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 > Charge wizard with Lithium upgrade to Converter charger?

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BFL13

Victoria, BC

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Posted: 05/05/21 08:39am Link  |  Quote  |  Print  |  Notify Moderator

otrfun wrote:

Finally got around to looking at the lithium charge options on our Renogy 40a dc to dc charger we have mounted in our truck camper. Bad news, the lithium mode is single-stage just like the PD, no float. However, the good news, in lithium mode you have 7 voltages to select from: 12.6v, 12.8v, 13.0v, 14.0v, 14.2v, 14.4v, and 14.6v. In lead acid/AGM/GEL mode it becomes a 2-stage charger (absorption and float). 3 absorptions choices: 14.1v, 14.4v or 14.7v. 3 float choices: 13.2v, 13.5v, and 13.8v.

Interesting that both Renogy and Progressive Dynamic (and no-doubt others) use single-stage lithium chargers. Got to wonder whether these manufacturers saw no harm in floating a LifePo4 indefinitely at higher voltages (let the BMS do the dirty work??), or they just assumed the end-user would simply disconnect/turn-off the charger for long-term storage (based on LifePo4's very low parasitics).


BB says you can leave it at 14.x for a week or two. Your DC-DC shuts off when you shut off the ignition, so no need for a float option. A converter stays on for as long as you are plugged in.

DC-DC is buck/boost so maintains 14.x whether alternator regulation has it above or below the chosen 14.x.


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otrfun

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Posted: 05/05/21 09:28am Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

otrfun wrote:

Finally got around to looking at the lithium charge options on our Renogy 40a dc to dc charger we have mounted in our truck camper. Bad news, the lithium mode is single-stage just like the PD, no float. However, the good news, in lithium mode you have 7 voltages to select from: 12.6v, 12.8v, 13.0v, 14.0v, 14.2v, 14.4v, and 14.6v. In lead acid/AGM/GEL mode it becomes a 2-stage charger (absorption and float). 3 absorptions choices: 14.1v, 14.4v or 14.7v. 3 float choices: 13.2v, 13.5v, and 13.8v.

Interesting that both Renogy and Progressive Dynamic (and no-doubt others) use single-stage lithium chargers. Got to wonder whether these manufacturers saw no harm in floating a LifePo4 indefinitely at higher voltages (let the BMS do the dirty work??), or they just assumed the end-user would simply disconnect/turn-off the charger for long-term storage (based on LifePo4's very low parasitics).
BB says you can leave it at 14.x for a week or two. Your DC-DC shuts off when you shut off the ignition, so no need for a float option. A converter stays on for as long as you are plugged in.

DC-DC is buck/boost so maintains 14.x whether alternator regulation has it above or below the chosen 14.x.
Yes, in an *typical* alternator application I agree there's very little to worry about. However, that's making an assumption on how the dc to dc charger will be used. It may or may not be turned off after a period of time depending on application. Bottom line, Renogy or PD did not qualify or restrict the use of the lithium mode in their dc to dc charger or converter in their user's manual.

Renogy and PD offer 2-3 stage charging (with float) for lead acid/AGM/GEL. The question is *why* not a float for lithium? I honestly believe they left out this option on purpose, for what they felt was a good technical reason to do so. It wouldn't have cost them a penny more to have simply added a float for lithium if they felt the need existed. Definitely more to this story than they simply forgot. Curious minds want to know why--lol!

FWC

The Wilderness

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Posted: 05/05/21 12:01pm Link  |  Quote  |  Print  |  Notify Moderator

Quite frankly I have very little confidence in either Renogy or PD. After the PD lithium converter debacle, I am not sure why anyone would trust them.

Victron is a far better option in this application as they don't presume to know how you want to charge your battery and allow you to adjust the charge parameters to your parameters.

StirCrazy

Kamloops, BC, Canada

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Posted: 05/06/21 08:13am Link  |  Quote  |  Print  |  Notify Moderator

Itinerant1 wrote:

This has been covered already. BMS is there (or should be) as a last line of protection not the first.

"Float" if used in a daily cycling of the batteries won't hurt it but if your going to float them at storage for long periods of time then it could shorten the battery life.


I dont think I would have a issue using a BMS to control the upper limit if it only shut down the charging but I dont know for sure if thats how the bigger ones work. I would rather use somthing like a smart shunt and capacity counter to shut off the charger automaticly when the battery is full and reconect when power is available if capacity is less than say 80%.

hmmm... could be another project in the making...

Steve


2014 F350 6.7 Platinum
2016 Cougar 330RBK

otrfun

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Posted: 05/07/21 06:51am Link  |  Quote  |  Print  |  Notify Moderator

StirCrazy wrote:

I dont think I would have a issue using a BMS to control the upper limit if it only shut down the charging but I dont know for sure if thats how the bigger ones work . . .

Steve
Most aftermarket BMS's have two sets of mosfets. One for charge, one for discharge. Each one is programmable independently. I would imagine this would be true for most sealed/prepackaged LifePo4/BMS units, too (no programmability though).

SFVdave

Southern California

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Posted: 05/07/21 08:01am Link  |  Quote  |  Print  |  Notify Moderator

I have shipped back the PD4560Licsv and am getting credited. I am using the original converter charger until PD comes out with a multi stage Li for unit. One nice thing about the original converter charger is at home, I can keep the shoreline plugged in and disconnect the house batteries from the converter and solar. This allows me to connect the engine battery back up to the system and keep it charged. Then the day before leaving for a trip I just isolate the engine battery again, reconnect the house batteries to the system to recharge and hit thge charge wizard. That will boost the converter charger to 14.4v for 4 hours allowing them to fully charge. Also, I switch the solar back on so the house batteries are continually charged while driving. All this switching is easily done by the Bussman resettable fuse switches.

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