Is this a deal?

[Texjbird]

Just now on Craigs list Mongomery AL in RVs,  low to high $, @ $100 each  there are 2   GNB Marathon 12v 155AH deep cycle batterys.  Sez they are telecom backup batteries and are 4ys old.  Also will include a free 75watt solar panel with each battery. 
 
I can't post a link so to anyone that will THANKS IN ADVANCE 
Also any input on these will be great!

Jewellann

[GotSmart]

My used batteries lasted about 5 years total. That gives you about 1 year use for $200.

You can do much better. IMO.

[rvpopeye]

The free solar panel makes it a bit better deal but the battery will have an unknown life expectancy.....

[sternwake]

Telly com AGMS are built a bit differently




https://www.wholesalebatteriesdirect.com...ttery.html

How much life is left in one of these batteries is entierly dependent on their average temperature, how often they were deeply discharged, how soon  they were recharged after discharge, and the float voltage they were held at and if it was temperature compensated or not.  

Pretty much like every other lead acid battery, but telecom usage might never even cycle the battery if the grid never goes down, and they have to swap them out on a schedule so they can guarantee the batteries can power it for X amount of time

If they never baked in a box, and were cycled infrequently, and floated properly, they could give many hundreds of deep cycles starting at 4 years old.

If they were actually cycled often and baking in direct sun, and not recharged very well or promptly and floated at too high a voltage. They might give a few dozen to perhaps a few hundred cycles.

Whether  a few 100% discharges followed by precise hail mary recharges might restore some capacity, is an unknown.  it would be difficult to quantify without doing 20 hour load tests.

Many people Cycle telecom batteries in RV's successfully.

Personally, With no experience of putting a heavy load on any  specific telecom battery myself, I dont know what to expect, as  far as I know, these are not meant to provide huge amperages, but be in a large series parallel bank, perhaps 16 or more batteries strong.

Meaning I would not really know how to test the used battery and guestimate remaining capacity, unless I could fully charge it and then dischrge it at the 20 hour rate, and see how close to 20 hours it can provide, in this case, 7.75 amps, before voltage falls to 10.5v.

Regular load testers designed for  starting batteries will not give much relevant information on this battery, not unless one could compare the results with the same load tester of  the same battery, when it was new.

A regular voltmeter placed on each battery might mean nothing, if they have been recharged recently, but if all were fully recharged a month ago, and sitting untouched since, then the higher voltage battery should be healthier, if one gets to choose.

100$ and a 75 watt solar panel?   Well I'd want 300+ watts for 155Ah of capacity, minimum, if I was cycling 75Ah each night. 

  I am not sure these tellycom AGMS are also for use on their sides.  They might not have the vibration resistance of CAR jar AGMs.  i do not know.

GNB is made by Exide.




So hard to say if they are worth it or not.  Without doing the 20 hour capacity test I'd just be guessing at their condition with shorter load tests, if I were there to test.  

Some fails/disqualifiers would be sub 12 volts, and if a small to medium load placed on battery dropped voltage singnificantly and quickly.

On the data sheet above, it claims to have:
Short circuit current of 3292 amps 
116.16Lbs
155Ah capacity
3.8m OHM internal resistance

The same size Northstar HTred specs are
5000
116.6
155Ah @ 10hr rate
2.4mOhm

Northstar NSB155
4200
101.2
155
3.1

Northstar Blue


A Lifeline GPL-30HT( top quality Deep cycle  AGM) GC-15 size

http://lifelinebatteries.com/products/ma.../gpl-30ht/

Short circuit current of 2622 amps
96lbs
150Ah capacity
4.92 mOhm resistnace

So this telly com battery has 20% more weight for not much more capacity.  and Lower resistance when new( increases with age)

More weight per AH,  is usually a very good thing for deep cycling.  It usually  means thick dense plates


An Odyssey PC2250( High end dual purpose AGM)
5000 amp circuit current
86Lbs
126Ah capacity
2.1 mOhm resistance

Odyssey touts their thin plate pure lead technology, as Does northstar

I think the tellycom battery when new and treated right would make an excellent house battery for an RV, but the condition of used ones is a crapshoot without having known how  hard they were used, how they were treated, and if testing them, having some new  performance baselines to compare them to.