New 52v battery with an existing 48V battery

razz

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Hi,

I'm looking for a second 52v battery. Have an existing 48v-14aH battery on my radmini4, and looking best way to either run them in parallel or separately. Any idea why a similar battery is prices differently from each company? Do you get what you pay for with batteries? The Electro Bike battery are $170 dollars more expensive, is it worth it?

Electro Bike World 52v 17Ah Fat Shark Battery $739.99 "uses AODA cells"
EUNORAU 52V17AH Down Tube Ebike Battery For Conversion Kit $569.00 USD "All the battery from EUNORAU with original SANYO,LG,SAMSUNG cells"

Anyone using a EUNORAU Dual Battery Hardware Converter or similar like the datex2? I've emailed Electro Bike World, and they said they don't recommend using this device as it degrades the batteries quicker. Recommends using one battery at a time instead. Can anyone comment?

Cheers,
Martin
 
D

Deleted member 4845

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You CAN NOT and MUST NOT parallel two batteries of different configurations and fully charged voltages.

Do you get what you pay for? Sometimes yes, sometimes NO. You are looking for an HONEST, used car salesman. Do you know that counterfeit, brand-name cell wrappers are widely available in China, and their use has been documented many, many times?

Two, IDENTICAL, SAME AGE, SAME USAGE, batteries, if paralleled, and kept that way, with Compatible BMS, Charged together, IF ALL THOSE REQUIREMENTS are met, will last longer than the same two batteries used seperately. If NOT identical, OR not same age, OR not same usage, OR not kept paralleled, OR not compatible BMS, OR not charged together, THEN they will NOT last as long and in fact have very good odds of spectacular failure and total loss due to fire.
 

razz

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Thanks for the info. So I'll side on the side of caution for now and not parallel the different spec batteries together unless they are the same specs and not 48v and 52v.

It's just from the website selling datex2 it is claimed different spec batteries can be joined in parallel.

As for parallel connections using the same 52v batteries, what do you mean charged together? Does that mean charging each battery with a separate charger the same amount of times. I.e. equal wear on the batteries?

For parralll setup. It's just a bit confusing cause how do you know the voltage on each of the identical batteries? Won't they always be a little different, discharge a little different, hold charge different, etc.
 
D

Deleted member 4845

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You are kinda getting close to the nature of the problem.

When you parallel two batteries, they will BECOME at the same voltage, very quickly. Whatever amount of juice necessary to equalize that voltage will pass thru the connecting cables, and into the cells, in a very short time. Seconds. If the difference is at all significant, spectacular damage can result.

Funky things can happen with two seperate BMS. Failure modes are no longer safe.

Just a note here. Examine commercial, consumer-grade power tools, made by companies with engineers and liability lawyers, with hi-quality batteries and wiring and electronics. Try and find one where the end-user can connect two batteries in parallel. Let me know if you do.
 

CrossRoads

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Apr 28, 2022
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Also consider that if you're extending your range with a two battery setup, swapping the controller leads from one battery to the other takes less than 10 seconds. Then ask yourself if saving that 10 seconds is worth the various risks that nelson37 mentioned.

In addition, it's a nice mile marker sort of thing to have one battery loose voltage and start to slow, at which point you stop and swap the terminals, and take mental note that you are now past the half-way point of your ride so might want to consider heading home.
 
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