Powermax 30-55lk setting for Lithium Batteries?

[jsmit209]

I have a Powermax 30-55lk from a previous power system that used lead acid batteries. I'd like to use it with my new system that has lithium batteries. It claims to be lithium compatible.

The documentation is very limited, but it seems that it has two charging options: 3-stage or fixed voltage, both of which are adjustable. How should I set up the charging?

Fixed voltage seems to be the best option, but at what voltage? Would I need to cut it off once the batteries reach full charge? Thoughts?

 

[sunshine_eggo]

I have 2X PM3-LK and one PM4-LK. Love 'em.

I don't use them on LFP but wouldn't hesitate to do so.

LK is bulk voltage adjustable and can operate in 3 stage or constant voltage.

The only issue with the powermax is the duration of the bulk voltage and your wires. Any significant voltage drop in your wiring/connections will have you at the lower absorption voltage almost immediately, particularly if this is in an RV with typical RV wiring. If you can locate the PM right next to the battery with a big beefy connection, great.

If using on shore power, 3 stage at 14.4V is fine. Will take awhile to charge, but you will get to 95%+ SoC. If charging with generator, switch to constant voltage power supply mode.

 

[jsmit209]

I have 2X PM3-LK and one PM4-LK. Love 'em.

I don't use them on LFP but wouldn't hesitate to do so.

LK is bulk voltage adjustable and can operate in 3 stage or constant voltage.

The only issue with the powermax is the duration of the bulk voltage and your wires. Any significant voltage drop in your wiring/connections will have you at the lower absorption voltage almost immediately, particularly if this is in an RV with typical RV wiring. If you can locate the PM right next to the battery with a big beefy connection, great.

If using on shore power, 3 stage at 14.4V is fine. Will take awhile to charge, but you will get to 95%+ SoC. If charging with generator, switch to constant voltage power supply mode.

Thanks for the info. Do you know which specific converter charger comes standard in the 30-55lk? I pulled the converter out but it's completely unmarked.

This will be in a camper van and used mainly when connected to shore power. I could see using a generator, but that wouldn't be normal.

I'm doing the entire system build from scratch. What wire would you recommend to run from the converter to the battery? I want the battery to charge as quickly as can be done safely (without damaging them). Would constant voltage be best for that? Would it need to be disconnected at full charge?

 

[sunshine_eggo]

Is this a power center or a stand alone converter?

 

[jsmit209]

Is this a power center or a stand alone converter?

It's a power center.

 

[sunshine_eggo]

To clarify, the units I have are standalone converters.

https://powermaxconverters.com/wp-content/uploads/2018/05/PPC-Series-Manual-2018.pdf

30-55 has a 55A charger.

Defaults to 13.8V (bulk), 13.6V (absorption), 13.2V (storage)

That's fine for shore charging, slow and gentle.

if you want to charge faster, bump bulk up to 14.4V with the POT B.

2awg in 4' lengths (4' positive, 4' negative) would result in a 0.07V drop @ 13.8V and 55A:

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

2awg might be too big, but I'd use as big as you can get in the terminals. I've been known to shave the portion of the wire down to get it to fit in the terminals, e.g., maybe the wire is 4awg as its in the terminal, but 2awg as it exits. IMHO, fine to do as long as your current won't exceed what the 4awg is rated for (more than 55A for sure), but you get the benefit of the 2awg over the longer run.

 

[jsmit209]

The charger in my 30-55LK seems like the equivalent to the PM3-55LK standalone.

I found some info on BattleBorn's website that recommends setting at 14.4v and using 3-stage. However, one of the commenters mentioned that he was seeing the absorption voltage drop below the 13.6v specified, resulting in slow charging. He asked about using constant 14.4, and the BattleBorn rep seemed to say it was safe, as long as the batteries were left on that charging voltage long-term.

Using a PowerMax AC to DC Converter Charger With Battle Born Batteries

The Powermax AC to DC converter charger works well with Battle Born LiFePO4 batteries and the voltage can be manually adjusted!

battlebornbatteries.com

 

[sunshine_eggo]

The charger in my 30-55LK seems like the equivalent to the PM3-55LK standalone.

I found some info on BattleBorn's website that recommends setting at 14.4v and using 3-stage. However, one of the commenters mentioned that he was seeing the absorption voltage drop below the 13.6v specified, resulting in slow charging. He asked about using constant 14.4, and the BattleBorn rep seemed to say it was safe, as long as the batteries were left on that charging voltage long-term.

Using a PowerMax AC to DC Converter Charger With Battle Born Batteries

The Powermax AC to DC converter charger works well with Battle Born LiFePO4 batteries and the voltage can be manually adjusted!

battlebornbatteries.com

That's what I referenced above. The commenter likely has "stock" wiring in an RV and may have > 0.5V voltage drop between source and battery. This really mucks with the charging current/staging. That same commenter should eventually see his voltage increase to 13.6V as the battery fills, and the current drops.

Charging to > 95% SoC at 13.6 is very easy.

If you minimize your voltage drop with short distance and beefy wires, the charger will behave much better.

Start with the default and see how it goes. Lower voltage/lower curent charging is less stressful tot he cells and generally improves cycle life. If it doesn't work for you, you always have the option of increasing voltage to 14.4V or even higher if you like.

 

[jsmit209]

That's what I referenced above. The commenter likely has "stock" wiring in an RV and may have > 0.5V voltage drop between source and battery. This really mucks with the charging current/staging. That same commenter should eventually see his voltage increase to 13.6V as the battery fills, and the current drops.

Charging to > 95% SoC at 13.6 is very easy.

If you minimize your voltage drop with short distance and beefy wires, the charger will behave much better.

Start with the default and see how it goes. Lower voltage/lower curent charging is less stressful tot he cells and generally improves cycle life. If it doesn't work for you, you always have the option of increasing voltage to 14.4V or even higher if you like.

I'm just happy to finally have some clarity that it's not going to harm my LFP batteries I appreciate the help!