Parallel batteries (again!)

[Yak]

I think I have read every post in every forum about running a second battery in parallel, and I’ve asked a few questions on here too, but I’m about to order parts and I don’t want to get it wrong, so cold someone check over my plans for me?

I was bought a second- hand Orbea Gain. (Yeah, I’m a very lucky boy). It has a 6.9ah internal battery with an integrated controller. Several others have hooked up their various external batteries through the proprietary charging port by cutting off the lead from their chargers (as the port is very non-standard) and connecting it to their external battery outlets with xt60’s. Blocking diodes/Schottky diodes have been Integrated into the lead by some, simple fuses by others, but these:

‘Ideal’ 50a mosfet diodes, seem to offer easier wiring, lower consumption and less heat production, meaning at low amps no heat sink is necessary. What I don’t know is if these wire directly into the cathode lead from the battery? I’m only able to use one as the internal battery is integrated with the controller…
My plan is to buy one of these:

and stick it in a larger saddle bag (along with the diode, sealed inside a suitable plastic box) as I want to keep both bottle cages available for drinks that I will need if I go on a 2 battery ride. The battery cable - from the charging port up to the xt60 from the external battery - I was going to leave connected at the charging port so I could tidy the cable away with zip ties, unplugging the xt60 when charging the external battery, but using the lead to the bikes charging port and internal battery to connect to the Orbea’s charger which will have an xt60 on it as I’d have cut off the original. Both batteries will be checked after charging separately for very similar voltages before connection ( despite the ideal diode) as that has been stressed many times on here as best practice.
It seems that I should power up the external battery first, which turns on the bike’s system. Apparently there should be no handshaking problems with the canbus.
If this works, I may later try to connect to the cabling beneath the charging port and run the cable internally up the seat tube and out of the top of the seat post for anal levels of neatness, as I expect to use the extra battery every ride to hopefully prolong the life of the very expensive internal battery.
All these bits, including the battery and seat bag, only cost €55 on AliExpress…it has to be worth a punt cos there’s no way I’m paying €560 for a ‘proper’ range extender.
Am I missing anything (other that how to wire that diode/mosfet pcb)? Just in-line on the + from the external battery?Do I need to ground it? Is it better as close as possible to the battery?
As ever, thanks in advance for your time and if more pics are needed please say.

 

[matthewslack]

You must have TWO ideal diodes, otherwise the higher voltage battery will always backfired into the lower, and if voltage difference is significant this may be expensive.

I don't have time to elaborate just now. I'm going down a similar route.

 

[Nealh]

Simply connecting the second battery to the first via the charging point/connection is not paralleling the batteries, all one is going to do in the least is charge the first up via the second till the second then becomes spent or hits lvc if a BMS is fitted.

If one inadvertently ends up with a 72v battery by wrongly wiring in series, the Orbea BMS will blow.

To parallel one has to connect the discharge side of both batteries together with a Y lead with parallel wiring and then the tail of the Y branch direct to the controller input v+/- wiring. One then ideally if wanting to prevent a discharge flow between batteries fit a schotky to each battery or on each branch of the Y lead.

 

[matthewslack]

I think I have read every post in every forum about running a second battery in parallel, and I’ve asked a few questions on here too, but I’m about to order parts and I don’t want to get it wrong, so cold someone check over my plans for me?

I was bought a second- hand Orbea Gain. (Yeah, I’m a very lucky boy). It has a 6.9ah internal battery with an integrated controller. Several others have hooked up their various external batteries through the proprietary charging port by cutting off the lead from their chargers (as the port is very non-standard) and connecting it to their external battery outlets with xt60’s. Blocking diodes/Schottky diodes have been Integrated into the lead by some, simple fuses by others, but these:
View attachment 45291
‘Ideal’ 50a mosfet diodes, seem to offer easier wiring, lower consumption and less heat production, meaning at low amps no heat sink is necessary. What I don’t know is if these wire directly into the cathode lead from the battery? I’m only able to use one as the internal battery is integrated with the controller…
My plan is to buy one of these:
View attachment 45292
and stick it in a larger saddle bag (along with the diode, sealed inside a suitable plastic box) as I want to keep both bottle cages available for drinks that I will need if I go on a 2 battery ride. The battery cable - from the charging port up to the xt60 from the external battery - I was going to leave connected at the charging port so I could tidy the cable away with zip ties, unplugging the xt60 when charging the external battery, but using the lead to the bikes charging port and internal battery to connect to the Orbea’s charger which will have an xt60 on it as I’d have cut off the original. Both batteries will be checked after charging separately for very similar voltages before connection ( despite the ideal diode) as that has been stressed many times on here as best practice.
It seems that I should power up the external battery first, which turns on the bike’s system. Apparently there should be no handshaking problems with the canbus.
If this works, I may later try to connect to the cabling beneath the charging port and run the cable internally up the seat tube and out of the top of the seat post for anal levels of neatness, as I expect to use the extra battery every ride to hopefully prolong the life of the very expensive internal battery.
All these bits, including the battery and seat bag, only cost €55 on AliExpress…it has to be worth a punt cos there’s no way I’m paying €560 for a ‘proper’ range extender.
Am I missing anything (other that how to wire that diode/mosfet pcb)? Just in-line on the + from the external battery?Do I need to ground it? Is it better as close as possible to the battery?
As ever, thanks in advance for your time and if more pics are needed please say.

I don't know your bike specifically so I am speaking in a general sense.

I have the use of a Shimano equipped bike which I do not own, so I cannot modify the 'fixed' wiring, because it is not mine! So I have a test rig which is a rack mount battery connected by extension cables to the downtube battery socket. This gives me access to the cable between battery and motor, so I can put an ideal diode in there, and link a second battery via a second ideal diode to the same wiring.

That way no current ever flows between the batteries, the highest voltage battery does all the work until voltages equalise, then they will share.

If the second battery is full and the first quite low, then the first may not get used at all.

In my setup, the rack mount battery has to be a proper Shimano, and it has to be turned on first, so the shimano communications are done properly. Then the theory goes that I turn on the second battery and the system is unaware.

The second battery must be turned off to allow the first to be turned off.

To replicate this on your bike you need access to the big fat cable between battery and controller. Otherwise you may not be doing what you hope to be doing!

Using only one ideal diode between the second battery and the rest of the system only protects your cheap second battery. The expensive first one is vulnerable to accidents.

 

[Nealh]

What ever way one looks at it correct and proper paralleling is two or more batteries linked up and both discharging proportionately together.
Bosh have a twin battery set up but is not a parallel set up as it sips power from one battery at a time, I believe switching between them.

Paralleling must be done via the discharge wiring and not the charge wiring.
Charge wiring is usually only 22/24awg and is usually limited to 7/8a.

 

[Nealh]

One will need a schottky or one way diode device in each battery supply feed on the positive line.

 

[Nealh]

This is a pretty good explanation with pics /drawings.
Parallel batteries (again!) | Pedelecs - Electric Bike Community

Done correctly one can use differing chemistries, I have done some with lipo and lion in parallel. The caveat with lipo is I also always have alarms on them and once one sounds I disconnect the parallel connection.

I don't use schottky's or any blocking diodes as I am particular with voltage when paralleling, it all depends on ones regime and thoroughness. Once connected even if the battery ah/wh is very different the voltage will stay pretty much in check during the discharge process.

Even if using blocking diodes it is pointless not charging both correctly to near same voltage +/- 0.025v if riding from home as one battery will either not supply much power or will be out of charge or at lvc before the other.

 

[Yak]

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…

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:

New Range Extender kit for Ebikemotion X35 systems | COMPONENTS FOR ELECTRIC BIKES

With the Range Extender kits for Ebikemotion X35 and X35+ systems you can increase the capability of the e-bike autonomy in 100%, 150% or 200% using the 252Wh, 378Wh or 504Wh models.

www.volabike.com

Argh! Thanks for this information and keeping me safe, btw. It is greatly appreciated.

 

[Nealh]

It might be then that the the BMS is a same port BMS, this means it charges and discharges from one BMS line/port. The discharge and charge wiring separate internally from the same BMS port, if that is the case then one may be able to connect a second battery but I can't see they will be in parallel if one simply plugs another battery in. The parallel connection still needs to occur after the BMS connection.
Each battery will have it's own BMS to deal with the cell balance/charging, one BMS on a battery doesn't monitor or control another batteries discharge or charge.


Generic BMS have a separate charge and discharge line/ports and these can't usually handle more the the 7/8a I mentioned.

 

[Yak]

Double darn! I’m hoping some of the guys who have made their own will see this. Sadly I think many don’t return here once their issue is sorted. I’d love to get my hands on one of Volabike’s batteries to dissect.

 

[Nealh]

So it looks like the internal battery has electronics to deal with adding a propriety range extender but whether the range extender also has extra protection one doesn't know but assumes so.
A third party battery as you have shown I doubt will be the same and certainly not have any electronics to prevent any issue.
One could try and add a third party battery but doubt it will a very safe idea and at minimum would need a diode on the positive line.

 

[Yak]

Maybe I should just get fitter. Or sell the Orbea and go back to my nice customisable Yose. The Orbea is lovely though.

 

[Nealh]

As I originally thought.
Having read the from the official Orbea page, it say's the range extender (when switched on) act's an on bike charger for the internal battery at a charge rate of 2a.

I would not be connecting any third party battery with out modifying the existing wiring between battery discharge port and controller.

Read page 5.
manual_range_extender_EN.pdf (orbea.com)

 

[Nealh]

As mentioned paralleling isn't to be toyed with without good knowledge or the whereabouts to add extra wiring.

The wording is ambiguous and gives the impression that the battery is being paralleled by saying it increases range and battery wh to those who don't truly understand what paralleling is and how to achieve it.

A range extender is just that it gives more riding time either by charging from one to another but no ultimately sipping power equally from the batteries at the same time.

 

[Yak]

Indeed it does, but originally I understand that the bike was designed and built for a 252w external battery, then the spec changed to a 208w charger. It must be how Volabike and the DIYers are getting their batteries to work, perhaps.

 

[Nealh]

Maybe I should just get fitter. Or sell the Orbea and go back to my nice customisable Yose. The Orbea is lovely though.

It is a good job you raised the issue/subject as it is obvious the extender electronics control the discharge/charge to the main battery, a third party battery would not do so.

 

[Yak]

This is a question/ answer to/ from Volabike about their range extender…it really sounds like parallel…

Ebikemotionuser said:
Hi Thomas.

Thanks for.the information.

Some questions:
A: So let's say I start with a full range extender and a 59% charged main battery. So the range extender powers the bike. Does it do so untill it's totally empty and only the the internal battery starts to power the motor?
B: What happens if at the start of a ride, for example the range extender is at 60% and the internal battery at 40%?
C: Will the range extender ever charge the internal battery? If so, in which case?
D: How can we get to know the price of the three range extender models? And how to order?

Thanks

You can use the extender is all these cases. No mater how much charged is any battery.
Battery with more charge will be the battery used until both batteries gets equaled, and then they will work together.
The best way to use our extender is with both batteries fully charged since the beggining, so they will work together all the time. That will distribute the motor load on both batteries and that will make batteries work with less stress and will extend their lifes.

 

[Yak]

this guy was clearly not convinced:

Ebikemotionuser said:
Hello Thomas,
Can you please explain how the range extenders work? Do they:
1) 'only' recharge the internal battery (as is the cas for the original range extender right?)? If so, do you charge it fast enough for it to never get empty as long as there is still juice in the range extender?
2) directly deliver power to the motor. If this is the case, do they deliver this power in parallel to the power from the internal battery and if so, what happens when the internal battery is empty but the range extender, for the bigger models, is not? Can the range extender then power the motor on it's own?) or is the external battery first used and emptied and only then the internal battery.
As you use the same connector as the one used to charge the internal battery, how do you manage to deliver power from your range extender directly to the motor trough this connector?

Thanks a lot!!
...

If you starts riding with both batteries at 100%, Volabike extender works in parallel with the internal battery. Both batteries are working together. There is an electronic for controll this operation in our battery.
We recommend allways use our extender this way, because motor load is shared by both batteries and that helps to extend batteries life.

 

[Nealh]

The Orbea isn't the ebikemotion though and though the same extender might be used the Gain may not have the same electronics on board.
The Gain may just use the extender as just that to charge the main battery where as the ebikemotion may be paralleling in the proper sense.

 

[Nealh]

The only safe option is to use the official extender for the bike.
It is the reason why they can charge a lot of money for the meagre range extenders usually preventing cheaper third party options.