Originally Posted by sailorboy1
I don't accept the new reduced battery capacity as the cause of the large voltage drop under load that I thought the thread was about.
It sounds like there are a myriad of other issues such as a .6V drop in a 4/0 wire which likely means poorly executed terminations, weak/bad switch, corrosion
Batteries could very well have been at sufficient voltage to drive the inverter
but the voltage drop in the wires caused the inverter
to drop out on low voltage. If there is a 0.6V drop in the positive there is a good possibility there is a 0.6V drop in the neg side too. 4/0 wire needs a swage type crimp with properly matched dies to the lug. A swage type
crimp is 360 degrees in compression
making the entire lug smaller around its circumference & the overall lug at the crimp bands smaller in OD.
Dimple crimps, hammer & screw driver, pliers or vice grips, bench vices etc. need not apply for the job of crimping 4/0 wire or voltage drops will occur more readily.. All poor crimping does is distort the lug and result in a poor termination that can't adequately handle the current
a 4/0 is intended for. There is one crimp tool maker out there that uses a hammer. They claimed, and perhaps still do, that the hammer crimp tool makes a UL Crimp. I asked them for UL documentation
of this claim, FOUR TIMES, all I got was dead silence..... If you are pulling big current
you need proper terminations.
Unfortunately I don't feel as if we have been given enough good technical information
on this issue..
We do know that best charging practices, for Lifeline batteries, have not been employed. It is very possible they have diminished by the amount claimed but we really need to know a lot more of the finer details to determine if that is in fact the case.
The simple fact is that a 750Ah bank of Lifelines should NOT drop out an inverter under a 0.3C load. Even if slightly diminished they should still handle this type of load with ease. Even at 50% SOC .3C is cake walk for Lifeline batteries.
Details that would help:
* How EXACTLY was this capacity test performed? DETAILS, DETAILS, DETAILS......
*At what temp were the individual batteries when tested?
*What was the discharge cut off voltage when measured at the battery terminals? Was it all the way to 10.5V? What tool was used to measure this? Where was the discharge voltage cut off point measured?
*How were the Ah's delivered counted?
*Details on the Ah counter settings & set up for the capacity testing?
*What was the load applied to the batteries during testing? Each battery, if 125Ah's, should have had a load of exactly 6.25A (+/- 0.05A) applied and HELD STEADY at 75-80F battery case temp until each battery hit a terminal voltage of 10.5V? Doing the test any other way will not result in accurate
*Was this 6.25A load held constant for 20 hours or until each battery hit 10.5V?
*How was "full" determined? MUST BE 14.4V at the BATTERY TERMINALS & 0.5% of bank capacity being accepted in current.
Full for a 750Ah Lifeline bank is 14.4V terminal voltage AND 3.75A or less in current flowing into the batteries. Your batteries must
be truly full, 0.5% acceptance @ 14.4V, for any capacity test to be meaningful. They can NOT be "cruiser full" or 2% acceptance otherwise we have GIGO data (garbage in, garbage out)... For an individual 125Ah battery full is 14.4V and 0.625A of accepted current. Any thing other than 14.4V and 0.625A or less is not
full enough for an accurate capacity test.
* You can do this test and stop at 2% acceptance and this will tell you your "cruising capacity" (a good idea actually) and this capacity will be LOWER than a true capacity test. If you base your Ah counter on factory Ah ratings (generally incorrect to do so unless you always get back to 0.5% acceptance) then to be fair, the capacity test must be done the exact same way the factory does it. You can't compare a 14.4V / 2% acceptance test to a factory capacity of 14.4V / 0.5%... Comparing cruiser full capacity to factory full new capacity results in GIGO data. A capacity test needs to be done the same as the factory does it to make claims sugch as "my batteries are XX% diminished"...
I am not doubting they are diminished at all. I see this in Lifeline batteries pretty regularly, more regularly than in quality deep cycle flooded batteries, but in almost
every case best practices
have not been adhered to for charging, discharging & wiring
Lifleline batteries, and many other AGM's too, need proper charging more so than some other types of batteries which can be more tolerant of charge/discharge abuse.. There is little room for error as these batteries can not be regularly overcharged and have the electrolyte replaced and they sulfate rapidly when not brought back to 100% regularly.
Lifelines need things regularly such as;
*20% of capacity in charge current as a bare minimum. Low current charging of Lifeline, or Odyssey TPPL AGM batteries, DIMINISHES CYCLE LIFE!
*They need regular equalization
(conditioning) charges if cruised.
*They need temp compensated charging especially in warmer climates.
*They need proper programing of the battery monitor
so they are not over discharged. This means yearly 20 hour capacity testing to ensure you are taking out what you KNOW to be 50% of capacity.
*They need to get to 100% SOC as often as is humanly possible.
*They need proper voltage sensing so the batteries actually get to the target voltage before charge sources get turned off or the sun goes down. This is especially true for sailboats with short motor
*They need proper float voltages.
*They need battery compartments that do not consistently exceed 80F or the coolest part of the vessel you can find to fit them....