Bad 8D Battery

[Tom Stewart]

One of my 8D batteries overheated and I assume is bad. Fortunately nothing happened other than the rotten egg smell. Consequently I'm in the market for a new battery or three. First question should I just replace only the bad battery or all three? All three batteries are the same vintage. #2 what is a good battery manufacturer? I don't need the very top of the line but don't want the bottom either. Price is a consideration but not over quality & piece of mind. If I have to replace all three I will probably go with AMG's presently the boat has gel. Any info you can impart would be appreciated.

Thaks very much!

Tom

[svWindfall]

I have 8 AGM batteries, the cost to replace is far too much compared to Flood type and I haven't seen "double life" for double the price. So, my next set of batteries will be flood.

[chrisjs]

I installed 2 x 8D Full River AGM's 5 years ago. Each weighs about 200lbs (more than my 8D lead/acid batts, presumably because of thicker lead plates. They were not much different in price compared to my Rolls wet 8D's. Needed AGM's because of difficult access for watering. Have not noticed any real difference in performance, though after a couple of months on the hook I did need to do a balancing overcharge just as with the wet batts. Was a bit nervous of buying Chinese batteries but quality seems fine.

[St. Elsewhere]

Originally Posted by Tom Stewart

Consequently I'm in the market for a new battery or three. First question should I just replace only the bad battery or all three?

Tom

You must change all three. Otherwise you will not have a reliable system.

[S/V Alchemy]

Originally Posted by svWindfall

I have 8 AGM batteries, the cost to replace is far too much compared to Flood type and I haven't seen "double life" for double the price. So, my next set of batteries will be flood.

AGMs are great if you have one on a racer that sits on a mooring or on a trailer most of the week and gets charged solely via the alternator. They are also great in RIBs where maybe some dodgy dynamo is the only charge source.

But building robust strapping, tie-downs and an acid-proof battery box is a lot cheaper, while "able to lie on its side" is over-rated if you can plan where you want that weight.

[djmarchand]

I would take this opportunity to clean up your battery installation.

Firstly 8Ds are way to heavy for a mortal human to handle. So get rid of them.

A Group 31 battery will start any diesel of 6 liters or less and weighs almost half of what an 8D weighs.

Then in the space that the other two 8Ds went, put in two pairs (four batteries) of golf cart batteries in Blue Sea or equivalent battery boxes wired in series/parallel. This will give you 440 amp hours of house capacity.

You can either wire the starting battery to one side of a 1,2,all swith and the house bank to the other side. Then you have to manipulate the switch when you hang out at anchor for more than a day. Or you can wire the starting battery directly to the starter and the house battery to the alternator and shore power charger through the 1,2,all switch that will only be used for emergency paralleling the two systems. Use a combiner or Echo Charger to charge the starting battery. That is a better, set and forget system.

Flooded cell batteries do take a bit of work checking water level and adding. In my experience in a moderate climate, I would check water every 2-3 months but never had to add more than twice each year.

The starting battery can be an AGM, but why spend more money. A flooded cell will be half or less.

David

[Pete7]

Originally Posted by djmarchand

Firstly 8Ds are way to heavy for a mortal human to handle. So get rid of them. David

I was wondering, that's the equivalent to a 60hp outboard engine

Tom, I can only concur with Davids suggestions.

Pete

[boatman61]

Having recently had 'cooking, singing D8's' I would recommend replacing all... I was/am in Panama and had to go the AGM route as servicing 'Wet's' was not possible.. at over $1000 each it was painful for the owners... the engine battery was something else and easy to access so went for a 4D 225w and that was less than $400.... go wet if you've good access... save the money for other things...

[Stu Jackson]

Originally Posted by S/V Alchemy

AGMs are great if you have one on a racer that sits on a mooring or on a trailer most of the week and gets charged solely via the alternator. They are also great in RIBs where maybe some dodgy dynamo is the only charge source.

AGMs require good charging systems or else they will die without any warning.

AGM Battery Issues (from Maine Sail)
AGM Batteries - Making The Choice - SailboatOwners.com

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
Darn AGM Batteries - SailboatOwners.com

I agree with others that wet cells are still the best bang for the bucks if you can access them easily. I still have no idea why boat builders put huge batteries in sailboats. Guess they get a good deal from the battery guys...

[Viking Sailor]

Three group 24 batteries can be used to replace an 8D battery. They will be the same size and provide the same or more AH's when wired in parallel.

Although wet batteries cost less, I wont have them on my boat. I've had too many problems with splashed acid damage. My experience with AGM have been OK but not great. I much prefer a good Gel battery setup. With a proper charging system they will provide longer battery life or more available AH's by allowing a deeper discharge for the same battery life as AGM batteries. Gel's also seem to be able to take more abuse then AGM's over the long haul.

Good luck on your project,

[Sandero]

I recently replaced a pair of 8 yr old AGM 8D... with a battery called universal and the pair cost $850. I sold the old ones for scrap lead and got $80 for them so the replacement was $375 e/o.. The old PowerTechs still had life in them but little capacity and required frequent charging.

The UB40s seem fine, but have not really put them to work. They are on a constant regulated solar charge from 110 watt panel. The re install was tight and lots of rewiring...

The batts are held down by cleats and a piece of plywood which has the various charge regulating devices mounted on it.