using a4 alt to charge house batteries
 

I currently have a small solar panel that maintians the charge on the twin marine batteries that I use for my house power. Is there a way, say, by wiring the house batteries to the Vreg from the engine, that I can use the alternator's charging power to recharge the other batteries? The solar panel has an external regulator, but I believe it would be quickly overloaded by the alternator.

James

I have my batteries charged by the alternator/VR via the battery selecter switch. I also have a 60 W panel that runs to a small charge controller then to the #1 bat. Never had any issues. Elecrical is not my best field so hopefully others will chime in. Dan S/V Marian Claire

What you want is something called a charge combiner. It will connect the batteries together when charging, and isolate them the rest of the time.

There are several different types, from a simple relay style one (often sold in WM), to a simple set of high-current isolation diodes (which can cause voltage drop issues), to fancy low voltage-drop electronic ones that have the best of all worlds but cost (lookup Hellroaring Technologies to see one of the better examples of this).

Selection criteria are:

• Manual/Automatic Operation
• Power Consumption
• Voltage drop and its effect on your charging system(s)
• Cost

The thing you absolutely want to look for in a charge combiner is that it is automatic! The last thing you need is to wake-up one morning and find that both your house and starting banks are dead because you left a manual combiner turned on!

EDIT: Link to Hellroaring Technologies

I have one of these types and it works great for me. I also have an adjustable voltage regulator on the alternator to compensate for the voltage loss (of approximately 0.70-0.75 volts).

On the other side of the isolator, I have a Gr 24 start battery, and two Gr 29 batteries stacked together as the house bank.

I also have a small solar panel with regulator & alligator clips..My standard practice has been to simply swap this from one battery bank to the other each visit to the boat. The little cheap regulators that go with solar panels will NOT handle the alternator...mine is max rated at 7 amps...good thing my 3.2 watt solar panel churns out a whopping ~220 mA. :D

Ed, can you recommend one of these for me, based on the set up I have described?

james

Yes, but I'll need to know a little more about your setup, and about what you want.

From what you've written, it sounds like you have two "marine" batteries in parallel for your house bank. I'm assuming there is a smaller, dedicated, starter battery for the engine.

Questions about your setup:

1. Are the "marine" batteries true, deep-cycle batteries?
2. Are they wet cells, gel-cells, or AGM?
3. Is the starter battery Wet, gel, or AGM?
4. What is the combined amp-hour capacity of the house bank?
5. What is the amp hour capacity of the starter battery?
6. What is the full-sun output of your solar charger?
7. Do you have a "smart" 3-stage charge system on the alternator, or just the standard "automotive" type regulator?
8. Do you have a shore-power charger?
9. If so, is it a "smart" 3-stage charger?
10. Does the shore power charger have multiple outputs for charging multiple batteries?

And some questions about what you want from the system:

1. How much engine runtime do you want per day to keep your batteries charged?
2. What is your daily amp-hour power budget for the house bank?
3. How much do you want to spend?

All of these will affect the type of charging system you want. The charge combiner is just one piece of the system.

The very simplest system is probably a manual Off-1-Both-2 switch. It is cheap, gives you lots of flexibility, but suffers from the big flaw that you must remember to manually switch it from "Both" to just the house bank after you're done motoring. It also allows the big DC transients at starting to effect all of the electronics.

The more complicated but fully automated system would use one of the two-sided Hellroaring combiner/isolators to use all charging sources to charge all batteries, while still keeping the engine/start battery isolated from the house bank and all the electronics. And then there are hybrid systems that use the 4-way switch and a combiner/isolator. Take a look at some of the circuits on the Hellroaring page:

Simple starting battery isolation
More complicated isolation

And I strongly suggest you get & read the battery chapter in Nigel Caulder's book.

+1! An excellent reference. This is the equivelant of the Moyer Manual for the rest of your boat.

Can someone tell me the characteristics of this battery charger for wet batteries?
For example will it supply a different rate of charge to each battery according to its needs?

That is a two bank three stage charger. The stages are bulk, absorption and float. If connected to two batteries or banks it works best when they are evenly discharged. If unevenly discharged it sends a greater charge rate to the battery with the most need. If connecting to a single battery, a 12 gauge jumper wire is required between output terminals 1 and 2.

Each output is capable of 5 amps output only. They call it a 10 amp charger because it has two independent 5 amp outputs. Fuzzy math if you ask me.

Because of the staging you are not supposed to have a load on the batteries during charging, it throws the stages out of whack.

Hope this helps

Great! Thank you. I have two batteries.

This is exactly why multi stage chargers are a bad idea on a boat that ever uses shore power.

"ever should read never" I assume. And an independant generator (Onan) would drive the multi stage chargers when out to sea. Is that your line of thinking?
Were you out with Jack Daniels last night?

I can't speak for Hanley but my interpretation was the "no load on the batteries during charging" requirement was the issue. That means no lights, refrigeration, blower, radio, instruments, nuthin', total dark territory during the charging stages.

Same interpretation here.
On a personal note I find the "Jack Daniels" Comment uncalled for. I have had the pleasure of spending time with Hanley and he has always been thoughtful, professional and sharp as a tack. Even at 0755. Dan S/V Marian Claire

The Jack Daniels comment made me a little uncomfortable as well. I gave him the benefit of the doubt, wrote it off as an attempt at humor.

Allow Me to Clarify
 

What I mean to say is that a vessel connected to shore power when loads are present should "never" use a multi stage charger as a maintenance charger. The reason for this is that most of the multi stage chargers are keyed on voltage. Hence when a connected system experiences a load such as a refrigerator which will momentarily drop the voltage, the charger will revert to bulk charge. By the type equilibrium voltage has been restored and the refrigerator stops cycling the process is ready to repeat. The batteries thus receive consecutive blasts at very high voltage when they don't really need it. The result is battery boiling.

Hanley, my statpower specifically says that it is to used as a power supply, while charging batteries. It is a 3 step charger.
That is what the company says.

http://www.moyermarine.com/forums/at...1&d=1305339750 I had the Pro Sport 20 hard wired while living aboard. It wouldn't stop overcharging the batteries. Now I use the IOTA 30 constant voltage maintainer and rarely add water.

The instructions for Sony's Guest 2610 specifically say not to have loads on while charging.

Reference:
http://www.marinco.com/files/support...nuals/2610.pdf
page 3, item 2.

I have not really used 12 volt power when the charger is plugged in. Only a few lights here and there. So I really cant say either way. My charger is 12 years old. The lights on the charger are strange. The 5 amp charge light stays on, and the lights never change. The batteries are always charged. I can see when it is charging, by a volt meter.

Always good to hear other people's experiences.