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CA Traveler

The Western States

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Posted: 03/17/22 05:57pm Link  |  Quote  |  Print  |  Notify Moderator

BTW If your OEM charger has been replaced the wiring should be a big red flag. [emoticon] [emoticon]


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LittleBill

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Posted: 03/17/22 06:21pm Link  |  Quote  |  Print  |  Notify Moderator

CA Traveler wrote:

As stated the wire is to small and/or to long for optimal charging. AND this can include the negative wire.

The 48A from the charger first goes to the loads which is 48-14A=34A and 14A into the battery from your numbers.

You can also check for the PD recommended wire size per the distance and compare that to your wire size. And as stated the connectors etc could also be part of the problem.


there are no loads. if voltage drop was the issue, wouldn't it would increase as the amperage goes up? thus somewhat limiting it?

it seems odd to me it can do full amperage at a lower charge. but then the voltage loss causes it not to correctly charge at like 90% full. IDK seems off to me. maybe i need to run some calculators.

at 5 amps the voltage is 14.4, the wiring has been replaced.





BFL13

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Posted: 03/17/22 06:30pm Link  |  Quote  |  Print  |  Notify Moderator

LittleBill wrote:

i think you missed what i said. the voltage is not rising above 13.6 yet the amperage is tapering.

the meter output of the PD is confirmed 14.4 during this.

there are no other loads, everything is off.


You said it finally got to 14.4 at 3 amps in the OP, not being stuck at 13.6

But what was "it" ? Very confusing. Please take longer and provide a complete blow by blow on what you saw. At the converter and at the battery with meter readings vs converter settings if that comes up.

It is a mystery as it stands.


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time2roll

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Posted: 03/17/22 07:20pm Link  |  Quote  |  Print  |  Notify Moderator

LittleBill wrote:

yes but the v drop changes depending on amperage, it was doing 10 amps at 14.1. v drop doesn't remain static.
Yes that is the nature of resistance. The more amps the more voltage drop.

Eventually the amps will drop to zero and the converter output and battery will be equal voltage.

Need to address the resistance with an improved battery connection, fatter wire or move the converter close to the battery. Or all three.

Been through all this over the years.


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LittleBill

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Posted: 03/17/22 07:56pm Link  |  Quote  |  Print  |  Notify Moderator

time2roll wrote:

LittleBill wrote:

yes but the v drop changes depending on amperage, it was doing 10 amps at 14.1. v drop doesn't remain static.
Yes that is the nature of resistance. The more amps the more voltage drop.

Eventually the amps will drop to zero and the converter output and battery will be equal voltage.

Need to address the resistance with an improved battery connection, fatter wire or move the converter close to the battery. Or all three.

Been through all this over the years.


yes but this is not the concern

v drop and resistance are the highest at low voltage yes?

at 12.8v at the battery it was putting out 46amps.

resistance goes down as amperage goes down right?

and on that same path voltage drop lessens. right?

so my problem should be going away as the battery comes up to charge, not making it worse.

my issue and my confusion, again is around 13.6v at the battery. PD is doing 14.4, but the amperage is going down around 20amps and still tapering, PD should be cranking the amperage up to get to 14, but its not doing it.

according to voltage drop calcs, v drop is cut in half during this.

I have never seen a charger cut its amperage before getting the voltage up to its cut off point. I can force and confirm the pd never left 14.4 at the converter.

BFL13

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Posted: 03/17/22 08:06pm Link  |  Quote  |  Print  |  Notify Moderator

Battery R goes up with higher resting V SOC That makes amps taper with charger constant V

LittleBill

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Posted: 03/17/22 08:07pm Link  |  Quote  |  Print  |  Notify Moderator

i guess the part i am struggling with is, if it was a voltage drop and insufficient wiring issue. then i should not be able to get full amperage at 12.8,

but I do

the voltage difference i guess is much smaller closer to the 14.4v so maybe its more sensitive there. but i can't wrap my head around why its an issue at 13.5 vs 12.8

LittleBill

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Posted: 03/17/22 08:08pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

Battery R goes up with higher resting V SOC That makes amps taper with charger constant V


the problem with this comment is we don't get to constant v, it didn't climb past 13.6 for over an hour, yet amps were tapering all the way from 30 amp to about 15, before i really saw the voltage start climbing.

and with increasing battery R, shouldn't that immediately cause battery V to climb?

time2roll

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Posted: 03/17/22 08:21pm Link  |  Quote  |  Print  |  Notify Moderator

LittleBill wrote:

my issue and my confusion, again is around 13.6v at the battery. PD is doing 14.4, but the amperage is going down around 20amps and still tapering, PD should be cranking the amperage up to get to 14, but its not doing it.
The PD only holds voltage. The battery pulls amps. Once the PD is hitting 14.4 it is done increasing and the amps taper. The PD has no idea what is at the other end of the wire. Only way to push more amps is to increase the supply voltage but the supply is topped out at 14.4 volts. PD can only hold the voltage and wait for the battery to catch up.

For fast charging the circuit voltage drop should be 200 mV or less at full current.

time2roll

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Posted: 03/17/22 08:25pm Link  |  Quote  |  Print  |  Notify Moderator

If the PD had a battery sensing wire like some solar controllers, the PD would continue increasing voltage until the battery was at 14.4 volts.
Probably go to 15.2 - 15.4 volts before dropping back. But the PD does not do this.

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