dedicated starting battery

[salty_dog_68]

I would like to add a dedicated starting battery to my boat in addition to the house bank. I would like to keep it properly charged without detriment to the house bank. So, my question is this. What are people using to charge seperate banks of batteries, from the aux engine, that require different charging regimens(without adding a second alternator)? I have read about battery paralelling relays and series regulators. I am most interested in a series regulator but can not find a lot of info about them on the internet. anyone...

thanks,
ep

[defjef]

I recently re did the batt sys on Shiva. For house I use 2 - 8Ds AGM as one bank and for a start an Optima Blue top which is only 55AH.

The charging is done with an echo charge for the start batt.... unless I combine start and house with the Blue Sea 8080 switch... The Echo charge simply uses the house bank as its charging source and the house bank are charged with a high output alt and an MaxCharge smart regulator.

When I shore charge or use solar these sources are connect ONLY to the house bank.

Jef
sv Shiva
Contest 36s

[salty_dog_68]

What is an "echo charge"? Is this a voltage regulator between the house bank and the starting battery? If it is, it is just what I am looking for. Where do I get one? thanks!

ep

[GordMay]

Xantrex Technology Inc. - Recreational Vehicles - echo~charge - Product Information

[Rick]

The Echo Charge is a simple series regulator with limited current carrying capability. One must make sure that if that is the only source of recharging the start battery along with the load placed by the engine electrics (on the same circuit presumably as the start-only start battery) that the Echo Charge will support a correct voltage.

Another method is to use a battery combiner. A simple one which has a single pull-in and single drop-out voltage (pull-in at 13.2 and drop-out at 12.9 for example) can be used with any house battery type if one uses a start AGM battery designed to operate on charge sources up to 15 V such as the Optima or Fullriver batteries. These types of AGMs will also give you higher starter voltage under heavy starting loads due to their high voltage and low internal resistance.

If you are "agricultural" in your choice of starting batteries and worry about subjecting a lousy flooded start battery to a high acceptance voltage then you need a combiner such as the PathMaker (another Xantrex product) that will combine at your choice of voltage, disconnect at another choice of a lower voltage and also disconnect at a choice of a value below a high acceptance or equalization voltage until float is reached.

[salty_dog_68]

Is the "pathmaker battery combiner" the same thing as a battery paralleling relay? Concerning the "pull-in" and "drop-out" voltage; does that statement mean that when the voltage on the house bank is greater than or equal to 13.2 the start battery is charged and the charging stops when the voltage on the house bank drops below 12.9?

As long as I am fussing with the dc system I would like to add a solar panel to the mix. What are the products used for voltage regulation on a solar charger? As always thanks for the response.

ep

[btrayfors]

IMO, an Echo~Charge device is the best solution for maintaining a separate starting battery. Echo~Charge is a product name used by the manufacturer, Xantrex. There are other such devices by other manufacturers which are comparable.

I've used an Echo~Charge for two years now and love it. Here's why it makes sense.

A starting battery is/should be maintained in a fully charged condition. When you start the engine, the starter draws a lot of amperage (sometimes 250A or so) but for a VERY SHORT TIME. My diesel starts with an average of less than 5 seconds starter time. Even if you use your starter for, say, 60 seconds @ 250A draw, that's only a total draw on your starting battery of 4.2AH. Mine is closer to a half amp-hour because the diesel starts easily every time.

So, you don't need a lot of charging to replace that small quantity of amp-hours. The Echo~Charge is a small, relatively inexpensive device which senses whenever there is a charging voltage (above about 12.8V) on your house batteries and, when there is, it will begin charging your starting battery with a current up to 15A. It will not overcharge your battery and, when there's no longer a charging voltage on the house batteries, it will automatically stop drawing current. Simple, clean, effective, relatively little RFI, relatively inexpensive, and maintenance free. What more could you hope for?

Thus the "preferred" setup, in my opinion and experience, is to connect all charging sources directly to your HOUSE batteries, and let the little Echo~Charge do its important but relatively easy job of maintaining a full charge on your separate starting battery.

Bill

[Rick]

Simple "Paralleling" relays merely combine the batteries according to the specifications of the relay manufacturer (those specs are not designed necessarily just for batteries and, therefore, are far from flexible much less being anything near optimal).

Battery combiners utilize relays, solenoids, or contactors to make the connection usually with some form of settable pull-in and drop-out value.

The PathMaker does that in addition to a "high voltage" disconnect along with a control algorithm designed to accommodate pv panels as well as shore chargers and alternators, but not wind generators.

Your understanding of "pull-in" and "drop-out" is correct.

[cal40john]

If you're just doing the battery combiner route, I went with a $30 solenoid that is turned on by the engine switch. As soon as you turn on the engine switch the batteries are combined. No fancy too high or low cutout stuff, but no $300 worth of electronics to fry either, though I recently saw that Blue Seas has some $100 versions now. I have a master switch so that the house bank can be removed from the circuit if it is low enough that I think it will hinder rather than help start the engine. I have yet to install either a high current bypass switch or a switch with a diode so the solenoid can be turned on by the house bank, so that I can emergency start from the house bank only.

I just have the alternator and regulator that comes with my Yanmar, so I don't have to worry about frying anything due to fancy charging schemes.

I got all this from Calder's book. He goes on to say if you want to get fancy wire it to the oil pressure switch. I believe though that you will need another relay with normally closed contacts to make the combiner work if you wire it to the oil sender.

John