I need a battery expert

jbell · Aug 2, 2021

I need to sort a battery pack for a side project and I am having trouble finding anything that meets this spec: 18.5v li-ion 4300mah
In addition to that I don’t know the difference between a high quality battery pack and one that is made in a child labor camp in China that will burn my house down.

thank you in advance

JBoomhauer · Aug 2, 2021

Not a battery expert,
It looks like you will need a 5s battery pack. It will most likely be made with 18650s. The mah will likely be much higher than what you are looking for. Not sure if anyone is making 5s 14500 packs, that would be more compact and closer to what you want.

I try to use battery’s made by companies like Sony, Panasonic, LG and such. I avoid anything with “fire” in the name.

Is Size or external dimensions important?

Hopefully someone more knowledgeable can swing by and help more.

pmclaine · Aug 2, 2021

Those analog Starrett calipers require no batteries.....

I think there are "stores" on Amazon that carry just about any battery you can think of but your second concern will come into play.

Duc · Aug 2, 2021

I've used this company with good results....

The Place to Buy Batteries Online

BatteryJunction.com is the place to buy batteries online. Our diverse inventory, affordable prices, and fresh products will satisfy your powering needs.

www.batteryjunction.com

jbell · Aug 2, 2021

Thanks guys

Nik H · Aug 2, 2021

You're not going to likely find this on the shelf anywhere. You may have to get the constituent elements and build it yourself.

Your chosen capacity is going to push you to 21700 cells. You can't get over 3,700 with 18650 reliably. The 21700 is better suited to producing > 4,000 mAh. This would allow you to use a single parallel string versus a 2P string like you would with 18650 cells. You did not mention an application either so it is difficult to really recommend anything as the discharge rate has to be taken into account when picking a cell.

All cells are made in Korea or China. Even LG is moving its operations to China now as it is easier to manufacture batteries there. Regarding the "burning down my house comment". That has to do with the BMS and not the cell. Even the best cells made today (think LG) will explode if not used properly. I am not sure if you can buy a rudimentary BMS that monitors the cells during operation.

If I were you, I would select a voltage that is available off the shelf and buy an integrated pack with BMS so you don't burn down your house.

Lithium cells are quite unforgiving if treated badly

pmclaine · Aug 2, 2021

Nik H said:
You're not going to likely find this on the shelf anywhere. You may have to get the constituent elements and build it yourself.

Your chosen capacity is going to push you to 21700 cells. You can't get over 3,700 with 18650 reliably. The 21700 is better suited to producing > 4,000 mAh. This would allow you to use a single parallel string versus a 2P string like you would with 18650 cells. You did not mention an application either so it is difficult to really recommend anything as the discharge rate has to be taken into account when picking a cell.

All cells are made in Korea or China. Even LG is moving its operations to China now as it is easier to manufacture batteries there. Regarding the "burning down my house comment". That has to do with the BMS and not the cell. Even the best cells made today (think LG) will explode if not used properly. I am not sure if you can buy a rudimentary BMS that monitors the cells during operation.

If I were you, I would select a voltage that is available off the shelf and buy an integrated pack with BMS so you don't burn down your house.

Lithium cells are quite unforgiving if treated badly

elwarpo · Aug 2, 2021

Instread of liion, look for life. Slightly lower power density so the pack will be a bit bigger, but life batteries do not catch fire like liion. They also take 2 to 4 times the charge cycles instead of Liion. They tend to be the go to battery type for high end battery backup. You will need a life charger instesd of a liion charger (some do both). Liion have a nominal charge of 3.6v while life is 3.3v. Life also known as LiFePo4 of LFI. they will cost more. Here is one place https://www.batteryspace.com/

Nik H · Aug 2, 2021

elwarpo said:
Instread of liion, look for life. Slightly lower power density so the pack will be a bit bigger, but life batteries do not catch fire like liion. They also take 2 to 4 times the charge cycles instead of Liion. They tend to be the go to battery type for high end battery backup. You will need a life charger instesd of a liion charger (some do both). Liion have a nominal charge of 3.6v while life is 3.3v. Life also known as LiFePo4 of LFI. they will cost more. Here is one place https://www.batteryspace.com/

Lithium Iron Phosphate uses a cathode made with lron phosphate versus manganese oxide or cobalt materials. Anodes both use graphite. The different cathode chemistry is what limits it energy density.

You are right about the longer life span. The LiFePO4 batteries can be cycled a lot more and they also have a higher discharge capability which can be an advantage if your application warrants it. Downside is they are larger, heavier and not as portable. They are also cheaper. A LMO or lithium cobalt battery with the same capacity as a LiFePO4 will cost more not less because the newer chemistries offer higher energy density and smaller overall volume which drives cost up not down

LiFePO4 also is supposedly a safer chemistry as well but not really. They are more stable under high temperature but all Li batteries require safe handling.

The OP still needs to find a complete pack with a BMS to avoid issues in a household environment

Nik H · Aug 2, 2021

pmclaine said:

LOL

I will keep my posts to single syllables to help you understand

Douglas-001 · Aug 2, 2021

"Check out the big brain on Brad..."

I thought the same thing as I read that post...funny as fuck!

huntingthem · Aug 2, 2021

They may be able to build what you're looking for..

SMC Racing

www.smc-racing.com

jbell · Aug 2, 2021

Right on guys, thanks for the info (great info!). This is for a LED light system that I use during my mountain bike racing, so weight and size is important. My current battery is still good but I know it only has a specific amount of cycles to it's life span. The company who built this system is no longer in business so I'm wanting to get another battery before this one goes tits up.

I do ride all night so a long life is important, I have a 24 hour race this weekend (which is what got me thinking about this project).

gnochi · Aug 2, 2021

jbell said:
My current battery is still good but I know it only has a specific amount of cycles to it's life span

The Company *warrantied* a specific number of cycles before it degrades too much to deliver acceptable performance. It’ll still *work* for more cycles than that.

My main area of professional expertise is batteries. Everything @Nik H says (in this thread, at least

) is correct. Just get an off the shelf pack of the same voltage that includes the battery management system; it’s a giant hassle to make a battery pack that’s not likely to catch fire when you charge it.

Ridgeback80 · Aug 2, 2021

Not a battery expert by any means just sharing a link for batteries! I've been buying all my batteries and chargers here for 2+ years, there shipping is super fast and have excellent customer service! I am in no way affiliated with them just a satisfied customer. Good luck with your project! https://www.18650batterystore.com/

buffalowinter · Aug 2, 2021

NikH beat me to it, oh well

elwarpo · Aug 2, 2021

You may want to look into racing car batteries, they have a hard case to take abuse and decent output. Here is an example, i have not used these. http://www.valuehobby.com/review/product/list/id/2932/category/134/

BikePilot · Aug 2, 2021

A 5s1p pack of Samsung 40T 21700 cells would be quite close and fairly light. There are places that will weld them up with your choice of bms. I had a pack bade by bicycle motor works and it’s done great. The pack I had made used the same cells but was much bigger as it powers an electric trials bike. These 40T cells have held up well to hard use, extreme temperatures, and numerous charge cycles.

You may be able to do a tad lighter with lipos, but they are also a bit more sensitive and harder to custom build with bms.

One option would be to deconstruct your pack and perhaps replace the cells, keeping the bms and everything else

gnochi · Aug 2, 2021

I prefer the Molicel P42A to the 40T; it has much better high-rate cycle life. But yeah, options. Don't just stick 5 batteries in something and hope it doesn't blow up in your face.

Ape_Factory · Aug 2, 2021

Might want to check out https://antigravitybatteries.com and if there's anything there that would work for you, like the small case/race batteries, reach out to me as I'm a dealer and can get you great pricing. Normally I wouldn't post this here but it's so far outside the realm of being a firearms-related dealer I thought it'd be ok. Just trying to help a fellow hide member out.

Clayman · Aug 3, 2021

jbell said:
I need to sort a battery pack for a side project and I am having trouble finding anything that meets this spec: 18.5v li-ion 4300mah
In addition to that I don’t know the difference between a high quality battery pack and one that is made in a child labor camp in China that will burn my house down.

thank you in advance

Would 18.5 5000mah work?

https://rcbattery.com/liperior-5000...MIu4PHwICU8gIVW25vBB3xBAzzEAQYASABEgLaifD_BwE

You can look into other drone, rc, etc type packs and see what fits your needs.

x2cross · Aug 3, 2021

Ok, I'm a lil bit of a lighting nut, so here it goes.........

Are you trying to replace existing 18650 sized cells in an existing battery pack, or rig up a secondary replacement pack? If adding an external pack to your light, my idea is wire up a mounting plate & use Dewalt 20V cordless batteries. Easy to carry a spare and swap em.

The best route would be to replace the internal cells with high quality LG cells. You should be able to keep the existing protection circuits in the light(if any)

x2cross · Aug 3, 2021

jbell said:
Right on guys, thanks for the info (great info!). This is for a LED light system that I use during my mountain bike racing, so weight and size is important. My current battery is still good but I know it only has a specific amount of cycles to it's life span. The company who built this system is no longer in business so I'm wanting to get another battery before this one goes tits up.

I do ride all night so a long life is important, I have a 24 hour race this weekend (which is what got me thinking about this project).

Any links available for the light and/or battery pack? It's hard to know what to recommend without seeing it

jbell · Aug 3, 2021

That is a lot of great info guys. I am trying to make a 2nd battery pack for my light as a spare for the day my original dies and in case I forget to charge a battery pack / have a multi day ride or event. I need to keep the battery pack as small and light as possible as I carry it in my jersey pocket which also makes me want to keep it somewhat soft sided (no hard plastic corners). I will post up a picture o my current one (although it is wrapped up in shrink wrap) and the charger.
I found the owner of the company who originally made these systems and sent him an email which is where I got the specs. I have since asked him a few follow up questions but I have not heard back from him so I thought I would reach out here. Here is the replay he sent me:

“Battery packs are 18.5v li-ion 4300mah you can pick up from multiple places. Smaller cells are possible for a smaller pack, but you have to maintain the voltage to work with the safety programing. Unfortunately unless you are local to the DFW area shipping batteries on an individual basis is a real pain so probably not feasible.

You can buy the connectors from Switchcraft

Funny enough they started making these after I ordered a ton of custom ones

Switchcraft : Product Summary

Those are the two pieces that normally would fail/degrade so should keep you running for a long time.”

Here is a review of the system I have (not that it is going to be much help):

Review: Trail Led XXX 1800 Lumen Helmet Light

Trail Led is a bike light company similar to the great handmade bike builders like Moots and Vanilla Cycles. It is run by craftsman Grady Pace who is meticulous about his work and craftsmanship. These lights are machined from billet aluminum and then assembled in Dallas TX. All components...

www.mtbr.com

jbell · Aug 3, 2021

Here is the best pack and charger

Thanks again for all y'all's help!

x2cross · Aug 3, 2021

@jbell here's what I would do:
Get 5 of these https://www.batteryjunction.com/samsung-30q-18650-3000-flat.html
and one of these https://www.amazon.com/18-5V-Lithium-Li-ion-Battery-Protection/dp/B07JRF9J3W
And wrap the final product in shrinkwrap
That'll give you 18.5 volts with 3000 actual mAh worth of runtime.

If its just 18650 cells inside that wrapping, it's not likely a true 4200mAh. There's a ton of inflated capacity numbers out there. It is possible that the builder used a larger size cell. These: https://www.batteryjunction.com/sanyo-ncr20700b.html will give you a slightly thicker package, but will get you to your 4200mAh

jbell · Aug 3, 2021

x2cross said:
@jbell here's what I would do:
Get 5 of these https://www.batteryjunction.com/samsung-30q-18650-3000-flat.html
and one of these https://www.amazon.com/18-5V-Lithium-Li-ion-Battery-Protection/dp/B07JRF9J3W
And wrap the final product in shrinkwrap
That'll give you 18.5 volts with 3000 actual mAh worth of runtime.

If its just 18650 cells inside that wrapping, it's not likely a true 4200mAh. There's a ton of inflated capacity numbers out there. It is possible that the builder used a larger size cell. These: https://www.batteryjunction.com/sanyo-ncr20700b.html will give you a slightly thicker package, but will get you to your 4200mAh

Very cool, I'll give it a shot

missed · Aug 3, 2021

Looks like a bunch is already covered.

I bet that is wrapped 18650's also.

As weight is a concern I would move to LIPO, you would most likely need a DC-DC converter to step the voltage down. But if the light manufacturer allows a higher input voltage you could grab about any 6S battery, as a 5S battery is kinda an oddball

Like

https://www.smc-racing.com/index.php?route=product/category&path=67_119

Which I have some of there graphene 2S and 4S batteries for the RC cars.

We charge with a DC to DC charger the Icharger X6 with a 24V DC power supply (old laptop power supply) Which is nice as you could charge off the 12V DC truck power if need be.

iCharger X6

High powered full featured charger in a tiny package

www.progressiverc.com

There are other simpler chargers that are less expensive also. With all LI-PO's you must balance charge.

We do also charge these batteries in a charge envelope to protect in case if a cell failure during charge. I have not personally had a cell failure but know of it occurring.

Wow, I have not seen any of Grady's lights in a long time. I have a bunch of the Outbound lights now. I had built a bunch of lights in the past, just time made me just buy lights last time I needed them. I was getting into building lights about 10 years ago, the proper optics is the roadblock I always had. The LED, power management, and housing design and manufacturing I had covered. Optics was the killer.

jbell · Aug 3, 2021

Damn I need to learn more about this stuff...

GlockandRoll · Aug 4, 2021

25 years of engineering, reading RFPs, and it still gets me every time.
We aren't going to initially tell you what we are going to do.
And we are asking for the wrong thing to make sure we won't be able to do it.

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