Converter / Charger recommendation

**leselmore** · 12-03-2022, 03:16 PM

Verify your battery's max charging amps. I use Battleborn batteries and max charging amperage for them is 50 percent of the battery bank total amp hour capacity. So buying a charger that charges at OVER 50 amps for a 100 amp hour battery could damage the battery. My point being, I would verify before buying the charger.

**Jerryr** · 12-03-2022, 03:52 PM

Originally Posted by leselmore

Verify your battery's max charging amps. I use Battleborn batteries and max charging amperage for them is 50 percent of the battery bank total amp hour capacity. So buying a charger that charges at OVER 50 amps for a 100 amp hour battery could damage the battery. My point being, I would verify before buying the charger.

Les,

Good point. I guess I now have a reason to buy a 2nd 200 amp battery and install it in parallel. I was going to do this anyway.

**leselmore** · 12-03-2022, 05:13 PM

I run the PD9160ALV as well. Very happy with it. When we ordered ours in Feb 2021, Progressive Dynamics just release it with a two-stage charging profile. I would make sure it says "two stage" on the labeling. If not, I would return it and order elsewhere.

**Butcher** · 12-03-2022, 08:30 PM

Most [if not all] lithium batteries have a built in BMS. The prebuilt batteries probably are set so they cannot accept a discharge/charge current more than specs. You could buy a 500A charger, but the battery will only accept what is programmed.

Those that have a DIY battery, you can set the parameters where ever you want it to and that may cause a problem.

I see no downfall to a large converter. If/when you add more capacity, you will have the charging capability to match. Make certain what every you pick that your AC is capable to support it. Anything more than 120A may need to have your wiring upgraded.

**leselmore** · 12-03-2022, 09:22 PM

Originally Posted by Butcher

Most [if not all] lithium batteries have a built in BMS. The prebuilt batteries probably are set so they cannot accept a discharge/charge current more than specs. You could buy a 500A charger, but the battery will only accept what is programmed.

Those that have a DIY battery, you can set the parameters where ever you want it to and that may cause a problem.

I see no downfall to a large converter. If/when you add more capacity, you will have the charging capability to match. Make certain what every you pick that your AC is capable to support it. Anything more than 120A may need to have your wiring upgraded.

Interesting... and thanks for the information. I didn't realize the BMS would limit the charge to what it should accept. I went back and re-read the Battleborn literature and it does imply the batteries "allow" the 50 percent charge. When I first read it, I took it to mean I needed to limit the charge to 50 percent charge. Here is the quote from their paperwork and thanks again

"What is the maximum amperage I can charge
my batteries?
Our batteries allow a charge of 50 amps per 100-amp hour battery bank. For
more than one battery, you can simply take the entire amp hours of the bank
and cut it in half (e.g. a total of 200-amp hours can be charged at 100 amps)."

**Scott'n'Wendy** · 12-04-2022, 06:47 AM

Originally Posted by xrated

So my choice was to use the Flooded Lead Acid setting (set to 3 stages of charging) which outputs 14.2V on bulk, and ends up on 13.4V on float. The float setting, which is a lower voltage than it takes to fully charge LFP batteries (13.8V) keeps the battery in a safer voltage point, and not at fully charged....which is good for LFP batteries.

Interesting. Almost everywhere you read on forums people say you can use a FLA charger but you will only get 80% SOC. I don't know what SOC you are ending up with at 14.2/13.4 but you are saying it is much easier on the battery ie lifespan?

**Butcher** · 12-04-2022, 10:47 AM

The amount of extra amps you get at the upper and lower ends of the charge is very small. It's the middle that stores all the ah. There are a lot of theories and in order to understand what people are saying, you need to research that. Most of the times when you start questioning someones opinion, you get arguments. I don't think anyone is wrong, everyone has a point that is valid.

I have 300ah batteries. If I fully charge them to 3.65v and fully discharge them to 2.50v, then I should have 300ah. If I only charge them to 3.4v-3.5v and discharge them to 2.7v, then I would have a capacity of around 290ah. The theory is, why stress the battery to get the last 10ah of current? That additional stress could limit the amount of charge cycles you get.

A fully charged battery may get 4k cycles, but a less stressed battery may get 5-6k cycles. The other side of the coin is the calendar life. If the battery only lasts 15 years and you only cycle them 150 times a years, who cares if you are stressing them out or not, they will be worn out in 15 years.

Those numbers are something I just pulled out of the air so they are not based on facts but I believe that is the fair assessment of the two camps.

I have always believed that updating the converter, to allow a faster charge, is the second best thing you can do after the lithium battery purchase. Waiting till you can afford it or to figure out what you want is ok. I'm satisfied that you can get at least 90% with the stock converter, slow, but it will get there. If you are constantly plugged in and use the lithium mostly during travels, you don't need to upgrade. You want to upgrade. The more ah you have, the larger the converter I would get.

**xrated** · 12-04-2022, 11:59 AM

Originally Posted by Scott'n'Wendy

Interesting. Almost everywhere you read on forums people say you can use a FLA charger but you will only get 80% SOC. I don't know what SOC you are ending up with at 14.2/13.4 but you are saying it is much easier on the battery ie lifespan?

Scott, you can get a fully charged (let's say 99% SOC to be safe) with 13.8V going to the battery. That number equates to 3.45V per cell....which is considered by most as a fully charged LFP cell. The catch is, it will take a lot longer to achieve that full SOC than if you are using a charger that will output....say 14.2V...or 14.4V....or the 14.6V that most LFP chargers put out. Think of it as taking your vehicle on a 200 mile trip. You can drive at 40 mph and get there in 5 hours. You can take the same trip but drive it at 60 mph and get there in 3.33 hours. Or you could drive it at 100 mph and get there in 2 hours. Charging a LFP battery is the same way.....mph is voltage and the higher the speed/voltage (to a point that is still safe) the faster you get there/the quicker you charge the battery. Going at a lower speed is usually considered safer and doesn't stress the vehicle as much....same with the battery.

As far as using a FLA charger and only getting to say 80% SOC....it will all depend on 1. The output voltage from the charger. 2. The amount of voltage drop and the resultant voltage that arrives at the battery. Many of the FLA chargers "may" put out that initial bulk voltage and then drop to absorption mode before the battery has a chance to get to that higher SOC that we are looking for. I had/have a WFCO 9855 that even when the LFP battery was less than 50% SOC, would never output more than basically absorption voltage levels. Then, if you throw in the voltage drop factor that most systems will have unless they have been redone with larger gauge cable and better connection point, you might suffer an addition .5 or .6 voltage drop like I did.

The new to me Meanwell NPB-750-12 converter/charger will output 14.2V and after redoing pretty much all the cables with larger gauge and replacing a battery disconnect switch and making new low resistance connections all the way through, I now get about .1V drop from the charger terminal to the battery. My charger is a 750W that is capable of putting out 43A. When it is charging in the CC mode, I am seeing 41.5 to 42.5 amps. It just doesn't get much better than that, and that is more than good enough for me. That is going into a DIY LFP battery that I built and top balanced and then capacity tested when I was done. The 302AH battery produced just under 306AHs and that was with a cell cutoff voltage of 2.6V ....or a battery voltage of 10.4V. The BMS that I used is configurable to stop discharge at whatever cell voltage you want. A LFP cell should never be run down below 2.5V...or battery voltage of 10.0V. So realistically, had I set the low voltage cutoff down to 2.5V per cell, I may have gotten another 4 or 5 amp hours out of the battery when testing. My feelings are that there is no really good reason to squeeze every single AH out of the battery, just like there is no really good reason to charge at 14.6V (3.65 per cell) and try to force every single AH into the battery when charging. If someone's needs are such that they have to have every single amp hour going in....and every single amp hour coming out....to do the job, they have sized the battery too small and/or they need additional battery reserve.

**huntindog** · 12-04-2022, 12:37 PM

Originally Posted by xrated

Scott, you can get a fully charged (let's say 99% SOC to be safe) with 13.8V going to the battery. That number equates to 3.45V per cell....which is considered by most as a fully charged LFP cell. The catch is, it will take a lot longer to achieve that full SOC than if you are using a charger that will output....say 14.2V...or 14.4V....or the 14.6V that most LFP chargers put out. Think of it as taking your vehicle on a 200 mile trip. You can drive at 40 mph and get there in 5 hours. You can take the same trip but drive it at 60 mph and get there in 3.33 hours. Or you could drive it at 100 mph and get there in 2 hours. Charging a LFP battery is the same way.....mph is voltage and the higher the speed/voltage (to a point that is still safe) the faster you get there/the quicker you charge the battery. Going at a lower speed is usually considered safer and doesn't stress the vehicle as much....same with the battery.

As far as using a FLA charger and only getting to say 80% SOC....it will all depend on 1. The output voltage from the charger. 2. The amount of voltage drop and the resultant voltage that arrives at the battery. Many of the FLA chargers "may" put out that initial bulk voltage and then drop to absorption mode before the battery has a chance to get to that higher SOC that we are looking for. I had/have a WFCO 9855 that even when the LFP battery was less than 50% SOC, would never output more than basically absorption voltage levels. Then, if you throw in the voltage drop factor that most systems will have unless they have been redone with larger gauge cable and better connection point, you might suffer an addition .5 or .6 voltage drop like I did.

The new to me Meanwell NPB-750-12 converter/charger will output 14.2V and after redoing pretty much all the cables with larger gauge and replacing a battery disconnect switch and making new low resistance connections all the way through, I now get about .1V drop from the charger terminal to the battery. My charger is a 750W that is capable of putting out 43A. When it is charging in the CC mode, I am seeing 41.5 to 42.5 amps. It just doesn't get much better than that, and that is more than good enough for me. That is going into a DIY LFP battery that I built and top balanced and then capacity tested when I was done. The 302AH battery produced just under 306AHs and that was with a cell cutoff voltage of 2.6V ....or a battery voltage of 10.4V. The BMS that I used is configurable to stop discharge at whatever cell voltage you want. A LFP cell should never be run down below 2.5V...or battery voltage of 10.0V. So realistically, had I set the low voltage cutoff down to 2.5V per cell, I may have gotten another 4 or 5 amp hours out of the battery when testing. My feelings are that there is no really good reason to squeeze every single AH out of the battery, just like there is no really good reason to charge at 14.6V (3.65 per cell) and try to force every single AH into the battery when charging. If someone's needs are such that they have to have every single amp hour going in....and every single amp hour coming out....to do the job, they have sized the battery too small and/or they need additional battery reserve.

Speed of charging can indeed be important. If you are in a campground without elec, and have to abide by generator hours, you will want to get the amps into the batteries within those hours. Or if fuel consumption is a issue.
The problem with keeping the stock convertor is that the WFCOs don't work very well with the LA batteries they are designed for, and work even worse with LFP. If it would stay in bulk mode they could do OK... But that is unlikely.

**xrated** · 12-04-2022, 01:32 PM

Originally Posted by huntindog

Speed of charging can indeed be important. If you are in a campground without elec, and have to abide by generator hours, you will want to get the amps into the batteries within those hours. Or if fuel consumption is a issue.
The problem with keeping the stock convertor is that the WFCOs don't work very well with the LA batteries they are designed for, and work even worse with LFP. If it would stay in bulk mode they could do OK... But that is unlikely.

That's the key for sure....staying in bulk mode long enough to charge the LFP battery. I gave up on mine when it didn't even go into bulk mode when the 302AH LFP battery was at about 50% SOC. WFCO claims that it will stay there for 4 hrs or until it detects the battery is ready to go into absorption mode. That simply did not happen with my 9855, so I knew that it was time to change it out and to with something that really works. If I would have had or needed something in the 500AH or more battery bank, I would have gone with the Meanwell NPB 1200-12.....it's rated to somewhere around 80+ amps for charging.....but it would have been a waste of money for me when the 750 meets my needs.