Stick with T-105 or Airstream stock AGMs?

[wareaglewalt]

We're taking delivery of a 2017 Flying Cloud 25FB in July and trading in our 2016 19' that has Trojan T-105s. The Trojans are about a year old. Our new rig will have the 160 watt solar on the roof and AGM batteries. We already have a 200 watt Zamp portable solar and we plan to be doing a LOT of boondocking on a long term basis, so I plan on using the portable whenever possible in addition to the roof panels.

I may be jumping the gun because I have no sure idea what the amp-hours of the AGMs are, but I want input as to whether to keep the T-105s (which Colonial Airstream says have a "little more" amp-hours) or go with the new AGMs they're supplying with this new 2017? Or does it really matter either way?

Thanks!

[uncle_bob]

Hi

Battery capacity is rated in amp hours. You might think that 100A for one hour is the same as 1A for 100 hours. Unfortunately it's not quite that simple. The lower the discharge rate, the better the amp hours. It's a +/10% sort of thing at normal discharge rates.

Your T-105's are rated at 180 to 220 AH (depending on rate). They are 6V each so to get 12V you need two in series.

You will need to check exactly which batteries your 25 FB. It might be a 2018 if it is arriving in July . The Airstream batteries are hooked in parallel (if there are two of them). The most common number tossed around on their capacity is 75 AH. Since they are 12V batteries, the AH numbers add. That gets you to roughly 150 AH.

Since both battery setups are lead acid, the higher capacity they are, the heavier they are. That will impact you tongue weight a little bit. They also have a limited life. That's true no matter who you get them from. How limited a life depends on a bunch of things. It's a good bet that you loose 10 to 20% of the capacity a year (with 10% being more likely). The stock AS charger is a bit of a beast and that would be the main reason for loosing capacity at the higher rate.

Bottom line will depend a bit on exactly which batteries (and which charger) you get with your trailer. Since things generally don't change a lot, you probably will still be in the "T-105's have a little more capacity (and a little shorter life after being used a year)".

Bob