Duracell Deep Cycle Group 31 Lead-Acid - 105 AH

[RobMinton]

Does anyone have experience with the Duracell Deep Cycle Group 31 size lead-acid battery? 105 AH. $94 ea. at Sam's Club. Components made in US and assembled in US.
$376 for 4 batteries (+core charge).
House bank total: 420 AH. at $376. at Sam's Club
Sounds like a deal. No? Experience?

[TMT2]

Can't speak for the flooded batts but I put in 12 x Duracell (6V) AGM GC2s this year to replace my house bank. Chose them specifically for the reason of completely US made (from research on specs), cost (good price $190 ea at SAMs) and I can get them at any SAMs. Happy so far!

[Crew of Turning]

IN some previous threads regarding batteries it was suggested that the East Penn battery manufacurer did the production of the Duracell product. It is a label on a EP battery. They build a pretty good product.

[GrowleyMonster]

Sams is now my goto for batts. My 48v propulsion bank is 8 Eveready GC2 220ah 6v batteries in series. I recently added a separate 12v bank, 2 Duracell GC2 6v batteries, 215ah I think but don't remember for sure. Zero complaints so far. I have been using the propulsion bank for 3 years and they are better now than when brand new. The Duracells are only a couple monthss old so the jury is still out. The price 3 years ago for the Evereadys was $85/ea and I think the new Duracells were actually a bit less. The magic of volume buying power.

No experience with the Duracell gp 31 but they should be okay if you need to go cheap. Standard warnings and disclaimers about parallel batteries apply. if you need more amp hours you might consider series 6v batteries. I suspect that golf cart batteries are more solidly built than general purpose or marine deep cycle. But the real attraction is bigger cell size, so 200+ah without parallel connections, but still easy to handle. They might not be ideal for you but they are for me.

Sams is pretty good about returns or honoring warranty. And they have pizza.

[Matt Johnson]

The only issue I have with Sams batteries is the warranty which is 12 months free replacement, but they are not prorated after that like most other manufacturers. 24 months prorated on Trojan T-105s. Had one bad battery after 13 months and had to buy a new one myself.

Matt

[RobMinton]

Thanks for the response. Very informative. Sounds like you're running a house bank very similar to some cruising friends of mine with 6V golf cart batteries run in series. Can you explain the "warnings and disclaimers" for paralleling 12V batteries? And the benefits of running 6V batteries in series? Thanks

[boeing1]

I installed Duracell group 27s lead Acid on a friends boat about 2 years ago still no problems. he is very satisfied with them

[GrowleyMonster]

Originally Posted by RobMinton

Thanks for the response. Very informative. Sounds like you're running a house bank very similar to some cruising friends of mine with 6V golf cart batteries run in series. Can you explain the "warnings and disclaimers" for paralleling 12V batteries? And the benefits of running 6V batteries in series? Thanks

Stay tuned for the arguments and flame fests.

My 48v propulsion bank actually moves my boat. I do power 12v loads from it, via a 48v-12v DCDC converter. So it does have a minor role as house bank but it is primarily for propulsion. Power for my motor. The separate 12v bank is a backup, primarily. One bilge pump runs off it while the other bilge pump runs off a converter on the 48v bank. The 12v bank is a pair of 6v batteries in series.

Others can explain the negative side of parallel batteries better than I can. Other folks present good arguments to the contrary. Personally I think it is better and simpler, maybe even safer, to avoid parallel batteries. YMMV. I will let the experts explain. Maybe they will do a better job than me and I don't feel like arguing today anyway.

There is no partticular benefit to running batteries in series per se. But there may be benefits to running 6v batteries, and since there is so much stuff that runs on 12v and so little that runs on 6v, two 6v batteries are used in series to make a 12v bank. The benefits of 6v are mostly related to the form factor and capacity, and also to the cost per watthour of storage. Most golf cart batteries are around 205 to 235 amp hours. Your group 31 is 105 to 110ah. You have to parallel gp31 batteries to get the capacity of golf cart batteries. Stay tuned for reasons not to parallel. You can get bigger 12v batteries such as 4D and 8D but they are heavy and bulky, difficult to wrestle around and they are not as cheap as golf cart batteries. Some will say that the golf cart battery is more robust and able to stand up to more physical stress. I don't know. But breaking it up into 6v blocks makes them easy to handle and install. And they are cheap, and widely available.

Perhaps the best way to power a boats house loads would actually be a high voltage series array, feeding an inverter, for 110 or 220VAC service. True sinewave inverters have gone down in price and up in efficiency to the point where this is looking more and more viable. High voltage means less current to get things done. Less current means less energy wasted, heating wire. High voltage banks give decent performance even if you lose a cell or a single monoblock battery. All that is needed to make this happen is a very flexible charger or else a full manual charger and a skipper who will go the extra mile, and monitor/charge his batteries properly. Each battery can also be controlled and charged separately using a BMS. Most yachtsmen are solidly stuck in the 12v way of looking at things so this will not be popular any time soon. Look maybe to electric car technology for ideas and components for such a system, for now. For those not inclined to tinker and operate/monitor diligently and attentively, 12v offers largely hands off service. Just check your batteries regularly and equlize every now and then and they will give many years of faithful service.

Lets say there is some rule written in stone that you cannot, on pain of death, violate; and that is that you will use group 31 or smaller 12v batteries for house loads. Lets say they are rated at 105ah. You know you shouldn't discharge your fflooded lead acid batteries to below 50% SOC so you have 52.5ah of storage. If you hook up a 5.25a load how long can you provide power to it? 10 hours, right? Simple arithmetic. If you connect a 52.5a load, you can power it how long? Only one hour? WRONG!!! Probably around 37 minutes. If you hok up a .525a load, you can power it how long... 100 hours? No, probably more like 140 hours. The amp hour rating is how many amp hours you can get out of the battery without killing it at the 20 HOUR DISCHARGE RATE. In this case, the 20 hour discharge rate is obviously 5.25a. At higher discharge rates, you get LESS power. At lower discharge rates, you get more. This is because of something called the Peukert effect. So in a nutshell, you want a high capacity relative to the normal current that you will be running. This is the main reason to run batteries in parallel, to enable more efficient usage at amperage above the Puekert neutral level. With very low current, you can safely ignore Peukert and completely give parallel wiring a total miss. But lets say you have a windlass. a refrigerator and freezer, and air conditioner. Different story altogether. Unfortunately, it is at high charge and discharge rates that bad stuff tends to happen with batteries. Nothing a BMS shouldn't be able to prevent, but you are adding cost and complexity to the system.

Work is done by watts. Watts are volts times amps. More volts and less amps is the same as more amps and less volts. Its all about watts. Assuming equivelant availability of hardware at various voltages, (which is not the case, unfortunately) a higher voltage system is easier to implement and more efficient. You get higher voltage by connecting more cells in series. You get problems by connecting them in parallel, along with of course more amp hours. But you also get more amp hours by using BIGGER CELLS. Which is why a golf cart battery weighing only a little more than a group 31 has more amp hours but less voltage. There are only 3 cells but they are twice as big. To oversimplify. A series of single cells is a great system because you only need to replace the one cell. And single cell batteries are usually pretty darn big. The more connections though, the greater chance of a loose or otherwise high resistance connection, and each connection must be checked when you otherwise check your batteries. Anyway, a 48v bank of golf cart batteries with inverter and DC/DC converter is a pretty practical solution if you have fairly heavy electrical house loads but need to watch the budget. I never gave it any thought until I started looking at electric propulsion and saw the advantages of a 48v system.

But I sortt of digress. Your gp31s will work. If 105ah is not going to do it for you, consider bigger batteries or 6v batteries rather than parallel. Nothing wrong with multiple switchable banks, NOT wired in parallel, except for the Puekert thingie. You want 4 group 31s? I myself would prefer 4 GC2 6v, in two separate banks. I won't claim it is hands down, no brainer superior for everyone. It is my preference nd I believe in view of my budget it is the superior choice for me. YMMV.

[ramblinrod]

Originally Posted by GrowleyMonster

Stay tuned for the arguments and flame fests.

My 48v propulsion bank actually moves my boat. I do power 12v loads from it, via a 48v-12v DCDC converter. So it does have a minor role as house bank but it is primarily for propulsion. Power for my motor. The separate 12v bank is a backup, primarily. One bilge pump runs off it while the other bilge pump runs off a converter on the 48v bank. The 12v bank is a pair of 6v batteries in series.

Others can explain the negative side of parallel batteries better than I can. Other folks present good arguments to the contrary. Personally I think it is better and simpler, maybe even safer, to avoid parallel batteries. YMMV. I will let the experts explain. Maybe they will do a better job than me and I don't feel like arguing today anyway.

There is no partticular benefit to running batteries in series per se. But there may be benefits to running 6v batteries, and since there is so much stuff that runs on 12v and so little that runs on 6v, two 6v batteries are used in series to make a 12v bank. The benefits of 6v are mostly related to the form factor and capacity, and also to the cost per watthour of storage. Most golf cart batteries are around 205 to 235 amp hours. Your group 31 is 105 to 110ah. You have to parallel gp31 batteries to get the capacity of golf cart batteries. Stay tuned for reasons not to parallel. You can get bigger 12v batteries such as 4D and 8D but they are heavy and bulky, difficult to wrestle around and they are not as cheap as golf cart batteries. Some will say that the golf cart battery is more robust and able to stand up to more physical stress. I don't know. But breaking it up into 6v blocks makes them easy to handle and install. And they are cheap, and widely available.

Perhaps the best way to power a boats house loads would actually be a high voltage series array, feeding an inverter, for 110 or 220VAC service. True sinewave inverters have gone down in price and up in efficiency to the point where this is looking more and more viable. High voltage means less current to get things done. Less current means less energy wasted, heating wire. High voltage banks give decent performance even if you lose a cell or a single monoblock battery. All that is needed to make this happen is a very flexible charger or else a full manual charger and a skipper who will go the extra mile, and monitor/charge his batteries properly. Each battery can also be controlled and charged separately using a BMS. Most yachtsmen are solidly stuck in the 12v way of looking at things so this will not be popular any time soon. Look maybe to electric car technology for ideas and components for such a system, for now. For those not inclined to tinker and operate/monitor diligently and attentively, 12v offers largely hands off service. Just check your batteries regularly and equlize every now and then and they will give many years of faithful service.

Lets say there is some rule written in stone that you cannot, on pain of death, violate; and that is that you will use group 31 or smaller 12v batteries for house loads. Lets say they are rated at 105ah. You know you shouldn't discharge your fflooded lead acid batteries to below 50% SOC so you have 52.5ah of storage. If you hook up a 5.25a load how long can you provide power to it? 10 hours, right? Simple arithmetic. If you connect a 52.5a load, you can power it how long? Only one hour? WRONG!!! Probably around 37 minutes. If you hok up a .525a load, you can power it how long... 100 hours? No, probably more like 140 hours. The amp hour rating is how many amp hours you can get out of the battery without killing it at the 20 HOUR DISCHARGE RATE. In this case, the 20 hour discharge rate is obviously 5.25a. At higher discharge rates, you get LESS power. At lower discharge rates, you get more. This is because of something called the Peukert effect. So in a nutshell, you want a high capacity relative to the normal current that you will be running. This is the main reason to run batteries in parallel, to enable more efficient usage at amperage above the Puekert neutral level. With very low current, you can safely ignore Peukert and completely give parallel wiring a total miss. But lets say you have a windlass. a refrigerator and freezer, and air conditioner. Different story altogether. Unfortunately, it is at high charge and discharge rates that bad stuff tends to happen with batteries. Nothing a BMS shouldn't be able to prevent, but you are adding cost and complexity to the system.

Work is done by watts. Watts are volts times amps. More volts and less amps is the same as more amps and less volts. Its all about watts. Assuming equivelant availability of hardware at various voltages, (which is not the case, unfortunately) a higher voltage system is easier to implement and more efficient. You get higher voltage by connecting more cells in series. You get problems by connecting them in parallel, along with of course more amp hours. But you also get more amp hours by using BIGGER CELLS. Which is why a golf cart battery weighing only a little more than a group 31 has more amp hours but less voltage. There are only 3 cells but they are twice as big. To oversimplify. A series of single cells is a great system because you only need to replace the one cell. And single cell batteries are usually pretty darn big. The more connections though, the greater chance of a loose or otherwise high resistance connection, and each connection must be checked when you otherwise check your batteries. Anyway, a 48v bank of golf cart batteries with inverter and DC/DC converter is a pretty practical solution if you have fairly heavy electrical house loads but need to watch the budget. I never gave it any thought until I started looking at electric propulsion and saw the advantages of a 48v system.

But I sortt of digress. Your gp31s will work. If 105ah is not going to do it for you, consider bigger batteries or 6v batteries rather than parallel. Nothing wrong with multiple switchable banks, NOT wired in parallel, except for the Puekert thingie. You want 4 group 31s? I myself would prefer 4 GC2 6v, in two separate banks. I won't claim it is hands down, no brainer superior for everyone. It is my preference nd I believe in view of my budget it is the superior choice for me. YMMV.

2 x Grp 27s in parallel are about a little lower volume, weight, and A-hr rating as 2 x 6 Vdc batteries in series. 2 x Grp 31s are a bit more. The big disadvantage of 6 VDC batteries is if you loose one, you loose 2. They also don't have enough electrolyte over the plates to handle heeling without plate exposure.

Trojan claims their T-105 6 volt batteries have a much longer life expectancy than their GRP 27 batteries. Doesn't make sense to me, and I haven't seen it
in practice, but that is the claim.

[S/V Illusion]

Originally Posted by ramblinrod

2 x Grp 27s in parallel are about a little lower volume, weight, and A-hr rating as 2 x 6 Vdc batteries in series. 2 x Grp 31s are a bit more. The big disadvantage of 6 VDC batteries is if you loose one, you loose 2. They also don't have enough electrolyte over the plates to handle heeling without plate exposure.

.

Intuitively, this makes no sense. Maybe I missed the point but simple geometry would indicate a wider 12v battery has more space for 'free flooding' effect than a smaller 6v battery in which the fluid is better confined.

As to your other contention that if one 6v goes bad, you lose two - while true, the net result is equivalent to losing one 12v battery. No advantage.

Did I miss something?

[MVNoPlans]

I have been using Duracell for years. For the house, I spent a bit more and got the 255 AH 6V
https://www.batteriesplus.com/replac...105/sligc145ut

For the start I got this Group 27
https://www.batteriesplus.com/batter...up-27m/sli27ma

I don't have any experience with the group 31, but I suspect somewhere on the case it may list CCA, and is likely not a true deep cycle battery.

I don't have a Sam's Club nearby, so it wasn't an option.

[GrowleyMonster]

Originally Posted by ramblinrod

2 x Grp 27s in parallel are about a little lower volume, weight, and A-hr rating as 2 x 6 Vdc batteries in series. 2 x Grp 31s are a bit more. The big disadvantage of 6 VDC batteries is if you loose one, you loose 2. They also don't have enough electrolyte over the plates to handle heeling without plate exposure.

Trojan claims their T-105 6 volt batteries have a much longer life expectancy than their GRP 27 batteries. Doesn't make sense to me, and I haven't seen it
in practice, but that is the claim.

If you lose a 12v battery, you lose all. If you lose 6v battery you still have 6v and only need another 6v battery which you should have already. This argument means less than nothing. Present a logical argument against 6v batts and I will support it. So far you have never done that.

[sstuller]

If you need 24 volts (trolling motor) two 12 volt standard batteries will give you the voltage with half the weight and half the connections (series) versus the standard 6 volt GC battery. This would be true for a 48 volt system also. Thanks.

[mitiempo]

Originally Posted by sstuller

If you need 24 volts (trolling motor) two 12 volt standard batteries will give you the voltage with half the weight and half the connections (series) versus the standard 6 volt GC battery. This would be true for a 48 volt system also. Thanks.

And about half the AH.

[sstuller]

And half the cost. As long as the 12 volt batteries meet your capacity requirement what is the point of using 6 volt GC's. All this assumes that the individual 6 volt and 12 volt batteries have about the same watt-hour capacity. Thanks.