Changing House Bank Battery Types

[SteveK]

So now I have to figure out how to get my 90 amp alternator to quit over charging. It is a Leece-Neville internally regulated alternator. Maybe have to go with an external regulator, although, I would think having high output alternators that don't cook batteries without external regulators are pretty common. Also, it is not sensing the output from the charger and just adds to whatever it's putting out.

Explain the bolded, how is it overcharging. ETA:

However, I've had instances of boiling and overheating one of the batteries

The external regulation would allow it to charge higher longer, but you are getting overcharging. Is it too large for the battery bank you have.


BTW, I have the 90 Leece and the external reg is no longer available unless someone has one on the shelf.

 

[TBill36]

Maybe I'm wrong about it overcharging. My understanding of battery C rate is that you should try to limit the max charging amps to whatever the C rate of your battery bank is. In my case with a 220 amp hr AGM battery bank it should be no greater than about .2C or 40 amps, and 20 or 30 is even better. So dumping 87 amps into the bank at one time is not good for the batteries and could possibly be the answer to why I was boiling the LAs and over heating them. I did not leave the engines running very long, and maybe the amps would have tapered down after some time passed, but I did not want to risk damaging the batteries.

 

[SteveK]

Bill. I am not sure if I am following. The boiling I thought was attributed to the inverter/charger. That inverter charger may need setting set to show the battery size in Ah. Mine started with 250Ah and is settable 50-1000Ah, if yours is still stock setting then it is trying to charge more batteries than you have. Also is it set for AGM now and was it set to FLA before.
The alternator may not be overcharging but you would have to first start with fully charged batteries, topped up with fluid, then allow then to be used before charging only with alternator to know for sure if it is overcharging or part of the boiling problem.

 

[TBill36]

This has been a long process so it's understandably confusing. I think I've ruled out the inverter/charger. Mine is a Magnum and is settable for max output and AGMs and has a temperature sensor. They're pretty well thought of. When I ran the engine with the batteries ~ 50% depleted, the alternator apparently put out about 60 amps. Turning the charger on and off did not affect the alternator output and simply increased the amperage going into the batteries. What I don't know is how battery voltage responds during charging and how an alternator voltage regulator is supposed to limit the amount of amperage output to keep it within the charge capacity of the bank. That sounds like a mouthful, but I think maybe my voltage regulator is not limiting the alternator output correctly.

 

[Flatswing]

Changing the batteries won’t fix your charging issues. Whichever batteries you finally select, ensure all your charging sources are customized to your battery manufacturers specs. Marinehowto.com has some good advice in that regard.
That said, I counted 17 batteries on this old tub. I have 4D AGM’s 2) bow & stern for 24v thrusters, with 4xGC15/4xL16 FLA as my house bank. Recently switched to Grp 31 Low maintenance LA (3) for starting (1) for gen. Grp31 AGM in dinghy.
So far the AGMS died @ 6-7 yrs, the house FLA’s also lasted 6-7 yrs. My FLA’s were a PITA to check & water. Installed a watering system, now takes literally 5 minutes per month?.
Value wise, it’s still hard to beat the East Penn/Deka FLA -cheapest at Costco, but also sold at Lowes, (Duracell) NAPA, etc. lust look at the battery weights/AHrs to compare - really little difference between East Penn, US Battery or Trojan if u charge ‘em right & keep them watered.

I love what Lithium has to offer, but presently, would cost me two to three times as much to upgrade my charging systems to really take advantage of their characteristics and would still have to deal with the 600A draw to start mains.