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PD4655 Charging Lithiums
I just replaced the OEM converter with a PD4655VL. I changed the jumper setting to lithium per the PD website and retained the stock distribution  board.

I hooked up a 100ah lithium with a 25% state of charge. The converter is charging 30.6 amps but only 13.65 volts. I was expecting to see 14.6 volts. Is this normal? Thanks.
jor
09 27' MB
10  Suby Forester

Re: PD4655 Charging Lithiums
Reply #1
I just replaced the OEM converter with a PD4655VL. I changed the jumper setting to lithium per the PD website and retained the stock distribution  board.

I hooked up a 100ah lithium with a 25% state of charge. The converter is charging 30.6 amps but only 13.65 volts. I was expecting to see 14.2 volts. Is this normal? Thanks.

The voltage should go up as the battery charges with 14.6 volts being a full charge. With the charger off, a fully charged lithium battery should float at 13.3-13.6 volts

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze

Re: PD4655 Charging Lithiums
Reply #2
Quote
The voltage should go up as the battery charges with 14.6 volts being a full charge.

This is my first exposure to lithiums. This battery is at 25%. So are you saying that if I just leave the converter on that the voltage will eventually rise to 14.6. I thought that the normal charging voltage was supposed to be a constant 14.6. Thanks.
jor
09 27' MB
10  Suby Forester

Re: PD4655 Charging Lithiums
Reply #3
The pd4655 will adjust the charging voltage as the batteries charge level increases. I leave my unit plugged in while in storage and the battery voltage shows 14.5 then. This is normal.
2010 RB "Monty"  & currently: 2021 RB "Villa Verde"
2004 Born Free 26'
1998 Beaver Patriot 33'
1992 Barth Breakaway 28'
1982 Fleetwood Jamboree 23'
1982 Dolphin/Toyota 22'

Re: PD4655 Charging Lithiums
Reply #4
What you're seeing is a charger in bulk mode. Remember how bulk charging works: the charger pumps in current as fast as it can, at a gradually increasing voltage (determined by the battery) until the voltage reaches a setpoint--14.6 volts in your case. Then it switches to absorb mode, which holds the voltage constant while feeding current at a decreasing rate; and finally to float--trickle-charging at a lower voltage.

That's with lead-acid batteries. With lithium batteries, there's no need for absorb; the charger pumps in the amps "full bore" in bulk mode until the setpoint is reached, and then switches to float. (In some cases there's a very brief absorb phase--my chargers are set to spend one minute in that mode, because I had to set something.) This results in much faster charging than with lead-acid batteries.

So in short, your charger is doing what's expected. The voltage will gradually rise to 14.6 V (assuming that's its bulk setpoint), and then pretty shortly thereafter switch to float charging at 13.5 V or thereabouts.
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"

Re: PD4655 Charging Lithiums
Reply #5
This is my first exposure to lithiums. This battery is at 25%. So are you saying that if I just leave the converter on that the voltage will eventually rise to 14.6. I thought that the normal charging voltage was supposed to be a constant 14.6. Thanks.

The voltage will rise to 14.4-14.6, at which point the batteries’ BMS will stop allowing charging.
The BMS controls the battery charging and discharge rates, preventing too high a charge or discharge rate
If you have a battery monitor, you will notice the charge rate significantly decreases as the voltage nears 14.6, during this period, the BMS equalizes the charge level of each cell in the battery(ies)

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze

Re: PD4655 Charging Lithiums
Reply #6
Thanks, guys. That's exactly what happened. All is well!!!
jor
09 27' MB
10  Suby Forester

Re: PD4655 Charging Lithiums
Reply #7
Jor - Your unit is a 55 amp charger (info gotten from progressive’s pages).
If you are on shore power you should get close to 55 Amps charge (minus your current battery usage - vampire stuff and any 12v you are charging or using).  We have a PD4060CSV 60 Amp and run 2-6 Amps below 60 depending on what we are charging.

However on generators they often don’t do the full amps as they are not producing they many watts.  I saw a table that showed kw generators and max they would supply to the charger/converter and it matched for our 2.8k generator (some lower number that I currently don’t remember) and our 4k generator (closer to 60).

I am guessing the 36amps was on a generator.
Jane & Scott
Currently have a 1989 TK  LD we did a lot of upgrades on.
Bigfoot 25RQ Twin on order with early summer 2024 ETA

Our smartphone autocorrects into very poor English.
 We disclaim the illusion of ignorance this creates as we have enough ignorance we rightly claim.