Newbie battery question

[keithgregg]

When I bought my 1970 Safari there was no battery installed.
I have three 12v 35ah SLA batteries by Universal Battery leftover from a solar system I had.
Would this be enough battery for my trailer?

[Ahab]

I use one GR29 battery, it's more than enough and I do a lot of boondocking.

[keithgregg]

Hmmm. I am having a hard time googling GR29 battery.
The only thing I can find is a Sony Vaio laptop battery.

[dznf0g]

Interstate is the only one, that I have ever seen, that makes a group 29 lead acid battery. I have 2 "shoehorned" into my compartments:

Interstate Batteries

Edit: I see now that there are others out there as well. I wonder if it is becoming more common. I didn't find anybody besides Interstate in 2011, when I replaced may Original group 27s.

[Rich W]

Try Group 29 instead of GR29. The 'Group' value is the size

[keithgregg]

Ah! Group 29. Sorry I am a newbie and didn't get the abbreviation.
So basically I should have about 200amp hours for my trailer?
I eventually plan on hooking up a 250w solar panel with a MPPT inverter to maintain the system.
Any advice regarding my still untested old Univolt IV system?
Should I just scrap it and start new?
Thanks for the info everybody.
Please keep the good advice coming.

[dznf0g]

Although the battery may be rated at 200Ah, you shouldn't regularly run a deep cycle battery below 50% (or 12.06 volts), so in reality you have 100Ah "usable" for your trailer.

I just finished a reprogram and battery test using my Trimetric monitor to find my ACTUAL Ah capacity on my 3 year old Interstate group 29s. I ran the batts down over about 28 hours to 12.06V and recorded the Ah used. It was right at 125Ah. So my total capacity is 250Ah and 125Ah usable. I reprogrammed my Trimetric using this actual performance.

Interstate does not rate their "hybrid" marine deep cycle batts by Ah, so I finally got around to working the performance numbers. I had swagged the initial programming number to 90Ah......now I know why when I was at 40% charge on the monitor, I was still at 12.2V