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 > Converter voltage drop

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mpvuk

Portland, OR

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Posted: 06/23/22 10:06am Link  |  Quote  |  Print  |  Notify Moderator

Just replaced lead acid with LFE (200ah) and want to change converter to a lithium specific unit. Current unit WFCO WF-9855. My LFE's suggest a 14.4v bulk charge. Converter's I'm considering all bulk at 14.6v.

Do I take voltage drop into account when determining bulk charge at the battery? And will a 14.6v at converter work in my situation?

I have 6g on an approx. 10' one way run between battery and converter. New converter will be a 45A model. A 1.5% drop will bring 14.6v down to 14.4v. Based on my limited knowledge, I'm thinking I'll have at least a 1.5% drop.

Also note that I'm planning on getting a 45A unit to replace the WFCO 35A. Am I correct that current wiring will handle that?

Thanks in advance for your input.

Lwiddis

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Posted: 06/23/22 10:14am Link  |  Quote  |  Print  |  Notify Moderator

It's up to you but with my expensive Lithium battery I follow the manufacturers recommendations to the letter and measure at the battery. I question the need to move to 45 amps. The old 35 will fill the battery very quickly IMO.


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time2roll

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Posted: 06/23/22 10:32am Link  |  Quote  |  Print  |  Notify Moderator

I do not recommend 14.6 volts to charge LFP batteries. Especially with a converter that can hold this voltage for an extended period. Use the converter rating directly, no adjustment for voltage drop should be used.

I would avoid WFCO if spending money. The existing WFCO will not hurt the LFP battery but may not charge at the 14.4 boost level and simply remain at 13.6 volts. This will charge the battery fine but slower than necessary. Fine for the first trip or two if needed.

Consider a PD9200 series (standard, not the lithium)
https://www.bestconverter.com/9200-Series-Deck-Mount

45 or 60+ amp is fine depending on the wire that connects to the battery is sufficient for the additional power. And the battery must be compatible with the full amp rating for charging. Some are limited to 50 amps.

#6 wire is good to at least 60 amps.

* This post was edited 06/23/22 10:38am by time2roll *


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Posted: 06/23/22 11:14am Link  |  Quote  |  Print  |  Notify Moderator

You might consider converting the WFCO to something better and more compatable:

https://battlebornbatteries.com/product/progressive-dynamics-lithium-replacement-converter-section-for-electronic-power-center-55-amp/

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mpvuk

Portland, OR

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Posted: 06/23/22 02:18pm Link  |  Quote  |  Print  |  Notify Moderator

Thanks all. I did try the WFCO and it supplied 14.4v for a few minutes before going to 13.6v. Not a good option to quick charge with a generator.

Regarding the PD 9200 series (non lithium)...I can use the charge wizard to bulk at 14.4v and hold it there for 4 hours. If before that 4 hour period is up and the battery is ready to absorption, will the PD move off the bulk phase?

For most part, will be zapping battery with generator for a few hours at most. So will still be in the bulk phase. But If I want to fully charge, will the PD9200 do that if I use the charge wizard set to bulk at 14.4 and absorption at 13.6, or will I have issue as the WFCO and bulk cuts out after a few minutes?

RickLight

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Posted: 06/23/22 02:26pm Link  |  Quote  |  Print  |  Notify Moderator

I went with a Boondocker (75A for 315AH) because it's output is dialed to what you want.

The BMS does most of the management.


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time2roll

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Posted: 06/23/22 02:46pm Link  |  Quote  |  Print  |  Notify Moderator

Yes the PD can be manually controlled with the Wizard.

I wonder if the WFCO would have done better if the battery was lower on charge. Always a new odd story on WFCO that never seems to operate as they would have you expect.

otrfun

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Posted: 06/23/22 03:27pm Link  |  Quote  |  Print  |  Notify Moderator

mpvuk wrote:

. . . I have 6g on an approx. 10' one way run between battery and converter. New converter will be a 45A model. A 1.5% drop will bring 14.6v down to 14.4v. Based on my limited knowledge, I'm thinking I'll have at least a 1.5% drop . . .
Based on the voltage drop calculator I'm using, a 10 ft (one-way) run of 6 awg at 45a will result in a .36v, 2.47% drop at 14.6v. This is best case and assumes all connections and terminals are properly tightened and crimped. Everyone has their own personal preference in terms of an acceptable voltage drop. We typically strive for less than 2%. YMMV.

valhalla360

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Posted: 06/23/22 03:30pm Link  |  Quote  |  Print  |  Notify Moderator

time2roll wrote:

#6 wire is good to at least 60 amps.


Depends on the cable length.

I ran the OPs numbers quick and 45amp would pull it down to 14.16v.

I don't know if that's too low compared the 14.4v recommendation.

Of course if the amps tail off at 10amps, it's up over 14.5. I don't know if that's too high.

It does seem logical that voltage drop is taken into account but how much variance can be allowed is really the question.


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theoldwizard1

SE MI

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Posted: 06/23/22 03:33pm Link  |  Quote  |  Print  |  Notify Moderator

Any QUALITY converter/charger will have a specific setting for LiFePO4. Use it !

Personally, I would just eliminate the converter and buy an inverter/charger/automatic transfer switch.

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