New batteries... looking for some advice.

[Jon Bastien]

Hello all,

I realize this topic has been covered in the forums at great length, but I'm kind of suffering from information overload researching it and doing my best to keep these thoughts as simple as possible.

When I purchased my boat, it had a pair of Group 31 Allied starting batteries- I believe they were for either a truck or some other heavy equipment. I seriously doubt they were designed for a cruising sailor, with weird power demands and charging profiles.

They finally gave out on me after 1 day of staying on a mooring. The only load placed on them was a thermo-electric cooler (2.5 amp draw), occasional water pump (enough to fill a glass of water, 6 or 7 times daily), and engine starts. I had been running the engine for 60-90 minutes twice daily, around 8 in the morning and 7 in the evening.

Prior to staying on the mooring, I had several long days of motoring, and was able to use shore power most nights; The last motoring leg was a 20 hour run from Marco Island to Key West.

So, now I have a whole list of new concerns, as I would like to take good care of the new batteries (Sears DieHard PM1, AGM Group 31 Deep Cycle; 100 Amp capacity/20 hr rate, 1150 CCA, 205 min Reserve Capacity). [Side note- I realize DieHards aren't really a forum favorite, but I'm working with what's available on the island- and the DieHards looked like the best bang for the buck with a decent reputation behind them.]

First off, there isn't an external regulator on the (stock) alternator for my Yanmar 2GM20. Is it possible that I cooked the old batteries by overcharging with all the motoring I've done in the last week?

Second, I intend to do a lot more motoring in the next year (Doin' the Great Loop!). Do I need to purchase an external regulator to prevent overcharging the batteries with the stock alternator, or will the stock regulator do the job?

Third, the on-board charger is a Guest 2611A charger (10 amps total, 2 battery outputs). The documentation for the charger indicates that it is a 3-stage charger, and appropriate for AGM batteries. Chatter on other websites seems to indicate that AGM batteries should be fed as much juice as possible in the 'bulk' charging phase... and 5 amps per battery ain't very 'bulky'. Do I need to up-size the charger?

Thanks for your thoughts on these...

--Jon

 

[Maine Sail]

Hello all,

I realize this topic has been covered in the forums at great length, but I'm kind of suffering from information overload researching it and doing my best to keep these thoughts as simple as possible.

When I purchased my boat, it had a pair of Group 31 Allied starting batteries- I believe they were for either a truck or some other heavy equipment. I seriously doubt they were designed for a cruising sailor, with weird power demands and charging profiles.

They finally gave out on me after 1 day of staying on a mooring. The only load placed on them was a thermo-electric cooler (2.5 amp draw), occasional water pump (enough to fill a glass of water, 6 or 7 times daily), and engine starts. I had been running the engine for 60-90 minutes twice daily, around 8 in the morning and 7 in the evening.

Prior to staying on the mooring, I had several long days of motoring, and was able to use shore power most nights; The last motoring leg was a 20 hour run from Marco Island to Key West.

How old were those batteries? Where are they located on the boat, engine room?

So, now I have a whole list of new concerns, as I would like to take good care of the new batteries (Sears DieHard PM1, AGM Group 31 Deep Cycle; 100 Amp capacity/20 hr rate, 1150 CCA, 205 min Reserve Capacity). [Side note- I realize DieHards aren't really a forum favorite, but I'm working with what's available on the island- and the DieHards looked like the best bang for the buck with a decent reputation behind them.

You got lucky. The Platinum AGM G31 from Sears is actually an Odyssey PCM 2150 TPPL AGM. They are one of the best AGM's on the market. They are a true premium AGM battery.

You would have paid about $400.00 each to have the Odyssey sticker and I see Sears currently has them on sale for $221.00. This is a STEAL for this Odyssey battery. Forget what ever Sears tells you about that battery and go directly to the Odyssey site and download the technical manual.

Odyssey Technical Manual

First off, there isn't an external regulator on the (stock) alternator for my Yanmar 2GM20. Is it possible that I cooked the old batteries by overcharging with all the motoring I've done in the last week?

Very unlikely your stock alt cooked those batts. For the new batteries you WILL want an external regulator with a bare minimum of alternator temp sensing but for the best battery performance you will also want batt temp sensing. Those Odyssey batteries take GOBS of current and tend to eat stock alternators for lunch when used in a deep cycling application.

Second, I intend to do a lot more motoring in the next year (Doin' the Great Loop!). Do I need to purchase an external regulator to prevent overcharging the batteries with the stock alternator, or will the stock regulator do the job?

If you are doing the great loop you become a trawler and for those batteries you will want a float mode for constant motoring. For regular use as a sailboat it is not very necessary but Odyssey TPPL's really dictate the need for external regulation..

Third, the on-board charger is a Guest 2611A charger (10 amps total, 2 battery outputs). The documentation for the charger indicates that it is a 3-stage charger, and appropriate for AGM batteries. Chatter on other websites seems to indicate that AGM batteries should be fed as much juice as possible in the 'bulk' charging phase... and 5 amps per battery ain't very 'bulky'. Do I need to up-size the charger?

Thanks for your thoughts on these...

--Jon

For the longest life in cycling applications Odyssey wants to see a minimum charger or alt capacity of 40% of the bank capacity. If you have 200Ah's then you'll want a charger that can supply 80+ amps and an alternator that can do the same, when hot. Your limitation will be your factory belt. I would advise a 120A Balmar 6 Series alternator dialed back to 80A with a Balmar MC-614 regulator using Belt Manager. This will allow you to drive 80A in bulk and keep the alt running nice and cool. It is never a good idea to run an 80A while asking for all 80A....

 

[Benny17441]

Jon, thermoelectric coolers are considered power hogs. Here in Florida warm temperatures even a thermostat controlled unit will consume upwards of 3.5 amps per hour. I would recommend you conduct a power survey for your needs to see much power you would consume in a 24 hour period. This will allow you to determine the proper usage that would be adequate for the size of your current bank and recharging capabilities. You may set different limits for when under sail or at anchor and when motoring. I would definitely would not run a thermoelectric cooler at anchor but would do it while running under power. Don't know what engine you are running but a high output alternator will rob valuable horsepower affecting the performance of the smaller engines the most as they have less horsepower to give up. I would have the stock alternator checked and make sure is operating properly and make do with it to avoid the cost and complications of an upgrade. Hope some of this helps.