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Old 19-08-2019, 08:53   #46
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Re: Keeping the starting battery charged

If your battery is a stand alone, not connected to anything but the engine, then buy one of the solar chargers for cars. You do have to buy a cigarette lighter adapter/female but that is cheap. Don't just cut of the male plug because the voltage is 22v out of the panel and needs the controller in the plug. I had the same problem as you and this solved it.

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Old 19-08-2019, 09:23   #47
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Re: Keeping the starting battery charged

We have used a Xantrex echo charger for more than 10 years and along with isolating the starter from the house bank, have not any issues with the starter not being charged. Given the choice, I would do this again - isolate the batteries (with the option of using "all" just in case) and install an echo charger.

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Old 19-08-2019, 09:47   #48
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Re: Keeping the starting battery charged

Never even gave this a thought. Here is how I deal with this, although I am on a power boat, with two engines, so it is a little more complicated, if on a single engine sail boat, just use half of this.

The company I work for makes an all electric APU for trucks, so I'm exposed to DC power quite a bit. I purchased two battery separators, and put them between each starting battery, and my house battery bank. A battery separator monitors voltage on both 'legs', or both battery 'banks' it is connected to. When it 'see' 13.2 VDC at one leg, it closes, and allows this charging voltage to flow to the other bank as well, so both banks get charged. Now, on a semi-tractor, if the starting battery drops to 12.8 VDC, the separator opens up, because starting takes precedence over anything else, as it should on a boat as well.

But because I have two 5.7 liter engines, with only 55 amp alternators, I cannot, and do not want just either one (just one 55 amp) alternator to try & charge what would end up being 5 batteries (4 house batteries, plus a starter battery). So, I have a special heavy duty relay that has two special posts. I use this relay to separate the house battery bank into two banks of two. When the engines are off, one post receives power, keeping the relay closed, so I have a completed 4 battery house battery bank, and my four inverters (one for the refrigerator & outlets throughout the boat, one for the microwave, and one for each AC system).

I purchased this 1982 Trojan Tri-Cabin this past March, with super low hours on the engines, and only 94 hours on the 6.5 KW Onan Gen set. I'm taking the Gen Set out this winter and selling it, and replacing it with another 4-8 AGM batteries. Today's cruisers don't want the noise & fuel use of a generator, and inverters have become so efficient. And between solar & wind, and I'm considering toying with a water current generator, if you aren't going anywhere for a longer period of time, you have the ability to recharge you batteries. Silent, or near silent energy is the future.
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Old 19-08-2019, 23:48   #49
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Re: Keeping the starting battery charged

Hello everyone,
My boat has two battery connector switches, one for the starter second for service batteries. I don't have a Both switch. Starter and service battery isolated with a diode type isolator. Shore power charger fills up the starter and service battery with separeted cables connected to its double outlet.

If you have had solar or wind power installed to your boat that can generate more energy than you need daily, then you don't use shore power and the charger that runs with shore power. That is why my starter battery might be neglected, if the engine does not run for a period of time. This time vary according to the starter battery performance or age. My solution is to link starter battery with service battery temporarily.

All batteries in my boat use the same negative pole net and their negative poles are already linked between them always. So you don't have to link negative poles to share the power from the service bank that has enough energy capacity. You can link positive poles of your service and starter battery with an extra cable which has proper thickness and put a simple switch-fuse between them to establish the link when you need to start up your engine quickly. This switch is hidden and only the captain knows its place in the boat. It works like the Both switch.

Otherwise if you have access to it, you must connect the shore power and wait untill the starter battery get charged to start up the engine. This might take a long time. Simply switch on the extra link cable switch to charge or support the empty starter battery. Make sure you choose proper cable thickness and switch-fuse amp. I recommend you to switch off this link after the engine runs or when the starter battery you connected to the service bank reaches to the desired voltage.

I also use a 220 V two pole automatic switch-fuse which has enough amperage capacity to connect and charge the battery which I use to power up dinghy's electric troling motor to my service battery bank. This is a double pole 220 Volt switch-fuse that connects possitive and negative poles simultaneously.
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Old 22-08-2019, 16:06   #50
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Re: Keeping the starting battery charged

I believe to pass meet Coast Guard and insurance requirements your starting battery has to be isolated from the house batteries.
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Old 22-08-2019, 16:18   #51
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Re: Keeping the starting battery charged

I don't think the combiners/relays are good for starting batteries if you are cycling your house batteries on the hook or at sea. If you are in float, then ya, just leave them combined, or if you have a charge source on house and a dead / low starting battery then ya, combine them. Otherwise you are just hammering your start battery every day with acceptance voltage when its probably already charged. I think the usual manual switch is the best, if you supplement with a separate maintenance charger that works too.
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Old 23-08-2019, 03:22   #52
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Re: Keeping the starting battery charged

Originally Posted by Knotyou View Post
I believe to pass meet Coast Guard and insurance requirements your starting battery has to be isolated from the house batteries.
Not correct.

Selby Bay, South River, Chesapeake Bay, USA.
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Old 23-08-2019, 04:12   #53
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Location: Maine
Boat: CS-36T - Cupecoy
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Re: Keeping the starting battery charged

Originally Posted by john61ct View Post

Interesting, we are able to offer the 7622 (with the manual activation switch) for the same as the 7620 you found on eBay and the 7620 for even less.... Occasionally dealers who actually know a bit about the product can be competitive too.

That said a simple 7610-SI ACR or Echo Charger are all that is really necessary for the OP. He could also just manually parallel in the start bank more frequently.

Course of the start battery is not starting the engine, in anything less than 8-12+ weeks, even in a hot climate, there is a parasitic load on it or the battery is likely bad..

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