Parallel batteries (again!)

matthewslack

Esteemed Pedelecer
Nov 26, 2021
1,845
1,334
And I thought I was nearly there!
I do know that the Orbea’s charge port was also designed to take a range extender battery and it had cables rated for 12a…certainly the cable from the controller/battery to the charging port is very chunky: if the thin cable to the right is the PAS sensor, and the long one goes to the motor, the short cable goes to the charge port…
View attachment 45295
What confuses me is that others are riding around with DIY range extender batteries connected to that port, working as a second battery and not the mini charger that Orbea/Ebikemotion/Mahle designed and sell. There is even Volabike who make 7ah bottle batteries for Orbea and other expensive brands that they say work in parallel - and the Gain version connects via the charge port. They charge ’only’ €460! I can’t see how theirs incorporate a second Schottky etc yet their blurb states either battery can be depleted when connecting and be safe:
Argh! Thanks for this information and keeping me safe, btw. It is greatly appreciated.
And I thought I was nearly there!
I do know that the Orbea’s charge port was also designed to take a range extender battery and it had cables rated for 12a…certainly the cable from the controller/battery to the charging port is very chunky: if the thin cable to the right is the PAS sensor, and the long one goes to the motor, the short cable goes to the charge port…
View attachment 45295
What confuses me is that others are riding around with DIY range extender batteries connected to that port, working as a second battery and not the mini charger that Orbea/Ebikemotion/Mahle designed and sell. There is even Volabike who make 7ah bottle batteries for Orbea and other expensive brands that they say work in parallel - and the Gain version connects via the charge port. They charge ’only’ €460! I can’t see how theirs incorporate a second Schottky etc yet their blurb states either battery can be depleted when connecting and be safe:
Argh! Thanks for this information and keeping me safe, btw. It is greatly appreciated.
The difficulty is knowing exactly what is going on in those other uses you are aware of. With cheap stuff or secondhand spares such as I experiment with, not much is lost by just taking things apart and having a look.

But the same rule applies here as to investment and gambling: don't risk something you are not prepared to lose!

If you learn more I'm interested to hear it!
 
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Nealh

Esteemed Pedelecer
Aug 7, 2014
20,882
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All I can add is that Orbea say their sytsem is a range extender via charging the in frame battery.
The other bike brand if they say it is in parallel have in place a different electronic system that routes the power separately then Orbea uses.
 
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Yak

Pedelecer
Mar 20, 2020
105
39
I’ve been talking to a guy who ‘built his own’. Actually he bought a bottle battery and used the charger lead to connect to the bike Vía the charging port. No protection at all. He’s convinced his battery acts as a charger and that the Gain has internal electronics to reduce the amps reaching the internal battery to 1.9. No fires in 4 months. Far too scary to try myself, just thought I’d throw it out there.
 

matthewslack

Esteemed Pedelecer
Nov 26, 2021
1,845
1,334
I’ve been talking to a guy who ‘built his own’. Actually he bought a bottle battery and used the charger lead to connect to the bike Vía the charging port. No protection at all. He’s convinced his battery acts as a charger and that the Gain has internal electronics to reduce the amps reaching the internal battery to 1.9. No fires in 4 months. Far too scary to try myself, just thought I’d throw it out there.
It's the not knowing what's inside that is so frustrating! But good to share these snippets of info. Maybe someone out there does know what's inside.
 

WheezyRider

Esteemed Pedelecer
Apr 20, 2020
1,690
938
Yak, have a look here, I've updated the thread...

 

Yak

Pedelecer
Mar 20, 2020
105
39
I’ve spent a lot of time trying to track down and talk with the guys that have built their own Gain range extenders. Most posted 2019/2020. I’ve had no luck reaching them and am beginning to picture their charred remains in various places around the world as their attC8B868F9-8374-4A35-BF3D-E4D63740260A.jpeg attempts ended badly! I’m going to go ahead though…I really need the range until I’m fitter - and look how stealthy that second 7ah battery is!!
 

AntonioAlfaro

Pedelecer
Mar 21, 2022
46
9
I’ve spent a lot of time trying to track down and talk with the guys that have built their own Gain range extenders. Most posted 2019/2020. I’ve had no luck reaching them and am beginning to picture their charred remains in various places around the world as their attView attachment 45511 attempts ended badly! I’m going to go ahead though…I really need the range until I’m fitter - and look how stealthy that second 7ah battery is!!
Hi Yak, I have read enough comments in this forum about DIY battery extender for Orbea Gain. I would like to know if you finally built your extender and if so what has been the behavior in reality.
 

AntonioAlfaro

Pedelecer
Mar 21, 2022
46
9
All I can add is that Orbea say their sytsem is a range extender via charging the in frame battery.
The other bike brand if they say it is in parallel have in place a different electronic system that routes the power separately then Orbea uses.
Hi Nealh,
I would like to know if in all your experience with battery extenders you have built one specifically for Orbea Gain. If so, what has been the actual performance?
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,882
8,517
61
West Sx RH
Hi Nealh,
I would like to know if in all your experience with battery extenders you have built one specifically for Orbea Gain. If so, what has been the actual performance?
I use battery extenders or paralleled battery packs on my bikes but have not any for the Gain. Typically now I just carry another battery for longer range.
 

Yak

Pedelecer
Mar 20, 2020
105
39
Hi Yak, I have read enough comments in this forum about DIY battery extender for Orbea Gain. I would like to know if you finally built your extender and if so what has been the behavior in reality.
Hi Antonio - I’m the same Yak as Yako Rides aGain, so yes I did and it works perfectly.
 

AntonioAlfaro

Pedelecer
Mar 21, 2022
46
9
Hi Antonio - I’m the same Yak as Yako Rides aGain, so yes I did and it works perfectly.
Hi Yako,
How small is the world.!
Let me know if you have made any improvements to your extender, or if you have made new measurements. I have ordered some components and battery to build one. I think I am clear about the difference in the operation of the Orbea extender versus the one you have built. Your reports have allowed me to validate my understanding. When I have the components I have ordered, I plan to do some voltage, current and power measurements on site. I'll let you know.
 
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Chamzamzoo

Finding my (electric) wheels
Feb 12, 2016
23
1
40
Hope I'm not offending jumping in here, but I've been watching this debate with interest from the sidelines and have some observations & queries:

Interestingly the Volabike blurb has removed (I assume it was there as you allude to it before, Yak) the section on parallel running for their ebikemotion extender. Compare the Bosch version to the MAHLE one:



This comment from Andy Collins on your youtube video sounded like a neat way of furthering the discussion:

"A practical test, maybe to half-charge the main battery and half-charge the range extender battery. Then just leave the bike switched on but not actually move the bike anywhere. Would then be interesting to see if the main battery was charged further, or whether both batteries sit there at a balanced voltage and remain both half charged. If they both remain at their status quo, then I think it may be a passive charging circuit relying on a higher voltage of the charged battery (or plugin charger), to derive the charge current for the internal battery. "


Further, the official ebikemotion range extender mentions parallel usage, but in a 2amp only way:

1.- Power bank for the main battery when the eBike is stopped or over 25Km/h: When Range extender is connected and switched on it starts to works as charger for the main on if there is no consumption of the main. Perfect solution for garages without plugs or charging while riding.

2.- Charging while riding: When the consumption of the motor will be lower than 2A (downhill, no assistance or over 25km/h, all the energy doesn’t consumed by the motor will charge the main battery. (by this way we compensate the extra consumption during uphill)

3.- Parallel supply: The motor unit consumption is over 2A, the Range extender will supply the first 2A and the additional energy will be supplied by the main one.


I'm still non the wiser really, but leaning towards suspecting that none of these external packs (inc DIY & Vola) can create a parallel connection, and that their input could be regulated to 2amps internally to the bike... but it would be great to know for sure. I would then buy the battery pack that Vola rebrand, with confidence, from the cheaper source.

The other thing holding me back from being more certain about this is the mention of the ebikemotion port being Max. 12A for external battery and 2A for charging, by MAHLE. But why would they have a port that can run 12a for external batteries when their own battery never goes above 2amp? Unless they built the capacity for future upgrades and then decided the 2amp charge was the better route over 12amp parallel, meaning the range extender may be the component limiting current.

Bet they deliberately keep all this confusing to drive sales of their "safe" OEM model.
 
Last edited:

AntonioAlfaro

Pedelecer
Mar 21, 2022
46
9
Hope I'm not offending jumping in here, but I've been watching this debate with interest from the sidelines and have some observations & queries:

Interestingly the Volabike blurb has removed (I assume it was there as you allude to it before, Yak) the section on parallel running for their ebikemotion extender. Compare the Bosch version to the MAHLE one:



This comment from Andy Collins on your youtube video sounded like a neat way of furthering the discussion:

"A practical test, maybe to half-charge the main battery and half-charge the range extender battery. Then just leave the bike switched on but not actually move the bike anywhere. Would then be interesting to see if the main battery was charged further, or whether both batteries sit there at a balanced voltage and remain both half charged. If they both remain at their status quo, then I think it may be a passive charging circuit relying on a higher voltage of the charged battery (or plugin charger), to derive the charge current for the internal battery. "


Further, the official ebikemotion range extender mentions parallel usage, but in a 2amp only way:

1.- Power bank for the main battery when the eBike is stopped or over 25Km/h: When Range extender is connected and switched on it starts to works as charger for the main on if there is no consumption of the main. Perfect solution for garages without plugs or charging while riding.

2.- Charging while riding: When the consumption of the motor will be lower than 2A (downhill, no assistance or over 25km/h, all the energy doesn’t consumed by the motor will charge the main battery. (by this way we compensate the extra consumption during uphill)

3.- Parallel supply: The motor unit consumption is over 2A, the Range extender will supply the first 2A and the additional energy will be supplied by the main one.


I'm still non the wiser really, but leaning towards suspecting that none of these external packs (inc DIY & Vola) can create a parallel connection, and that their input could be regulated to 2amps internally to the bike... but it would be great to know for sure. I would then buy the battery pack that Vola rebrand, with confidence, from the cheaper source.

The other thing holding me back from being more certain about this is the mention of the ebikemotion port being Max. 12A for external battery and 2A for charging, by MAHLE. But why would they have a port that can run 12a for external batteries when their own battery never goes above 2amp? Unless they built the capacity for future upgrades and then decided the 2amp charge was the better route over 12amp parallel, meaning the range extender may be the component limiting current.

Bet they deliberately keep all this confusing to drive sales of their "safe" OEM model.
Hello Chamzamzoo,
Allow me to make an explanatory summary about the Mahle extender system and the options we have when building a DIY extender. These conclusions that I will summarize are the result of my careful analysis of the Mahle and Orbea specifications on their battery extender. As a professional I start from the premise that a serious manufacturer does not lie in its specifications.
The Mahle extender is designed to behave like a main battery charger, supplying only 2 Amps of charging current and a voltage that will depend on the level of charge remaining in the extender. It means that in its electronics, the extender includes a current limiter at 2amps max. and also a reverse current block device to prevent the main battery charging the extender. In other words, it is a system equivalent to the 110/220 VAC ---> 42VDC 2Amp charger that we use to charge the main battery at home.
The question that arises at this point is why only 2 amps does the Mahle extender deliver? What's wrong with that? I'd say there's a lot of good in it. I explain.
A battery bank in a 10S2P arrangement, as is the case, requires 2Amp max as recommended for charging. So far the Mahle system is doing well, because the extender system marketed by a manufacturer must be safe and easy to use by any user and in any condition (this will be better understood when I explain the operation of a DIY extender).
Let's remember a basic principle of the theory of movement of charges: for there to be an electric current (movement of electric charges) from point A to point B, point A must be at a higher potential (voltage) than point B. Keeping this in mind, let's assume that the Mahle extender is point A and the internal battery is point B, and that they are fully charged (same voltage, so no current from the extender to the main battery).
The trip begins and we begin to demand assistance from the Ebike, the motor begins to consume energy. From where? From the main battery and the battery extender. But with one big limitation: the extender will never deliver more than 2 amps. Suppose the assistance level demands 4 amps (which is a lot: 4x36=144 W), 2 amps will come from the main battery and 2 from the extender, and both systems are discharged equally at the same voltage. We stop pedaling: nothing happens since there is no difference in potential between both systems, both are at the same level of charge, there are no currents.
Now, what happens if at that moment (both batteries are equalized in voltage) the level of assistance required is so great that it demands 200W ( 200/36=5.6 Amps). For this demand, 3.6 Amps will come from the main battery and only 2 Amps from the extender. The main battery begins to discharge faster than the extender and at the end of that demand we stop pedaling, we will have the main battery more discharged than the extender, that is, there is a difference in potential and the extender begins to charge the main battery at a rate of 2 amps max. only. It may happen that it fully charge it, or that it charges it just a little, because another request for assistance may occur and the differences in potential will never be the same.
I will continue...
 

Yak

Pedelecer
Mar 20, 2020
105
39
I'm still non the wiser really, but leaning towards suspecting that none of these external packs (inc DIY & Vola) can create a parallel connection, and that their input could be regulated to 2amps internally to the bike... but it would be great to know for sure. I would then buy the battery pack that Vola rebrand, with confidence, from the cheaper source.

The other thing holding me back from being more certain about this is the mention of the ebikemotion port being Max. 12A for external battery and 2A for charging, by MAHLE. But why would they have a port that can run 12a for external batteries when their own battery never goes above 2amp? Unless they built the capacity for future upgrades and then decided the 2amp charge was the better route over 12amp parallel, meaning the range extender may be the component limiting current.

Bet they deliberately keep all this confusing to drive sales of their "safe" OEM model.
No, jump on in! I am definitely coming to the conclusion, reinforced by the gurus here and many others, that all of these extenders work the same way. Passive ‘charging’, with some form of reverse protection and relying on the internal battery‘s BMS to limit the incoming amps to 2. If you take the charge port apart on the gain there are two thick wires and two thin. Perhaps this does relate to an original intention to somehow parallel the extender using the thicker wires with the two thin wires used for the mains charger, but for me, I am simply happy that mine works. If we ever get reasonable weather here and I get the time I will def run some tests, but I think both the Mahle and Volabike extenders may well be simple batteries with the addition of a Schottky or Ideal diode used for protection. Pretty cynical stuff if so, and an opportunity for a small-scale manufacturer to steal the market, like Volabike should have done, if they hadn’t been greedy.
 

AntonioAlfaro

Pedelecer
Mar 21, 2022
46
9
No, jump on in! I am definitely coming to the conclusion, reinforced by the gurus here and many others, that all of these extenders work the same way. Passive ‘charging’, with some form of reverse protection and relying on the internal battery‘s BMS to limit the incoming amps to 2. If you take the charge port apart on the gain there are two thick wires and two thin. Perhaps this does relate to an original intention to somehow parallel the extender using the thicker wires with the two thin wires used for the mains charger, but for me, I am simply happy that mine works. If we ever get reasonable weather here and I get the time I will def run some tests, but I think both the Mahle and Volabike extenders may well be simple batteries with the addition of a Schottky or Ideal diode used for protection. Pretty cynical stuff if so, and an opportunity for a small-scale manufacturer to steal the market, like Volabike should have done, if they hadn’t been greedy.
Hi Yako,
I agree with you. There is little point in racking our brains trying to figure out whether or not the Mahle system has a 2 amp limiter on the main battery, whether or not it has a limiter on the extender, whether it does passive charging, whether or not it works in parallel with the main battery, etc etc. The important thing is that your DIY extender works fine. It is there where we must focus to leave the operating conditions, mode of use, and care in its use well established.
My opinion is that if a DIY system does not work in parallel with the main battery, there is not much point in developing it. But based on your previous reports of experience with your DIY extender, everything seems to indicate that it works in parallel.
Your most recent test ride reported, you started with same voltage (main and extender) and used a maximum assistance level, presumably the current draw of the motor was well in excess of 2 amps. If you at the end of that test found the two batteries with the same voltage level (charge) it shows a parallel work.
For me, the most important thing at this moment is to carry out measurements of currents drained from the main battery and from the DIY extender at each moment of time.
I have bought a wattmeter and I plan to do some initial tests in the lab, to later mount the ebike on a smart trainer and make measurements simulating a real route.
 

Chamzamzoo

Finding my (electric) wheels
Feb 12, 2016
23
1
40
Hello Chamzamzoo,
Allow me to make an explanatory summary about the Mahle extender system and the options we have when building a DIY extender. These conclusions that I will summarize are the result of my careful analysis of the Mahle and Orbea specifications on their battery extender. As a professional I start from the premise that a serious manufacturer does not lie in its specifications.
The Mahle extender is designed to behave like a main battery charger, supplying only 2 Amps of charging current and a voltage that will depend on the level of charge remaining in the extender. It means that in its electronics, the extender includes a current limiter at 2amps max. and also a reverse current block device to prevent the main battery charging the extender. In other words, it is a system equivalent to the 110/220 VAC ---> 42VDC 2Amp charger that we use to charge the main battery at home.
The question that arises at this point is why only 2 amps does the Mahle extender deliver? What's wrong with that? I'd say there's a lot of good in it. I explain.
A battery bank in a 10S2P arrangement, as is the case, requires 2Amp max as recommended for charging. So far the Mahle system is doing well, because the extender system marketed by a manufacturer must be safe and easy to use by any user and in any condition (this will be better understood when I explain the operation of a DIY extender).
Let's remember a basic principle of the theory of movement of charges: for there to be an electric current (movement of electric charges) from point A to point B, point A must be at a higher potential (voltage) than point B. Keeping this in mind, let's assume that the Mahle extender is point A and the internal battery is point B, and that they are fully charged (same voltage, so no current from the extender to the main battery).
The trip begins and we begin to demand assistance from the Ebike, the motor begins to consume energy. From where? From the main battery and the battery extender. But with one big limitation: the extender will never deliver more than 2 amps. Suppose the assistance level demands 4 amps (which is a lot: 4x36=144 W), 2 amps will come from the main battery and 2 from the extender, and both systems are discharged equally at the same voltage. We stop pedaling: nothing happens since there is no difference in potential between both systems, both are at the same level of charge, there are no currents.
Now, what happens if at that moment (both batteries are equalized in voltage) the level of assistance required is so great that it demands 200W ( 200/36=5.6 Amps). For this demand, 3.6 Amps will come from the main battery and only 2 Amps from the extender. The main battery begins to discharge faster than the extender and at the end of that demand we stop pedaling, we will have the main battery more discharged than the extender, that is, there is a difference in potential and the extender begins to charge the main battery at a rate of 2 amps max. only. It may happen that it fully charge it, or that it charges it just a little, because another request for assistance may occur and the differences in potential will never be the same.
I will continue...
Many thanks for this detailed post. I think my query pivots on is it the extender that is limiting its discharge, or the port, via the BMS or other mechanism, limiting the charge current. It could be either, and the manufacturers would still be technically correct I believe.

Considering also that the charger only outputs 2amps (42v) as well. Nothing in the official system exceeds this...

If there was a higher amperage source available, would the system draw it? I recall one poster on Ebike review mentioning a message about over current on his app, so perhaps? This is just one data point though.


No, jump on in! I am definitely coming to the conclusion, reinforced by the gurus here and many others, that all of these extenders work the same way. Passive ‘charging’, with some form of reverse protection and relying on the internal battery‘s BMS to limit the incoming amps to 2. If you take the charge port apart on the gain there are two thick wires and two thin. Perhaps this does relate to an original intention to somehow parallel the extender using the thicker wires with the two thin wires used for the mains charger, but for me, I am simply happy that mine works. If we ever get reasonable weather here and I get the time I will def run some tests, but I think both the Mahle and Volabike extenders may well be simple batteries with the addition of a Schottky or Ideal diode used for protection. Pretty cynical stuff if so, and an opportunity for a small-scale manufacturer to steal the market, like Volabike should have done, if they hadn’t been greedy.
The two sets of wires is puzzling! it does beg the question as to why a potential parallel system was abandoned..

Appreciate all you've done so far and still considering whether to follow your footsteps or buy an ali express battery like the volabike. Agreed, Volabike are seriously gouging with those, I can't understand why anyone would buy them when the official one isn't a huge amount more.

Another test that occurred to me could be to get your bike down to say 25% or so and then connect your range extender. Leave it connected for 15 minutes perhaps, and see what the SOC is.

Then repeat drain the bike battery back down to 25% or so and the experiment with the mains charger, if the battery has put more juice in then we know it's been supplying more than 2 amps.

No idea how much time or inclination you have for this, I realise you're quite happy yours works! I may end up just buying the Ali express one and seeing what happens... presumably they are set up to resist charge coming into them.
 

AntonioAlfaro

Pedelecer
Mar 21, 2022
46
9
Many thanks for this detailed post. I think my query pivots on is it the extender that is limiting its discharge, or the port, via the BMS or other mechanism, limiting the charge current. It could be either, and the manufacturers would still be technically correct I believe.

Considering also that the charger only outputs 2amps (42v) as well. Nothing in the official system exceeds this...

If there was a higher amperage source available, would the system draw it? I recall one poster on Ebike review mentioning a message about over current on his app, so perhaps? This is just one data point though.




The two sets of wires is puzzling! it does beg the question as to why a potential parallel system was abandoned..

Appreciate all you've done so far and still considering whether to follow your footsteps or buy an ali express battery like the volabike. Agreed, Volabike are seriously gouging with those, I can't understand why anyone would buy them when the official one isn't a huge amount more.

Another test that occurred to me could be to get your bike down to say 25% or so and then connect your range extender. Leave it connected for 15 minutes perhaps, and see what the SOC is.

Then repeat drain the bike battery back down to 25% or so and the experiment with the mains charger, if the battery has put more juice in then we know it's been supplying more than 2 amps.

No idea how much time or inclination you have for this, I realise you're quite happy yours works! I may end up just buying the Ali express one and seeing what happens... presumably they are set up to resist charge coming into them.
If there was a higher amperage source available, would the system draw it? To answer this just take into consideration that a LiPo cell has a maximum charge capacity ( aprox 3,3 amp/h), so 1C=3,3 Amps/h. The cell could be discharged at a highier rate (more than 1C). But in order to prevent cell destruction, explosion and fire, it should be charged at a rate less than 1C. See cell
specifications attached.

espec
 

Attachments

AntonioAlfaro

Pedelecer
Mar 21, 2022
46
9
Many thanks for this detailed post. I think my query pivots on is it the extender that is limiting its discharge, or the port, via the BMS or other mechanism, limiting the charge current. It could be either, and the manufacturers would still be technically correct I believe.

Considering also that the charger only outputs 2amps (42v) as well. Nothing in the official system exceeds this...

If there was a higher amperage source available, would the system draw it? I recall one poster on Ebike review mentioning a message about over current on his app, so perhaps? This is just one data point though.




The two sets of wires is puzzling! it does beg the question as to why a potential parallel system was abandoned..

Appreciate all you've done so far and still considering whether to follow your footsteps or buy an ali express battery like the volabike. Agreed, Volabike are seriously gouging with those, I can't understand why anyone would buy them when the official one isn't a huge amount more.

Another test that occurred to me could be to get your bike down to say 25% or so and then connect your range extender. Leave it connected for 15 minutes perhaps, and see what the SOC is.

Then repeat drain the bike battery back down to 25% or so and the experiment with the mains charger, if the battery has put more juice in then we know it's been supplying more than 2 amps.

No idea how much time or inclination you have for this, I realise you're quite happy yours works! I may end up just buying the Ali express one and seeing what happens... presumably they are set up to resist charge coming into them.
Another test that occurred to me could be to get your bike down to say 25% or so and then connect your range extender. Leave it connected for 15 minutes perhaps, and see what the SOC is.
I do not recommend to do that with a DIY extender.