PD4645 charging amps

[RT-NY]

So, I was expecting my Progressive Dynamics PD4645 to charge my LifePO4 at 45 amps. But it seems that the charger is only around 15 amps, I suppose the 45 amps refers to the converter output overall.

Does anyone have experience with the Powermax PM4 series? Will, say, the 55 amp model actually deliver 55 amps to an empty battery?

[booster]

Originally Posted by RT-NY

So, I was expecting my Progressive Dynamics PD4645 to charge my LifePO4 at 45 amps. But it seems that the charger is only around 15 amps, I suppose the 45 amps refers to the converter output overall.

Does anyone have experience with the Powermax PM4 series? Will, say, the 55 amp model actually deliver 55 amps to an empty battery?

How many amp hours of battery do you have? What type (AGM or wet cell) and brand.


A single 80ah wet cell might only take 15 amps, same size AGM probably 35 amps is at 20% state of charge.

[RT-NY]

Its a 100AH Chin LifePO4. It was about 1/2 charged when I hooked it up to the PD. I am supposing that the maximum output of the charger is 15amps because there is a 15amp breaker on the 120 volt panel for the charger. But I do need to charge more quickly than that so I was thinking of the Powermax PM4 series.

[RT-NY]

Originally Posted by RT-NY

I am supposing that the maximum output of the charger is 15amps because there is a 15amp breaker on the 120 volt panel for the charger.

Though now that I think about it, that isn't right because 15amps at 120 volts is sufficient to charge a 12 volt battery at 45 amps. Any yet, the charging current at 1/2 full was under 15 amps and dropped steadily over a few hours to 1 or 2 amps at 14.4 volts.

[booster]

A lithium battery should easily take the full output of a 45 amp charger unless some of the charger output is going to other loads like a frig on DC.


How are you measuring the charge current?

[RT-NY]

Originally Posted by booster

A lithium battery should easily take the full output of a 45 amp charger unless some of the charger output is going to other loads like a frig on DC.


How are you measuring the charge current?

I am using an inexpensive generic battery monitor with a 100 amp shunt, but I would think it is accurate enough for this purpose.

I was wondering if the "45 amp" rating of the PD4645 might not be for the charger alone. It has a "Maximum DC Output Current" of 45 amps, but perhaps that is for the entire 12 volt system on the coach and the amperage for the charger is only part of that?

[@Michael]

The PD is capable of outputting 45 amps to the battery, minus whatever other load present in the camper. That load is unlikely to be more than a few amps.

I'd start by checking:

• Wiring - size and length
• Connections
• The specifications of the battery itself

It's possible that the battery is configured to limit charge rate. I just bought one that has that feature.

Edit: From the Amazon listing:

Standard charge current 20A, Charging time approximately 6 hours

Other sources says anywhere from 70A to 1C (100A), so who knows.

[RT-NY]

Originally Posted by @Michael

The PD is capable of outputting 45 amps to the battery, minus whatever other load present in the camper

Thanks! That is good to know. I will get the battery to 90% discharged and try again with better wiring -- I had first tested with a temporary set up -- and see if I can get a better charging rate. I will post the results.

Originally Posted by @Michael

It's possible that the battery is configured to limit charge rate. I just bought one that has that feature.

Your battery's BMS limits the charging rate? Which battery is that? I do not think that the cheap batteries (like the Chins) have this.

Originally Posted by @Michael

Other sources says anywhere from 70A to 1C (100A), so who knows.

True -- even other sources on the same Amazon page posted by the same person (the seller, I presume) are not consistent on the specs. My impression was that 20 amps is a recommendation to best preserve battery life overall for LifePO4: the battery will accept much higher rates but at the cost of a (slight?) reduction of charge cycle count.

[eric1514]

For what it’s worth, I have never seen anything close to 45 amps from my PD charger.

[RT-NY]

Originally Posted by eric1514

For what it’s worth, I have never seen anything close to 45 amps from my PD charger.

Thanks! What kind and size of batteries are you charging with it? What is the maximum you have seen?

Can anyone else on the forum using the PD4600 series report the maximum rates they have gotten out of these chargers?

[Winston]

You haven't commented in which "mode" your Progressive Dynamics is operating. In reviewing the manual, it does not appear that you have much control over the output settings except you can override the automatic mode using the "Wizard Mode" button. When operating in the "normal" mode (green light flashing once per second), the PD is set to 13.6 volts which itself could explain the relatively low charging current you are experiencing (it all depends on the state of charge of your battery and the 'quality' of the wiring between your PD and battery). Try forcing your PD to the Boost Mode (using the noted Wizard button - you'll get a continuous green light) and see what your charge rate is. PD says that the Boost Mode voltage is 14.4 volts. This should cause your PD to output full current to a lithium battery. Note that PD doesn't recommend this mode . . . and we concur with PD in that 14.4 volts could overcharge a lithium battery. Thus, in forcing your PD to the Boost mode, be sure to monitor the battery terminal voltage, charge current, and/or state of charge of the battery.

[RT-NY]

Originally Posted by Winston

PD says that the Boost Mode voltage is 14.4 volts. This should cause your PD to output full current to a lithium battery.

I set the charger to Boost Mode. Starting with a 1/2 full battery, the voltage measured at the battery terminals slowly went up from about 13.4 to 14.4 while the current went down from about 13 amps to about 1 or 2 amps, which is what is supposed to happen except I expected that the initial charging current would be much higher.

Originally Posted by Winston

In forcing your PD to the Boost mode, be sure to monitor the battery terminal voltage, charge current, and/or state of charge of the battery.

And this reminds me of another question that I had: my LifePO4 battery is rated for a maximum voltage of 14.6. Would I damage it if I hook up a charger with a higher charging voltage, say 14.8, but only leave it connected until the voltage at the terminals gets to 14.6? In other words, whatever the full voltage is far a given charger, it will ramp up to that voltage only slowly. Will over-voltage damage occur during that ramping up or only when the voltage as measured at the battery terminals exceeds the battery's maximum voltage?

[eric1514]

Originally Posted by RT-NY

Thanks! What kind and size of batteries are you charging with it? What is the maximum you have seen?

Can anyone else on the forum using the PD4600 series report the maximum rates they have gotten out of these chargers?

I can't give you hard numbers because I wasn't expecting this thread but in my van with 2 100Ah AGMs or in my Class C with 4 GC2s (400+Ah) I don't remember ever seeing more than 18 amps going into the batteries, but again, I wasn't paying really close attention over a long length of time. I'm just saying, regardless of how deeply I discharged the batteries I never saw 45 amps or anything close to that in Boost mode.

The van had a Trimetric battery monitor and the C has a Victron. The van converter was a PD9245 and the C has a PD4645.

[Winston]

Originally Posted by RT-NY

I set the charger to Boost Mode. Starting with a 1/2 full battery, the voltage measured at the battery terminals slowly went up from about 13.4 to 14.4 while the current went down from about 13 amps to about 1 or 2 amps, which is what is supposed to happen except I expected that the initial charging current would be much higher.

And we, too, expected a higher initial charging current. If you were to connect a 'real' 14.4 voltage source to a 13.4 lithium battery, you would have a huge current (much higher than the maximum output specification of the PD). Since you're not seeing a huge current, there are two options: 1) you have some very poor wiring/connections that are causing a voltage drop of a "full volt" with only 13 amps flowing; or, 2) your PD isn't outputting 14.4 volts as advertised. So, try the experiment again when your battery is 1/2 full (at the 13.4 volt level) and, this time, measure the voltage directly at the output of the PD. If the PD is dropping its output voltage below the advertised 14.4 volt level with only 13 amps flowing, then, as you have opined, the PD is not operating as expected. If the voltage remains at, or near, the 14.4 volt level with only 13 amps flowing, you either have 'bad batteries' or a very high resistance wire/connection between the PD and batteries.

By the way, our lithium pack resting voltage at 50% State of Charge is 13.19 volts. At 13.36 volts, our pack is at a 90% State of Charge. So we wonder whether, in fact, you are trying to charge a nearly fully charged Lithium battery rather than a 50% SoC as you're suggesting. (And without seeking to make this too technical, our SoC voltage measurements are taken after a 10 hour resting period in which the battery is, essentially, disconnected, i.e. neither charging nor discharging during this period). Do you have s State of Charge meter?

Originally Posted by RT-NY

And this reminds me of another question that I had: my LifePO4 battery is rated for a maximum voltage of 14.6. Would I damage it if I hook up a charger with a higher charging voltage, say 14.8, but only leave it connected until the voltage at the terminals gets to 14.6? In other words, whatever the full voltage is far a given charger, it will ramp up to that voltage only slowly. Will over-voltage damage occur during that ramping up or only when the voltage as measured at the battery terminals exceeds the battery's maximum voltage?

Keep in mind that damage occurs on a single cell basis . . . thus, if any one cell gets too discharged, or too charged, that cell can be damaged even though the the full battery voltage (which is the series sum of 4 individual cells) is within an acceptable prescribed ranged. Assuming all cells are equally charged (balanced), our answer is that "no", you will not damage your pack by placing a 14.8 voltage charger on you pack until the pack exceeds its maximum rating of 14.6 volts.

[RT-NY]

Originally Posted by Winston

If you were to connect a 'real' 14.4 voltage source to a 13.4 lithium battery, you would have a huge current (much higher than the maximum output specification of the PD). Since you're not seeing a huge current, there are two options: 1) you have some very poor wiring/connections that are causing a voltage drop of a "full volt" with only 13 amps flowing; or, 2) your PD isn't outputting 14.4 volts as advertised.

My understanding (which may be incorrect) is that when you connect a 14.4 volt charger to a LifPO4 battery it is not supposed to read 14.4 volts at the battery terminals until the battery is nearly full (as in the red line in the chart below, approximately). I thought that this was because the battery itself causes the voltage to drop by absorbing the charger's power output. It sounds to me that you are suggesting otherwise. Can you explain this more fully?

Also, to be clear, I am not suggesting that the PD is not operating as expected according to its specs. I only said that I expected it would charge at 45 amps but my expectation might have been faulty. I have not yet heard from anyone with a PD4645 say that they have seen that kind of rate in practice!

[Winston]

Originally Posted by RT-NY

My understanding (which may be incorrect) is that when you connect a 14.4 volt charger to a LifPO4 battery it is not supposed to read 14.4 volts at the battery terminals until the battery is nearly full (as in the red line in the chart below, approximately). I thought that this was because the battery itself causes the voltage to drop by absorbing the charger's power output. It sounds to me that you are suggesting otherwise. Can you explain this more fully?

Also, to be clear, I am not suggesting that the PD is not operating as expected according to its specs. I only said that I expected it would charge at 45 amps but my expectation might have been faulty. I have not yet heard from anyone with a PD4645 say that they have seen that kind of rate in practice!

Your understanding is correct. If one could actually connect a 14.4 volt source (that would supply 14.4 volts at any current) DIRECTLY (meaning: no resistance) to the terminals of a lithium battery 'resting' at 13.6 volts, there would be near explosive results - - the current flow would be measured in the hundreds of amperes.

So when you connect your PD to the battery there are two factors (in addition to the battery capacity and state of charge) which will intervene to limit such high currents: 1) the resistance of the wiring and connections between the PD and battery; and, 2) the intrinsic output (current) limitations of the PD itself.

Now, assuming that you have a relatively good connection between the PD and battery (i.e. low resistance), we expect most of the current limitation will occur in the PD itself. We assume that the PD is designed to limit its current to 45 amperes (without blowing an internal fuse or circuit breaker). Thus, if you were to measure the voltage at the output terminals of the PD under these "attempted" heavy loads, we would expect the PD's output voltage to sag/drop to that level necessary to maintain its rated 45 ampere output current. How much will it sag? That depends on the actual charge state of the battery and the wiring between the PD and battery. And, frankly, it's not important how much it sags, what is important is that the PD is outputting its rated 45 amperes.

Assuming your battery is not defective, if you are getting only 13 amperes (and the PD is set to 14.4 volts output [unloaded]) you either have very poor connections between those two devices or your PD is not performing properly - - you should be able to get 45 amperes from a rated 45 ampere charger. If the PD is working properly, the only reason you wouldn't see 45 amperes is 1) the battery is already sufficiently charged; and/or, 2) you have unusually high resistance in the wiring.

Our next step would be to rerun your test, but do it with a really low battery State of Charge (when we run our battery voltage and capacity tests, we use a long length of low gauge wire as a load . . . the length of the wire is adjusted to create a 10 ampere load. We attach it, set a timer, and come back in 5 hours (or 10). At that point, even without a State of Charge meter, we have an accurate measure of battery charge percentage (assuming we started from a fully charged battery). There is no reason you can't discharge your batteries to, say, 25%). Then reconnect the PD and measure the voltage at the output terminals of the PD and at the battery terminals. Of course, you'll also note the current. With this information we can probably reach some conclusions . . .

[RT-NY]

Beginning a second round of tests, starting with a depleted Chins 100ah LifePO4, I have the following results so far:

- on shore power or generator, the PD4645 put 37 amps into the battery.

- engine charging from the alternator alone put a bit fewer amps in, but near the same

- using the PD4645 (generator or shore power) while running the engine put 50 amps into the battery

I am surprised that the alternator does not put more amps into the battery (but that is a good result because it suggests that I can use the lithium in place of agm without a DC to DC charger)

The amps do drop steadily as it charges, so the results I saw last time were largely due to the battery being half full.

I checked the voltage at the terminals marked "battery" on the fuse board of the PD4645 (Winston: is that what you meant by checking at the "output terminals of the PD"?) It does look like the voltage is higher there, so perhaps the reason I am getting 37 amps out of the PD rather than 45 amps is owing to resistence in the wiring. I would imagine that some amount of voltage drop is expected from the wiring because of the distance in any case. Any guesses as to how much that might be?

[booster]

When I looked at the specs for the charger it said it was 45 amps with rated output voltage at 12.6v. Change that to watts and then back to amps at 14.4v, which the PD should be running at, and you get a touch under 40 amps so you are not in bad shape at all when consider some wiring losses.

[RT-NY]

Originally Posted by booster

you are not in bad shape at all when consider some wiring losses.

I am guessing that another reason that my initial results were less that 20 amps is that I was using a temporary wiring setup with very long cables hooked up temporarily. How much loss of charging power would be expected from, say, a six foot run of 8 awg copper cable at 40 amps?

[dmb496]

My information is for comparison purposes. Same size battery, same brand charger but 20 amps larger.

I use a Progressive Dynamics PD9160ALV (rated @ 60 amps) to charge my Lion Energy 105 ah lithium batteries.

I charged one battery at a time. Initially the battery's SOC was at 45-50%.
The PD9160 was plugged into a 15 amp duplex outlet in my home.
No extension cord.
Connection wires between the PD9160 and battery are 6 ga., and 30" long.
I attached a DC clamp-on amp gauge to a connection wire.

Always saw 56-58 charging amps until the batteries were almost fully charged, and amperage roll-off began.

I charged 12 batteries, one at a time, and saw the same indications.