Upgrading your Battery Banks and Alternator in 2014 is a Waste of Money.

[d design]

99% of lead is recycled

[onestepcsy37]

Originally Posted by boatpoker

six golf cart batteries, $120ea. inexpensive charger,put some water in them once in a while.

No Boeing explosions, no expensive BMS, no manual charge switching, no concerns about over charging or under charging. no balancing cells, no BS.

For the techie types who must have the latest and greatest, more power to you but my cruising is about inexpensive simplicity and reliability.

You got that right. I understand my FLA and how to use them and maintain them. They're simple and inexpensive and replaceable in the remotest corners of the earth. Someday there will be a better way but not in the next 5 years as the OP dreams about...

Sent from my GT-P3113 using Cruisers Sailing Forum mobile app

[kmacdonald]

Originally Posted by noelex 77

You are forgetting the battery bank with the higher state of charge is 4 times larger, to use your example. So each battery in larger bank only has to accept 1/4 of the charge current for the overall charge acceptance to be equal between the larger and smaller bank.

For example if we use 100Ahrs for the small bank and 400 AHs (4x100AHrs) for the larger bank. If each 100AHr battery in the larger bank is accepting 10A then the bank is accepting 40A overall. For the smaller bank the single 100Ahr battery has to accept 40A on its own for the battery acceptance and speed of charging to be equal between the smaller and larger bank at that point.

You have removed the same amount of energy from the smaller and larger bank which must be replaced to get them back up to 100% SOC so I don't understand why you feel say the solar panels can be smaller and less expensive for the smaller bank. The energy replaced is identical.

In practice the battery charger and alternator can be made smaller for the smaller bank, but only because the charge acceptance is lower. It will therefore take longer to recharge. The opposite of your contention.

Because charging is not 100 percent efficient you must add more Amp hours than you take out. Charging is less efficient for the final 10 or 20 percent charge. You only take that inefficient once for the 100AH battery but 4 times in the 400AH bank. Once for each of the 4 batteries.

[Maine Sail]

Originally Posted by kmacdonald

Because charging is not 100 percent efficient you must add more Amp hours than you take out. Charging is less efficient for the final 10 or 20 percent charge. You only take that inefficient once for the 100AH battery but 4 times in the 400AH bank. Once for each of the 4 batteries.

In parallel they are one battery... You also can't forget that guy Peukert when using LA. Batts....

[kmacdonald]

Originally Posted by Maine Sail

In parallel they are one battery... You also can't forget that guy Peukert when using LA. Batts....

But four times the capacity that has to be back in at an inefficient rate.
What I am saying is buy the smallest bank that will get the job done. It seems to me there are a lot of people comparing battery bank size with penis size---------

[kmacdonald]

Originally Posted by Maine Sail

In parallel they are one battery... You also can't forget that guy Peukert when using LA. Batts....

Im sure you know the issues with banks with a large number of batteries. The fewer the better.

[d design]

Originally Posted by Maine Sail

In parallel they are one battery... You also can't forget that guy Peukert when using LA. Batts....

https://www.youtube.com/watch?v=rWr7hdmuLUU

https://www.youtube.com/watch?v=rFdNeIneTVQ

[nugeo]

Interested thread with may diverse opinions but my two cents worth is that to a certain degree you need to stop worrying about hard science and start worrying about what you experience when out on the water.

My own experience: At the beginning of the season I upgraded the house batteries to 2 x 150 Ah Flooded Deep Cycle lead acid maintainable (I hate maintenance free) and I replaced the engine start battery for good measure too. In addition I added a Balmar MC-614 external alternator regulator to our Electromaax 80amp alternator. The nett result, forgetting the science, is that I can now run my fridge much longer after running the engine for an hour or two. The objective was achieved, colder beer for longer :-)

In my opinion, making the buy/no-buy decision based on futures is a bad idea - you will probably end up never buying. This applies to everything in life from buying a home appliance to buying a car to buying that laptop you had your eye on. So unless there really is a compelling reason to hold off upgrading your LA batteries and charge system then do it now and enjoy the benefits it brings. Lead acids are cheap, so what if you throw them away in a couple of years, you probably would anyway if you use them a lot.

Investing in a totally new technology charge system and battery type is a long way off and will cost you a lot of money. A vast majority of boats have and electrical system designed around today's alternators and lead acid batteries and/or gel. In 5 or 10 years time new boats will have new technology, but in my old boat I'll stick with old technology as long as it's doing the job I need it to do. "if it ain't broke don't fix it"