what's the difference

[xjr 1300]

Hi guys I'm new to your sight so bear with me .
I live in France but I'm British & have lived here for 17 years. The past 6 years I have been stand alone on solar. My batteries are trojan L16P-AC x8 as a 48v system. In 6 years I have gone through 2 sets of these batteries the first set lasted 4 year's & the set I'm on now has give up after 2 years. I've been trying to get another set but there not available in france. But thay can supply a set of L16P-DT . Can anyone please tell me what the difference between the L16P-AC & THE L16P-DT. Or is there a better battery for me. Meny thanks Paul.

[SunEagle]

Hello xjr 1300 and welcome to Solar Panel Talk

We need to also know the specifications of your PV panels and Charge controller as well as the inverter model. Without knowing the system it is hard to tell if you have the proper battery size or what the replacement ones should be.

[xjr 1300]

Hi SunEagle we have yingli YL230 in two strings of 3 .
Tristar 60 MMPT.
Studer RCC02
Studer XTM 4000-48
Hope this is what you need.
thanks for getting back. Paul.

[SunEagle]

Based on the info from Trojan, those L16P-AC are 6V 420Ah batteries. So with 8 wired in series you have a 48V 420Ah system. The L16P-DT are also 6V 420Ah batteries so I am not sure of the difference except maybe for cost or availability.

Now as to maybe why your battery system failed.

With 6 x 230W panels you have 1380 watt system. With a 60A MPPT CC you might get 28 amps of charging for a 48volt battery system. That seems too low to keep a 420Ah battery system properly charged and happy. You really need between 35 to 50 amps of charging and less then 30 may be too slow to do the trick.

With a 60 amp 48V charger you can increase your panel wattage to get you 45 - 50 amps of charging. But to keep the system balanced you would need 6 more of those 230watt panels to get a 2760 watt system and just under 60 amps of charging which is the maximum you can use. Depending on the Voc rating of those panels you might be able to use less than 12 but you will still need at least 10 panels wired 5S2P if the Tristar can accept that high an input DC voltage.

[Sunking]

Well it is obvious why your batteries failed twice and will fail the 3rd time prematurely. You do not have near enough panel wattage. At a minimum 2250 watts and in that part of the world 2600 watts is required. Hold off on batteries until the fix the real problem.

[xjr 1300]

Thank you guys. But one thing puzzles me in summer the batteries are bubbling like mad & the smell is overwhelming
The RCC02 reads 60.8 vds. Now the sun is not so strong we are on around 56.7 vds but still have to put the generator to last through the night.
I've gone back to the place I brought the system fro,m ( my solar shop ) in England & thay say thay can't help & don't even bother to reply to me anymore.
So that's why I've come to you guys seeing most of my set up is built in the USA. Thanks guys for all your help. Paul

[Mike90250]

Thank you guys. But one thing puzzles me in summer the batteries are bubbling like mad & the smell is overwhelming
The RCC02 reads 60.8 vds. Now the sun is not so strong we are on around 56.7 vds but still have to put the generator to last through the night.
I've gone back to the place I brought the system fro,m ( my solar shop ) in England & thay say thay can't help & don't even bother to reply to me anymore.
So that's why I've come to you guys seeing most of my set up is built in the USA. Thanks guys for all your help. Paul

Do you add distilled water on a regular basis ? 56.7 is barely charging, so that's not too good

[SunEagle]

Do you add distilled water on a regular basis ? 56.7 is barely charging, so that's not too good

It sounds like there may be more issues than not enough charging amps. But something is boiling off the water in the batteries.

[xjr 1300]

Hi guys yes I check the batteries once a week & toping up with Distilled water I'm using approximately 3L over the 8 batteries. Sorry for the delay in getting back I think the time difference is about 8hrs.

[Raul]

Hi Paul, in my opinion is that you chronic undercharge and run in deficit power.
You need a lot more PV panels to keep healthy a 420ah bank in winter months. At least 3kw of panels. I have a off grid retreat with a bank of 375ah Rolls and 4600w PV for winter. I average 3kwh AC a day consumption. For that the PV has to harvest 4,5kwh DC daily, and on overcast dull weather I run the generator in the morning before daylight. So when the panels kick in, accumulates the power to reach a reasonable charging rate.

Oh, and in summer I back of on the voltage to 58v, in winter goes to 60v. You need to adjust with the season and time availability to charge. More hrs in summer than winter; no wonder you boil away in summer. A hydrometer is a must to keep on top of it.

[xjr 1300]

Many thanks guys for all your help.
looks like I need moor panels & moor batteries.
Paul.