Lifeline AGM's Fully Charged Voltage?

[john61ct]

Originally Posted by rom

It would take about 90mn to go down to 1% from 2% and the batteries would stay there accepting 1% forever.

Could it be that some of us have been waisting time and money trying to reach the 0.5% trailing amps advocated here every single day by our forum expert ?

There is no endAmps spec that covers all batts, you should use the one from the maker.

As has been stated many times, as a bank ages and wears, it gets harder, takes longer, and at a certain SoH% does eventually become impossible to reach the spec'd endAmps.

Nothing to do with overcharging, and may in fact indicate time to schedule replacing that bank.

An alternative spec to use is Deka's:

> Absorption End Point =*Current change over 1 hour period of less than 0.1A

Note the current **change** point there, no actual absolute value given for endAmps

Thus it will work even with an old worn-out no-name Wally's batt that has trouble hitting .05C

But when that batt is fresh and new, and you can't find the specific protocol from the maker, then .005C is a good default to start with, especially for FLA.

For a sub-par AGM, maybe use .02C if you're worried about overcharging.

As a side note, if you can't easily find detailed specs like endAmps from a batt maker, it's a sure sign IMO that you should avoid purchasing that brand.

The point is to have an objective benchmark to hit consistently "most cycles" if possible,

rather than assuming "going to float" is an indicator of the bank being Full.

[Maine Sail]

Originally Posted by sailinglegend

Lifeline say replace the bank when down to 50% - and then only if the capacity is too low for normal use. Other manufacturers recommend replace at 80%.

We are full-time liveabords in the Med - not weekenders!!!

So we started with a very big bank of 1050Ah and when it got down to 450Ah it is was too low for our cruising needs so we replaced them - this time only 610Ah - but with more solar.

This worked out at £123 per year!!!!!

We will no longer send a customer off shore without strong guidance to replace the bank once AGM batteries get below about 70% SOH. The batteries below were at 72% SOH when he left Maine.






We have seen a number of AGM failures, including Lifeline's as above, once approaching 70% SOH. Going to 50% can be fine for a boat that mostly does coastal stuff, and I do have banks out there plugging away at 55% SOH etc., but we can no longer recommend or suggest off-shore cruising use once below 70% SOH.