Over Accumulation of Amp Hours on Link 2000

[jbbmillar]

I have a Link 2000 and Freedom 25 inverter/charger installed on our Mainship 390, with 2 ~5 year old West Marine 8D AGM (240 ah ea) batteries. They are combined with a Yandina 100 battery combiner.

I recently replaced the Link because I was seeing anomalous Data readings (manual page 15) on the old one (impossible deepest discharge readings). The new one isn’t showing those.

I have the Link set to show amp hours instead of percent remaining (manual pg 13). I notice that once they get into float stage one of the batteries is accumulating more than double the number of positive amp hours compared to the other one. After a couple of weeks one is +10 and the other is +25 or more.

Does this imbalance indicate the battery is failing?

FWIW, I used the Link 2000 manual suggested battery test: use inverter to draw a steady ~10-12 amp load until the inverter shuts down (manual pg 17). Both batteries delivered a disappointing ~120 ah.

Manual: Discontinued Products

 

[DavidM]

Nor surprising that you are only getting 120 AH from your 8Ds. They are almost certainly not designed for deep cycle use.

I would replace the 8D that you use for house loads with two 6V golf cart batteries- they will fit in the 8D box.

Then to make it easier next time, replace the other 8D with a good Group 31 starting battery. Make sure that you use the starting battery for starting and the deep cycle batteries for house loads.

The Freedom should self reset to full when it sees x volts for a period of time (can't remember the values but the manual says) and stay that way until you put loads on them.

David

 

[CharlieJ]

djmarchand:

They are almost certainly not designed for deep cycle use.

Said a different way, the 8Ds are not designed for deep cycle use.

jbbmillar:
I agree with Post #2. Do yourself a favor and follow his advice. With reasonable care you will get more service life from your house bank and the Group 31 will certainly start any engine that requires <900CCA.

I would only add that you test the batteries individually with either an old school carbon pile tester (about $70 at Harbor Freight) or with a conductance tester like a Midtronics (about $350). A good marine electrician should have both of these pieces of test equipment.

 

[john61ct]

Dyno and Rolls / Surrette do make true deep cycle 8Ds.

But lots more expensive than the mass market ones, dual use or starters.