I was going to buy a gentrax lookalike; see this post: https://thegreynomads.activeboard.com/t71042510/gentrax-12v-100ah-lfp-look-alike/?page=1#comment-71122144
But I ended up buying a PowMr 100ah 12.8 LIFePO4 for $231 with coupon from ebay.
So far I've been really happy with it and have had 103ah running my CF35 Waeco fridge on freezer mode (empty)
I installed a 200A 6.5-200V DC Power Battery Meter with External Shunt into my battery box and set the cut out at 11v and the fridge to 10.5v
For those who are interested here are some pics and links to the Battery. The youtube tear down shows the battery and its components which look to be well built. I'll also include the specs PDF or link to the battery.
These LiFeOp4 batteries are really starting to push the lead acid deep cycle batteries off the market.
I am certainly impressed with my Jaycar 120 ah LiFeOp4 battery we purchased on special back in March last year.
Time will only tell how long it last, if it goes past the 5 year mark, I will be excited.
Scubadoo said
07:53 AM Jan 17, 2025
Well done.
Treat your battery well and it should last a long time.
Our 300Ah LiFePO4 battery has survived 11 years of full-time travelling and counting.
valiant81 said
08:21 AM Jan 17, 2025
Hi all; I too have upgraded from 2 x 220 Ah agm batteries in our caravan that only lasted around 4 years. Cost the earth when new. I Now upgraded to lithium ( 1 x 300 Ah 12 volt battery ) besides the weight saveing, this battery has really supprized me after free camping in Tassie for over 2 weeks. Besides running the caravan and 2 x 40 liter compressor fridges i have found that over night i have only used around 20 % of the batteries capacity and fully recharged by around 11 Am. So far so good.
TimTim said
11:37 AM Jan 17, 2025
Lucky the guy didn't become a dentist or surgeon. There are easier ways to take the cases apart without so much damage
LiFePO4 batteries are dropping in price in some instances but some companies raise their prices as they become more popular. VoltX is an example. There are still some cheap batteries around but like yourself if anyone is thinking of buying them do a search of the video tear down and capacity test.
I did like the fact that they use a JBD BMS. Having little or no difference in cell voltages as you charge is quite normal, unless there is a poor connection somewhere. However, when the SOC charge reaches what we call the knee it generally after that point that the differences in cell voltages appear. In this case 6mV is nothing and all the cells appear to have a similar resistance.
Hope it all works out for you.
67HR said
03:46 PM Jan 17, 2025
Thanks Tim, and others who responded.
I took a bit of a gamble but looks like I may have jagged a half decent one.
As I've mentioned before it's to run my fridge via the battery box, but if the 2yo AGM in the van dies I'd be happy to use one of these.
PS: loved your dental surgeon quote, I did note he had minimal tools at his disposal.....
-- Edited by 67HR on Friday 17th of January 2025 03:48:56 PM
67HR said
11:32 AM Jan 18, 2025
I've just completed another test on this battery after getting a full charge into it (via dc-dc while driving), I set up the fridge again and the result after 36 hours is shown below. To borrow a quote from Allan Millward " I'm well pleased "
For the price I'm banking on maybe 2000, plenty more than a AGM.
Scubadoo said
10:48 AM Mar 23, 2025
What is a cycle?
You will never be able to count them anyway.
Our LiFePO4 battery has now survived 4000 days of fulltime travelling typically at c80% SOC when the sun rises with just a c5% capacity loss.
Has it survived 4000 "cycles" or just the 32 "total charge cycles" as reported by the Victron SmartShunt?
TimTim said
05:23 PM Mar 24, 2025
A cycle is one complete discharge and recharge. So if you have a 100Ah LiFePo4 battery and draw 50Ah from it and charge it back up to full, then you have only completed half a cycle.
If you were to then draw 50Ah from it then charge it by putting 25Ah back in, discharge down to by drawing another 50Ah out and then charging back up to 100% then again you have completed just one cycle.
If you were to discharge your battery down to 50% every day for a year and then charge it back up each day you would only use 182.5 cycles. Do you get the picture .
The claim of 6000 cycles is greatly exaggerated. The Eve cells I buy from China have 4000 cycles although they do manufacture cells with 6000 cycles.
But just for argument sake, say we put a 2000 cycles figure on the PowMr battery. If you were to discharge the battery down 100% and recharge it every day then in theory it would last you approximately 5.5 years. What you need to remember that the end of life for a LiFePo4 battery is when it it only has 80% capacity so at the end of 5.5 years you now have an 80Ah battery. For the vast majority of people it will still be working fine for them.
In other words don't even worry about cycles because in the majority of cases the batteries will outlast you.
I'm not recommending that make of battery but I hope it works well for HR67.
Scubadoo said
06:20 PM Mar 24, 2025
At that rate and a quick calculation our 11 year old 4 cell 300Ah LiFePO4 battery will only last another 70 years or so.
I expect both me and the battery will die of old age long before that ever eventuates.
67HR said
04:05 PM Mar 31, 2025
Quotefrom Tim, "In other words don't even worry about cycles because in the majority of cases the batteries will outlast you.
I'm not recommending that make of battery but I hope it works well for HR67."
Tim, I had to replace my CF35 waeco due to the gas escaping from a crease in the copper line. Not wanting to spend money on an Engel that my kids would get most benefit from after I depart this earth I decided on a 40lt kings unit. It's for use maybe 4-6 times a year so I think it's reasonable value.
On recent test with fridge set on eco and @ 3deg I got over 142 hours of run with a draw of 105ah before the BMS cutting out.
I have no doubt that if the battery holds up it will be suitable for your needs and your kids can fight over it . The Kings fridge states it has an average draw of 1.0A -1.3A but it doesn't state in relation to what and of course outside temperature, location of fridge, how often it is opened etc all have an affect on the amount of power is used. In your case the the fridge is using an average of 0.7A an hour.
When properly testing the capacity of LiFePO4, the test is run at what we call 0.2C so in the case of a 100Ah battery that is a 20A draw which should run for 5 hours in theory and deliver the 100Ah. So in your case, when drawing an average of 0.7A one would expect to get more than 100Ah. If one was to draw a current of 100A from it then it would not actually last 1 hour and not yield 100Ah. This is due to the internal resistance of the battery and other efficiency losses.
I recently bought a 100Ah VoltX battery that was on special for $269, not that I needed it as I build my own so it will used by my sons. They have good reviews in the video tear downs and a 0.2C test produced 107Ah. It seems their prices have now increased due to their popularity.
I was going to buy a gentrax lookalike; see this post: https://thegreynomads.activeboard.com/t71042510/gentrax-12v-100ah-lfp-look-alike/?page=1#comment-71122144
But I ended up buying a PowMr 100ah 12.8 LIFePO4 for $231 with coupon from ebay.
So far I've been really happy with it and have had 103ah running my CF35 Waeco fridge on freezer mode (empty)
I installed a 200A 6.5-200V DC Power Battery Meter with External Shunt into my battery box and set the cut out at 11v and the fridge to 10.5v
For those who are interested here are some pics and links to the Battery. The youtube tear down shows the battery and its components which look to be well built. I'll also include the specs PDF or link to the battery.
https://cdn.shopify.com/s/files/1/0746/0415/1079/files/PowMr_POW-100AH-12.8V_LiFePO4_Battery_Specification_Sheet_compressed_2c6011a2-14b2-4c54-ad79-6e979b3dc0ce.pdf?v=1728355512
Here's a pic of the shunt fitted to tne battery box withe Atem DC-DC 25a charger
-- Edited by 67HR on Thursday 16th of January 2025 07:41:03 PM
-- Edited by 67HR on Thursday 16th of January 2025 07:42:36 PM
These LiFeOp4 batteries are really starting to push the lead acid deep cycle batteries off the market.
I am certainly impressed with my Jaycar 120 ah LiFeOp4 battery we purchased on special back in March last year.
Time will only tell how long it last, if it goes past the 5 year mark, I will be excited.
Well done.
Treat your battery well and it should last a long time.
Our 300Ah LiFePO4 battery has survived 11 years of full-time travelling and counting.
Lucky the guy didn't become a dentist or surgeon. There are easier ways to take the cases apart without so much damage
LiFePO4 batteries are dropping in price in some instances but some companies raise their prices as they become more popular. VoltX is an example. There are still some cheap batteries around but like yourself if anyone is thinking of buying them do a search of the video tear down and capacity test.
I did like the fact that they use a JBD BMS. Having little or no difference in cell voltages as you charge is quite normal, unless there is a poor connection somewhere. However, when the SOC charge reaches what we call the knee it generally after that point that the differences in cell voltages appear. In this case 6mV is nothing and all the cells appear to have a similar resistance.
Hope it all works out for you.
Thanks Tim, and others who responded.
I took a bit of a gamble but looks like I may have jagged a half decent one.
As I've mentioned before it's to run my fridge via the battery box, but if the 2yo AGM in the van dies I'd be happy to use one of these.
PS: loved your dental surgeon quote, I did note he had minimal tools at his disposal.....
-- Edited by 67HR on Friday 17th of January 2025 03:48:56 PM
I've just completed another test on this battery after getting a full charge into it (via dc-dc while driving), I set up the fridge again and the result after 36 hours is shown below. To borrow a quote from Allan Millward " I'm well pleased "
If anyone is interested, these have popped up on my ebay feed with a discount price.
-- Edited by 67HR on Monday 27th of January 2025 05:11:36 PM
For the price I'm banking on maybe 2000, plenty more than a AGM.
You will never be able to count them anyway.
Our LiFePO4 battery has now survived 4000 days of fulltime travelling typically at c80% SOC when the sun rises with just a c5% capacity loss.
Has it survived 4000 "cycles" or just the 32 "total charge cycles" as reported by the Victron SmartShunt?
A cycle is one complete discharge and recharge. So if you have a 100Ah LiFePo4 battery and draw 50Ah from it and charge it back up to full, then you have only completed half a cycle.
If you were to then draw 50Ah from it then charge it by putting 25Ah back in, discharge down to by drawing another 50Ah out and then charging back up to 100% then again you have completed just one cycle.
If you were to discharge your battery down to 50% every day for a year and then charge it back up each day you would only use 182.5 cycles. Do you get the picture
.
The claim of 6000 cycles is greatly exaggerated. The Eve cells I buy from China have 4000 cycles although they do manufacture cells with 6000 cycles.
But just for argument sake, say we put a 2000 cycles figure on the PowMr battery. If you were to discharge the battery down 100% and recharge it every day then in theory it would last you approximately 5.5 years. What you need to remember that the end of life for a LiFePo4 battery is when it it only has 80% capacity so at the end of 5.5 years you now have an 80Ah battery. For the vast majority of people it will still be working fine for them.
In other words don't even worry about cycles because in the majority of cases the batteries will outlast you.
I'm not recommending that make of battery but I hope it works well for HR67.
At that rate and a quick calculation our 11 year old 4 cell 300Ah LiFePO4 battery will only last another 70 years or so.
I expect both me and the battery will die of old age long before that ever eventuates.
Quotefrom Tim, "In other words don't even worry about cycles because in the majority of cases the batteries will outlast you.
I'm not recommending that make of battery but I hope it works well for HR67."
Tim, I had to replace my CF35 waeco due to the gas escaping from a crease in the copper line. Not wanting to spend money on an Engel that my kids would get most benefit from after I depart this earth I decided on a 40lt kings unit. It's for use maybe 4-6 times a year so I think it's reasonable value.
On recent test with fridge set on eco and @ 3deg I got over 142 hours of run with a draw of 105ah before the BMS cutting out.
Hi Trevor,
I have no doubt that if the battery holds up it will be suitable for your needs and your kids can fight over it
. The Kings fridge states it has an average draw of 1.0A -1.3A but it doesn't state in relation to what and of course outside temperature, location of fridge, how often it is opened etc all have an affect on the amount of power is used. In your case the the fridge is using an average of 0.7A an hour.
When properly testing the capacity of LiFePO4, the test is run at what we call 0.2C so in the case of a 100Ah battery that is a 20A draw which should run for 5 hours in theory and deliver the 100Ah. So in your case, when drawing an average of 0.7A one would expect to get more than 100Ah. If one was to draw a current of 100A from it then it would not actually last 1 hour and not yield 100Ah. This is due to the internal resistance of the battery and other efficiency losses.
I recently bought a 100Ah VoltX battery that was on special for $269, not that I needed it as I build my own so it will used by my sons. They have good reviews in the video tear downs and a 0.2C test produced 107Ah. It seems their prices have now increased due to their popularity.
Good luck
Tim