Alternator output vs Link 20 Ah reading

Allen · Post by **Allen** » Sun Sep 14, 2008 9:35 am

My understanding of how a charging system works is that the alternator amperage out dorps to around 2 amps when the batteries are around 80% charged. My Link 20 battery monitor records negative amp hours which are suppose to be related to battery capacity remaining. If the above assumption is correct, the Link 20 should indicate the -Ah reading to be in agreement with the alternator output, however, the -Ah reading seems to grow over time relative to alternator output.

Am I off base here, or is there a correlation?

FYI...

Two 6V T-105s in series
65A Beta Marine Alternator

The engine starting battery does not exhibit the same problem.

Popeye1865 · Post by **Popeye1865** » Fri Oct 03, 2008 12:30 pm

the last 10 percent of bat capacity is very difficult to get while running the engine i just takes too long try plugging in the boat overnight to charge the batteries the link will automaticly reset after all the charging perameters have been met. also you may not have the correct values set for the pukert factor in the link this is one of the primary ways that the link 20 calculates AH make sure all of you settings are correct on the link plug the boat in for an extended period and see what happens it should automaticly zero the AH after a good charge. also the link always couts backward AH from zero so all numbers shown will be negative with the exception of a near complete charge. the manual is available online

Allen · Post by **Allen** » Fri Oct 03, 2008 5:30 pm

Popeye,

I have set the Pukert factor based on my batteries but I still keep getting a build up of used (negative) Ah over a period of tome. I have a A/C charger on order and will connect it when it arrives, until then I just reset the Link 20 when the alternator charging amperage drops to <3A and the -Ah reading is excessive causing the two yellow lights to be on. This usually keeps it happy for a week or so.

Popeye1865 · Post by **Popeye1865** » Sat Oct 04, 2008 9:58 pm

i assume you have the amp hours set correctly for the battery bank and the pukert factor you have is from the battery mfg. i'd look thru the setup procedure and make sure your settings are correct for the batt. bank you have. Things like charge voltage, charge amperage and make sure you are obtaining these specs with your charge setup because you shouldn't have to reset the link every week. Also as your battery bank ages you may have to change the pukert factor to accommodate. there is a way to calculate this by charging the batteries then applying a load for an extended period i'm not sure but i'm sure the process is available online somewhere.
good luck
Brandon