How Bad Did I Mess Up?

[donradcliffe]

Yes brother, you have sinned and the outlook for the batteries looks grave. Yet, they might fully recover! For just a $10 donation, the entire congregation of the Free Electron Church will pray for your batteries.

That and a good charge may do the trick, but some times it takes more than one donation.

[Madehn]

to donradcliffe and others of the Free Electron persuasion- have sent donation electronically - please commence prayers to the rest- am going back to the boat tonight to see where we stand- the 40 amp charger is pretty much toast i believe- going to see what my backup to the backup charger has done with them over the last 24 hours. Big lesson learned- i found this out when i installed a digital volt meter versus the old analog style- the analog was accurate enough but in the position was hard to read and i just missed it-- a big vote for digital and for big easy to read numbers!!

[CaledonianCruis]

"Practical Sailor" magazine has run excellent articles on AGM batteries - deep charging and recovery. The articles have been quite useful! What is clear is that battery lifetime will be degraded if AGM batteries are discharged more than half. How soon the AGM battery gets recharged after discharging it has a lot to do with how much sulfidization (SP?) occurs. Leaving a battery discharged does some amount of permanent damage. Lithium batteries are better than AGMs, but cost a lot more and need a carefully designed charger. Actually, different brands of AGM batteries have different recharge requirements so it is always best to consult the AGM battery or Lithium battery manufacturer about which re-charger to use. Both AGM and Lithium batteries are more "Hightech" and finicky than your car battery or 6 VDC golf-cart batteries. There have been fire issues with some Lithium batteries ... especially very light weight ones used by Boeing on airliners and by Samsung on smart phones, but well designed Lithium batteries for marine use with the proper charger are probably as good as AGM batteries but more expensive. I suspect that 12 VDC Victron Lithium batteries (as Elco recommends) and the 24 VDC battery sold by Torqeedo are very good batteries ... if you use the charger the manufacturer recommends. Lithium batteries can go through far more charge discharge cycles than AGM batteries (longer lifetime) and do not have the "memory" issues of AGM batteries (i.e, can be discharged further than 50% and fully recover).