Replacing House Batteries

[nelsmay]

Looking for advice. I currently have four 6V, 240 AH Lead Acid Batteries. Now about 8 yrs old. I'm looking to replace and local supplier can order in identical batteries. However, has in stock 6V, 225 AH Lead Acid Batteries at 50% of the cost. So what's my trade off here. Price vs Capacity. 200W of solar power installed as well.
Any thoughts of advice would be appreciated.

[verb88]

Are the 225 of the same quality as the 240’s? …. Thin lead plates won’t last 8 years like your current bank.

[nelsmay]

Same manufacture. Trojan. Rated to last 10 yrs, however I am getting frequent low battery alarms.

[tkeithlu]

+1 on verb88's reply. That said, have you been skirting the bottom edge of your capacity between charges? If you have generous capacity now (or had it before you battery bank showed it's age), I don't think you'd miss the 15 AH difference.


Among lead-acid batteries, the Sam's Club Duracell batteries have gotten lots of positive prss on the forum, such as these:

https://www.samsclub.com/p/duracell-...c2/prod3590228

Oops. Missed your reply that you are indeed skirting the bottom. Sounds like you could use a bit more, not less.

[Quebramar]

If you are repeatedly shortish, why not move to AGM? It would give you more flexibility.

[StuM]

Originally Posted by tkeithlu

Oops. Missed your reply that you are indeed skirting the bottom. Sounds like you could use a bit more, not less.

Frequent low battery alarms on 8 year old batteries doesn't necessarily mean that he is skirting the bottom of 480Ah @ 12V. It may be that the batteries are on their last legs and have a much smaller actual capacity.


Without know what his daily usage is, it's impossible to say (although if his use hasn't changed and he has only recently started getting the alarms, then that's a reasonable assumption)


We don't know his use case but it's also worth noting that the 200W of solar is not much to support a 480Ah battery bank if use is fairly heavy, it's probably only generating 60-70Ah per day )

[Joli]

Eight years on a set of golf cart batteries is pretty good. We usually swap ours out every 6 years. We use Sam's Club batteries which are actually Deka's. The cost is around $125 each. At anchor we have enough solar to keep them at 100% most days, passaging we run the generator twice a day.

[nelsmay]

Thanks for the comments. Very Helpful.

[Bowdrie]

IIRC, in the GC2 size Trojan has a T105, T125, and a T145.
All three are "deep cycle".
If we adhere to the 50% axiom the OPs choice only amounts to ~7 AH difference per bank.
Thats only ~100WH per bank, an average cell phone batt is ~10WH.
With two banks we're looking at ~200WH.
Would I give up 200WH for a 50% price reduction?
In a heartbeat, it's a no-brainer.

[nelsmay]

Sailing on Lake Ontario. Usage is pretty much the same as previous seasons. VHF, Autopilot, GPS /Depth Sounder, Refridgerator, various pumps and internal lights/occasional nav lights at night, charging cellphones and a coffee maker and/or hair dryer in the a.m. It's the alarms and low input warning from my inverter that are new this year. Solar panels are flexible mounted on Bimini - so not likely providing 100% efficiency.

So I am going to play it safe and make the change. Question (mostly for self but feedback appreciated) If I go with the 225 Ah (Trojan T-105s) vs the 240 Ah (Trojan T-125s) Are there setting changes required on:
- Solar Charge Controller
- Inverter
- Battery Charger
- Battery Monitor (Xantrex)
Options:
1. Four Trojan T-105, 6V, 225 AH, Connected in Series/Parallel (6V+6V=12V=225AH+225AH=450AH) or Watt-hours = 450AH*12V = 5400
2. Four Trojan T-125, 6V, 240AH, Connected in /Series/Parallel (6V+6V=12V=240AH+240AH=480AH) or Watt-hours = 480AH*12V = 5760

T-105s are 50% the cost of the T-125s (????)

Anything else I might have overlooked.