Lithium-ion battery pack

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SteveS
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Lithium-ion battery pack

Post by SteveS » Sun Sep 01, 2019 8:03 am

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I’ve been looking at sourcing a battery for my current project. I’m limited on space so have been considering going the lithium route. Most of the ready-made 12v lithium batteries still seem very expensive so thought about making up my own battery pack.
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Requirement 12v, 12AH, small as possible
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I’ve looked at 18650 Lithium-ion Batteries (3.7v) which measure 18mm diameter by 65mm, just a bit bigger than a standard AA (MN1500) battery.
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If I go for the 2.5AH battery and configure 3S5P (3 in series, 5 in parallel) I should get 11.1v at 12.5AH
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Or
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3.0AH, 3S4P, I should get 11.1v at 12AH:
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https://www.ebay.co.uk/itm/18650-Li-ion ... 1685340077
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18650 3000mAH.JPG
Battery pack
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This would measure approx.:
  • 70mm tall 2.3/4”
  • 80mm long 3.1/4”
  • 63mm wide 2.1/2”
I would need to include a BMS (Battery Management system) as below:
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https://www.ebay.co.uk/itm/3S-12V-25A-1 ... 2543772966
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BMS.JPG
BMS
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Li-ion batteries also have specific charging requirements so I would require a new battery charger, something like below, which also charges conventional batteries:
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https://www.ebay.co.uk/itm/Optimate1-DU ... 2382259330
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Optimate 1.JPG
Battery Charger
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Based on the above I reckon I can make up a battery pack for less than £40 (plus the battery charger which I need anyway).
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Anyone got any thoughts on this?
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Looking at previous threads I believe the B50 standard charging system would be ok with the Li-ion battery pack?
Steve Sewell

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Re: Lithium-ion battery pack

Post by skippy » Sun Sep 01, 2019 11:49 pm

Look at the specs of the BMS as it should control the charging of the batteries. The lithium battery I have just says to use a charger of 14.4V the BMS does the rest.
Doug
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Re: Lithium-ion battery pack

Post by beat » Mon Sep 02, 2019 8:00 pm

SteveS wrote:
Sun Sep 01, 2019 8:03 am
I believe the B50 standard charging system would be ok with the Li-ion battery pack?
mine dos work well with LI-ion from Shido.
Batteri charger with max 15 V required....

beat :ok

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Re: Lithium-ion battery pack

Post by Jack Gifford » Tue Sep 03, 2019 5:13 am

I'm amazed how inexpensive miniature electronics are. A BMS for $5? Wow!
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Re: Lithium-ion battery pack

Post by koncretekid » Tue Sep 03, 2019 11:54 am

Interesting, but what would be the best combination to run a "total loss" system with Boyer or similar ignition? Is 11.1 volts sufficient or would 14.8 be better and would 14.8 volts harm any of the components?

I also note that the charger is only rated to charge up to 13.2 volts, so would it just charge up a 4 pack of Lithium batteries (14.8 volts) to 13.2 volts?
Tom
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Re: Lithium-ion battery pack

Post by Jeff K » Tue Sep 03, 2019 1:46 pm

We tried going with the LI-ON battery on the last Norton Project. After sending the 2nd one back and several lengthy conversations with the company. We found out that they require a special charging/regulating set up and the neither the stock Lucas or the Podronics were a good fit for this. For a total loss setup, just remember that once they get close to the end of their charge, the voltage drops off fast. Not like a lead acid of gel cell where you get a weak spark/misfire to warn you.
Jeff

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Re: Lithium-ion battery pack

Post by Jeff K » Tue Sep 03, 2019 1:51 pm

koncretekid wrote:
Tue Sep 03, 2019 11:54 am
Interesting, but what would be the best combination to run a "total loss" system with Boyer or similar ignition? Is 11.1 volts sufficient or would 14.8 be better and would 14.8 volts harm any of the components?

I also note that the charger is only rated to charge up to 13.2 volts, so would it just charge up a 4 pack of Lithium batteries (14.8 volts) to 13.2 volts?
Tom
Tom
Most of the EI units have serious problems once the voltage drops. That is why Fred at Old Brits only uses the Power Arc units. The Power Arc is the only one that I am aware of that will still function at 6v. And a Norton MKIII can really pull the voltage down when using the electric starter. Low voltage on most units will cause them to go to full advance and the resulting kick back is known to break the expensive Norton starter clutch sprague.
Jeff

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