Battery Banks- AGM or wet Golf Cart???

[mkh8911]

I just purchased an 1979 Albin 36 classic. The batteries are shot so I'm going to replace them. Currently there are 2 banks, house and starting. It has 2 6volt golf cart batteries per bank for a total of 4 batteries. I've priced batteries locally and found the 6 volt Golf Cart batteries for $88 and Marine AGM deep cycle 12 volt for $100. Any thoughts on which would be better? Obviously, the money difference is insignificant.

Since I just got this boat, I'm tempted to just put it back the way it is. I have thought about enlarging the house bank since there's no gen.

Thanks for your thoughts...

[amber jj]

You most likely will get more amp hours from the 2 six volts in series. In my mind a better choice.
Bob

[jleonard]

I also think 6 volt GC. I am currently upgrading from a 2 6V house bank to a 4 6V bank.
Mine wore out after 6 plus years and I want a little more capacity.

[crowra]

I agree with the golf cart (or scrubber/sweeper 6v) batteries. Also recommend checking the amp hour rating of the batteries you are purchasing. For example, you buy four 250AH batteries you will have a total of 500AH (assuming a series/parallel configuration). But you really only have about 250AH since you shouldn't discharge below 50%.

[Captn_Dwt]

Hello!
I did "off-grid" living for 27 years in NH. For deep-cycle service you absolutely can not beat Trojan t-105 6 volt golf cart batteries. I got 10 years of full-time 24/7/365 service out of my first set! That said, these are plane old "wet" batteries, and require maintenance. [Personally, I like these old "manual care" batteries. If you learn how to care for them, you will get many more years of service from them than the maintenance free units]. Upgrade to sealed AGM's and you'll get great service without the watering "if" you take care of them. Group 24 or 27 size 12v Deep cycle's are never rugged...they just don't take the deep cycle service and survive.
Purchase "matched" batteries...all from the same production group (there's a code on the case), and never replace just one. The minor differences between batches, and even more so between a used battery and a new one will degrade the entire bank. Immaculate wiring is essential.
12v banks made up of 6v batteries will "finish" charging at about 14.4-6v (get specific with the battery you buy; call the manufacturer if the dealer does not have all the specifications for your batteries)...that's hi for a standard charging system, so you need an adjustable regulator on your alternator and/or your battery charger. If you don't bring the bank up to this finish-charge, it will never be fully charged...and your batteries will sulfate in just a few years. Tenth's of a volt make all the difference, so meters that read to 10ths are a must. Finally, you can not inter-tie a 12v starting battery to this deep-cycle bank -ever. One way to manage this is to purchase a 8D deep cycle starting battery that will operate at the exact same voltage as your house bank (again, your battery dealer must have specific knowledge). Another is to have the engine alternator charge the starting battery, and some other system to charge the house.
Lots of ways to make it all work; but today's batteries and inverters are awesome!
Best wishes for a great season on the water!

[mkh8911]

Thank you all for your input. I guess my gut instinct was correct, put it back the way it's been for the past 33 years, get used to the boat, then change it if there's a need.

I am worried about the battery charger. It's called a DYTEK S-Class. I can't find any info on it to know if it's a smart charger or if its the old style that will keep charging until the batteries are fried. I may change it out with a newer model.

Again, Thanks for your input. I'm sure I'll have plenty more questions as I progress.
Kevin

[crowra]

Captn_Dwt: That's interesting that you cannot inter-tie the starting battery with the house batteries. Mine is configured with a combiner to charge both the house batteries and starting battery at the same time no matter what the power source (shore, alt or gen). I never really gave it much thought until reading your post.

Kevin: I have never heard of a DYTEK charger. What kind of inverter do you have? It sounds like you don't have an inverter/charger. If you ever need to replace, let me know. I just had the pleasure of replacing my inverter last summer.

[N4QC]

A Google of DYTEK turned up some background info... Hope this helps...

Have fun,

[mkh8911]

Crowa,
No inverter that I can find. Do you have suggestions for an inverter?

Looks like Dytek was made or distributed by Charles Industries. I guess I can take some measurments and try it for a while.

[Captn_Dwt]

Hi folks,

Good point about the "combiner" allowing one source to charge to disparate banks. I'd not thought of that, as in my mind, they're not a good idea. For each bank that gets charge "through" a combiner, you're loosing about 8 tenths of a volt to the diode that accomplishes the "isolation". The situation is managable with a regulator that will allow you to set up the charging voltage to compensate for that, but not ideal. One more item to fail.

As for Chargers, I'm sold on the inverter / chargers from Heart or Xantrex. These are the heart and soul of the off-grid power systems for homes (Like mine was). They're rugged, fully automatic, and fully intelligent chargers. Their AC output is either modified sine wave or full sine wave depending on model. The modified sine wave is excellent for almost every application, and when the unit senses "no load"..it will sleep using only milliwatts! Mine is on all the time, ready to power the AC refer or whatever.

OK. Best wishes.

[C lectric]

You are thinking of an Isolator which will cause a Vdrop of between 0.5 to 0.8V. That is a lot to a battery and is enough to keep it in a constantly undercharged condition. There are ways to compensate but can be unweildy at times depending upon setups.

A Combiner is an electronically controlled Relay which usually has a Vdrop in the uV level unless something is wrong with it. They are a good means of providing a charge to another set of batteries, often the starting batteries, with the house batteries being the primary recharge target.

Typically they require a minimum voltage for them to 'combine' so if the house set is really down they will wait untill the house voltage level has come up partially, then bring the start batteries online. The initial turn on current can be very heavy so installation, at least for most of them, requires a very specific wire size and length.

Then upon charge source shutdown, engine, they will disconnect the two banks to provide isolation.

You do still need to monitor the system. It is possible, even with a combiner, to discharge the start batteries if for some reason the house set never gets to the minimum turn on point or does so for too short a period too often or the combiner fails for some reason.

Check out the Yandina:
http://www.yandina.com/c160Info.htm
There are others, many of them. I just happened to be looking at this one today.

There is also an ECHO charger which bleeds off a fixed current to the start batteries but agin it is electronicly controlled. They too work.