The Long & Short of Battery Choices...

[Npkp]

I have 4 12vdc Deka 110 AH solar batteries connected to 3 200 watt solar panels. I have 2 of the same for the engine, 2 in my boat and 1 in my snowcat. These batteries take a beating and last up to 10 yrs. we used them at work for everything and they never lets us down. Kind of pricey, but well worth it. Thank you

[Searching_Ut]

Originally Posted by RVownr

Reading your response it seems that you have a great deal of knowledge about the flooded batteries. I am trying to decide if it is acceptable to use two 6 volts batteries (wired to create a 12 volt bank) and one 12 volt battery to make up my complete battery bank. I have room for 3 batteries - not 4 or not the really tall batteries. I have a "Midnight" charge controller and three 215 watt solar panels.

Thanks in advance.

While not the individual you addressed this to, I have a lot of experience in evaluating battery systems in the field to establish and update time change criteria for batteries used in critical systems where batteries are changed out prior to reaching certain degradation levels.


Flooded lead acid batteries in particular, do tend to self balance in parallel use due to several characteristics of the batteries. At the same time, it causes issues. The two types of batteries you mention have fairly different characteristics, with one being a deep cycle design, and the other most likely a hybrid. They will have different internal resistance values throughout the charging process, with the 12 volt charging at a different rate than the 6 volt pair, and thus either a consistent overcharge of one, or undercharge of the other. If you're lucky, mixing batteries like this might only reduce the packs life expectancy by 20 percent or so, but it will most likely be significantly more. I'm not even sure what you would base life expectancy on, as if you deep cycle the batteries much, the 6 volt batteries should last much longer than the 12 volt battery.


Bottom line, it's really best to build and maintain parallel battery packs with battery cells as balanced to one another as possible. Generally means same battery type, manufacture, age etc.

[twinboat]

Originally Posted by LargeMarge

re:
connecting multiple batteries:

This makes the most sense...
www.smartgauge.co.uk/batt_con.html

*****

re:
Bugging-Out

You and I think alike!

We planned, designed, and engineered our ExpeditionVehicle as a self-contained self-sustaining rough-country mobilized home for extended independent living.
We boondock exclusively; we never visit RecreationVehicle resorts.

We can pack-n-git pretty quick.
We practice and rehearse leaving anyplace at a moment notice.
Another advantage of the last time we owned a television set sometime last century:
Living mostly outside teaches us to rely on our senses.
We are so tuned to our environment, we are better predictors of weather and forest-fires and rioters than the folks on televisionprogramming.
But that isn't saying much...

They are using 2 gauge jumper wires and drawing 100 amps from a 4 battery bank. There will be voltage drop.

The proper gauge cable would be 2/0. A much heavier cable with much less voltage drop.

Someone else can figure out the math but the numbers will be much better and within usable range.

[lwmcguire]

Originally Posted by theoldwizard

Based on past history with Ford vehicles, it is more likely that you have "maintenance free" flooded batteries (they cost less than AGM). Maintenance free flooded batteries have a vent system that is designed to capture any "vapor" that escapes, return it to a liquid state and then place it back in the battery. These work pretty well, but I still think it is worth CAREFULLY prying off the vent system and checking the liquid level once a year. If you have one cell that is very low compared to the others, your battery will need to be replaced sooner than later.

Well right on the battery it says group 7 AGM

My older Fords did have sealed batteries

[lwmcguire]

Originally Posted by Iancmrn

This is all great info for me but can someone tell me how I know when my batteries are down to 50%. I just recently read something that stated that you should not take them (flooded) below 10.5 Volts. Is that 50%?
Thanks.

Read up on batteries, and verify your voltage reading
Best way and only way is voltage

[lwmcguire]

F150 in the garage with oem

[R.Wold]

Originally Posted by theoldwizard

What make and model are the batteries ?

2/3 of a 2014 Nissan Leaf battery.

[R.Wold]

Originally Posted by Jim Schings

As an EE myself, I would love to see some of your calculations on this comment. I can't see any reasonable calculations that validate that statement. References ?

Based on another of his posts elsewhere on this forum, my guess is he’s comparing solar to nuclear energy, a comparison which may or may not have merit elsewhere (I don't know and couldn't begin to care) but for RV purposes, is so far beyond useful commentary that it kind of makes me wonder what he’s doing here.

My 1500w of solar on my little coach are serving me quite well and are certainly more environmentally friendly than a generator. But then, that's from an RV perspective.

[RVownr]

Originally Posted by Searching_Ut

While not the individual you addressed this to, I have a lot of experience in evaluating battery systems in the field to establish and update time change criteria for batteries used in critical systems where batteries are changed out prior to reaching certain degradation levels.


Flooded lead acid batteries in particular, do tend to self balance in parallel use due to several characteristics of the batteries. At the same time, it causes issues. The two types of batteries you mention have fairly different characteristics, with one being a deep cycle design, and the other most likely a hybrid. They will have different internal resistance values throughout the charging process, with the 12 volt charging at a different rate than the 6 volt pair, and thus either a consistent overcharge of one, or undercharge of the other. If you're lucky, mixing batteries like this might only reduce the packs life expectancy by 20 percent or so, but it will most likely be significantly more. I'm not even sure what you would base life expectancy on, as if you deep cycle the batteries much, the 6 volt batteries should last much longer than the 12 volt battery.


Bottom line, it's really best to build and maintain parallel battery packs with battery cells as balanced to one another as possible. Generally means same battery type, manufacture, age etc.

Thank you for your response.
The 6v & the 12v batteries would all be Trojan batteries {true deep cycle}. I am currently using 3 of the T1275 12v batteries but after 5 years of service I'm finding that I may have to replace them. ( I would never tell anyone that I had done a perfect job of maintenance for these batteries - LOL)

I'm Just checking to see which configuration would work best:
Three new 150ah 12v batteries as used previously
Two of the largest 6v batteries that I can fit into my storage area
or the two 6v + the one 12v
I will likely contact Trojan as well to check & compare the "charge rates" for the three stage charging system.

Again, thank you for your response.

[theoldwizard]

Originally Posted by lwmcguire

My Trojans AGM in the Tuscany was the best update ever ...

Just curious, where did you buy your Trojan AGM batteries ? T105-AGM ?

[theoldwizard]

Originally Posted by RVownr

The 6v & the 12v batteries would all be Trojan batteries {true deep cycle}. I am currently using 3 of the T1275 12v batteries but after 5 years of service I'm finding that I may have to replace them. ( I would never tell anyone that I had done a perfect job of maintenance for these batteries - LOL)

Trojan does make a T1275-AGM $$$$ !!

Originally Posted by RVownr

I will likely contact Trojan as well to check & compare the "charge rates" for the three stage charging system.

I have done some research on this topic and the answer is not good ! Trojan recommends charging voltages slightly HIGHER than any charger I have been able to find !

[RossWilliams]

Originally Posted by Iancmrn

This is all great info for me but can someone tell me how I know when my batteries are down to 50%. I just recently read something that stated that you should not take them (flooded) below 10.5 Volts. Is that 50%?
Thanks.

No, 10.5 volts is 100% discharged. Here is one version of state of charge by voltage (different manufacturers sometimes use different specs):


100% 12.7
90% 12.62
80% 12.5
70% 12.37
60% 12.24
50% 12.10
40% 11.96
30% 11.81
20% 11.66
10% 11.51


Its important to remember these charts are almost all using resting voltages, with batteries having been left unused for 24 hours. Any other use is a very rough approximation. Immediately after charging, the voltage will be higher. If you have a significant load on the battery, the reading will be lower.

[5spd97]

Choosing house batteries...I feel your pain. I went down that path about a year ago researching and reading forums and such and here is the bad news; there is no definitive answer. In the end I decided to replace my two aging 100 amp/hr AGMs with one 100 amp/hr LifePo4. We almost exclusively boondock and our electrical needs are modest. (Fridge, chargers, fan, etc) I reduced my battery footprint by 50%, and reduced the weight from 108 lbs to 31 lbs. I installed a new converter charger designed for Li batteries which saved me more weight and space over my old portable charger. The new battery can be mounted in any orientation. Its also tied into my 200 w solar system. We are absolutely delighted with the performance after a half dozen trips of 7 to 10 days duration. I carry a 2k watt generator but no longer bring extra gas. The last couple of trips Ive probably not run the generator more than two hours total. I can charge at 45 amps.

Everyone has different needs and priorities.

[photraveller]

Originally Posted by RossWilliams

No, 10.5 volts is 100% discharged. Here is one version of state of charge by voltage (different manufacturers sometimes use different specs):


100% 12.7
90% 12.62
80% 12.5
70% 12.37
60% 12.24
50% 12.10
40% 11.96
30% 11.81
20% 11.66
10% 11.51


Its important to remember these charts are almost all using resting voltages, with batteries having been left unused for 24 hours. Any other use is a very rough approximation. Immediately after charging, the voltage will be higher. If you have a significant load on the battery, the reading will be lower.

Agree with everything you said. 10.5V is 100% discharge cut-off during a discharge load test. A normal fully discharged battery will bounce back to the low 11's during rest.

BTW, one of the reasons why different manufacturers have different curves, is due to different plate chemistry and acid specific gravity. For instance, flooded JCI batteries read higher especially at the lower discharge levels. With fully charged in the mid 12.7's. However other manufacturers you might struggle to see full voltage levels much above 12.6's.

Of course AGM's have a different curve that is mostly much higher than flooded.

Steve