Second power supply one controller?

smalltruck
smalltruck Registered Users Posts: 11 ✭✭
I could use some help with this. I have solar panels and a charge controller. What I want to do is to add a bike generator (that I already have) into the mix. My question is this how do I have two power sources with one charge controller. If I just connect the generator and the solar panels then run the wire into the controller would I not be sending the solar power to the bike during the day? Should I put a blocking diode on each line before connecting them? Any advice would be great.

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Second power supply one controller?

    Probably need a little more information... Different sources may need different types of charge controllers...

    Solar panels are sort of like current mode batteries... You can turn them on and off (via a charge controller) and nothing will be damaged.

    For some installations, like wind and water turbines, they need a constant load (typically the battery bank for off-grid systems)--If the load is removed, the device will over-speed and self destruct (in high winds or with lots of water flow). In this case, the turbine based generators are connected directly to the battery bank through a blocking diode (or diode bridge for single/three phase alternators--You should use a fuse/circuit breaker whenever the amperage from the battery bank can be at a dangerous level--A common failure for diodes is to short closed and pass high current in both directions). And a second charge controller is configured as a "dump" controller--when the battery is charged, excess electricity is sent to a dump load (diversion load) and any excess power is wasted as heat.

    In your case, the bike generator (motor cycle? human powered bicycle? electric powered bike?) probably will not over speed, but it is possible that it would develop so much voltage that it could damage a solar panel connected in parallel behind a solar charge controller.

    You also need to look at the "power" or amperage available from your charging sources... If it is less than 1% of bank capacity--then you may not even need a charge controller... If it is over 5% of capacity, it may be a good idea. And if it is over 10% a charge controller of some sort is really required...

    The above is based on Lead Acid chemistry battery... If you are using something else (NiCAD, NiMH, various Lithium chemistry)--Each battery type has its own unique charging requirements. And it can be damaging (or even dangerous) to charge a particular chemistry incorrectly.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: Second power supply one controller?

    Well the simple answer is NO, the charge contoller will only allow the current to flow into the batteries.

    ...Now "bike generator" what?

    A center wheel motor your spinning as a generator? or a friction generator for a bike light? or a pulley/chain and generator?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • smalltruck
    smalltruck Registered Users Posts: 11 ✭✭
    Re: Second power supply one controller?

    What I have is an indoor trainer for a pedal bike that I took the mag. resistance off and replaced with a motor. Much like you would find on a home built wind turbine. I am not worried about making more energy then the batteries can hold with that because I could just stop my ride early if that is a problem. However, when there is space in the battery bank I would like all the energy to be going into the battery bank not out to the solar panels that in the dark of night would be an energy draw. Maybe that helps clear up what it is that I am trying to do. Thanks for the input guys, keep it coming.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Second power supply one controller?

    If the generator is compatible with the voltage of your battery bank, just add a diode, fuse/breaker, and wire it directly to the battery bank... The solar panels behind a solar charge controller will not need any additional diodes/protective devices.

    You can place multiple generating sources directly to the battery bank...

    For your setup, say this is a 12 volt battery bank and you can average 100 watts (perhaps 200 if you are an athlete):
    • 200 watts / 14.4 volts charging a 12 volt battery bank = 13.9 amps
    For the short period you are charging the bank, you could run a C/20 rate into a:
    • 13.9 amps * 20 = 278 AH @ 12 volts
    Without any problem for your 1/2 hour to several hour workouts.

    If this was a fully charged AGM battery bank (instead of flooded cell)--You would probably want to look at a dump/diversion/shunt type controller to keep the AGM sealed battery from overcharging (sealed batteries do not take overcharging well).

    Also, you would want a shunt controller (or a manually controlled) load if the system was ~150 AH @ 12 volts or less...

    Sort of depends on what you are looking for... Something to play with yourself, or are you looking for a very reliable setup (say a bike at a gym where you may have multiple people a day riding and need a shunt controller to prevent damage to your emergency battery bank).

    A quick look around seems to be the Xantrex C35 is one of the less expensive solar charge controller that has a shunt/diversion controller option.

    Somebody might know of a smaller/less expensive Shunt Controller if you still need one.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • smalltruck
    smalltruck Registered Users Posts: 11 ✭✭
    Re: Second power supply one controller?

    With the bike I am getting about 24-27 Volts. About 12 amps. I am using a 12 Volt battery system. That is what works best for me. I might be wrong but given the diffence I think that it is best to run it through a controller. I would use the bike between 1/2 hour and one hour. Not every day but a few days a week. I am trying to give you the best info that I have and I am very happy for everyones help, however I do not know what this part means

    "For the short period you are charging the bank, you could run a C/20 rate into a:

    13.9 amps * 20 = 278 AH @ 12 volts "

    It shoulds like you are going in the direction that I am trying to go maybe you could help me understand.
    Thanks again
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Second power supply one controller?

    Not a problem.

    Basically I am trying to understand what capacity battery bank you have.

    If you have a very large battery bank, you don't need any charge controller at all.

    Also the type of battery you have can also make a difference too. AGM and other types of sealed batteries are very sensitive to over charging. Flooded cell batteries are not as sensitive as you can add distilled water if they get over charged once in a while.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • smalltruck
    smalltruck Registered Users Posts: 11 ✭✭
    Re: Second power supply one controller?

    I have two six volt sun Xtender batteries 305 amp. They are AGM sealed batteries. I would imagine that this thing should be set up the same way that someone would have solar panels and a small wind turbine hooked together to charge one bank. thanks BB for your help
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Second power supply one controller?

    You have a 305 AH rated bank (at 12 volts)--If you worked really hard and got 200 watts or ~14 amps out of the alternator:
    • 14 amps / 305 AH capacity = 0.05 or 5% of bank capacity (C/20 charge rate---0.05=1/20)...
    If you where doing this hours a day, every day, and had no other loads on the battery--I would look at a shunt controller (or a manual load)... But in your case, I would not got to the trouble of attaching a shunt controller...

    If you wanted to check if you are overcharging--Connect a fairly accurate digital volt meter and see what the charging voltage is while you are peddling... If you are under 14.2 volts--No problem at all... If you are over 14.4 -- you may need to add an optional load or a shunt controller.

    And you will need a blocking diode (if DC generator) or diode bridge/rectifier (if AC alternator) + ~20 amp fuse/breaker.

    Worst case, get a couple of 50 watt 12 volt bulbs (for an RV) and turn them on when peddling (or a small inverter/DC Adapter and run your TV/Computer).

    Do you have other loads on the battery bank (lighting, computer, etc.)--Or do they just sit charged for an emergency?

    If the batteries do not normally need charging (standby operation 99% of time)--I would just place loads directly on the Alternator (light bulbs, resistive heater, etc.). AGMs and other batteries don't really do that well with constant over charging.

    -Bill

    PS: Forgot to link in the SunXtender technical manual (PDF Download).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • smalltruck
    smalltruck Registered Users Posts: 11 ✭✭
    Re: Second power supply one controller?

    Yes the batteries have other load like lights and pump and other things. I was trying to do this cheap just to add a little extra juice with a quailty workout. This whole project is not worth messing up some nice batteries over. I am not sure that I would be able to ride at a pace that would be steady enough to get a constant volatage. If I put a cheap charge controller between the bike and the batteries, that I did not connect to the charge controller that I already have would that work or would that make other problems?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Second power supply one controller?

    It may cause other problems... Generators/Alternators tend to have the voltage double or more without loads. You would have to make sure that the charge controller could withstand the peak voltages.

    Second, generators/alternators tend to be inductive sources (loads)--anytime you switch on / off one of them, you do run the risk of causing an inductive voltage spike. For charge controllers, they tend to be solid state switches--which can be damaged by one over voltage event (aka spark). You could minimize this by using a capacitor across the generator/alternator to absorb some of the energy and reduce the voltage kick. (if you are old enough--this is the function of the condenser aka capacitor at the points of an old ignition system). But there still is a good chance that the capacitor / inductive loop would cause issues (too small of capacitor, voltage can still go over 300 VDC; too large of capacitor and when the switch closes again, the capacitor dumps all its energy across the closing switch and causes an over current condition--also damaging to solid state devices).

    Normally, you can get around that by using a flyback or snubbing diode across the across an inductive load to keep the voltage from spiking when the switch opens. But with a generator/alternator, the current is flowing the wrong direction to do this.

    A shunt regulator (generator to battery, shunt regulator turns on and dumps excess energy to load) is still the only "automatic" solution. If you are into electronics, it would not be too difficult to set up a circuit to turn on a load at 14.5 volts volts (assuming the batteries are at a stable temperature--and you don't need temperature compensation).

    The more I type--the worse "sky is falling" I sound--I don't really mean that. :blush::roll:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • phred01
    phred01 Solar Expert Posts: 35
    Re: Second power supply one controller?
    smalltruck wrote: »
    Should I put a blocking diode on each line before connecting them? Any advice would be great.
    Very good idea the diodes will block volts from feeding back to the panels. With summing diodes whatever produces the higher volts will be the power contributor. Say on a cloudy day u could top up the battery from the bike at the same time
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Second power supply one controller?

    Be careful adding blocking diodes everywhere...

    The solar charge controller should include the blocking function--plus, you really don't need the blocking diodes until you get to 24 or 48 volt battery banks.

    If you add a blocking diode to the output of the solar charge controller--you will have a 0.2-1.0+ volt error (diode voltage drop) and really mess up the charging of your battery bank.

    If you do not have a solar charge controller, then you can add a blocking diode--but make sure that it can handle the current and has an appropriate heat sink (and watch out for insulation as larger diodes have metal tabs, bodies that are typically electrically bonded to one lead or the other).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • smalltruck
    smalltruck Registered Users Posts: 11 ✭✭
    Re: Second power supply one controller?

    Ok BB you have been very helpful and I think that I may have an idea tell me what you think. What if I leave the solar panels and charge controller the way they are. Find a 13 or 14 Volt regulator to put between the bike and the batteries. Then simply disconnect the bike from the battery when not in use. I know that I will lose power by putting the regulator in however, it is not like I am trying to run my house off the bike just a little extra when I am riding. Can you see any other down side to trying it like that? If that sounds like it would work can you tell me any good place to find a regulator?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Second power supply one controller?

    Personally? I would connect the generator directly to the battery bank through a 15-20 amp rated diode (at least 20 volts--you could put several smaller diodes in series if you find only smaller ones) (if needed to prevent power flowing back to the generator--Alternator should not need blocking diode). And place a fuse/circuit breaker near the battery rated for 20 amps (and use 14-12 awg copper wire for carrying the current).

    I would either purchase a Xantrex C35 or equivalent charge controller (with shunt/diversion/dump mode). And connect to a ~100 watt heater (or light bulbs) as a diversion load.

    Or, instead of a C35/etc. shunt regulator, you could use a Voltage Controlled Switch to turn on at ~14.5+ volts and turn on a relay driving your dump load.

    But me, being the cheap guy I am, I would use a DMM (digital multimeter) to monitor my battery bank voltage while peddling--If it never gets above 14.5 volts--I would not bother with a regulator at all.

    Or even just hook a switch/optional load (like a DC fan to cool the rider) to burn off some power.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Second power supply one controller?
    BB. wrote: »
    Or even just hook a switch/optional load (like a DC fan to cool the rider) to burn off some power.

    -Bill

    I think you want that fan near the bike !
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,