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3rd battery

Old 09-21-2008, 11:48 AM
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Default 3rd battery

Thought about installing a third battery in my boat.My question is... I have a two bank charger, and I don't want to have to mess with changing out a perfectly good charger. Is there a way I can get the two bank charger to also charge the third battery? While still isolating the 3rd battery from the other two. I want to use the third battery just for my electronics and livewell pump, and leave the other two batteries for starters, lights, bilge pumps, etc. That way, I can leave electronics on while drifting or at anchor without any worry about draining down the starting batteries.

Can I splice into the wire coming from the battery charger going to one of the batteries, without causing the second battery to drain down if the thrid one gets weak? Or can I tie the third one in with the second battery (just by puttingjumper cables onto the positive and negativeterminals of the second battery), which should charge and drain both batteries together,and use the first battery just for starting? That way, if I can start one engine and run it a few minutes, I can then start both engines from the 'Both' position on the battery switches.

Any advice appreciated!
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Old 09-21-2008, 11:54 AM
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Default Re: 3rd battery

Just add a combiner from one of the existing batteries and the third one. As long as those two batteries are in similar condition and age you'll be fine. The charger will charge those two batteries as one.
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Old 09-21-2008, 12:16 PM
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Default Re: 3rd battery

Is that the best/cheapest way to go about it? And I know those two things don't usually go together!

I know what a combiner does, but never really looked closely at them. Where's the best place to buy one, and what do I need to look for as far as amperage and features? Do I wire it in between the 2nd battery and the third battery (to be installed)? Or between the battery charger and the 2nd and 3rd batteries? Guess I need to go by and look at the wiring instructions on the package and see what it looks like.
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Old 09-21-2008, 01:22 PM
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Default Re: 3rd battery

JB2C - 9/21/2008 12:16 PM Is that the best/cheapest way to go about it? And I know those two things don't usually go together! I know what a combiner does, but never really looked closely at them. Where's the best place to buy one, and what do I need to look for as far as amperage and features? Do I wire it in between the 2nd battery and the third battery (to be installed)? Or between the battery charger and the 2nd and 3rd batteries? Guess I need to go by and look at the wiring instructions on the package and see what it looks like.
Personally I install Yandina combiners more than anything else. A C100 is good for 100 amps and can be had on the web for about $60 - check Defenders.The Yandinas have a couple of features standard but in you case you really don't need to use them. The features are: you can wire it to either turn the combiner on manually OR manually shut it off and it has a lead to attach to a gel battery to keep the voltage from getting too high when you have a wet or AGM battery connected to a gel battery.

You just wirethe combinerbetween the batteries. In your case between either one of the existing batteries and the third one your going to add. Of course the batteries will all have the negatives connected together. Set up this way with the combiner the third battery will be charged by the battery charger at the dock and by the engine while underway but be isolated when no charging is going on. The only potential downside is if you have two very different batteries connected with the combiner the charger will see it and charge it as one battery. Very different meaning one old marginal battery and one new one or two batteries of very different size. With 2 wet batteries or 2 AGM batteries that are not more than a single size difference (like one grp 24 and one grp 27) you will be fine.

You can wire the third battery to add it into the starter batteries with the proper cabling and an on/off switch for emergency cranking capacity (normally switch would be off) if you wanted but with 2 cranking batteries already sounds like your covered pretty well there. Make sure that when you wire the third battery in to use an on/off switch to the accessory load, don't skimp on the wire size and fuse it close to the battery with a fuse to protect the wire.
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Old 09-21-2008, 01:51 PM
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Default Re: 3rd battery

I may just install the third battery and the combiner. Then connect nothing to the third battery at all. Use it strictly as a backup starting battery. I've had no problem at all with battery power. But I do worry about it sometimes. And I have an Optima battery just sitting in the garage, so might as well make use of it!

Thanks very much sickcat! I really appreciate the pointers. That's what makes THT a great place.
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Old 09-23-2008, 09:11 AM
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Default Re: 3rd battery

The Combiner 100 does not require any matching of battery size. You could have a motor cycle battery and a monster industrial battery linked with a C100 and it will work fine.

It is a common misunderstanding that equal currents would flow into the batteries so the smaller one would get overcharged but this is totally incorrect. Since they are in parallel it is the VOLTAGE that is the same, not the current. Since they are at the same VOLTAGE, you cannot overcharge the smaller battery without simultaneously overcharging the large one and since the voltage is limited by the charger this will not happen.
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Old 09-23-2008, 01:40 PM
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Default Re: 3rd battery

Yandina, the batteries are the same, or very close. Group 24 and about the same CCA. One is an Optima and one is a West Marine. So I wouldn't need the feature of the Combiner 100. Is there another combiner that would work for similiar batteries? It looks like there is a wide range of prices on these combiners.
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Old 09-24-2008, 07:44 AM
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Default Re: 3rd battery

Well I'm slightly biased. We invented the Combiner in 1993 so any since then are copies. Ours is the only one that comes with a one word warranty "Unconditional". We could not offer that guarantee if they were not extremely reliable. With over 30,000 out in the field under warranty, this has been a BAD year with 5 replacements so far. The "features" don't cost anything and add less than $1 to manufacturing cost for the piece of wire and attaching it. Although prices went up this year for the first time in 10+years, it is still the lowest price Combiner on the market.
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Old 09-25-2008, 06:55 AM
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Default Re: 3rd battery

Yandina,
does it matter if the batteries are two different types i.e. wet cell and AGM?
Eric
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Old 09-25-2008, 07:49 AM
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Default Re: 3rd battery

No it doesn't matter if you mix types, Lead-Acid, Gel, AGM, Deep Cycle or Starting. The charge profile is handled by the charger, not the Combiner. Since most modern chargers are now set to handle the restricted voltage range of Gel batteries there are no worries. If you have an older style charger that was designed for Lead-Acid you could have a problem charging some Gel and AGM sealed batteries but this is a charger problem, not a Combiner problem.
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Old 09-28-2008, 02:24 PM
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Default Re: 3rd battery

Yandina, would one of the Combiner 50's that you made for West Marine do the job? I only have Yamaha OX66 twin 150's on my boat, and I think they have an output of either 30 or 35 amps each. Either way, the Combiner 50 is rated for 100 amps, so seems it would do the job.

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Old 09-28-2008, 06:18 PM
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Default Re: 3rd battery

yandina - 9/25/2008 7:49 AM No it doesn't matter if you mix types, Lead-Acid, Gel, AGM, Deep Cycle or Starting. The charge profile is handled by the charger, not the Combiner. Since most modern chargers are now set to handle the restricted voltage range of Gel batteries there are no worries. If you have an older style charger that was designed for Lead-Acid you could have a problem charging some Gel and AGM sealed batteries but this is a charger problem, not a Combiner problem.


If the OP has a gel battery and a wet battery on the same leg of the charger then how will both charge properly without charging the gel through a Yandina combiner and using the gel battery voltage limiting function??
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Old 09-29-2008, 08:04 AM
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Default Re: 3rd battery

Yes, JB. The Combiner50 will be more than adequate for that job.

sickcat: I would guess that less than 1% of installations today require the use of the voltage limiting function for Gel/sealed batteries. The feature was added to Combiners over 10 years ago when Gel batteries were being introduced and in those days it was not uncommon for the lead-acid chargers and ferro-resonant chargers to get up to over 15 volts which was somewhat beneficial for lead-acid batteries although it did increase water usage.

Very few of those old unregulated or SCR automobile chargers are around today and they are even less likely to be seen on boats. We will be dropping the high voltage feature from the next production run, it no longer justifies the cost. Gel batteries are routinely used by millions of people who don't even know what a Combiner is and they are not having any problems.
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Old 11-25-2008, 03:24 PM
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Default Re: 3rd battery

yandina - 9/29/2008 11:04 AM Yes, JB. The Combiner50 will be more than adequate for that job. sickcat: I would guess that less than 1% of installations today require the use of the voltage limiting function for Gel/sealed batteries. The feature was added to Combiners over 10 years ago when Gel batteries were being introduced and in those days it was not uncommon for the lead-acid chargers and ferro-resonant chargers to get up to over 15 volts which was somewhat beneficial for lead-acid batteries although it did increase water usage. Very few of those old unregulated or SCR automobile chargers are around today and they are even less likely to be seen on boats. We will be dropping the high voltage feature from the next production run, it no longer justifies the cost. Gel batteries are routinely used by millions of people who don't even know what a Combiner is and they are not having any problems.
yandina (an amateur tech working out of his garage) unjustly blasting BOE (a long time supporter of THT) is an absoluteCROCK!!!

http://www.thehulltruth.com/forums/thread-view.asp?tid=223800&start=1

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