AGM Battery + Charge Controller Question

[Jake Jacobson]

Hi,

I am moving house and want to take my 4x 85watt panels with me.

Does an AGM battery need a special charge controller?

I have purchased a Xantrex C35 because it has a setting for AGM and also changeable charge point settings.

My question is what are the best settings to use for an AGM battery with this controller, should i leave it on the default AGM setting or customise it for the battery?

They are 2 x 200AH AGM batteries, on the side they say

CONSTANT VOLTAGE CHARGE

Cycle Use 14.4-15v
Standby Use 13.6-13.8

Thanks in advance :)

JJ

[Jake Jacobson]

Still wondering about this, i have manually set the charge points but it does not appear to be charging correctly, when battery level drops the controller still shows it as full (green light) to get it charge again i have to initiate then cancel the equalisation mode, the light then flashes and charges as normal.. but doing this every day is frustrating! any ideas?

[Rob Beckers]

Hi Jake,

All charge controllers these days can be set for AGM batteries. There should be generic voltage settings either build-in, or provided so you can enter them. All battery manufacturers also provide voltages that are specific to their batteries, in case you want to fine-tune it.

I'm not too familiar with the C35, though I have heard good things about. The manual states that float voltage has to dip below the lower limit for one hour before it will restart a charge cycle. Could that be it?

Hopefully someone on the forum with the same controller will speak up. You can also try contacting Xantrex (they've been helpful in past when I did).

-RoB-

[Sean DEpagnier]

I use the C35, and it works for me. I have flooded batteries and about twice the capacity though.

Maybe you can adjust the float voltage with a screwdriver until it charges again. Also it could be doing temp compensation. I don't know if you have the temp sensor installed or not, but the voltage set points change based on this.

[Ken Reid]

With this control and AGM batteries just set the bulk to 14.2 and float to 13.5
When the voltage reaches 14.2 and held there for 2 hours the control will go in to float and hold the batteries at 13.5 with the light staying green until the voltage drops to 13 volts where the control will start another bulk charge.
DO NOT try to equalize the AGM batteries. hope this helps
Ken