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Charging from multiple sources

Nadad said:
Good day please, are there charge controllers that charge with generator/public utility power supply?
Click to expand...

Battery chargers. Most are meant for temporary use recharging automotive or forklift batteries, so difficult to get the right voltage and regulation.

There are inverter/chargers. Some stop inverting and pass through grid to loads while also charging battery (common mobile units for RV). Some are grid interactive, synchronize inverter to grid and draw just some power from grid. Some have built in battery chargers powered from grid, and output is always from inverter.

It may be possible to feed utility grid into "PV" input of some charge controllers. That would be an electrical design project - probably isolation transformer, rectifier, and need to limit inrush current charging capacitors.

A better way to do that could be an AC to DC power supply (or 48V battery charger) connected to the input of a charge controller which has suitable profile. Probably not "PV" input, but one that has "turbine" input settings. Outback and Midnight have such SCC.
 
Hedges said:
Battery chargers. Most are meant for temporary use recharging automotive or forklift batteries, so difficult to get the right voltage and regulation.

There are inverter/chargers. Some stop inverting and pass through grid to loads while also charging battery (common mobile units for RV). Some are grid interactive, synchronize inverter to grid and draw just some power from grid. Some have built in battery chargers powered from grid, and output is always from inverter.

It may be possible to feed utility grid into "PV" input of some charge controllers. That would be an electrical design project - probably isolation transformer, rectifier, and need to limit inrush current charging capacitors.

A better way to do that could be an AC to DC power supply (or 48V battery charger) connected to the input of a charge controller which has suitable profile. Probably not "PV" input, but one that has "turbine" input settings. Outback and Midnight have such SCC.
Click to expand...

Hedges said:
Battery chargers. Most are meant for temporary use recharging automotive or forklift batteries, so difficult to get the right voltage and regulation.

There are inverter/chargers. Some stop inverting and pass through grid to loads while also charging battery (common mobile units for RV). Some are grid interactive, synchronize inverter to grid and draw just some power from grid. Some have built in battery chargers powered from grid, and output is always from inverter.

It may be possible to feed utility grid into "PV" input of some charge controllers. That would be an electrical design project - probably isolation transformer, rectifier, and need to limit inrush current charging capacitors.

A better way to do that could be an AC to DC power supply (or 48V battery charger) connected to the input of a charge controller which has suitable profile. Probably not "PV" input, but one that has "turbine" input settings. Outback and Midnight have such SCC.
Click to expand...
thanks for the response. though my post was in error as I meant the normal battery charger as you indicated the first paragraph of the response. However, I will need some guidance on the possibility of equalizing a 12v 220ah flooded tubular battery with a 600w array and a 60amp charge controller.
 
Here are the S.G values of the said battery:
Cells;
1) 1.245
2) 1.275
3) 1.275
4) 1.270
5) 1.260
6) 1.250
 
2640 Wh battery, 600W would be 0.223C and 50A.

For normal charging, FLA might want 0.12C (check the manual).
I think orienting PV panels multiple directions could reduce peak current an sustain 0.12C for more hours.
SCC hopefully can be configured for a target maximum current, e.g. 26A if 0.12C is desired.
Some can use a shunt to regulate battery current while supplying additional current for loads like inverter.

The question is what voltage and current should be used for equalization. Sunny Island has default 2.50V/cell, adjustable 2.3V to 2.7V and default 10 hour cycle (page 169). See if you can find a manual for your battery. I don't know how much current is required.


For old, tired AGM batteries (which aren't normally supposed to be equalized, but what do I have to lose?) I follow parameters in the following manual. First charging at 14.5V, then equalizing at 15.5V (a bit higher than the 15.0V default for FLA). I think it draws about 1.0 A for a 100 Ah battery.

 
So this thread is great, thanks. My question is what happens if/when you have multiple chargers that are set for different battery types or profiles? One of the chargers I have the manual for has two "AGM" battery settings, "AGM1" is 14.1/13.4v, and "AGM2" is 14.6/13.7v.

If I were to wire up two of these chargers with different settings to the same battery (or the same group of parallel batteries...) what would actually happen? (and to be clear I realize it's dumb, I'm trying to understand how it works...)

I read above where the chargers can't act as a current sink, which (sort of) makes sense to me, but I'm also looking at my picture here and what I see is a pair of battery chargers wired together to each other, which seems kinda like a bad idea?

Assuming these chargers basically "ignore each other" -- I **think** that what will happen here is just a function of the four different voltages, right?
  1. less than 13.4v, behavior 1
  2. between 13.4 and 13.7v, behavior 2
  3. from 13.7 to 14.1v, behavior 3
  4. from 14.1 - 14.6v, behavior 4
  5. above 14.6 behavior 5 (I'm pretty sure I know this one: nothing happens!)
or... maybe not?{2B1AB71D-A78D-495D-8A1B-28A51F6A3F6F}.png
 
Last edited:
ljwobker said:
So this thread is great, thanks. My question is what happens if/when you have multiple chargers that are set for different battery types or profiles? One of the chargers I have the manual for has two "AGM" battery settings, "AGM1" is 14.1/13.4v, and "AGM2" is 14.6/13.7v.

If I were to wire up two of these chargers with different settings to the same battery (or the same group of parallel batteries...) what would actually happen? (and to be clear I realize it's dumb, I'm trying to understand how it works...)

I read above where the chargers can't act as a current sink, which (sort of) makes sense to me, but I'm also looking at my picture here and what I see is a pair of battery chargers wired together to each other, which seems kinda like a bad idea?

Assuming these chargers basically "ignore each other" -- I **think** that what will happen here is just a function of the four different voltages, right?
  1. less than 13.4v, behavior 1
  2. between 13.4 and 13.7v, behavior 2
  3. from 13.7 to 14.1v, behavior 3
  4. from 14.1 - 14.6v, behavior 4
  5. above 14.6 behavior 5 (I'm pretty sure I know this one: nothing happens!)
or... maybe not?View attachment 127019
Click to expand...
Having them set at different voltages doesn’t do anything bad. It just means that one charger will eventually be sat there doing nothing whilst the other charger finishes charging.

Whilst both charges are current limited, it literally makes no difference at all.
 
snoobler said:
One can have as many independent charging sources running concurrently as they like provided they are programmed properly for the voltage of one's battery bank.

Examples (some or all at once, even multiples of a single type, different brands, etc.):
  1. Solar PV via MPPT
  2. Solar PV via PWM
  3. AC-DC input via MPPT (using a AC to DC power supply feeding an MPPT solar controller with voltage/current consistent with a solar panel)
  4. Wind with suitable controller
  5. Grid/Generator AC via inverter/charger
  6. Grid/Generator AC via RV AC-DC converter
  7. Hydro with suitable controller
  8. Anything else someone might use to charge an off-grid energy storage system.
This is true for any battery chemistry.

Again, important that all chargers are appropriately configured to handle the battery bank with suitable absorption and float voltages.

Also very important that the sum of all charge currents do not exceed the recommended max charge current of the battery bank.

Note:
Multiple chargers only offer benefit when the battery is below the absorption voltage. Once the absorption voltage is hit, it is now a voltage limited charge and thus current will be lower than the sum of all sources. The battery bank will only accept as much current as it needs to maintain the absorption voltage. As the battery bank fills, current is reduced and chargers can no longer deliver current at the absorption voltage. They will drop out and go to float. Typically, the highest current charging source will always be the last source charging while all others are at 0A and likely in float mode.

Comments and corrections are welcome.
Click to expand...
Good day, please I need help. I have a 30amp. Pwm Charger (not charge controller). How can i bypass the pwm mode to enable me equalize my lead acid batteries?
 
Nadad said:
Good day, please I need help. I have a 30amp. Pwm Charger (not charge controller). How can i bypass the pwm mode to enable me equalize my lead acid batteries?
Click to expand...
If the unit doesn't have a pre-programmed equalization program, there's no way to do it. A PWM charger can still equalize, it just needs to know how to do it in the firmware.
 
If using Victron system, it has a setting in DVCC that would share voltage, temperature, manage battery charge voltage, set max charge current, etc. It will control the battery but allow any extra current to be used by other loads, like ac. Work great. I would think there are other system, but I am not aware of any at this time. ( I never looked, lock on to Victron right away). I am using LifePo4 which has bms, so more options. I would think AGM would all be the same setup required.

I only have 2 AGM for my diesel truck and only a victron solar unit with 200 watt panel. Keep it top up when parked for period of time.
 
Aly_Oops said:
If using Victron system, it has a setting in DVCC that would share voltage, temperature, manage battery charge voltage, set max charge current, etc. It will control the battery but allow any extra current to be used by other loads, like ac. Work great. I would think there are other system, but I am not aware of any at this time. ( I never looked, lock on to Victron right away). I am using LifePo4 which has bms, so more options. I would think AGM would all be the same setup required.
Click to expand...

and FLA and GEL.

I initially used DVCC on my FLA bank. 4S2P Trojan T-1275. They were limited to .13C charge or 39A. Array was capable of > 50A, so I used DVCC to limit current to the FLA but had the extra for loads.

DVCC also allows my Batrium to prohibit charging of the Lithium bank between 1 and 7°C through BMS control It permits PV power, but restricts battery current to 0A. Below 1°, Batrium triggers critical fault and disabled MPPT completely.
 
snoobler said:
One can have as many independent charging sources running concurrently as they like provided they are programmed properly for the voltage of one's battery bank.

Examples (some or all at once, even multiples of a single type, different brands, etc.):
  1. Solar PV via MPPT
  2. Solar PV via PWM
  3. AC-DC input via MPPT (using a AC to DC power supply feeding an MPPT solar controller with voltage/current consistent with a solar panel)
  4. Wind with suitable controller
  5. Grid/Generator AC via inverter/charger
  6. Grid/Generator AC via RV AC-DC converter
  7. Hydro with suitable controller
  8. Anything else someone might use to charge an off-grid energy storage system.
This is true for any battery chemistry.

Again, important that all chargers are appropriately configured to handle the battery bank with suitable absorption and float voltages.

Also very important that the sum of all charge currents do not exceed the recommended max charge current of the battery bank.

Note:
Multiple chargers only offer benefit when the battery is below the absorption voltage. Once the absorption voltage is hit, it is now a voltage limited charge and thus current will be lower than the sum of all sources. The battery bank will only accept as much current as it needs to maintain the absorption voltage. As the battery bank fills, current is reduced and chargers can no longer deliver current at the absorption voltage. They will drop out and go to float. Typically, the highest current charging source will always be the last source charging while all others are at 0A and likely in float mode.

Comments and corrections are welcome.
Click to expand...

That's as accurate and succinct as an amateur/layman can get without a ton of $30 words and a master's degree.

Over the past 10 years with Lithium batteries I've had to educate myself with 'C Rate' (Coulomb Law Rates).

It's about Time & Amps dumped (into or out of)

Basically, if you have a 100 Ah battery, and you charge or discharge it at 1C, that's charging or discharging 100 Amps per Hour.

Most of the Lithium I've had can dump amps faster than they charge, sometimes 4X or 5X faster.

If you have 100 Ah battery and you charge at 50 Amps, it's going to take 2 hours (hypothetically), and that's a 1/2 C Rate.

Ideally, I try to keep charge/discharge to 0.2 C ... I like BIG battery banks off grid, and charging at .2 C means full charge in 5 hours of peak sun.
 
ljwobker said:
So this thread is great, thanks. My question is what happens if/when you have multiple chargers that are set for different battery types or profiles? One of the chargers I have the manual for has two "AGM" battery settings, "AGM1" is 14.1/13.4v, and "AGM2" is 14.6/13.7v.

If I were to wire up two of these chargers with different settings to the same battery (or the same group of parallel batteries...) what would actually happen? (and to be clear I realize it's dumb, I'm trying to understand how it works...)

I read above where the chargers can't act as a current sink, which (sort of) makes sense to me, but I'm also looking at my picture here and what I see is a pair of battery chargers wired together to each other, which seems kinda like a bad idea?

Assuming these chargers basically "ignore each other" -- I **think** that what will happen here is just a function of the four different voltages, right?
  1. less than 13.4v, behavior 1
  2. between 13.4 and 13.7v, behavior 2
  3. from 13.7 to 14.1v, behavior 3
  4. from 14.1 - 14.6v, behavior 4
  5. above 14.6 behavior 5 (I'm pretty sure I know this one: nothing happens!)
or... maybe not?View attachment 127019
Click to expand...

The only issue I see (from experience) is one charger with lower top voltage cut out.

This isn't particularly a bad thing.

When I use more than one charger on a battery, the load (charging battery) will demand amps, pulling voltage down, everything runs along swimmingly.

As the battery demands less, voltage rises to above the upper threshold of one charger, and it shuts down, exactly what it should do.

Usually the battery is well within the Amp load of the second charger and just final top off charging anyway, so no big deal.

Where I sometimes get into trouble...

Not checking EXACTLY where the cut off voltage is. I like a little differential so they 'Cascade', or shut down in sequence as the battery reaches top charge.

Having EVERYTHING blink On/Off if they are all the same is an issue when they all have exactly the same cut off voltage...

That's a lot of cycling surge load on my system... Little steps between the shutdown voltage keeps that from happeneing.
 
We charge our marine lithium bank in the following way;
Solar via a single Victron MPPT
Wind turbine via a dump type regulator/ resistor
Ditto hydrogenerator
Victron B2B from engine battery when engine is running
Diesel genset via a pair of chargers giving up to 100amps output
Most of the time to solar and wind do everything
 
If an inverter draws current from the battery while it is charging, does it affect the charger in any way? Say a 20A charger is charging a 12V battery and the inverter draws 50A. Is the load spread across the charger and the battery? Can an inverter damage the charger by drawing current out of it?
 
Shouldn't cause damage to charge controller.

A charge controller delivers amps, into a battery of some voltage. The voltage of battery varies with current (charging or discharging) and state of charge.
Inverter draws current from battery, pulling its voltage a bit lower.

Charge controller won't deliver more than its maximum output current. It may deliver less when transitions to constant voltage mode, and battery accepts less current.
If inverter then draws current, charge controller would deliver more, up to its limit.

Voltage and current changes might make charge controller transition to a different mode (go to float, etc.) prematurely.
Lead-acid battery would prefer a particular current, and inverter steals some of that.

Some charge controllers (Victron, Midnight) can work with a shunt and regulate battery charge current to desired amount, while delivering more current when inverter draws it.
Hybrids with built in charge controller and inverter should also do that.

A charger/inverter could also deliver current to battery from grid/generator. With shunt or lithium BMS communication, it can be aware of charge controller current so it adjusts its current accordingly.
 
s0larcuriosity said:
If an inverter draws current from the battery while it is charging, does it affect the charger in any way? Say a 20A charger is charging a 12V battery and the inverter draws 50A. Is the load spread across the charger and the battery? Can an inverter damage the charger by drawing current out of it?
Click to expand...
Yes it affects the charger by drawing load from it first. In your example of a 50a load the charger would supply 20a and the battery would make up the 30a remaining. No it will not damage the charger.
 
snoobler said:
One can have as many independent charging sources running concurrently as they like provided they are programmed properly for the voltage of one's battery bank.

Examples (some or all at once, even multiples of a single type, different brands, etc.):
  1. Solar PV via MPPT
  2. Solar PV via PWM
  3. AC-DC input via MPPT (using a AC to DC power supply feeding an MPPT solar controller with voltage/current consistent with a solar panel)
  4. Wind with suitable controller
  5. Grid/Generator AC via inverter/charger
  6. Grid/Generator AC via RV AC-DC converter
  7. Hydro with suitable controller
  8. Anything else someone might use to charge an off-grid energy storage system.
This is true for any battery chemistry.

Again, important that all chargers are appropriately configured to handle the battery bank with suitable absorption and float voltages.

Also very important that the sum of all charge currents do not exceed the recommended max charge current of the battery bank.

Note:
Multiple chargers only offer benefit when the battery is below the absorption voltage. Once the absorption voltage is hit, it is now a voltage limited charge and thus current will be lower than the sum of all sources. The battery bank will only accept as much current as it needs to maintain the absorption voltage. As the battery bank fills, current is reduced and chargers can no longer deliver current at the absorption voltage. They will drop out and go to float. Typically, the highest current charging source will always be the last source charging while all others are at 0A and likely in float mode.

Comments and corrections are welcome.
Click to expand...
The amp of each source will double the total amp charging, right? Let's say chargecontroller1 is set to 50a and the other chargecontroller2 at 50a will be 100a.
Trying to understand your statement:
Also very important that the sum of all charge currents do not exceed the recommended max charge current of the battery bank.
 
alvirtuoso said:
The amp of each source will double the total amp charging, right?
Click to expand...

No. The use of "double" is incorrect. Sources sum, but only in bulk phase.

alvirtuoso said:
Let's say chargecontroller1 is set to 50a and the other chargecontroller2 at 50a will be 100a.
Click to expand...

Yep.

alvirtuoso said:
Trying to understand your statement:
Also very important that the sum of all charge currents do not exceed the recommended max charge current of the battery bank.
Click to expand...

If your batteries are rated for 200A charging, the sum of all charge sources must be less than 200A.
 
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