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post #17 of Old 07-21-2015
Maine Sail
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Re: Not getting enough charge voltage.

Quote:
Originally Posted by msogin View Post
Again I thank you for helping AND for your past posts on this subject. You are absolutely correct that I did not understand the charging process using the alternator and 614 controller. I was fooled by the fact that the shore charger reaches higher initial voltages AND I did not realize that the initial bulk phase charging from the alternator would have a much lower voltage until it approached a higher SOC. Using advice from your earlier posts, I reprogramed the 614 to bulk charge at 14.7 volts and absorption rate at 14.7 volts. The float is set to 13.6 as your advised. I also set the belt parameter to "2". The batteries do not go to 14.6 volts instantly unless they were fully charged on the shore charge. Last night I used my fridge, freezer, instruments etc to draw down the batteries as much as possible. With the new settings the charger initially had a value around 13.2 or 13.3 volts and after a couple of hours had reached a higher level - close to 14.1. I will plan to adjust the absorption time to 4 hours later today and I need to investigate temperature sensing on the batteries - the shore charger does have temperature sensing but I imagine I need a second sensor or a sensor for each battery for the 614 to detect temperature. This has been a good learning process.
The MC-614 has a port for alternator temp and battery temp. You can actually monitor two batteries with the MC-614. Place the batt temps sensor on the neg terminal of the battery with the ability to become hottest (eg: the battery next to the engine room bulkhead).

If your shore charger does not have temp compensation I would pick a profile that is slightly below 14.7V (14.5V or so) so that if the batteries exceed 80F we are not also pushing to hot of a voltage. This will not be optimal for the Odyssey's but it will be safer especially if you are in a hit climate.. If your batteries normally stay below 80F then 14.6V, due to bilge temps, should be fine...

To give you an example of charge rate vs. voltage yesterday & overnight I capacity tested a 2 year old 100Ah Lifeline battery. It delivered 81.26 Ah's at a 5A discharge rate. At 7:30 am this morning it began recharging at a 5A charge rate. I just walked by it now, at 12:28 PM, 5 hours later, and the battery terminal voltage is just 12.604V.... At a low charge rate an AGM spends a LOT of time in bulk..... The absorption voltage is set for 14.4V but I don't anticipate it will get there for another 9+ hours or so....

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-Maine Sail / CS-36T


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Last edited by Maine Sail; 07-21-2015 at 12:31 PM.
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