Hello everyone, I purchased a powermax pm3-55lk it has a bulk charge of 14.4 volts, absorption of 13.6 and a float of 13.2 volts. The batteries I have are 4 lishen 272’s. These batteries will be in my boat used as trolling motor batteries and sometimes used multiple days in a row charged up at night and other times not used for weeks. Since absorption faze starts at 13.6 volts should I only charge the batteries when they are below 13.6 volts so the batteries get into the start of the absorption faze?
Powermax pm3-55lk charger question
- Thread starter Lucky360
- Start date
55A/272Ah = 0.2C rate
LFP needs little to no absorption to get nearly fully charged. Even more true when charging at such a low C rate. By the time they hit 14.4V, they are probably about 85-90% charged. At 13.6V, they will peak at about 95% charged after a few hours.
I would simply plug it in to charge when you want to charge and unplug it when you don't want to charge.
The thing to watch for is voltage drop between the PM3 and the battery terminals. If you use wires that permit too much voltage drop, the charger will see 14.4V before the battery. This isn't a huge problem, but it might mean you're hitting 70-80% instead of 85-90% when you get to 14.4V.
LFP needs little to no absorption to get nearly fully charged. Even more true when charging at such a low C rate. By the time they hit 14.4V, they are probably about 85-90% charged. At 13.6V, they will peak at about 95% charged after a few hours.
I would simply plug it in to charge when you want to charge and unplug it when you don't want to charge.
The thing to watch for is voltage drop between the PM3 and the battery terminals. If you use wires that permit too much voltage drop, the charger will see 14.4V before the battery. This isn't a huge problem, but it might mean you're hitting 70-80% instead of 85-90% when you get to 14.4V.
Thanks for helping me out so much snoobler, I will be using a four foot run of 2awg, I have read of problems with the powermax with what a would assume would be voltage loss. I also read that they might be coming out with a new charger this month I may call them on Monday and see what changes they made.
.07V is fine.
When you dig a little deeper, you'll find these complaints with most brands. All issues with RV converters rarely have anything to do with the converters themselves. It has to do with the typical RV wiring. They are often located a significant distance from the battery. Thus they hit 14.4V WAY before the batteries do. I have a motorhome that has about 20' between the converter and the batteries. At best, the wiring is 8awg. Here's what mine looks like:
Yep... 1.38V, so my battery is at 13V when the charger hits 14.4V, and it drops to 13.6V in moments.
Not the converter.
PowerMax PM3-55LK 12 Volt, 55 Amp Converter/Charger - Gobi Review
PowerMax PM3-55LK 12 Volt, 55 Amp Converter/Charger I bought this from DonRowe, promptly shipped and they had the best price. Reason I bought it - After some adult beverages, the 55 amp charge current and ability to adjust charging voltage looked very attractive. Additional justification -...
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PowerMax PM3-55LK 12 Volt, 55 Amp Converter/Charger - Gobi Review
PowerMax PM3-55LK 12 Volt, 55 Amp Converter/Charger I bought this from DonRowe, promptly shipped and they had the best price. Reason I bought it - After some adult beverages, the 55 amp charge current and ability to adjust charging voltage looked very attractive. Additional justification -...
Working exactly as documented. At 3.55V/cell and 0.2C current, you're nearly fully charged. If you'd left it at 14.4V, you'd be further along. What's the complaint?
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