Batteries concern

[SunsetSteve]

My Riv 28 runs on 2 Grp 31 batteries that are intended to do all things with the 1-2-both-off switch. Old school, but OK for a dock queen with day trip outings. Not good enough for my planned windlass upgrade. But . . . Normally my NOCO charger shows 2 green lights until last week one green and one red. Low on electrolyte on Batt 2 so I topped the cells up. Next weekend - 2 green.
Day outing today with the fridge breaker off, so only dash gauges and electronics on, but when I returned to dock, 2 red on the charger.
It seems odd to me that the alternators can't keep those "marine" batteries up. I am looking at a battery system upgrade (windlass), but now I wonder if I can rescue these 2 in a new configuration. Pics of the batteries below.

[uchu]

How old are the batteries? Have you tested them with a multimeter?

[km1125]

How long was the return trip after you had been sitting for the day? Are you sure your alternator(s) are working correctly and delivering the right voltage?

As uchu says, how old are those batteries? Does "red" on your charger just mean the batteries are taking current (the charger is actually charging instead of float)?

Not sure why you think those two batteries couldn't handle your winch. I ran with two Group 29's for nearly 10 years with big blocks and a winch and never had an issue. Unless you're running 1000' of very heavy chain, even just ONE of those batteries could handle a winch for that size boat.

[Viper]

Ya check alternator output and test the batteries with a proper tester. The charger and alternators may be bringing them up but they may not be holding a charge.

[SunsetSteve]

I've researched how to check out the batteries and alternator with my multi meter, so I will get to that asap. We only stopped the motors for 15 minutes for a swim, and turned off the refer breaker before heading out. The red lights show that both batteries are being charged (which means they need a charge!)

Interested to hear (see) KM1125's opinion that the 31s should suffice to run the windlass - that would solve a number of issues, including where to locate the 3rd battery. But if either one of these 31s are showing poorly -please god it's not the alternator) I have to delve into the question of how to build the new bank.

Thanks everyone!

[buster53]

A pair of 31’s is all you need for your boat. I have a 356 with big block 8.1’s and windless. I also have a pair of 31’s. Of course, I do have a separate starting battery for my genset.

[Midnightsun]

If the batteries are bad and you need replacement and you want to stick with Group 31, I can vouch for the Cummins brand. Have only had them for 2 years but they seem to indicate perfect health. Could not believe how cheap they were. If you ever get down to the Montreal area, the Cummins center is just off the Trans Canada. https://shop.cummins.com/CSSNAStore/s/s ... 1&store=EN

[Viper]

QR_BBPOST I've researched how to check out the batteries and alternator with my multi meter.....

That only gives you a partial look at their condition, it doesn't give you a full picture IMO. If all you're doing is taking a one-time reading, you could be mistakenly giving a passing mark to a bad battery. There is a process to determining the true condition with just a multi meter. I prefer a proper battery tester in conjunction with a load type tester.