Battery bank: are they still good?

[laurier]

Is it feasible to check each battery without having to separate them.
Seems that they do not keep charge anymore....
AGM batt= lot of $$$$$$$

[tedgard01]

How old are they?

[laurier]

Originally Posted by tedgard01

How old are they?

5 to 6 years. AGM

[beenthere]

you can check the voltage of each battery while hooked up just attach to pos and neg of each battery...

[Luv2go]

You really need to separate them to check them correctly. I have had one bad battery drag the whole bank down. I'd charge them fully together, then separate them to check them. If one is bad, letting it sit there for a day or two, then measuring them all with a DMM will show you the bad one, it will have a much lower voltage then the others. Another way would be to bring them all to an auto parts store, they usually have load testers and will test them for free.

Depending on brand, 5-6 years is a good life out of an AGM, IMHO. Some, like Lifeline, have been reported to last as long as 10 years, but the more typical ones I've used last 5 years with typical use.

[Luv2go]

Originally Posted by beenthere

you can check the voltage of each battery while hooked up just attach to pos and neg of each battery...

If they are two 6V in series, yes, this can be done, but with batteries in parallel there will be a no or a negligible difference between the batteries, caused by the resistance of the wires if there is significant flow between the batteries.

[beenthere]

on the coaches the way there hooked up you can do do each batt

[Wolfpack Fan]

My suggestion for what it's worth is to check each cell with a hydrometer. They can be purchased from just about any auto parts store or online for less than $20.

["007"]

A few pointers in this link.

[Wolfpack Fan]

I read the info from the last post and checked the link and it has me wondering. Just out of curiosity though. My house batteries are less than 2 years old and in great shape.

I've got what I think is the norm with class smaller class A's, a 34 footer, 2-6v wired in series to produce 12v. They're from Batteris Plus and are comparable to Trojans. The same as used in golf carts from what I understand.

Here's the curiosity part. I know the 6v true deep cell's are designed for the rigors of constant discharge and re-charge. Way better than the pseudo deep cells sold at parts stores with marine labeling on them. If the chart holds true you don't have extended capacity with 2-6v. Does someone make a true deep cell 12v similar to the Trojans and their equals? If they were wired in parallel you'd get better capacity than 2-6v, according to the chart. Right?

Not trying to start a P'ing contest. Really just curious.

[Dunner]

I believe they do, but from what I've read, they are quite expensive.

[Mr_D]

Originally Posted by Luv2go

Depending on brand, 5-6 years is a good life out of an AGM, IMHO. Some, like Lifeline, have been reported to last as long as 10 years, but the more typical ones I've used last 5 years with typical use.

I'm surprised they have that short a life, our standard lead/acid Interstate U-2200's lasted one month short of 10 years and even then were still good enough for our use but we were headed out on a trip and I didn't want trouble on the road.

[TQ60]

Someone stated to measure the specific gravity, no water in the battery, so cannot do.

AGM batteries are designed for a 10 to 20 year installed life when in float service, which is when they provide backup power for fixed equipment for short periods of time, and maintained within a few degrees of 77 degrees.

This also has a cycle count of about 1000 cycles, depth of cycle variable, but expected less than 40 % discharge, with average about 10% MAX.

If used for "cycle" service, UPS is one of these, livespan can be as short as 2 years, the 1000 cycles still applies, but the cycle service usually has a deeper discharge more often, so the battery will wear out in lesser time.

AGM batteries were not designed to be used in anything with wheels on it...

What the heck is "RV" service...?

RV has wheels...so AGM battery not really designed for general RV use, but when the RV is configured to work with the AGM batteries they will perform very well (as designed, when system is engineered as battery manufacturer specifies)

If t
Temperature, charging (float)voltage, charging current, depth of discharge are a few things that each by themselves determine the performance and life of the battery.

When the temperature reaches 90 degrees for extended periods of time the battery is damaged, the more over 90 the higher the damage, and it cannot be reversed.

Unless the the battery is specifically designed and rated as a "deep cycle" battery then when boondocking on the battery one is consuming one of the 1000 cycles the battery has, the deeper the discharge the higher impact or more degradation to the battery you will get.

Look at the tops of your batteries, look for wite stuff around the circle shaped inserts on the top, should be six.

White stuff is indication of gassing off, this happens when the current flow exceeds the capacity of the chamber to retain the gases that occur when charging.

If the battery gasses it looses water that cannot be replaced.

Charge them for a couple days with a trickle charger.

Turn OFF the main disconnects, place charger directly on the battery,

The HF cheap one for $4.99 on sale is perfect, will take a week or so to do the job, when voltage reaches 13.5 the battery is charged.

Disconnect the ground cable from both batteries so they are each isolated, now let them sit for a few days.

A 100 amp load can load test the batteries, or time with your MH loads.

Both should measure the same, about 12.6 to 12.8 volts.

Less than this they are self discharging, if one low and other ok, the low one is bad, both low, both bad.

If both are ok, reconnect grounds (one at a time) and measure voltage with a load, say the inverter, both should react the same.

This is an easy but not fast way to do it, you can purchase some equipemnt as well to make it quicker.

There is a ton of information on this forum about battery testing, design and performance, myself and a few others have posted many times, do a few searches and you will discover a great amount of information.

Flooded batteries will surviive better if maintained, and they cost less $$$, AGM has less resistance so they can output higher currents, but usually this is not a concern.

[Tony Lee]

Assuming you have 12V batteries connected in parallel.

Connect shore power for a few hours so they are charging.

Not essential to make sure they are fully charged as you are looking for differences.

Disconnect shore power and disable solar charging.

Leave for a couple of hours

Disconnect the NEGATIVE cables from all batteries.

After 30 minutes, measure the voltage of each battery.

If one or more is considerably different - say 0.3V different to the others, then that battery is suspect.

To be sure, get a 12v headlight bulb and connect it to a battery and measure the voltage after 10 minutes and then again after an hour and then - if you have the patience, at 5 hours. Record the readings. Disconnect the load and read the voltage after sitting for 30 minutes. Record it.

Do the same for the other three and record the results.

Those readings should be enough to make a crude judgement about all the batteries

BTW My OKA has two 256Ah house batteries and last year we spent 6 months driving through the centre of Australia - mostly on tracks that haven't been maintained for 50 years. Several thousand kilometres of really, really bad washboarding, scalloped sand dunes and generally the worst roads Australia can dish up - including the Canning Stock Route that broke a team of 6 Mercedes 4WDs last year - and my AGMs are still in perfect condition ---- so I would be interested in the science concerning the claim that they are no good on wheels.