Battery testing with new load test meter.

[dsolo]

Per the forum's advice I purchased the recommended battery load test meter. Thanks g36
I knew the age of the three group 31 batteries, but not their condition. I paid the marina to charge monthly, all records indicate they were. I personally charged them on my last visit to the boat. Checked fluids, everything was good. Tester found batt #1 bad, batt #2 weak, and gen batt marginally OK.
I thought the battery and charger upgrade would happen sometime this summer. WRONG! Just bought two group 31 Batts and four GC2 Batts. Was very fortunate to find my local Advance Auto store wanting to make a deal. All six Batts for$600. No core charge. The batteries are the ones made by Johnson Controls. Again guideness from the forum suggested saving money on purchasing them versus the more expensive Trojan, which were twice the price.
New battery charger is the promarine 1230P. Yes, I am staying with the 30 amp. I figure the vessel's 10k Genny will need some exercise. Purchased the optional monitor also.

Will cut and paint the new battery platform tonight.

Thanks for the guidance.
Dan

[Viper]

Don't know what tester you have but you ARE using the correct standard when testing the batteries correct? ie: CCA or MCA spec. It makes a difference. They should also be disconnected when testing.

[dsolo]

Batteries were disconnected and per the meter instructions the scale was based on CCA. Also checked charger output at 13.7 volts. Initial meter reading on hook-up would show charging 5 amps and shortly go to zero.

Batteries were going on 5th year. I have no history of their care? I am sure they were test correctly.

[Viper]

If you don't know a battery's history, and you have your doubts about their condition, then it's probably best to replace. Out of curiosity though, do your deep cycle batteries have CCA ratings on them? Not all do as the main concern with deep cycles is reserve capacity and not cranking power. If they don't state CCA, how did you arrive at a CCA setting on the tester so you know you're getting an accurate reading of their condition?

[dsolo]

These did have the rating of 950 CCA. I don't believe they were deep cycle batteries, perhaps dual purpose? That could be one of the issues with their short life cycle?

The meter I have has a scale reading. You must know the CCA in order to read and determine the battery's condition. 950 CCA was at the upper limit of the meter's limit of 1000 CCA.

[Viper]

It's uncommon for a true Deep Cycle battery to have a CCA label as that is not its intended use. A start and dual purpose design will but neither are comparable to a deep cycle design for house loads. Unfortunately, the lack of the CCA rating has always posed a challenge for accurately testing deep cycle batteries. There is a formula to get from AH to CCA but it's a ballpark at best and doesn't work for all deep cycle designs. The problem is that if you don't set the meter to the correct reference, you may fail a good battery or pass a poor one. Sometimes a call to the supplier/manufacturer can result in getting an acceptable CCA spec to test by based on their design.

[km1125]

At 5 years you probably weren't going to get many more from them anyways, so without a history you're just saving yourself from an unplanned change later. Great that you got a deal and you might have saved more in the long term because if you were forced to replace them one-by-one and didn't have the luxury of shopping around, you'd have paid much more.

No matter how the batteries are rated (CCA/MCA, deep cycle, etc) to get good results you really need to test them according to their intended usage. Even if a battery fails a cranking test doesn't mean it's not useful as an inverter source but it will likely have reduced capacity. Depending on how you use the boat, that might not matter. Also, even if it DOES have a good cranking capacity, it may not be useful as an inverter source if you're looking for long overnighters and depending on a lot of use of the inverter (or other loads). The best way to test an unknown deep-cycle is to actually do a cycle that drains the battery down 20% or so and track voltage drop over time.

[dsolo]

Thanks for the in depth analysis of energy storage, their different purposes, and challenges in testing. All three batteries on the boat were CCA rated and not deep cycle units. Their CCA we're 950 on positions 1&2 and 650 on the generator batt. Manufacturing dates were 11/12, 1/13. I am confident the testing found the problem early and not on the water. As observed this gave me time to shop and consider how the boat will be used.

I purchased 4 / 6 volt GC2 (deep cycle) batteries for the house load. They will be in series/parallel and in position#1. I purchased (2) 950 CCA commercial group 31 batteries for starting batteries. One will be in position #2 and the other connected to the generator. Ideally I would like to have the (2) cranking (950 CCA) batteries with the optional parallel switch. Not sure how to do this? All three batteries will be connected to the new ProNautic 1230p digital charger.

[g36]

I also use golf car batteries for my house bank. I installed a victron battery monitor it will keep up with the house bank status you might consider one also.or similiar

https://www.jamestowndistributors.com/m ... y+Monitors

[km1125]

Seems like a group 31 is mega-overkill for a genset battery, but if you use it as a backup starting battery for you main engine it makes sense.

All you'd need to do is run an appropriate ga wire back to a parallel relay near your main switch or primary start battery, then rig up a switch to activate the relay. You could just put in a manual switch too. Also make sure there is a negative cable of appropriate size connecting both the group 31's negative terminals.