Anyone have experince with Noco Genius chargers and FRC batteries?

[fox46]

That just sounds wrong to me. If the two chargers are not synced (and it is highly unlikely they are) and calibrated the exact same way, one may go into load test while the other is supplying current. If not closely calibrated, then one charger may go into secondary charging while the other is in primary charging.

I used four banks to charge the 100AH on-board battery on one of our carts and it seemed to work flawlessly. I don't know that it is that hard to see multiple bays working together- The charger likely senses current to identify when a battery needs to be charged and when it has had enough. If they are all running in parallel, the current the battery will accept is split between them all and assuming all the transformers are identical, they all put out the same voltage and hence see the same current. When the current drops to a level that each individual bay is happy with, it shuts down into maintain mode which applies a slightly lower voltage to the battery. If that bay is seeing a higher voltage than its maintain cycle (ie other bays are still in charge mode) it likely just sits in maintain mode and each bay will eventually shut down as each one becomes content that the battery is drawing a low enough current to indicate fully charged. I never witnessed the entire charge cycle because it charged overnight but I would expect each bay would switch to maintain mode one at a time depending on their sensitivity and calibration so you would end up with a 7.2A > 5.4A > 3.6A > 1.8A main charge cycle as the battery approached full capacity.

[Al Skierkiewicz]

Fox,
What I am thinking is that many smart chargers switch between charge and load during the charge cycle. This allows them to determine the state of charge in the cells. This switch cannot be synchronized between individual chargers. So if these chargers do indeed switch, they cannot all do that at the same time. In the better case, one charger feeds current into another and little or no current passes to the battery. In the worst case, the chargers become confused and add current when the battery is at a point where the charge current should back down. Damage would result over time in that second case. In the maintain mode, the switching is likely to play havoc with voltage sense. I would run some tests with a load current tester like the CBA III to determine the load characteristics of a battery charged under a three charger 5.4 amp run and that of a 6 amp one charger run.

[fox46]

What I am thinking is that many smart chargers switch between charge and load during the charge cycle.

I've had a fair bit of experience with batteries from being involved with radio control aircraft. The majority of chargers use current sensing to determine the charge condition of conventional batteries. For a specific voltage, current approaches 0 as the cell voltage approaches the applied charge voltage. When this happens the charger switches from a "charging voltage" in the case of the accumate 5, it is 14.3V as illustrated on the graph of charge schedule on their website. Once the current drops to a predetermined rate, the charger goes into a "mantain" or trickle charge mode where it applies 13.5V. It holds this voltage unless it senses the current draw to exceed a threshold indicating the battery is accepting more charge due to a depleted state. It then switches back to charge mode applying 14.3V. This is the same method used by the KOP battery chargers which have the yellow and green light that flip flops back and forth as the battery approaches a fully charged condition. The yellow light indicates a charge cycle, the green, a maintain cycle.

Should you use more than one of these chargers on a single battery, they will each apply a charging voltage. Power will not backfeed into the charger as I understand they are equipped with a diode to prevent this. When they are both applying their 14.3V charge voltage, if the total current being drawn by the battery is greater than the 2x the threshold current which kicks the chargers into their maintain cycle, they will continue holding a 14.3V charge cycle. As this current drops and approaches 2x the threshold current, the more sensitive of the two chargers will kick into maintain mode of 13.5V. Since the other charger is still applying 14.3V it will see a jump in current which will keep it in its charge cycle. When the current drops to the threshold limit again, the second charger should kick off and both will continue in their maintain mode.



Why do you think that it is unlikely that the charge controllers on multiple banks are linked? They are all in the same housing, in the same unit.

I would think that if the manufacturer advertises that it is acceptable to bridge the banks, I would bet that the system has been designed to do this.

[Al Skierkiewicz]

Fox,
The point at which the chargers are sampling cell voltage, applying charge current and checking for load conditions are made at the processor level within each smart charger. There is no easy way to sync those cycles within multi chargers. Multiport chargers in the majority of cases, are simply multiple chargers within the same enclosure, with a common power line connection. I know that our six port charger that is available from many sources including McMaster is connected this way.
In my discussions with MK lab personnel and the Battery Council International here in Chicago, there are many "recommendations" made by manufacturers that are simply not good practice. In the case of simple chargers, where no switching/monitoring/status takes place, multiple outputs can be combined IF the chargers are connected to the same power-line phase and the total current does not exceed the max charge current specification.
Please note that the curves shown above also demonstrate the charge current during and after the addition/removal of an additional load in parallel with the battery charger.

[Cal578]

Al, what is this six port charger you speak of? Specs and/or link would be great.

[Al Skierkiewicz]

Gerry,
It is a Auto Meter BusPro-600s. Six station, 5 amps per station smart charger. Actually six charger in one unit. We removed the clips and replaced with Anderson SB50 plugs to match the FRC battery. They are in the $500 range now but we bought one years ago for far less.

[Cal578]

Thanks, Al. That looks like a great charger, especially if mounted on a wheeled charging station with holders for 6 batteries.

Agreed, adding SB50 plugs is a must. We've always done that with all our chargers. I can't count how many problems it avoids over the years. Since most chargers come with smaller leads, it helps to get the right crimp connectors for the SB50. AndyMark only sells the #6 connectors, which makes for an unreliable connection on the #12 to #16 wire that is common on chargers.

[Al Skierkiewicz]

Gerry,
That is the only size contact for that connector as I remember. What I do is strip the wire about 1-1.5" and fold over the wire until it fills most of the contact. Then crimp and solder.

[Cal578]

We have bought some contacts for 10 AWG wire from mouser.com. Later, I found them for a better price from helmarparts.com. The wire may still need to be folded once, but no more, so I think it's a better connection.

One pair of #10 contacts: http://www.helmarparts.com/product_p/904g1.htm

Complete SB50A connector with #10 contacts: http://www.helmarparts.com/product_p/6331g2.htm

[Bill_B]

This what I did for the charger output wires on the combined group I just put together. I had to remove some of the #6 strands to get them to fit into the terminal strip segments. Admittedly, this is something of a hack using the materials I had on hand. The zip tied loop provides adequate strain relief. Since then, the "bare" connectors arrived, so maybe I'll rework the leads into a hard-mounted SB50 for each of the chargers. RSN.