Agm batteries and charging voltage

Cutwater28GG

Cutwater28GG

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Joined
Jan 14, 2016
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1,996
Location
seattle
Fluid Motion Model
C-28
Non-Fluid Motion Model
Cutwater 28
Vessel Name
Living The Dream
My boat has the AGM factory option which has since been replaced with the same model universal AGM batteries. To my knowledge this means the charging circuit should only be putting in about 14.2 volts into the batteries to charge - less than with regular wet cell 12 volt batteries. which is happy with the higher 14.6

Today however I finished the install of a new smartgauge and noticed I have a 14.6 volts charging rate which is too high for AGM's causing a over volt error on the smartgauge. (it made me realize the error as its hard to see the difference between 14.2 vs 14.6 on the blue seas analog panel - and I never noticed!)

question. are the universal AGM's actually real AGM's with the required lower charging rate or are they the "fake" AGMs which are wet cell batteries with a glass mat but no additional special chemicals which require the lower volts?
I ask, as the smartgauge manual in the battery selection menu talks about two different types of AGM's.

I'm confused as I'm pretty sure the solar charger is set to AGM's and I thought the promariner charger was set to charge AGM's with the lower rates. seeing 14.6 volts is concerning as im probably killing the AGM's prematurely at this rate.

Im going to have another look at the promariner tomorrow but keen for other ideas
 
I would first check your settings on the solar and the promariner. If you still have the issue then you need to isolate which one is the culprit. Once you find out you may want to call the manufacturer and ask them about it. Then from a practical sense how long did your old batteries last with this same setting?
 
Hmmm, I routinely charge my agm batteries at a charge rate of 14.6V- 14.8V following deep cycle use.... 13.6V-13.8V for standby use. Never had a problem...on their 6th season.
 
Different mfrs agms have different charging voltage reqmts. Not all the same. You need to know voltages specified for your particular agm's
 
interesting. found the spec sheet. http://files.upgi.com:8086/UPGFileService.svc/GetSpecSheet/45824

Am I reading this right under the charge method section, when it says the control voltage is 14.6 to 14.8Volts is that the required charging voltage? if so, these look like AGM's that are in the class of typical wet cell batteries rather than true AGM's.

this makes me wonder that the promariner is on the correct setting and its fine, but perhaps I need to change the solar charger to be more like a typical wet cell charger as the volts from the solar charger is set to AGM and potentially too low!?
 
From what I understand, bulk charging AGM’s at 14.6 to 14.8 is pretty standard. 14.4 volt or more. Not sure what you mean by “real” AGM’s. Perhaps you are thinking of Gel Cell batteries? AGM’s are not Gell Cells. Gel cells require a lower bulk charge voltage. 14.4V or less.

The following link gives a general table of specs for different types.
http://batteryuniversity.com/learn/article/bu_214_summary_table_of_lead_based_batteries

As far as the solar controller goes unless you were living on the boat indefinitely with only solar charging the solar charge voltage would have little impact on life. In low light conditions you won’t even get 14volts. The solar panels get you through the times you do not have shore power. You’ll typically get your bulk charge from the alternator and your float and maintenance charging from shore power. The float charge voltage is more critical for AGMs than the bulk charge.
 
interesting. I am trying to correlate this to the guidance in the smartgauge manual. page 4 of the manual talks about the different types of AGM's (both of which are separate from Gel)
http://www.balmar.net/wp-content/uploads/2018/05/PDS-44-SG-1224.pdf

Separately on the solar front. isnt the PWM controller dropping the volts down from the panel voltage to a suitable volts for charging? therefore what the solar controller drops volts down to, is important for battery health? if this wasn't the case why would we bother with a controller at all? but maybe a PWM controller is more dumb than I thought!
 
I emailed universal power group who make these batteries asking if they can clarify
 
I also use a Balmar smart gauge.... you want to use the group 1 setting for the battery type selection.
Actually the side panel on the UPG battery has much of the info you are seeking.
I have the Promariner charger on the AGM selection. Don’t get too hung up on the solar aspect....Red Raven is right, solar is mostly a maintenence charge. Hope this helps.
 
Cutwater28GG":22hkyygt said:
interesting. I am trying to correlate this to the guidance in the smartgauge manual. page 4 of the manual talks about the different types of AGM's (both of which are separate from Gel)
http://www.balmar.net/wp-content/uploads/2018/05/PDS-44-SG-1224.pdf

Separately on the solar front. isnt the PWM controller dropping the volts down from the panel voltage to a suitable volts for charging? therefore what the solar controller drops volts down to, is important for battery health? if this wasn't the case why would we bother with a controller at all? but maybe a PWM controller is more dumb than I thought!
Click to expand...


AGMs: As NewMoon says it is ultimately up to the manufacturer of the specific batteries. It doesn’t appear the UBS batteries are the special type stated in the Smartguage manual that act a bit like Gell cells.

Solar Controller: Unfortunately no, a PWM controller does not drop the voltage. It just connects the batts to the solar panel for controlled lengths of time based on the charge state. Thus the name Pulse Width Modulation (PWM). You need an MPPT controller to be able to drop the voltage (that is the advantage and what you pay for). A PWM controller still protects your batteries by cycling the connection at a rate appropriate for charge state. It is just limited by the sunlight available and may not be able to reach bulk charge voltages at all. The voltage applied is always what is ever on the panel though the battery will pull the panel voltage down considerably based on charge state. With either controller if the panel voltage is too low due to limited sunlight (low meaning near the battery voltage for a PWM and higher for a MPPT) you will not get much charge. This is why the MPPT controller doesn’t help much (or at all in some cases) if the panels are in parallel but outperform if the panels are in series (or a higher voltage panel is used).
 
Excellent thank you all! Much appreciate the assistance
 
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