New batteries and Terminals

[mikekomm]

I just bought a 42' boat that will need some of the batteries replaced. At least one of the Group 8 batteries and 3-4 of the Group 12. I want to purchase high quality "real" deep cycle marine batteries. Any suggestions on where to purchase the batteries, cables and terminals?

[Wolverine]

I did months of research and ended up with Life Line AGM batteries. They are US made, with German-made terminals.

Here are some things I recommend:

-Don't mix batteries
- use AGM batteries
- Don't skimp on wire size
-properly protect the cable with the correct fuses
-Use a modern programable voltage regulator. One on the charger and one on the alternator.

[mikekomm]

Originally Posted by Wolverine

I did months of research and ended up with Life Line AGM batteries. They are US made, with German-made terminals.

-properly protect the cable with the correct fuses

-Use a modern programable voltage regulator. One on the charger and one on the alternator.

Thanks Wolverine - regarding "fuses" ... are there fuses for the battery cables themselves or are you referring to the various fuses used for different pieces of equipment on the boat?

[Steve Olson]

Originally Posted by Wolverine

I did months of research and ended up with Life Line AGM batteries.

What model, volt, AH are the Lifeline batteries you ended up going with?

[Wolverine]

You use the normal fuses.

I highly recommend Charles Wing's book on boat electrics.
I also recommend Nigel Calder's book. ( I think it is titled "Boat Owner's Handbook)

Even though I am an electrician, I was not equipped to rewire a boat without these two books

[Wolverine]

Sorry, forgot.

215 Ah (4 D) [which denotes the physical size]

4 of them. 12 volt in parallel yielding 860 A/h

As you will learn from your upcoming reading, you don't really get 860 A/h because you will probably be down to 11 volts at 40%.

[btrayfors]

Wolverine,

The two books you referenced are excellent sources.

A couple of notes on your other recommendations.

1. AGMs are great for SOME but not all marine applications. They are the absolute WORST choice for many boaters, expecially those without adequate charging sources to bring them to FULL CHARGE frequently;

2. You can't just use "any fuse" to connect to these batteries. You can only use one of three types: AGM, MRBF, or Class-T. Other common fuses don't have adequate Ampere Interrupt Capacity (AIC) for direct connection to house batteries.

3. Fuses should be installed very close to the batteries....ABYC specifies "within 7 inches" unless protected by conduits or special sheathing, in which case the fuses can be located up to 40 inches from the batteries.

4. AGM batteries at 40% discharge or even at 60% discharge will have voltage much higher than you mentioned. If you see 11.0VDC the batteries are very nearly DEAD and should never be this deeply discharged.

The attached graph shows the voltages and State of Charge (SOC) for AGMs and Gel batteries (red line) vs. Flooded batteries (green line).



With 860AH capacity, you'll very likely get more than that because of Peukert's effect. The capacity is established at the 20-hour discharge rate which would be an average discharge of 43 amps, or 1032AH usage per 24 hours. Very few cruising boats draw anywhere near this much amperage, more like a quarter of that or even less. Thus the effective AH capacity is a lot more than 860AH.

The lifeline AGMs you mentioned are excellent batteries. A couple of years ago I did some longitudinal research on this specific battery, together with Concorde -- the manufacturer -- and with two other colleagues. Just be sure you charge them with AT LEAST the recommended voltages and that you bring them to FULL CHARGE frequently. This takes many hours, no matter the size of your charging source.

The attached graph shows the approximate percentage of capacity accepted by the AGM batteries with three different sizes of charger. The blue line shows what a 190% capacity charger would do (in your case, a charger capable of putting out over 1,600 amps!!). The red line shows what happens when the charging source is about 25% of the battery capacity, or 215 amps in your case. Few boats have this much charging capacity.



Notice that no matter the size of the charger, battery acceptance during charging drops considerably after an hour or two, and it takes several hours to get anywhere near 100% full charge.



FWIW,

Bill

[Pelagic]

Originally Posted by btrayfors

Wolverine,

1. AGMs are great for SOME but not all marine applications. They are the absolute WORST choice for many boaters, expecially those without adequate charging sources to bring them to FULL CHARGE frequently;

FWIW,

Bill

Interesting notes Bill….
One of the reasons I chose AGM’s (Fullriver 280Ah -8Ds) was that I understood that due to the physical properties of the glass mats they were less susceptible to stratification.

To reduce generator hours JUST for charging, I sized bank so that I only consumed 10% of batteries in 24hrs at anchor.
Therefore I thought it gave me the option to keep house bank in the range of 70 to 80% SOC without any damage.
I normally shut off at 80%, so as not to get into the low charge rate of absorption phase.

Anchorage reality is that I would usually need to run gen for other things every 3 or 4 days and get a full charge. Is that a mistake?
What do you consider a guideline for FREQUENT FULL CHARGE? How many days?

Thanks… Nick

[btrayfors]

Hi, Nick...

Well, yes and no.

There's no doubt that bigger is usually better, both because of increased effective capacity due to the Peukert effect and, with flooded batteries, the greater charge acceptance of a large bank, provided that you have enough charging capacity.

The problem with AGMs is that practically nobody has enough charging capacity aboard to take advantage of their incredible charge acceptance properties during the initial hour or two of charging. And, all LA batteries -- AGMs, gels, flooded -- will dial way back in terms of how much charge they will accept in the later stages of charging. If you're only drawing 10% capacity, the batteries will only accept relatively little charging current during those last 5-10% of charging to get to fully charged condition.

Trying to reach full charge by mechanical means (engine, generator) is VERY VERY EXPENSIVE. You must run these engines for a very long time...way beyond what most cruisers would want to do, unless they're in a power boat or are doing a LOT of motoring.

A good strategy seems to be to beef up your onboard charging capacity as much as possible (engine/generator) AND count on adequate sized solar panels and/or a wind generator to get the batteries up to full charge during the day. Basically, you don't want to be running your engine or generator late in the day. Run them in the morning to get a lot of charge back into the batteries, then let the solar panels and/or wind generator do the rest of the charging.

Bill

Originally Posted by Pelagic

Interesting notes Bill….
One of the reasons I chose AGM’s (Fullriver 280Ah -8Ds) was that I understood that due to the physical properties of the glass mats they were less susceptible to stratification.

To reduce generator hours JUST for charging, I sized bank so that I only consumed 10% of batteries in 24hrs at anchor.
Therefore I thought it gave me the option to keep house bank in the range of 70 to 80% SOC without any damage.
I normally shut off at 80%, so as not to get into the low charge rate of absorption phase.

Anchorage reality is that I would usually need to run gen for other things every 3 or 4 days and get a full charge. Is that a mistake?
What do you consider a guideline for FREQUENT FULL CHARGE? How many days?

Thanks… Nick

[Wolverine]

OMG! btrayfors and pelagic are sure informed!
I have a 110 amp alternator on my Yanmar and it seems to keep things up to the point where I can leave two small fridges and one small freezer, along with 4 or 5 lights on for 54 hours before I drop to a point where the inverter shuts off on " low voltage" By the way, I just discovered that my alternator is cutting back on output because of the voltage regulator's temperature sensor. (the alternator is getting too hot) I am about to install a fan blade on the alternator to provide more cooling.

[goboatingnow]

I agree fully, if you do a careful examination of the characteristics of AGMS, they would never be used on a boat.

Dave

[ey frija]

Someone new coming in now; I'm now completely confused. so what battery IS reccomended? I was thinking i was reading a series of reccomendations for why i should be buying AGMs and now it seems not!! I just bought a boat with a virtually croaked battery bank and i need to replace in june when i take possession. I do have a wind generator and will have a honda auxiliary generator on hand. Help!

[MarknLori]

Hello, we just bought a boat that needs batteries replaced. Right now we have Trojan J305HC 6v 335Ah arranged in two strings. I was thinking of replacing them with Lifeline GPL-L16T batteries. The physical dimensions are the same, and I would go from 670 Ah to 800 Ah. What do you think?

[MarkSF]

Genuinedealz.com for custom battery cables. I just bought some for my boat, and they are selling complete cables for less than I can buy the wire itself for, locally.

The cables I bought were nicely made, too.

[sailinglegend]

Originally Posted by Pelagic

Interesting notes Bill….
.....
What do you consider a guideline for FREQUENT FULL CHARGE? How many days?

Thanks… Nick

Bill you didn't answer this very important question from Pelagic!!!

Lots of people say that AGMs need "FREQUENT FULL CHARGE". Lifeline say this in their instructions, but surely ALL Lead Acids batteries need the same treatment. Where is the evidence that AGMs need special treatment?

Lifeline AGMs can be equalized and that helps remove the sufation build up. I only fully charge mine every 2-3 weeks and they have lasted 10 years as a fulltime liveaboard in the Med with only 140 watts of Solar and a 400 watt wind Genny.

If you go for AGMs the most important thing to do is get your charging capacity as high as you can to take advantage of their fast charge. We have 120 amp shorepower, a 100 amp alternator and a 280 amp DC genny. That's still not really enough for a 1050 Ah bank, except when we are running the genny. Lifeline say a MINIMUM charging current of 20% of capacity = 200 amps.