diy solar

diy solar

What the CCA test can tell about deep cycle batteries?

ldsfreire

New Member
Joined
Sep 5, 2021
Messages
1
Hello DIY Solar community! This is my first post over here and I appreciate the opportunity to talk with all of you.

I'm a marine electrician, and I am willing to learn a little bit more about lead acid batteries.
I have some more solid background when it comes to lithium, but well, almost 100% of the service bank batteries, at least here in Brazil still using the lead acid technology.

A lot of times people ask me in the first evaluation of the boat the State of Health (SOH) of their battery banks. As a simple as it is, for the cranking side of the system I use a Conductance Battery Tester, and it tells me a lot of useful information. Battery Voltage, SOH, SOC, alternator ripple voltage, and etc.

But when it comes to the deep cycle side of the system (service bank) it isn't that obvious. CCA information is not normally shown on the deep cycle batteries, with only a few exceptions, so I have some CCA tests of deep cycle battery models that are mostly found on the boats over here, and I use this as comparison to give a shallow idea of the SOH of the batteries (Probably good, regular, and need to be replaced).

But the truth is what does it actually tell me about the SOH of the batteries? CCA can tell me how much instantaneous current I could demand from the battery, but for sure it isn't a good method to tell for how long the batteries could stand If I apply some continuous current.

I thought a few times to make a device that applies some constant current for a given amount of time while take some measurements. With this measurements, I could theoretically find the peukert exponential for that given battery and compare with the number that I actually expect from that chemistry. But the thing is that It would be a bulky equipment as it would have to dissipate a lot of heat (and well, whoever knows how it is to take all of your tools in a dingy to a boat knows that weight and volume does all the difference), and would be also time consuming both to develop and to test on the field.

So the thing is. Anyone here knows a good method to know the SOH of deep cycle batteries without actually cycling it?
 
Deep cycle batteries won’t actually be able to be evaluated in a meaningful way with a CCA test. Specific gravity of the electrolyte will indicate ‘health;’ a resting static voltage after a good absorption charge may indicate lifespan decay or not; and then a load test of, say, 10A for an hour or hitting 11.9V whichever happens first will tell you a lot.
Probably the best way is to charge for several hours, then after a two-hour resting period use an inductive pickup to measure amps while discharging to 12.1 then 11.9V at a 10A load, recording the time.

A CCA test will hit a deep cycle battery way harder than it’s designed to deliver. 10A is more in line with the design.

But you probably don’t have the luxury of that much time, either. And I’m not an engineer…
 
Back
Top