Marine Battery Replacement and Charging

[RaymondP]

Recently acquired an older sailboat, an 86 Catalina 34. So much to learn. The boat has two batteries and charges them when in the dock or while running the engine (I think?).

Two questions....
1. If I upgrade to AGM batteries, will my regular marine on board battery charger be OK, or do I need to replace the existing charging set up for a specific AGM system? (I understand the charging algorithm is different for AGM batteries in cars.)
2. Running "both" batteries all the time - options are 1, 2, "Both". Still to determine if one is deep cycle and the other is for starting or if they are dual purpose. What is the best solution to replace them. AGM or regular dual purpose or specific (Starter and deep cycle). AGM and Lithium are a lot more and crazy expensive respectively. I think the sizes are 24, 27 or 31.

Thank you for your assistance.

 

[Cujet]

Batteries are not the same today as they were even 15 years ago. Nearly all lead-acid batteries are made from recycled lead, and it's associated impurities. My point is that today's batteries are a bit of a gamble. Known good brands are not that way anymore, and while the difference between AGM and Flooded LA batteries remain, both can be of awful quality, despite paying a fortune.

Sure, if you go to WalMart and get their cheapest FLA battery, don't expect that it will contain as much lead or provide as much power as a name brand. But just as easily, you could spend $600 for two batteries and get just a few years of use.

There is a reason people are switching to LiFePO4 lithum (deep cycle/long term power type) batteries. They are energy dense, no more expensive by energy content, and they last.

 

[thastinger]

I would stick to good FLA deep cycle batteries. They should be wired to where 1 battery is only for starting the engine and the other runs everything else. That way, when you are anchored in a haven somewhere, you switch over to the "house battery" in run your 12V cabin lights etc but you can't kill your starter battery. Of course, you can control how much of that you do with the "both" position on the battery switch.

 

[BrendanC]

we installed 4 Everstart Platnium AGM's for starting/house batteries in our boat 6ish years ago alongside a new charger. each engine has two H7's in parallel and only the starboard bank is set for use on the few 12v systems on the boat. (bilge, shower bilge, emergency lighting and Furuno MFD). Both engines still start much easier than when each engine was on its own dedicated 8D sized battery, often having to hit the parallel solenoid to get them to crank fast enough to start (old penske 6-71TI's. but the boat is always on battery charger power regardless of tied up or on generator. with yours having to do deep cycle duty aswell (i assume there will be no charging while at sail), i would look into a dual purpose AGM along side a good AGM charger. Autozone sells one. As far as isolating them, i would put a bluesea systems automatic charging relay between them for when the alternator is active.

 

[bbhero]

Thin Plate Pure Lead batteries CAN be worth the $350 to $450. That eliminates the poor lead quality issue seen by other regular batteries.

If you charge them properly and maintain them properly.

We had a member on here get 1,200 deep cycles out of a TPPL battery… That’s over 500 more than is typically expected. And that was a group 27 battery.

Northstar batteries are TPPL and there are several others. Trojan, Odyssey and Fall River are that too.

 

[eljefino]

Go, right now, and see what the float voltage is dockside when you're plugged in. AGMs don't like more than 14.0 or thereabouts.

What size engine? What's the watt rating of its starter?

I'm running Wally World Marine dual purpose (start/ deep cycle) regular old lead acids in my off-grid solar cabin with, so far, success.

What's your actual use plan? Dockside 99% of the time? Fair weather sailing? All weather sailing? Canals etc where you have to be under motor power?

If this were my boat I'd punt with the tried-and-true lead acids while I figure everything else out about it. It's easy to spend too much, and a boat isn't a place for whiz-bang latest tech.

 

[vwmaniaman]

I have a Roadtrek camper and I switched from deep cycle to AGM about 5 years ago. My onboard charger seems not to care and it has been well worth it for me. The deep cycles would only last a couple year and performance drops of on the second year. This one has been great for wufe and I and runs our lights water pump and ventilation fan all night. The charger is built in from the factory on the camper. It also has an isolater that separates the house and motor battery when we stop. AGM was the way to go for us.

 

[Donald]

If you go with the AGMs from Walmart or West Marine or NAPA a normal charger for flooded lead acid can handle then with no issue. If you go with the spiral wound or other high end AGM then they need to be charged differently. Some chargers have selectable settings.

The West Marine and NAPA AGM around my area of the East Coast are East Penn so high quality batteries.

AGMs on a boat make sense as they go months and months with little self discharge.

 

[PontiacHO]

Batteries Plus = Johnson Controls. Regular leaded Marine batteries. No need for deep cycle for house batteries. Personally I like the conditioner-chargers from ProMariner.

 

[Donald]

Go, right now, and see what the float voltage is dockside when you're plugged in. AGMs don't like more than 14.0 or thereabouts.

What size engine? What's the watt rating of its starter?

I'm running Wally World Marine dual purpose (start/ deep cycle) regular old lead acids in my off-grid solar cabin with, so far, success.

What's your actual use plan? Dockside 99% of the time? Fair weather sailing? All weather sailing? Canals etc where you have to be under motor power?

If this were my boat I'd punt with the tried-and-true lead acids while I figure everything else out about it. It's easy to spend too much, and a boat isn't a place for whiz-bang latest tech.

I am not sure a $200 AGM is really a whiz-bang latest tech.

 

[JHZR2]

I am not sure a $200 AGM is really a whiz-bang latest tech.

Really? What do you think is then? What do you think the difference is that is whiz bang in a chemistry that has been in use for over 100 years now?

Sure, there’s pure lead, then there is alloyed lead, and there is recycled which likely has some alloys in there, which aren’t necessarily a bad thing.

The thing I would not do is run two different size and rating operating and charging in parallel at the same time.

Particularly if fully charging them it can result in abusive conditions, or even fires.

Mixing lead acid and Li-ion can also be an issue. While drop-in LFP batteries are a thing, charge control of mixed setups can be a major hazard.

Some battery switches allow for these setups where the batteries are in parallel. Thus the concern.

 

[BrendanC]

Really? What do you think is then? What do you think the difference is?

Sure, there’s pure lead, then there is alloyed lead, and there is recycled which likely has some alloys in there, which aren’t necessarily a bad thing.

The thing I would not do is run two different size and rating operating and charging in parallel at the same time.

Particularly if fully charging them it can result in abusive conditions, or even fires.

Mixing lead acid and Li-ion can also be an issue. While drop-in LFP batteries are a thing, charge control of mixed setups can be a major hazard.

Some battery switches allow for these setups where the batteries are in parallel. Thus the concern.

AGM’s are still just lead acid batteries. they are better suited for boats due to not having a “loose” electrolyte. i don’t recall anyone talking about mixing chemistry either.

 

[JHZR2]

AGM’s are still just lead acid batteries. they are better suited for boats due to not having a “loose” electrolyte. i don’t recall anyone talking about mixing chemistry either.

I’m acutely aware. That’s kind of my point about what else is whiz bang tech in the AGM segment.

Whenever there is a 1-2 switch there is usually the position to combine. And there is always the potential to use a different battery for hotel and starting, thus the point.