Batteries for Solar System

SamSpring

New Member
Hello, I just wanted to learn more about battery selection. These batteries were given to me and I decided to use them for my solar panel system in my off-grid cabin.

TEL-12-210FA (x2)

As well, I have these:

US 185HC XC US Battery (x2) 12V Flooded Lead Acid

Each battery is hooked up in series, then in parallel, to provide 424AH @24V

I just wanted to know if mixing these batteries is a bad idea and if the "TEL-12-210FA" is not suited for this kind of application.

Thank you
 

snoobler

Solar Honey Badger
Moderator
Welcome to the forum.

The TEL-12-210FA appears to be designed for standby operation, i.e., held at 100% for long periods of time and then used briefly to provide emergency backup power. The basis for my opinion is:

the emphasis in the data on "Long life float service design"
ratings consistent with C10 or higher discharges, not the typical C20 of deep cycle batteries
I see no cycle life vs. depth of discharge data
I see no reference to "deep cycle"
They appear to be targeted to telco applications

BUT

They were free. :)

from (for XC2, can't find XC):


C10 is 195Ah, so less than the TEL batteries.

They have compatible cyclic absorption values, but the 185HC appear to prefer a much lower float voltage of 13.02V. If you're cycling them daily, that's not a big deal, but if you're going to be cycling them rarely, they should be floated separately and connected only when needed for use.

If you're talking the TEL in 2S for 24V in parallel with 2S 185HC, then that should be fine.

Worst case, the TEL batteries will wear out faster, but they are still reducing the workload on the 185HC batteries extending their life.

See "Wiring" in link #2 in my signature for best practices when connecting batteries in banks.

Best to use a clamp ammeter to confirm the currently flowing through each battery set is within limits for the battery under high charge and discharge scenarios.
 

SamSpring

New Member
Welcome to the forum.

The TEL-12-210FA appears to be designed for standby operation, i.e., held at 100% for long periods of time and then used briefly to provide emergency backup power. The basis for my opinion is:

the emphasis in the data on "Long life float service design"
ratings consistent with C10 or higher discharges, not the typical C20 of deep cycle batteries
I see no cycle life vs. depth of discharge data
I see no reference to "deep cycle"
They appear to be targeted to telco applications

BUT

They were free. :)

from (for XC2, can't find XC):


C10 is 195Ah, so less than the TEL batteries.

They have compatible cyclic absorption values, but the 185HC appear to prefer a much lower float voltage of 13.02V. If you're cycling them daily, that's not a big deal, but if you're going to be cycling them rarely, they should be floated separately and connected only when needed for use.

If you're talking the TEL in 2S for 24V in parallel with 2S 185HC, then that should be fine.

Worst case, the TEL batteries will wear out faster, but they are still reducing the workload on the 185HC batteries extending their life.

See "Wiring" in link #2 in my signature for best practices when connecting batteries in banks.

Best to use a clamp ammeter to confirm the currently flowing through each battery set is within limits for the battery under high charge and discharge scenarios.
I see, thank you for that. Just to add on to connecting batteries in banks, because they are different batteries with different resistances, is there a possibility of each battery being charged and discharged at a different rate? or as long as I use the correct size wire they should be fine?
 

snoobler

Solar Honey Badger
Moderator
I see, thank you for that. Just to add on to connecting batteries in banks, because they are different batteries with different resistances, is there a possibility of each battery being charged and discharged at a different rate? or as long as I use the correct size wire they should be fine?

It's not just a possibility, it's probable - hence the check with an ammeter to confirm the setup is still operating within battery specs for each string.
 

Diysolar123

Solar Enthusiast
do a capacity test at the rate you intend to pull amps from each battery(especially important with unknown battery history)...this way you will know what you can expect when put into service.
Once you know the capacity of each put them in series to best match each other (try to get same capacity per string).

make sure to get a bms, and enjoy your free batteries hehe
 

snoobler

Solar Honey Badger
Moderator
do a capacity test at the rate you intend to pull amps from each battery(especially important with unknown battery history)...this way you will know what you can expect when put into service.
Once you know the capacity of each put them in series to best match each other (try to get same capacity per string).

make sure to get a bms, and enjoy your free batteries hehe

These are lead acid. No BMS.
 
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