Experience of TN-Power LiFeP04 Batteries

[rusty69]

1 minute ago, dingo said:

Wow you're good! That is correct, they were set to lead acid charging profile. 

With the drop in performance i started to investigate which is when i noticed the programming was wrong on the MT50. i have since set the programming to custom as i cannot see an option for lithium. 

I'm thinking when i come to replace the batteries i should probably look at replacing the solar controller.  

So, what was it set to 14.4 V for 3hrs?

[dingo]

14.6v max, not sure on charging time though. 

 

Sorry - I changed the programming to 'user' not 'custom'.. 

Well hopefully that was the cause of the problem and no further damage is done now the max charge is turned down.  

[rusty69]

Just now, dingo said:

14.6v max, not sure on charging time though. 

 

Sorry - I changed the programming to 'user' not 'custom'.. 

Well hopefully that was the cause of the problem and no further damage is done now the max charge is turned down.  

It will depend what you set them at. Read the data sheet again.

 

That is only the solar charging too, you haven't mentioned your other charge sources, or how you are monitoring battery voltage. The BMS will protect from over and under voltage, but, I'm guessing as its not programmable , maybe not from  overcharging.

[dingo]

Thanks for you help and advice, really is appreciated! I'll check the data sheet again and run through the programming on the MT50 to see what it was originally set to.  

I use a battery to battery Sterling power charger. this doesn't charge above 13.6v and i rarely turn it on because the solar has been so efficient. I can also see a lithium PO4 light come on when i use the Sterling power charger which made me rule that out as the cause. 

I have a few different ways to monitor the voltage. i have two voltage meters in my van and a dometic fridge freezer which has voltage on an app.  

I have rarely seen the voltage above 14v however, there were a few times it did when i was travelling in Spain. Also, there were times when i left my van unattended with the solar on when it could've got up there. 

[rusty69]

19 minutes ago, dingo said:

Thanks for you help and advice, really is appreciated! I'll check the data sheet again and run through the programming on the MT50 to see what it was originally set to.  

I use a battery to battery Sterling power charger. this doesn't charge above 13.6v and i rarely turn it on because the solar has been so efficient. I can also see a lithium PO4 light come on when i use the Sterling power charger which made me rule that out as the cause. 

I have a few different ways to monitor the voltage. i have two voltage meters in my van and a dometic fridge freezer which has voltage on an app.  

I have rarely seen the voltage above 14v however, there were a few times it did when i was travelling in Spain. Also, there were times when i left my van unattended with the solar on when it could've got up there. 

Ok. Bear in mind limiting  the charge current to 0.2 capacity, then stop charging when current falls below 0.02C.  The only settings you have on the solar charge controller are probably boost and float voltage, and boost duration (and a few others). You do not want to be holding it at 14.6 V for hours on end.The fridge voltmeter is not really a good indication.

 

You would be better off with either a handheld multimeter directly on the battery terminals, or a high end battery monitor e.g Victron, Nasa, etc.

Also, check your sterling gadget is not exceeding the battery charge limitations.

Edited December 3, 2022 by rusty69

[magnetman]

Another factor could be low temperatures.

 

I am convinced that some of the branders who market LifePO4 (LFP) batteries as drop in replacements do so knowing that the item will not last very long in this usage. What was the warranty for the TN batteries? It wasn't 2 years by any chance was it? At the end of the day longevity is irrelevant once you have sold the product to the customer. it just needs to last for the warranty period. Cynical? Moi?

 

Lithium batteries of various sorts are good (I have LFP, LTO and NMC types) but they are not a 'true replacement' for a normal lead acid. It will be a compromise. In the case of drop-ins I suspect this compromise may be lifespan of the battery block.

 

Sterling put a 5 year warranty on their LFP batteries but I think they have a heating element in them.

 

 

Heated Sterlling

https://sterling-power.com/products/heated-lithium-iron-phosphate-batteries-12v-leisure-battery-5-year-warranty

 

5 year warranty

 

Non-heated Sterling

 

https://sterling-power.com/collections/entire-lithium-battery-range/products/12v-100ah-lifepo4-lithium-iron-phosphate-battery-w-bluetooth

 

Warranty not mentioned. Maybe it is 2 years?

 

 

Looking closer it seems they might both have 5 year warranties

 

 

Also TN seem to do 5 years as well.

 

So have you considered claiming on the warranty?

https://advancedbatterysupplies.co.uk/tn-power-lithium-batteries/

 

Edited December 3, 2022 by magnetman

[rusty69]

1 hour ago, magnetman said:

Lithium batteries of various sorts are good (I have LFP, LTO and NMC types) but they are not a 'true replacement' for a normal lead acid. It will be a compromise. In the case of drop-ins I suspect this compromise may be lifespan of the battery block.

 

I suspect you are right. They are likely a compromise, either on the quality of the cells used, or more likely the BMS. I am not sure the one in question is fully programmable, like other offerings from the likes of life batteries, which seem pretty popular on facebook, that use the JBD type.

1 hour ago, magnetman said:

 

So have you considered claiming on the warranty?

Probably only likely to cough up if they have been treated in the manner that the spec sheet suggests.

[dingo]

2 hours ago, rusty69 said:

Ok. Bear in mind limiting  the charge current to 0.2 capacity, then stop charging when current falls below 0.02C.  The only settings you have on the solar charge controller are probably boost and float voltage, and boost duration (and a few others). You do not want to be holding it at 14.6 V for hours on end.The fridge voltmeter is not really a good indication.

 

You would be better off with either a handheld multimeter directly on the battery terminals, or a high end battery monitor e.g Victron, Nasa, etc.

Also, check your sterling gadget is not exceeding the battery charge limitations.

 

Thanks for the info - i will take a handheld multimeter with me on my next trip as i have one in the garage. I am off to Spain again in the next couple of weeks so it'll be a good test having sunshine. 

 

I did consider warranty but had the exact same thought - they'll come back and say the reason they are faulty is because they have been misused. i still may end up trying if they offer 5y. 

I don't think it was cold weather that caused the problem.. I have spent the winter months in EU since purchase avoiding the UK - temperatures:  

• Wider temperature range:-20°C-60°

I have two damaged 100ah TN batteries at the moment. Instead of replacing them, i am thinking about just adding a third. The two on their own manage to still run my heater, lights and fridge all night and as long as i do a bit of driving or we get some sun it's fine for the second night too. The charge doesn't last as long as it did but the main problem is the power draw. I'm thinking a third tn would stop the power draw problem and the system would once again be able to run my water heater.  I'll ensure the data sheet matches the programming on the mt50 to hopefully save the new battery and stop any further damage to the existing two. 

I'll just check what the MPPT is programmed to now i've changed it from the lead acid to 'user'. i'll report back shortly.

 

  

[Alan de Enfield]

5 minutes ago, dingo said:

I have two damaged 100ah TN batteries at the moment. Instead of replacing them, i am thinking about just adding a third.

 

 

Would it not be better to add a NON damaged one ?

[dingo]

Just now, Alan de Enfield said:

 

 

Would it not be better to add a NON damaged one ?

Yes thats the plan - Add a non damaged 100ah TN to my two damaged 100ah TN's 

Right - After swapping from lead acid to 'user' on the MT50 the programming is now as follows: 

 

temp comp coeff

-3mv/c/2v
rated V auto

Over Volt. Disc. 16v
Charge Limit 14.6v

Over Volt. Rec. 15v

Equal Charge 14.6v

Boost Charge 14.4v
Float charge 13.8v

Boost Rec 13.2v 
Low Volt Rec 12.6v

Under Volt rect 12.2v
Under volt warn 12v

Low volt Disc 11.1v 
Discharge lim 10.6v

Equalise Time 120min 
Boost Time 120min 

[rusty69]

14 minutes ago, dingo said:

Yes thats the plan - Add a non damaged 100ah TN to my two damaged 100ah TN's 

Right - After swapping from lead acid to 'user' on the MT50 the programming is now as follows: 

 

temp comp coeff

-3mv/c/2v
rated V auto

Over Volt. Disc. 16v
Charge Limit 14.6v

Over Volt. Rec. 15v

Equal Charge 14.6v

Boost Charge 14.4v
Float charge 13.8v

Boost Rec 13.2v 
Low Volt Rec 12.6v

Under Volt rect 12.2v
Under volt warn 12v

Low volt Disc 11.1v 
Discharge lim 10.6v

Equalise Time 120min 
Boost Time 120min 

The boost time and equalisation do not look good.

[dingo]

I thought that to be honest.. Should be alot lower ay? 

[rusty69]

7 minutes ago, dingo said:

I thought that to be honest.. Should be alot lower ay? 

Hopefully Nick will comment in a bit.

[nicknorman]

Also the temperature co-efficient should be zero.

1 minute ago, rusty69 said:

Hopefully Nick will comment in a bit.

I never really understand the terminology on solar controllers, but what you want with Li is very short absorption time, like 15 mins. So that when the voltage hits the target, say 14.4v, it holds it for 15mins then goes to float. Li float should be around 13.3v maybe 13.4.

[dingo]

2 minutes ago, nicknorman said:

Also the temperature co-efficient should be zero.

Thanks both - really appreciate the suggestions. I'll make some tweeks and look at adding a third battery.  

[rusty69]

51 minutes ago, nicknorman said:

Also the temperature co-efficient should be zero.

I never really understand the terminology on solar controllers, but what you want with Li is very short absorption time, like 15 mins. So that when the voltage hits the target, say 14.4v, it holds it for 15mins then goes to float. Li float should be around 13.3v maybe 13.4.

Yes, mine are set for 10 minutes at 14.2 V. I think the boost voltage is what is commonly known as Absorbption or acceptance.

 

Equalisation duration set to zero, and float around 13.4.

Edited December 3, 2022 by rusty69

[MtB]

1 hour ago, dingo said:

Thanks both - really appreciate the suggestions. I'll make some tweeks and look at adding a third battery.  

 

A completely different approach would be to carefully cut the tops off your existing damaged batteries and identify the prismatic cells probably inside, then replace just the damaged cells with new identical. That way you get to keep the BMS, box and whatnot which are probably still perfectly good and the new bare cells will be significantly cheaper than whole batteries. Probably.

[rusty69]

2 minutes ago, MtB said:

 

A completely different approach would be to carefully cut the tops off your existing damaged batteries and identify the prismatic cells probably inside, then replace just the damaged cells with new identical. That way you get to keep the BMS, box and whatnot which are probably still perfectly good and the new bare cells will be significantly cheaper than whole batteries. Probably.

If they can find cells that like to be charged at 14.6V on what is likely a fixed BMS. I have never seen cells that like such a high voltage. Is it normal? 

[nicknorman]

10 minutes ago, rusty69 said:

If they can find cells that like to be charged at 14.6V on what is likely a fixed BMS. I have never seen cells that like such a high voltage. Is it normal? 

Yes, it is normal. LiFePO4 cells tend to specify charge voltage of 3.65v per cell, which is 14.6. Assuming they are top balanced of course! But just because it says you can charge at 14.6v doesn’t mean you have to! I charge to 14.3v when I want a full charge, the extra % I would get charging at 14.6 is much less than 1%.

[rusty69]

Just now, nicknorman said:

Yes, it is normal. LiFePO4 cells tend to specify charge voltage of 3.65v per cell, which is 14.6. Assuming they are top balanced of course! But just because it says you can charge at 14.6v doesn’t mean you have to! I charge to 14.3v when I want a full charge, the extra % I would get charging at 14.6 is much less than 1%.

I think I top balanced mine at 14.6, but didn't think it was recommended for normal use as it decreased the lifespan. 

[rusty69]

Actually just checked the data sheet on mine. It says charge to 3.65v/cell.

 

I stand corrected. 

[dingo]

1 hour ago, rusty69 said:

If they can find cells that like to be charged at 14.6V on what is likely a fixed BMS. I have never seen cells that like such a high voltage. Is it normal? 

 

Pretty sure this would result in me stop, drop and rolling to put the fire out lol 

Think i'll just get the cheaper 84ah TN battery and add to the system. I can pick one up for £400. Hopefully now the solar controller is programmed correctly and with 84ah worth of fresh cells i should be good to go for years. 

1 hour ago, MtB said:

 

A completely different approach would be to carefully cut the tops off your existing damaged batteries and identify the prismatic cells probably inside, then replace just the damaged cells with new identical. That way you get to keep the BMS, box and whatnot which are probably still perfectly good and the new bare cells will be significantly cheaper than whole batteries. Probably.

Pretty sure this would result in me stop, drop and rolling to put the fire out lol 

Think i'll just get the cheaper 84ah TN battery and add to the system. I can pick one up for £400. Hopefully now the solar controller is programmed correctly and with 84ah worth of fresh cells i should be good to go for years. 

 

•  

[rusty69]

7 hours ago, dingo said:

 

Pretty sure this would result in me stop, drop and rolling to put the fire out lol 

Think i'll just get the cheaper 84ah TN battery and add to the system. I can pick one up for £400. Hopefully now the solar controller is programmed correctly and with 84ah worth of fresh cells i should be good to go for years. 

Pretty sure this would result in me stop, drop and rolling to put the fire out lol 

Think i'll just get the cheaper 84ah TN battery and add to the system. I can pick one up for £400. Hopefully now the solar controller is programmed correctly and with 84ah worth of fresh cells i should be good to go for years. 

 

•  

Yeah. I reckon the chances of identifying the cells, let alone matching them and top balancing them may well not be worth the effort. 

[MtB]

4 hours ago, rusty69 said:

Yeah. I reckon the chances of identifying the cells, let alone matching them and top balancing them may well not be worth the effort. 

 

You're probably right, but I think the BMS eventually will balance them as they are quite likely to come off the pallet all at much the same SoC. 

 

Identifying them shouldn't be too difficult, there is usually one of them square Q code thingies on the top of cells to scan with yer fone. 

[rusty69]

6 minutes ago, MtB said:

 

You're probably right, but I think the BMS eventually will balance them as they are quite likely to come off the pallet all at much the same SoC. 

 

Identifying them shouldn't be too difficult, there is usually one of them square Q code thingies on the top of cells to scan with yer fone. 

 

Me, right? Seems unlikely to be honest. I never have been in the past.