Dual batteries - different type??
02-05-2004, 06:32 PM
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Dual batteries - different type??
I have dual batteries and switch, single 7.4. Right now, I have the stock batteries that came with the boat. I'm thinking of replacing one with one of the marine type batteries that they use for trolling and running electircal items. I have a norcold portable frig that seems to suck the ones I have now dry in no time. Thinking that this other type of battery will give me a longer frig run time.
Is there any issue with having the two different types of batteries working in tandem with one another?? Alternator charging issues??
Is there any issue with having the two different types of batteries working in tandem with one another?? Alternator charging issues??
02-06-2004, 07:32 AM
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In general there may be no issues whatsoever. But, if your boat lives parked on shorepower your charging system could be problematic with different types of batteries because of charger feedback. I would check the specifications on my charger to be confident that I was getting a full charge. Call the charger manufacturer and ask them. On the other hand, if you charge only with alternator, and you are discharging to very low levels as you stated, you may have alternator problems down the road. Alternators don't really like charging a very weak, very low voltage battery. If you discharge frequently at high rates, you might be happier with using a 130 amp alternator to satisfy the high charging rate of your heavily discharged batteries.
I have twin 130 amp alternators and six group 30 batteries on my boat. I use lots of DC at anchor with invertor power, lighting and accessories and have abundant charge at dock and while running. Most people don't want as many batteries as I have because of the weight but I am pleased with what I can do on batteries.
Your Norcold should typically use about 3 amps per hr ( based on model of course ) and that is 72 amps per day. With two batteries, you should not be running them down too quickly. Check the setting on your fridge and operate at the lowest setting that cools sufficiently. Make sure it is cycling on/off and not just staying on all the time. A bad thermostat could cause it to run continuously and discharge you batteries much quicker than needed. I keep only food stuffs in the fridge and drinks in coolers. The coolers are opened all the time but the fridge only at snack or meal time.
Consider your charge/discharge rates, wire sizes, overall electrical system health and equip yourself accordingly based on those factors.
I have twin 130 amp alternators and six group 30 batteries on my boat. I use lots of DC at anchor with invertor power, lighting and accessories and have abundant charge at dock and while running. Most people don't want as many batteries as I have because of the weight but I am pleased with what I can do on batteries.
Your Norcold should typically use about 3 amps per hr ( based on model of course ) and that is 72 amps per day. With two batteries, you should not be running them down too quickly. Check the setting on your fridge and operate at the lowest setting that cools sufficiently. Make sure it is cycling on/off and not just staying on all the time. A bad thermostat could cause it to run continuously and discharge you batteries much quicker than needed. I keep only food stuffs in the fridge and drinks in coolers. The coolers are opened all the time but the fridge only at snack or meal time.
Consider your charge/discharge rates, wire sizes, overall electrical system health and equip yourself accordingly based on those factors.
Last edited by deboatmon; 02-06-2004 at 07:43 AM.
02-08-2004, 09:53 AM
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I have a norcold portable model U-2000 MRFT-630, it opens from the top. It seems to run on and off all day, but consume a lot of energy. I'm going to keep this in my truck and just purchased a dometic portable ac dc propane, we'll see how it works on the boat. Like you said, we use this for our food stores and a cooler for the beers, nothing beats ice for the beer.
Thanks everyone!!
Thanks everyone!!
02-08-2004, 12:35 PM
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A deepcycle battery will not hold a charge any longer than a starting battery (assuming they are the same "size", as in Group 27, etc). What a deepcycle will do is it will allow you to run it down a whole bunch of times and then recharge it without it going tits-up. A starting battery won't enjoy being run down very many times before it just refuses to hold a charge.
Wet deep cycle batteries are good for maybe a hundred deep "cycles". A starting battery may be good for maybe ten.
An AGM or gel battery will supposedly let you cycle them many hundreds of times.
Battery capacity is directly correlated to its weight. An 8D battery has a lot more capacity than a grp 27, but it weighs a lot more.
Fridges are big battery drainers. On my Formula, I run my fridge when the motor is running, but turn it off within an hour after turning the motors off. I keep it set very cold (not enough to freeze cokes, but close), but I turn the breaker off to it a couple times a day when on the battery.
Wet deep cycle batteries are good for maybe a hundred deep "cycles". A starting battery may be good for maybe ten.
An AGM or gel battery will supposedly let you cycle them many hundreds of times.
Battery capacity is directly correlated to its weight. An 8D battery has a lot more capacity than a grp 27, but it weighs a lot more.
Fridges are big battery drainers. On my Formula, I run my fridge when the motor is running, but turn it off within an hour after turning the motors off. I keep it set very cold (not enough to freeze cokes, but close), but I turn the breaker off to it a couple times a day when on the battery.
02-08-2004, 05:31 PM
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mcollinstn
I think that actually by technical definition, deep cycle batteries will "hold a charge" longer than non deep cycle. By chemical and physical makeup they cannot deliver amperage at the same high rate as a starting battery. They cannot discharge at the same rate as start batteries. They are specifically designed to deliver smaller amounts of amperage over longer periods of time.
The Norcold DC small fridges use 2.7 amps per hr at rated cooling levels.Check out their website. That's 64.80 amp hrs per 24 hr period. On only one battery that probably would not be a smart thing to do. But, anyone that overnights regularly and doesn't have a genset, 2-4 batteries might be considered appropriate by many boaters. As I said earlier, I have 6.
I would consider 4 batteries as minimum for anyone that overnights frequently on a boat with a fridge, a larger than stock stereo, lighting, fans, etc.
No doubt some will consider my 6 batteries overkill. But, I entertain a lot and spend many nights many miles from home port and I have never been without adequate power either for starting or stereo and entertainment center.
I would also give much consideration to LED lighting for every lighting need. I did and I cut my lighting power consumption by almost 85%.
If you only daycruise, no worries. If you spend the night, think about it lot's.
I think that actually by technical definition, deep cycle batteries will "hold a charge" longer than non deep cycle. By chemical and physical makeup they cannot deliver amperage at the same high rate as a starting battery. They cannot discharge at the same rate as start batteries. They are specifically designed to deliver smaller amounts of amperage over longer periods of time.
The Norcold DC small fridges use 2.7 amps per hr at rated cooling levels.Check out their website. That's 64.80 amp hrs per 24 hr period. On only one battery that probably would not be a smart thing to do. But, anyone that overnights regularly and doesn't have a genset, 2-4 batteries might be considered appropriate by many boaters. As I said earlier, I have 6.
I would consider 4 batteries as minimum for anyone that overnights frequently on a boat with a fridge, a larger than stock stereo, lighting, fans, etc.
No doubt some will consider my 6 batteries overkill. But, I entertain a lot and spend many nights many miles from home port and I have never been without adequate power either for starting or stereo and entertainment center.
I would also give much consideration to LED lighting for every lighting need. I did and I cut my lighting power consumption by almost 85%.
If you only daycruise, no worries. If you spend the night, think about it lot's.
02-08-2004, 08:35 PM
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Deep cycle batteries definitely cannot deliver the huge surges that a starting battery can deliver.
This is indeed a function of the chemistry in play. Antimony is alloyed into the cells of a deep cycle battery to combat the primary cause "shot betteries". This is sulfation. Sulfation is a nonconductive "scab" that forms on the conductive surface of lead battery plates and makes them go south.
Lead and sulfuric acid are the two active ingredients in a flooded battery. The reaction betwen these two components is such that electron exchange is encouraged and happens very freely. Free oxygen, however, will combine with sulfur on the surface of the lead plates and make lead sulfate. The normal release of the oxygen component of the acid (H2SO4) is not an aggravating factor in a charged battery because it reacts with and combines to make sulfides in a dissolute form within the liquid electrolyte. In a discharged battery, the molecular activity balance is changed in a manner that encourages the formation of sulfates on the surfaces of the lead plates. Antimony has proven to offer resistance to this sulfation, but its drawback is that it causes the conductive properties of the lead to become somewhat compromised. It's a trade off. Lack of ultimate current capacity, but improved resistance to low-voltage sulfation.
This, in and of itself, does not make a deep cycle battery hold more stored energy. Most deep cycle batteries have thinner sandwiched plates and more lead in them which makes them hold more stored energy.
Goes back to the weight issue.
This is indeed a function of the chemistry in play. Antimony is alloyed into the cells of a deep cycle battery to combat the primary cause "shot betteries". This is sulfation. Sulfation is a nonconductive "scab" that forms on the conductive surface of lead battery plates and makes them go south.
Lead and sulfuric acid are the two active ingredients in a flooded battery. The reaction betwen these two components is such that electron exchange is encouraged and happens very freely. Free oxygen, however, will combine with sulfur on the surface of the lead plates and make lead sulfate. The normal release of the oxygen component of the acid (H2SO4) is not an aggravating factor in a charged battery because it reacts with and combines to make sulfides in a dissolute form within the liquid electrolyte. In a discharged battery, the molecular activity balance is changed in a manner that encourages the formation of sulfates on the surfaces of the lead plates. Antimony has proven to offer resistance to this sulfation, but its drawback is that it causes the conductive properties of the lead to become somewhat compromised. It's a trade off. Lack of ultimate current capacity, but improved resistance to low-voltage sulfation.
This, in and of itself, does not make a deep cycle battery hold more stored energy. Most deep cycle batteries have thinner sandwiched plates and more lead in them which makes them hold more stored energy.
Goes back to the weight issue.
02-09-2004, 06:04 AM
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Originally posted by mcollinstn
Lead and sulfuric acid are the two active ingredients in a flooded battery. The reaction betwen these two components is such that electron exchange is encouraged and happens very freely. Free oxygen, however, will combine with sulfur on the surface of the lead plates and make lead sulfate. The normal release of the oxygen component of the acid (H2SO4) is not an aggravating factor in a charged battery because it reacts with and combines to make sulfides in a dissolute form within the liquid electrolyte. In a discharged battery, the molecular activity balance is changed in a manner that encourages the formation of sulfates on the surfaces of the lead plates. Antimony has proven to offer resistance to this sulfation, but its drawback is that it causes the conductive properties of the lead to become somewhat compromised. It's a trade off. Lack of ultimate current capacity, but improved resistance to low-voltage sulfation.
Lead and sulfuric acid are the two active ingredients in a flooded battery. The reaction betwen these two components is such that electron exchange is encouraged and happens very freely. Free oxygen, however, will combine with sulfur on the surface of the lead plates and make lead sulfate. The normal release of the oxygen component of the acid (H2SO4) is not an aggravating factor in a charged battery because it reacts with and combines to make sulfides in a dissolute form within the liquid electrolyte. In a discharged battery, the molecular activity balance is changed in a manner that encourages the formation of sulfates on the surfaces of the lead plates. Antimony has proven to offer resistance to this sulfation, but its drawback is that it causes the conductive properties of the lead to become somewhat compromised. It's a trade off. Lack of ultimate current capacity, but improved resistance to low-voltage sulfation.
