Battery Rating Standards

[TC of NC]

I have a question regarding amp hour ratings of 6 volt flooded batteries. I plan to replace the batteries that came with the trailer with some GC type batteries. I am confused how the amp hour rating are specified. Some list the ratings at 5hr, 10hr, 20hr and 100hr. Some rate only one of two of those rating and some just say like 230ah and don't specify number of hours it was rated at. Can someone tell me what is the standard? Thanks.

For example Trojan T-105 is rated at 5hr 185, 10hr 207, 20hr 225 and 100hr 250. But other brands just say like 210 ah or what ever.

[Chuck_S]

Use the Trojan T-145, it's got more amp hours than the 105.

I recall 100, 20, and 8 hours are the standard ratings but battery makers aren't required to list them all. 20 being very common.

-- Chuck

[Chewman]

When spending a few nights in a partially shaded campsite a few weeks ago my batteries drained to the point that the DVD movie started surging, and the heater would not come on. I am running 2 wet batteries and have a 100 watt solar panel on my 2019 G19FD. This past summer we had never even come close to low battery power so I wasn't paying attention. Obviously with the time change and more time in the trailer at night I need to start paying attention! Do trailers have some device that prevents it from draining the batteries past 50%? I have read that drawing them down to 40% can permanently damage them.

[Chuck_S]

You need bigger batteries and less current draw.

Deep cycles can discharge deeper than below 40% but that's 11.9vDC and some devices will not run on that low voltage. There may be aftermarket devices to shut down power at a certain point -- and put you completely in the dark -- but the easiest thing for me is a battery amp-hour meter that shows the remaining capacity (not just voltage) in the battery.

I assume you mean furnace rather than heater. The furnace in my Roo draws 3.4 amps and in an 8 hour flame cycle will suck 27 amphours from the battery which is half what a Group 24 battery can furnish. Forget the 80 amphour rating for these batteries, at about 55 amp hours the voltage remaining is too low to power anything. A pair of them can be expected to reliably supply 110 amphours if nothing else is used. A 100 watt solar panel will do little to replace battery power. Good for trickle charging the camper when in storage though.

Got LED ceiling lights? The conventional lights pull 2.5 amps each. I replaced all mine with cheap Ebay LEDs a couple of seasons ago to help minimize electrical load when on battery power.

-- Chuck

[BehindBars]

In regards to the original thread questions, reading here https://batteryguy.com/kb/knowledge-...r-or-amp-hour/ it seems like the 20 hour rating is the industry standard. But, for batteries that don’t disclose all data, or the rating methods, I would not trust them to be accurately describing the battery capacity. If the battery listed only an amp hour number but no time or end voltage number, I would assume they are playing a marketing game to mislead buyers, and I would just avoid those batteries.

[chriscowles]

If you search the manufacturer's web site you can find technical specifications with the details you're looking for.

When choosing a battery, also look at the expected cycle life. I bought some Sam's Club Duracell 6V GC2 flooded lead-acid batteries which meet my current needs. I knew they were cheap but didn't know quite how bad they were until I found the expected cycle life graph. At 50% depth of discharge, they're expected to live about 300 cycles.

Other brands of lead-acid batteries, such as the Trojans you referred to, have an expected cycle life of over 1500 cycles. They certainly cost more but you can do some simple math to figure out whether it's cheaper to buy good batteries that last longer or cheap batteries that you replace more often.

LiFePO4 life cycles are in the 3,000-5,000 range.

[TitanMike]

Originally Posted by BehindBars

In regards to the original thread questions, reading here https://batteryguy.com/kb/knowledge-...r-or-amp-hour/ it seems like the 20 hour rating is the industry standard. But, for batteries that don’t disclose all data, or the rating methods, I would not trust them to be accurately describing the battery capacity. If the battery listed only an amp hour number but no time or end voltage number, I would assume they are playing a marketing game to mislead buyers, and I would just avoid those batteries.

Testing a lead acid battery capacity is pretty much an industry standard.

As mentioned above, the ampere hour rating of a battery is based upon a continuous discharge, starting with a specific gravity of 1.280-1.300, and finishing with 1.150. The end of the discharge is also considered to be reached when the voltage per cell has dropped to 1.7.

Not based totally on end voltage but rather on specific gravity. Voltage is affected more by internal battery resistance but specific gravity is more of a standard.

Unless one wants to buy a battery and test it themselves they just have to rely on what the Marketing department puts on the labels.