shut off because the battery was full again.

Fully charged and capacity are 2 different things. Yiu have a full charge battery but with no Capacity left. Meaning it’s instantly dead. And then instantly full again.

An led light should not budge the voltage on a good 8d. Maybe from 12.85 to 12.8.

[Sailon1]

Thanks for tip on using 1500 W inverter and frying batteries. I have a 1500 W converter that has not been installed. I will think again about using the inverter with my two 100 amp hour AGM batteries. I’m also curious about the so-called old-school battery switch and what the new school is?

[TrailerCruiser]

Remember the inverter didn't fry the batteries. The charger that is in the inverter did, only because it started charging at 16 volts. I'm not sure how long it was charging at this rate before I figured that out. Now the question you might ask is "how can you install an inverter/charge, or charger for that matter that so it doesn't fry batteries if the charge fails and starts over charging battery". I have to wonder if there is a solution to insulate your batteries from damage should the inverter/charger stop functioning properly.

[stormalong]

Originally Posted by TrailerCruiser

My boat is a Hylas 44, 1985 model. Yes it is true the boat came with different 2 battery banks. One bank has just a group 27 lead acid battery that I use as a backup or starting battery. I have another bank, that I call house that has 2 AGM 12 volt batteries hooked in parallel. I also have a 1500 watt inverter charger that is hooked to one of my AGM batteries. The original problem that fried the AGM batteries was do to my inverter/charger charging at 16+ volts.


What is the new way to hook up two banks if a 1+2 switch is old school.

Originally Posted by Sailon1

Thanks for tip on using 1500 W inverter and frying batteries. I have a 1500 W converter that has not been installed. I will think again about using the inverter with my two 100 amp hour AGM batteries. I’m also curious about the so-called old-school battery switch and what the new school is?

What I am writing here is common knowledge among many boat owners so I hope I don't bore you too much.

Years ago boats had two batteries and an off-1-both-2 switch to select which battery to use for everything. The thinking was to use one battery until it got weak and then switch to the other. When running the engine the both position was selected to charge both batteries. Among the problems with this idea was that you had to keep track of which battery was being drawn down and to remember to use the both position for charging and to separate them after charging.

A lot of research on battery life was done and it was discoverd that the depth of discharge was a very big factor in the lifespan of a battery. So deeply discharging one battery and then switching to the other was shortening battery life. By paralleling the batteries the depth of discharge is lower and the batteries last longer. Also because many boaters left the two banks joined with the both position on the switch either by accident or intentionally, when it came time to start the engine to get into harbor there were a lot of dead batteries that could not start the engine.

This resulted in a different design philosophy for battery systems: one battery dedicated to the engine and a separate battery for all the other (house) loads. That way no mater how discharged the house battery was, the engine could be started to recharge.

One piece was missing: how to charge two batteries with one alternator. The earliest way to charge two batteries was a splitter. A set of two high current diodes split the output to the two batteries. This has it's own issues. There is a voltage drop across a diode, about .6 volts. .6 volts does not sound like much but it is a big number when talking about twelve volt batteries. If the batteries are being undercharged their life is shortened. The internal voltage regulator of an alternator senses the voltage at the alternator output, not at the battery. That makes .6 volts significant.

There are other issues with internal regulators. They are designed for cars where the battery is only used to start the engine and the alternator supplies the power while the engine is running. On a boat you are using a lot of power with the engine off so the batteries get discharged more and the alternator has to put that power back in. But, most alternators are not up to the task of high output to put that power back into the battery.

That is why today we have high output alternators and external regulators. Some boats, like mine also have two alternators. And it gets more complicated. Today there are multiple charging sources - shore power chargers, solar, wind and some even have drag prop generators. How to manage it all and keep the batteries topped up?

Now we have ACRs (Automatic Charge Relays) also known as battery combiners - a brilliant idea. What these do is whenever a battery voltage rises above a set point there is a charging source on that battery. The ACR makes a connection between the two batteries so both can be charged. When the charging source goes away the voltage drops and the relay opens isolating the two batteries.

So, if your electrical system uses a single off-1-both-2 battery switch to control all of the power on your boat you are still using that old, outdated philosophy.

The more evolved system in use today is to have one battery connected to the engine and one battery or group of paralleled batteries to supply the other loads. Each battery has an on-off switch for total isolation, they are charged from multiple sources and combined when charging.

PS: If you have two different battery types such as Flooded Lead Acid and Gel Cells paralleled there is an issue. The rested voltage of these two different battery types is different so one battery is continuously discharging into the other until it is at an equal voltage of the other. So your higher voltage battery will be discharged into the lower voltage battery.

[stormalong]

Originally Posted by TrailerCruiser

Remember the inverter didn't fry the batteries. The charger that is in the inverter did, only because it started charging at 16 volts. I'm not sure how long it was charging at this rate before I figured that out. Now the question you might ask is "how can you install an inverter/charge, or charger for that matter that so it doesn't fry batteries if the charge fails and starts over charging battery". I have to wonder if there is a solution to insulate your batteries from damage should the inverter/charger stop functioning properly.

There are over voltage alarms available but you have to be there to hear the alarm.

[smac999]

A charger will rarly fail and give high voltage. 99% it will just stop charging. I wouldn’t worry about it. Just don’t buy cheap stuff.

[TrailerCruiser]

Well I guess I fit into the 1%, or at least I think I'm in the 1% since my volt meter at the battery terminal reads 16 volts when the inverter is charging. It is always nice to be special, but I'm not sure about that this time. Is a Xantrex Freedom 15 a cheap inverter/charger? If you where to put on a 1500 watt inverter today what inverter brand and model would you buy to replace the failing Xantrex inverter?

[ferrailleur]

maybe unrelated yo your problem:
Have you checked the electrolyte level in each battery cells?

[TrailerCruiser]

I have West Marine AGM 245 AH batteries. There at caps on the batteries, but I don't think they come off, or leak. I say this because I thought AGM batteries where sealed and able to be mount in main positions, like on its end or side. If the caps could come off they would leak if turned on there side. Therefore I don't think I can check the electrolytes in the batteries. Am I wrong here?

But I have noticed that there is a little vapor round each cap. I have to wonder if the vents popped when the inverter charged at 16+ volts.

Thoughts?

[TrailerCruiser]

I have West Marine AGM 245 AH batteries. I thought these batteries where sealed, since they can sit on their side or end. There are caps on the top of battery but they do not appear to be able to be removed to check the electrolytes. Am I wrong in thinking I can't check the electrolytes?

Also I have noticed now that there is a small amount of wet vaper around each cap. I'm wondering if this vaper was cause when the batteries where over charged at 16+ volts by the inverter/battery charger. I have to wonder if the seals popped when the inverter/charger failed to charge at the correct voltage. Any thoughts here?

[TrailerCruiser]

Oops sorry for the same similar posts. My browser appeared to remove my reply, but of course it did then when it posted my reply accidentally.

[taftke01]

Not sure if this would apply to your situation, but I was using a plug in (120 ac v) charger on my two battery boat. There are in-line fuses on both battery charge wires, one wire had water enter the fuse case causing corrosion, and preventing full charging of the battery. The charger would come on, then shut itself off, I imagine this is due to an over-charge protection system in the charger itself. I checked the voltage of the charger wires to find a loss in voltage through the wire with the corrosion. This investigation lead to the finding and removing of the corrosion. The battery received a full charge after this and was still Ok to use. For what it is worth.

[RodLovell]

Originally Posted by stormalong

The more evolved system in use today is to have one battery connected to the engine and one battery or group of paralleled batteries to supply the other loads. Each battery has an on-off switch for total isolation, they are charged from multiple sources and combined when charging.

Is there a diagram of this setup?

[HeinSdL]

Originally Posted by TrailerCruiser

Thanks a lot guys for help here. Here is what I found out today

I did the load test as suggested. With my 8d AGM battery totally disconnected I measure the voltage with a voltmetter from the + (plus) to the - (Minus) post on the battery. The voltage read 12.85 with nothing attached. I then hooked a LED flood light to directly to the battery. The LED light eliminated. With the LED light running I read the voltage again with my voltmeter. Now it reads 6.92 volts with the flood light running. Based on earlier discussion someone said this meant the battery was dead. But is it really dead, or does it need a good charge? I hooked up my battery charger to the battery and put it in AGM mode. I then turned on the charger. The charger ran for a little while and then shutoff. I assume this means the battery is too low to take a charge. Is there any way to bring this AGM battery back to life or is it really dead and needs to be replace. Thoughts?

That really looks like the battery is completely dead. How old is it?

[RodLovell]

From what I can work out, this is the wiring on my Deltacraft.
Why would the Dual Battery Isolator be wired up to charge the Fridge Battery and not the House Battery. It appears the previous owner had 3 batteries.