New Charger & AGM Batteries but Old Alternator - Problem ?

[GMer]

Hello all,

I purchased a 1989 C&C 30' MKII earlier this year - has been running well but recently found the 14 year old 10 amp Guest battery charger was dead and the 2 existing flooded 12v batteries would not hold a charge properly (used a Craftsman charger to see if they would hold).

On the recommendation of a friend I have purchased a new 20 Amp Xantrex 3 stage Charger and am planning to purchase 2 new AMG batteries to replace the ones I currently have.

After some research and reviewing several old posts I'm a bit concerned that I may have issues with my existing alternator and/or regulator (am pretty certain it is the one attached to the original Universal M3-20A 3 cylinder engine).

Am I taking a risk with my current setup adding AMG batteries? Can I get away with not replacing my alternator?

Some additional information:

- Boat is at a marina hooked up to shore power most of the time, fed by 30 amp 125 Volt AC plug.
- Use auto helm, depth & speedometer but no fridge, windlass or major power draws when under way.
- Usage is generally limited to day trips and occasionally anchoring out for 1 or 2 nights, and generally only run lights and occasionally use electric flush toilet.

Any suggestions or comments would be greatly appreciated!

Thanks much in advance,

George M.
1989 30' C&C MKII

[GordMay]

Greetings and welcome aboard the CF, George.

Consult your AGM battery manufacturer for recommended charging regimes.

[mbianka]

George:

Sounds like with your boat usage would be a good candidate for adding a solar panel for charging the bank in most cases. I will say AGM's do make life easier. But, as GordMay says best to check with the manufacturer to make sure they are not cooked by the alternator.
There is another alternative you might want to consider. I pulled out my diesel engine three years ago to go with electric propulsion. Therefore I no longer have an alternator for charging. Don't miss it at all. I use a Honda 2000 generator for charging both my 12 volt and 48 volt banks. You might be able to scrap the alternator all together and just use something like a smaller Honda 1000 for charging through your AC charger on occasions when you are not at the dock. You then elminate any charging issues with the bank and alternator.

[gonesail]

why do you feel like you need to pay extra and then have to worry about the AGM batteries?

[mbianka]

Gonesail:

Nothing wrong with flooded batteries but, IMO AGM's make more sense on a boat. I installed 4 8A4D batteries three years ago for my 48 volt propulsion system and have not had to do any maintenace on them in that time unlike with the previous flooded batteries. I had. Plus I have no acid burns in my clothes either and don't have to carry or find a jug of distilled water to keep them topped up when cruising. One less maintenace chore to deal with leaves more time for all the others.

[GMer]

Thanks all for the responses and additional information.

It sounds like there are very specific requirements forAGM batteries, i.e. maximum of 14.6 volts from alternator (requiring a regulator if I don't have one which I don't believe I do) but some real advantages (low maintenance among others).

So I think I will stick with the flooded batteries for now (which will allow me to go sailing this weekend!) and explore some additional upgrades as time & budget permit.

Capt Mike I am intrigued by your electric propulsion conversion - sounds like it's probably a major undertaking but a a great benefit in many ways I'd be very interested in finding out more! (especially interested in range, cost, etc. if you're willing to share...)

Best,

George

[mbianka]

"Capt Mike I am intrigued by your electric propulsion conversion - sounds like it's probably a major undertaking but a a great benefit in many ways I'd be very interested in finding out more! (especially interested in range, cost, etc. if you're willing to share...)"

George:

Installing the electric propulsion system was rather easy. Most of the work was pulling out the iron pig (diesel engine) and all the stuff needed to operate it.
I have cruised over 1000 miles since I installed the electric system and my only maintenace cost has been about $5.00 for the oil change for the Honda 2000 generator I sometimes use for charging or extended motoring (up to four hours so far on a windless day). The Honda can push my boat about 3 knots without drawing any amps from the battery bank until it runs out of fuel. If I want to go faster I can start pulling amps from the 48 volt bank too. Also have solar and a 48 volt wind generator in the mix. Cost was about $10k in 2008. Cheaper than a replacement diesel and easier to install too. I did have a local yacht refitter redo the stringers to mount the electric motor because my Westerbeke diesel had a V drive transmission. But, other than that I did the entire installation. I've got a 20 part post on my blog that shows the entire process I went through starting with this post:
THE BIANKA LOG BLOG: Going electric: Part 1: The why and how
I would not pull out a good running diesel to go electric. But, if you ever think about repowering I would certainly recommend you look at electric propulsion. All I can say is I'm glad I made the switch. I like the smell of "clean" too much now to ever go back.