24V battery on Panasonic 26V

traceour

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Jul 23, 2024
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Hey!

Just got an Helkama Cargo Bike, not sure the model..
Asuming its 26V. Panasonic motor.
The OEM battery are a fortune and I wonder how the bike will run on 24V?
Could it work? If so, I build my own battery and 3D print a new case
 

thelarkbox

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Aug 23, 2023
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36v motor controllers generally cut off power due to low voltage when a battery drops below 29-31v, (mine is 31v but others ??) iirc a 24v battery fully charged is 29v.. so while a 24v battery fully charged may start a 36v motor system on the bench it wont have any juice to move you any distance before the battery protection kicks in.
 

saneagle

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Oct 10, 2010
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Hey!

Just got an Helkama Cargo Bike, not sure the model..
Asuming its 26V. Panasonic motor.
The OEM battery are a fortune and I wonder how the bike will run on 24V?
Could it work? If so, I build my own battery and 3D print a new case
IIRC, the Panasonic crank-motor won't run with an ordinary battery. It has to be the Panasonic one. Try german Ebay. There's usually a few large capacity ones there. Search for "Panasonic akku"
 

Nealh

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36v motor controllers generally cut off power due to low voltage when a battery drops below 29-31v, (mine is 31v but others ??) iirc a 24v battery fully charged is 29v.. so while a 24v battery fully charged may start a 36v motor system on the bench it wont have any juice to move you any distance before the battery protection kicks in.
The Op doesn't have 36v , it is the panasonic 26v battery.
 

traceour

Finding my (electric) wheels
Jul 23, 2024
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IIRC, the Panasonic crank-motor won't run with an ordinary battery. It has to be the Panasonic one. Try german Ebay. There's usually a few large capacity ones there. Search for "Panasonic akku"
IIRC, the Panasonic crank-motor won't run with an ordinary battery. It has to be the Panasonic one. Try german Ebay. There's usually a few large capacity ones there. Search for "Panasonic akku"
Hm, sure? Only 3pins on my bike, but if I bypass that, my question is how the bike will behave on 24V?20240724_094159.jpg
 
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Nealh

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Both 26v or 24v will work, the 26v rating was simply down to the battery chemistry used such as nicad/nimh. In fact using 24v lithium one should perform more sprightly and last longer.
 
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flecc

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Oct 25, 2006
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Hm, sure? Only 3pins on my bike, but if I bypass that, my question is how the bike will behave on 24V?
No, it not 3 pins it is a 5 pin system, different pins used for drive or charging. You have to use a correct Panasonic battery and charger only. See this web page and scroll down for pin information:

.
 

traceour

Finding my (electric) wheels
Jul 23, 2024
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In the case of lithium-ion batteries, 24v is 26v. It's just a preference for what people call them. They're both 7S, which charge to 29.4v and run down to 21v.
Thanks for that, will give it a go then
 

traceour

Finding my (electric) wheels
Jul 23, 2024
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No, it not 3 pins it is a 5 pin system, different pins used for drive or charging. You have to use a correct Panasonic battery and charger only. See this web page and scroll down for pin information:

.
Okey, thanks for the link, will give it a read
 

saneagle

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Okey, thanks for the link, will give it a read
You need to look at the battery connector on the bike. If it has only two wires connected to it, you can use any 24v battery. If it has three wires, you need to investigate the function of the third wire, then either provide it or spoof it.
 

flecc

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Oct 25, 2006
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You need to look at the battery connector on the bike. If it has only two wires connected to it, you can use any 24v battery. If it has three wires, you need to investigate the function of the third wire, then either provide it or spoof it.
It has to have three connections to operate the motor and four connections between charger and battery with this motor and battery system.

basecharger.jpg
 

saneagle

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It has to have three connections to operate the motor and four connections between charger and battery with this motor and battery system.

View attachment 58947
What's the function of the third wire?

AFAICS in your pictures, the battery connector has two wires-red and white. Is that a very old one with NiHM battery?

This one seems to show 4 wires:

This shows comms with 4 wires:

This shows three wires:
 
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flecc

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AFAICS in your pictures, the battery connector has two wires-red and white. Is that a very old one with NiHM battery?
Yes.

Here's the loom for these lithium battery motors showing the three battery connections lower left: Link

People across Europe have been trying for years to run these with other batteries, seemingly without success. When Kalkhoff wanted to run them with larger capacity batteries that Panasonic provided, they employed German battery maker BMZ who faithfully followed the Panasonic system in every detail.
.
 

saneagle

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There's something about how to do it here. There's a link to a French forum, where there are more details. On ES, the guy said that he by-passed the BMS and it worked, but on that French forum, the it looks like the BMS was used.
 

flecc

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Oct 25, 2006
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There's something about how to do it here. There's a link to a French forum, where there are more details. On ES, the guy said that he by-passed the BMS and it worked, but on that French forum, the it looks like the BMS was used.
They of course had their units to play with, something I never had with the lithium system. A further difficulty is that these had different versions according to the bike maker's requirements. That thread starts with a BH bike with the lower power system and 8Ah battery originally created by Panasonic for Dutch maker Gazelle, and these motor versions had internal differences.

When my French contact who had access to some units expired through heart attacks, my source of information on those differences went with him.

And since Panasonic soon changed to 36 volts and European bike makers dropped them anyway, there was little point in pursuing this.
.
 

Nealh

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Traceour's pic only shows three pins , I would unscrew the top and investigate if all three are wired and or what the third may connect to or do if connected.
If indeed only two wires are connected then a generic 24v battery can be used or even have the original recelled into the old case.
 

saneagle

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Cheers i thought it was a typo,, doh!!
Easy mistake if you haven't been involved with ebikes since the dark ages, like we have. Why did they call it 26v, when everyone else calls it 24v? It's not as bad as when KTM called their bike 47v, when it had a 13S battery. I think that was a trick because EN15194 says "up to 48v" and they wanted to make sure that it was definitely below, even though it charged to 54.6v.
 

SHA222

Finding my (electric) wheels
Jul 13, 2022
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If you are using a 26v panasonic battery on an old 24v panasonic motor it will still work. I recently tried that and all works OK. Old NiMH batteries were designated as 24v.
The red wire is positive 26v and it is protected by a fuse or a resettable safety cut out within the battery. The middle wire is also positive 26v but not protected by the fuse. I think it simply provides a low current to displays etc. The black wire is the negative terminal.
If your old panasonic motor has only 2 wires then it is important to connect the positive wire to the red fused supply because there is no protection fuse within the panasonic motor. If the safety cut out operates you have to open the battery case to reset it.