Best Practices for Battery Life?

[jrpend]

Greetings!! -

We have for a while been having issues with lack of capacity with our 12v system. We have a Residential Refrigerator with 4 AGM batteries and Magnum inverter/convertor.

We finally got it into the local Camping World - they tested it and told me the batteries are completely fried and need to be replaced.

So I asked why? After all you buy AGMs because they have a lot of capacity and need no maintenance. The CW tech said that it is possible that the Magnum was set incorrectly and that could damage the batteries. I could buy that - I noted sometime after I took delivery that the magnum was set to "wet" rather than AGM2 which is correct for my batteries. I changed that at the time, but batteries continued to deteriorate. Maybe the damage was already done?

So what should I do to avoid shelling out another $1200.00 for batteries? We full time but because of work, we are mostly plugged in. I'm thinking having it plugged most of the time might damage the batteries.

There is a very nice switch in the basement that disconnects the batteries from the inverter/convertor. I'm thinking, when I'm parked maybe I should open that switch and keep the batteries disconnected. The CW tech thought the inverter could be killing the batteries (yeah - through use. Is there anything else that can damage the batteries). If the battery is disconnected the 12v systems could be run off the convertor (I think).

Is anyone else having problems like this or doing something to manage the problems?

Thanks,
Jerald Pendleton

[mel s]

Originally Posted by jrpend

Greetings!! -
We have for a while been having issues with lack of capacity with our 12v system. We have a Residential Refrigerator with 4 AGM batteries and Magnum inverter/convertor.
what should I do to avoid shelling out another $1200.00 for batteries?
Is anyone doing something to manage the problems?
Thanks,
Jerald Pendleton

jrpend
Read this: https://handybobsolar.wordpress.com/...ging-puzzle-2/
(Google "managing rv agm battery life" for more).
Mel
'96 Safari

[MtnTrek]

Sorry to hear you've had an unfavorable experience with your battery bank.
Often other readers can offer more pointers having more detailed info.

I'd probably not disconnect the house bank, for numerous reasons. I won't go into.

Surely you've rarely if ever discharged you bank below 40-50% cap.?
Or do you know?

4 AGMs, Do you know what voltage they are and how they are configured? There can be issues with equalizing and matching cells.
What are the actual Manufactured dates stamped on the batteries?
Issues can arise from mismatched batteries from the get go causing them to fall to the lowest common denominator quickly. More advanced processes require research. Solar sites deal with battery maint. in depth.

You mentioned that they continued to degrade even after the inverter had been reconfigured to AGM. How did that present itself?

Generally the Magnum Inverters are a very good choice. They offer some of the best performance & reliability in the industry. Which model are you using? Any installed options?

There are options available such as a remote status panel that shows your operation & charging mode.
Mine (MMS1012) has a small panel in the controls bay, LEDs that indicate bulk, absorb, float. On shore power my float LED intermittently blinks.
There can also be remote Temp. probes that come with some models. Whether they're installed ??

Battery Temperature Sensor (BTS)
A plug-in external Battery Temperature Sensor (BTS) is provided
for units with the battery charger feature. When installed, the BTS
automatically adjusts the battery charger’s BULK, ABSORB, and
FLOAT voltage set-points (based on temperature) for better charging
performance and longer battery life. If the temperature sensor is
NOT installed and the batteries are subjected to large temperature
changes, battery life may be shortened.

AGM's despite their other merits do not like high temps. Temps. over 77 deg. F can reduce service life by 50%.

You might want to consider installing one of the more advanced battery monitoring devices most of the seasoned solar power users employ. They cost a mere fraction of the battery replacement cost you're incurring. This rather than just reading voltages use a shunt that tracks the actual amperage flowing in both directions. This offers a truer representation of capacity.

Do your current power usage patterns really merit 4 AGM's?

We explored many of the more expensive options (solar array, large AGM, Lithium banks) with unrealistic self-reliant expectations. Finding ourselves generally in CGs we opted to bypass/delay some of the more expensive additions. Thinking of Moore's law, costs decrease, capacities increases, till we really need the added capacity.

Happy motoring.

[Melmoses]

Go to a Sam's Club and buy yourself 4 U2200 wet cell batteries for about $400. If you are plugged in most of the time you don't need AGMs. Just remember to change the Magnum settings.

[vsheetz]

Originally Posted by Melmoses

Go to a Sam's Club and buy yourself 4 U2200 wet cell batteries for about $400. If you are plugged in most of the time you don't need AGMs. Just remember to change the Magnum settings.

Agree. The prime advantage of AGM is low maintenance. With wet batteries just check the water once a month. And clean with some battery cleaner a couple three times a year. That that big a deal to do, IMHO.

[powercat_ras]

Personally I would stay with the same kind that Winnebago designed your RV with as your inverter and or converter-charger was matched to them. If you change from that you will have to replace the converter-charger to match unless it can be re-configured to match.

I know a lot of irv2 posters have and like AGMs but they have CONs as well as pros. Also there are some really poor quality AGM batteries from China that will not last long at all so don't be tempted by cheap no-name AGM batteries - buy from a dealer who will stand behind your purchase. Suggest you check for reviews and positive / negative posts of the brand you are considering using Google or IRV2 search.

[jrpend]

[QUOTE=MtnTrek;3130637]
Surely you've rarely if ever discharged you bank below 40-50% cap.?
Or do you know? [\QUOTE]
We never went below 50% until this trouble started and we starting hitting the "invertor cutoff" voltage level.

[QUOTE=MtnTrek;3130637]
4 AGMs, Do you know what voltage they are and how they are configured? There can be issues with equalizing and matching cells.
What are the actual Manufactured dates stamped on the batteries?
Issues can arise from mismatched batteries from the get go causing them to fall to the lowest common denominator quickly. More advanced processes require research. Solar sites deal with battery maint. in depth.
[\QUOTE]
The batteries being replaced for the original batteries shipped from Winnebago. The batteries being replaced are 4 NAPA 9831DT

Originally Posted by MtnTrek

You mentioned that they continued to degrade even after the inverter had been reconfigured to AGM. How did that present itself?

We monitored the amount of time we would go from what we perceived to be full charge (many hours plugged in) to "invertor cutoff". That amount of time continued to drop until it was basically zero. I suspected charger issues hence a trip to Camping Worlds (shout out to the good folks at Camping World San Martin). They put it on a charge and then told me the battery bank was completely dead.

I don't yet have any temperature sensors or ammeters on it yet. I'm looking at seeing what I can retro fit.

Do I need 4 AGMs? I think so - it is a residential refrigerator and even though we haven't boondocked a lot yet (there is thing called work) we believe we will do so in the near future.