Dual Battery Module

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LewTwo   1 MW

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Dual Battery Module

Post by LewTwo » Jan 21 2022 6:13pm

So has anyone tried a FBC (Fusion Battery Combiner) ?
https://www.electromotivemods.com/shop/ ... knspnoks37
This unique FBC (‘Fusion Battery Combiner’) combines the power of two batteries, by allowing both to power your bike at the same time! This device works with the new series of modular wiring harnesses (sold separately), which are interchangeable with a conventional switch. The batteries can be of different Ah capacities; they will discharge in unison, once the voltage is equal between them.
US$50.00
The more I learn the more obvious the immensity of my ignorance becomes.
Weight Wennie E-Bike https://endless-sphere.com/forums/viewt ... 3#p1173723
Shaft Drive Grocery Getter https://endless-sphere.com/forums/viewt ... =6&t=90718
...and thanks to Justin!

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E-HP   1.21 GW

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Re: Dual Battery Module

Post by E-HP » Jan 21 2022 6:23pm

LewTwo wrote:
Jan 21 2022 6:13pm
So has anyone tried a FBC (Fusion Battery Combiner) ?
https://www.electromotivemods.com/shop/ ... knspnoks37
This unique FBC (‘Fusion Battery Combiner’) combines the power of two batteries, by allowing both to power your bike at the same time! This device works with the new series of modular wiring harnesses (sold separately), which are interchangeable with a conventional switch. The batteries can be of different Ah capacities; they will discharge in unison, once the voltage is equal between them.
US$50.00
Seems like you could do that with a couple of big diodes, but if that's what's inside, it might not work with regen.

john61ct   100 GW

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Re: Dual Battery Module

Post by john61ct » Jan 21 2022 6:41pm


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E-HP   1.21 GW

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Re: Dual Battery Module

Post by E-HP » Jan 21 2022 6:44pm

john61ct wrote:
Jan 21 2022 6:41pm
https://boltonebikes.com/products/dual- ... -connector

WattWagons used to do one
No regen, and I noticed the FBC doesn't support regen either, so probably diodes:
NOTE-5: “REGEN” circuits will not work with this combiner

LewTwo   1 MW

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Re: Dual Battery Module

Post by LewTwo » Jan 21 2022 7:31pm

E-HP wrote:
Jan 21 2022 6:44pm
john61ct wrote:
Jan 21 2022 6:41pm
https://boltonebikes.com/products/dual- ... -connector

WattWagons used to do one
No regen, and I noticed the FBC doesn't support regen either, so probably diodes:
NOTE-5: “REGEN” circuits will not work with this combiner
Well I run geared motors so I do not see that as a problem :)
The more I learn the more obvious the immensity of my ignorance becomes.
Weight Wennie E-Bike https://endless-sphere.com/forums/viewt ... 3#p1173723
Shaft Drive Grocery Getter https://endless-sphere.com/forums/viewt ... =6&t=90718
...and thanks to Justin!

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Steven Sheng   1 mW

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Re: Dual Battery Module

Post by Steven Sheng » Jan 22 2022 12:29am

CDBM2 Dual Battery Manager

1. Material and appearance size
The CDBM2 product adopts a low-pressure injection molding structure, and the heat-dissipating aluminum strip is half-coated structure, which has good heat dissipation, and the low-pressure injection molding material is resistant to high temperature and wear. The material of the shell allows normal use in the temperature of -35℃ to 170℃, and can guarantee good mechanical properties.

Physical picture
CDBM2.png
CDBM2.png (155.33 KiB) Viewed 326 times
CDBM2 Installation renderings.png
CDBM2 Installation renderings.png (85.83 KiB) Viewed 325 times
2. Function introduction
CDBM2 is a dual battery management module that can connect two batteries at the same time, expanding the battery life of electric vehicles.
1. Isolate the two batteries to prevent the two batteries from charging each other due to voltage difference when they are directly connected, resulting in power loss and battery damage caused by high current charging each other.
2. Two batteries can be discharged at the same time, which relieves the pressure of deep discharge of the battery, prolongs the service life of the battery, and has a longer driving mileage, achieving the effect of 1+1>2 battery. For example: the controller current limit is 15A, If only one 10AH battery is discharged, this battery discharges 15A, which is 1.5C discharge. According to the discharge curve, when the battery voltage is low, high current discharge will pull down the battery voltage, causing the battery to enter low-voltage protection and unable to use the battery 100%. electrical energy. After using our company's dual battery management, battery A and battery B each discharge 7.5A, and only 0.75C discharge. According to the battery discharge curve, the voltage drop caused by 0.75C discharge is smaller than that caused by 1.5C, and it is not easy to enter the low-voltage protection. , which can maximize the use of all the electric energy of the battery to achieve the purpose of longer riding mileage. The riding mileage of 1+1 battery discharged at the same time is greater than the riding mileage of 2 batteries discharged alone.
3. The temperature rise of the BMS caused by the 0.75C battery discharge is smaller, which is beneficial to improve the service life of the BMS, and the smaller discharge current of the battery cell is beneficial to improve the service life of the battery cell.
4. Measure the battery voltage and capacity, and intelligently distribute the discharge current of battery A and battery B. The discharge current of battery A and battery B is large. Battery B has the same state of discharge current.
5. The CDBM2 dual battery management module complies with the original parameters of the controller and the battery. It does not need to modify the parameters of the instrument, controller, battery hardware and software in the original model system. It can be used directly and is well compatible with 24V, 36V, and 48V batteries. .
6. The two batteries are evenly discharged, and the remaining power and voltage are the same. The user can clearly grasp the battery usage and charge the battery in time to avoid the battery running out of power.
7. The maximum load current of the CDBM2 dual battery management module can reach 18A.

3. Working principle
CDBM2 can detect the input voltage of two batteries at the same time, and compare.
1. When two batteries are connected and turned on, CDBM2 will preferentially select the battery with higher battery voltage to discharge, and the other will not discharge. If the battery voltage is high and the discharge amount is small under load conditions, when the voltage of battery A is almost close to the voltage of battery B, battery A and battery B are discharged at the same time.
2. If only one battery is connected, the connected battery can be discharged directly regardless of no-load or load.
3. The CDBM2 dual battery management module itself has a power consumption current of 3.5mA.
Last edited by Steven Sheng on Jan 22 2022 12:41am, edited 1 time in total.

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Steven Sheng   1 mW

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Re: Dual Battery Module

Post by Steven Sheng » Jan 22 2022 12:33am

CDBM1 Dual Battery Manager
1. Material and appearance size
The CDBM2 product adopts a low-pressure injection molding structure, and the heat-dissipating aluminum strip is half-coated structure, which has good heat dissipation, and the low-pressure injection molding material is resistant to high temperature and wear. The material of the shell allows normal use in the temperature of -35℃ to 170℃, and can guarantee good mechanical properties.

Physical picture
CDBM1.png
CDBM1.png (106.5 KiB) Viewed 326 times
CDBM1 Installation renderings.png
CDBM1 Installation renderings.png (74.75 KiB) Viewed 325 times
2. Function introduction
CDBM2 is a dual battery management module that can connect two batteries at the same time, expanding the battery life of electric vehicles.
1. Isolate the two batteries to prevent the two batteries from charging each other due to voltage difference when they are directly connected, resulting in power loss and battery damage caused by high current charging each other.
2. Two batteries can be discharged at the same time, which relieves the pressure of deep discharge of the battery, prolongs the service life of the battery, and has a longer driving mileage, achieving the effect of 1+1>2 battery. For example: the controller current limit is 15A, If only one 10AH battery is discharged, this battery discharges 15A, which is 1.5C discharge. According to the discharge curve, when the battery voltage is low, high current discharge will pull down the battery voltage, causing the battery to enter low-voltage protection and unable to use the battery 100%. electrical energy. After using our company's dual battery management, battery A and battery B each discharge 7.5A, and only 0.75C discharge. According to the battery discharge curve, the voltage drop caused by 0.75C discharge is smaller than that caused by 1.5C, and it is not easy to enter the low-voltage protection. , which can maximize the use of all the electric energy of the battery to achieve the purpose of longer riding mileage. The riding mileage of 1+1 battery discharged at the same time is greater than the riding mileage of 2 batteries discharged alone.
3. The temperature rise of the BMS caused by the 0.75C battery discharge is smaller, which is beneficial to improve the service life of the BMS, and the smaller discharge current of the battery cell is beneficial to improve the service life of the battery cell.
4. Measure the battery voltage and capacity, and intelligently distribute the discharge current of battery A and battery B. The discharge current of battery A and battery B is large. Battery B has the same state of discharge current.
5. The CDBM2 dual battery management module complies with the original parameters of the controller and the battery. It does not need to modify the parameters of the instrument, controller, battery hardware and software in the original model system. It can be used directly and is well compatible with 24V, 36V, and 48V batteries. .
6. The two batteries are evenly discharged, and the remaining power and voltage are the same. The user can clearly grasp the battery usage and charge the battery in time to avoid the battery running out of power.
7. The maximum load current of the CDBM2 dual battery management module can reach 18A.

3. Working principle
CDBM2 can detect the input voltage of two batteries at the same time, and compare.
1. When two batteries are connected and turned on, CDBM2 will preferentially select the battery with higher battery voltage to discharge, and the other will not discharge. If the battery voltage is high and the discharge amount is small under load conditions, when the voltage of battery A is almost close to the voltage of battery B, battery A and battery B are discharged at the same time.
2. If only one battery is connected, the connected battery can be discharged directly regardless of no-load or load.
3. The CDBM2 dual battery management module itself has a power consumption current of 3.5mA.

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E-HP   1.21 GW

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Re: Dual Battery Module

Post by E-HP » Jan 22 2022 8:46am

LewTwo wrote:
Jan 21 2022 7:31pm
E-HP wrote:
Jan 21 2022 6:44pm
john61ct wrote:
Jan 21 2022 6:41pm
https://boltonebikes.com/products/dual- ... -connector

WattWagons used to do one
No regen, and I noticed the FBC doesn't support regen either, so probably diodes:
NOTE-5: “REGEN” circuits will not work with this combiner
Well I run geared motors so I do not see that as a problem :)
Mainly trying to identify what's inside to see if it's a reasonable purchase vs. building one. Two 50A diodes at $10 each, plus some 10 gauge wire, a few XT-90 connectors and the housing; so seems like you could make one a little cheaper if you're pinching pennies, but not by too much, so maybe worth buying.

LewTwo   1 MW

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Re: Dual Battery Module

Post by LewTwo » Jan 22 2022 9:56am

E-HP wrote:
Jan 22 2022 8:46am
Mainly trying to identify what's inside to see if it's a reasonable purchase vs. building one. Two 50A diodes at $10 each, plus some 10 gauge wire, a few XT-90 connectors and the housing; so seems like you could make one a little cheaper if you're pinching pennies, but not by too much, so maybe worth buying.
Agreed. I have a new project and thing that I might use one so I can connect a spare battery if/when needed.
The more I learn the more obvious the immensity of my ignorance becomes.
Weight Wennie E-Bike https://endless-sphere.com/forums/viewt ... 3#p1173723
Shaft Drive Grocery Getter https://endless-sphere.com/forums/viewt ... =6&t=90718
...and thanks to Justin!

User avatar
E-HP   1.21 GW

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Re: Dual Battery Module

Post by E-HP » Jan 22 2022 10:06am

LewTwo wrote:
Jan 22 2022 9:56am
E-HP wrote:
Jan 22 2022 8:46am
Mainly trying to identify what's inside to see if it's a reasonable purchase vs. building one. Two 50A diodes at $10 each, plus some 10 gauge wire, a few XT-90 connectors and the housing; so seems like you could make one a little cheaper if you're pinching pennies, but not by too much, so maybe worth buying.
Agreed. I have a new project and thing that I might use one so I can connect a spare battery if/when needed.
In theory, you would experience a minor voltage drop (0.7V), but in practice, I don't think anyone would notice any performance difference, relative to the benefits of using two batteries.

Oli.Hall   1 W

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Re: Dual Battery Module

Post by Oli.Hall » Jan 24 2022 8:29pm

E-HP wrote:
Jan 22 2022 10:06am
In theory, you would experience a minor voltage drop (0.7V), but in practice, I don't think anyone would notice any performance difference, relative to the benefits of using two batteries.
The loss of voltage is less of an issue, the thing to consider is that this voltage drop is converted into heat. Dropping 0.7V at an average battery current of 25A generates 17.5W of heat. This is like putting a small halogen lightbulb in your controller bag/enclosure. It's going to get hot in there, quickly.

There is a solution called an Ideal Diode. This is what is usually used inside those dual battery adaptor boxes you linked. Here is what is usually inside a parallel battery adaptor:
https://www.aliexpress.com/item/4001143652124.html

This ideal diode circuit replicates a diode by only letting current pass one way, but this circuit uses mosfets and an ideal diode controller. This removes the forward voltage of 0.2V - 0.7V that you would usually see with a regular diode which would ordinarily be turned into heat. The ideal diode wastes far less power and doesn't need as big heatsink.

The circuit I linked basically contains four ideal diode circuits arranged to allow current to flow from each battery to the controller, but they prevent current flowing back from the controller into the batteries, this is a necessary feature to stop the higher voltage battery from charging the lower voltage battery, but it is this feature that also sadly prevents regen. The circuit does have an input for charging from a charger however.

You should be careful when using any type of parallel battery adaptor because ideal diode circuits can sometimes be damaged if you have a large inrush current when you connect your batteries. You should always use an anti-spark solution if using a parallel battery adaptor.

Thanks,
Oli.

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