Found on FleaBay: Headway 38120HP

LewTwo

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These have a terrible power power density but they also have the advantage of maximum continuous discharge of 120 amps. They might make a good replacement for 7Ahr SLA in a UPS or EXCELLENT power source for a battery spot welder (30 second discharge = 240 Amps).

https://www.ebay.com/itm/203613239129
*** USED *** four each for US $44.99
Includes terminal hardware but no bus-bars or cell holders.

View attachment HeadWAY38120HP(8Ah) LiFePo4 Specification.pdf
 
That's a familiar seller to many of us.

https://batteryhookup.com/products/used-headway-38120-hp-3-2v-8ah-lifepo4-battery

I have nothing but good experiences to report from my many transactions with them. I haven't bought any Headway cells, but maybe there comes a time for that.
 
BatteryHookup? They're awesome. Buy with confidence. But do you really need that high C rating? 38120s come in a different flavor too. A 10ah variant with a slightly lower C rating.
 
Although I read on a Kweld forum that a Headway 4S-2P will power one user's spot welder, I had no luck with a 4S-1P combo on my cheap spot welder, Not enough power, so still using RC Lipo to run it. I should see if I can start a car with mine.

A better deal on ebay, because I paid about $20-23 shipping for for four $7.99 cells from the Battery Hookup website,
 
docw009 said:
Although I read on a Kweld forum that a Headway 4S-2P will power one user's spot welder, I had no luck with a 4S-1P combo on my cheap spot welder, Not enough power, so still using RC Lipo to run it. I should see if I can start a car with mine.

A better deal on ebay, because I paid about $20-23 shipping for for four $7.99 cells from the Battery Hookup website,
I ordered two sets to be on the safe side :)
I do not have access to car battery. This will be more like a motorcycle battery but with a longer life expectancy (I hope).
Only 16 Amp hours but the equivalent of around 480 cranking amps at 12 Volts (and only 6-7 pounds).
I also have a 120V 650 watt inverter in a closet somewhere so I figure multiple uses :)

EDIT: Pulled it out of the closet: It is only 600 watts :?
 
LewTwo said:
These have a terrible power power density but they also have the advantage of maximum continuous discharge of 120 amps. They might make a good replacement for 7Ahr SLA in a UPS or EXCELLENT power source for a battery spot welder (30 second discharge = 240 Amps).

https://www.ebay.com/itm/203613239129
*** USED *** four each for US $44.99
Includes terminal hardware but no bus-bars or cell holders.

HeadWAY38120HP(8Ah) LiFePo4 Specification.pdf
I bought 8 of these very cells in 2018 on Ebay. Seller was alarmhookup (Check your seller's store....its the same guy). In the end, 3 of 8 cells were unusable (over 25% under rated capacity and very high voltage sag under load). I ended up putting a 3S1P pack together and use it as a spare pack for my E-Kayak motor.
 
pullin-gs said:
LewTwo said:
These have a terrible power power density but they also have the advantage of maximum continuous discharge of 120 amps. They might make a good replacement for 7Ahr SLA in a UPS or EXCELLENT power source for a battery spot welder (30 second discharge = 240 Amps).

https://www.ebay.com/itm/203613239129
*** USED *** four each for US $44.99
Includes terminal hardware but no bus-bars or cell holders.

HeadWAY38120HP(8Ah) LiFePo4 Specification.pdf
I bought 8 of these very cells in 2018 on Ebay. Seller was alarmhookup (Check your seller's store....its the same guy). In the end, 3 of 8 cells were unusable (over 25% under rated capacity and very high voltage sag under load). I ended up putting a 3S1P pack together and use it as a spare pack for my E-Kayak motor.

Jehu has a video on these cells, not sure if he picked used cells or new cells, but those cells sagged a bunch, and my experience with used cells has been hit/miss and in my books not worth it.

you can get NEW prismatic LFEs, 40 ah to 100 ah for cheap.

I bought 100ah LFE from aliexpress (major seller) it came to $168 shipped and they ROCK.
I use for everything, light and power can do 100a plus sustained.
 
Just a heads up, LiFePO4 cells DO NOT play well with gas powered vehicle alternators.

https://www.youtube.com/watch?v=jgoIocPgOug
 
john61ct said:
That's what DCDC chargers are for.

Sterling is my choice

So, DC-DC converter to charge, and diode protection on the discharge side?
 
pullin-gs said:
I bought 8 of these very cells in 2018 on Ebay. Seller was alarmhookup (Check your seller's store....its the same guy). In the end, 3 of 8 cells were unusable (over 25% under rated capacity and very high voltage sag under load). I ended up putting a 3S1P pack together and use it as a spare pack for my E-Kayak motor.
That is disturbing but I have had good fortune with them in the past. I will have to see if my luck holds. emoji_finger_thumb(small).jpg

gobi said:
you can get NEW prismatic LFEs, 40 ah to 100 ah for cheap.
Ultimately I am interested in a LiFePO4 battery for my next E-Bike project. My past experience is that a new LiFePO4 battery can last over 6 years. At this point I plan on using new Headway 40152S (16 Ah) cells for that project. This will give me a bit of experience working with headway cells ... all-be-it a different size/model.

The prismatic cells may have a bit higher energy density but that is because they pack more material into slightly higher volume container. Hard to find them under 20Ah. Thus they tend to be a bit heavier as well.

gobi said:
Jehu has a video on these cells, not sure if he picked used cells or new cells, but those cells sagged a bunch, and my experience with used cells has been hit/miss and in my books not worth it.
H'mmmm .. ... ..
So I chased down the video: https://youtu.be/MdhyOFeOqyE
He got the same 'used' cells from the same vendor.

He first ran four (4S1P) at over a 10C (closer to 12 C) discharge rate for 5 minutes and the cells got up to 135°F (57°C ). He pushed these cells close to their maximum limits and yes he a voltage sag ... that is to be expected.

I do not plan on pushing them anywhere near that hard and also plan on using a 4S2P configuration. Jump starting a car needs about 400-500 Amps for less than 30 seconds. A battery spot welder needs 150 Amps for less than a second. The 600 Watt AC inverter (worst case 80% efficient) has maximum draw of 62.5 Amps (that is a bit less than a 4C discharge rate). My portable 3/8 inch Electric drill draws 4.2 Amps at 115 volts AC (483 watts). My tablet PC draws 1.4 Amps at 115 volts AC (when charging).

My first project for these batteries is to test/document/review a Daly Smart BMS. I find the Chinglish documentation to be sketchy at best. After that I can use the 12 Volt Battery pack for those instances (not often) where/when I need a 12 Volt battery.

Edit:
It is the copper bus-bars that drive the cost up on this project but I figure that they are better than those 0.3mm thick nickle strips 8)
 
LewTwo said:
He first ran four (4S1P) at over a 10C (closer to 12 C) discharge rate for 5 minutes and the cells got up to 135°F (57°C ). He pushed these cells close to their maximum limits and yes he a voltage sag ... that is to be expected.
He'll say and do things that are so wrong sometimes.

It is the copper bus-bars that drive the cost up on this project but I figure that they are better than those 0.3mm thick nickle strips 8)

For my test of the red Headways, I hammered some copper tubing flat, trimmed it, and drilled the necessary holes.
 
Chalo said:
john61ct said:
That's what DCDC chargers are for.

Sterling is my choice

So, DC-DC converter to charge, and diode protection on the discharge side?

Sorry what is the diode preventing?

And a charger is different from a converter.

Check out Sterling BB series manuals are available online.

They include a VSR/ACR and are strictly one-way, if that's what the diode question was about.
 
john61ct said:
Chalo said:
john61ct said:
That's what DCDC chargers are for.

Sterling is my choice

So, DC-DC converter to charge, and diode protection on the discharge side?

Sorry what is the diode preventing?

And a charger is different from a converter.

I thought you were talking about using a DC-DC converter as an intermediary between a vehicular alternator + voltage regulator and a lithium iron phosphate battery used in place of a lead acid battery. In that case, you'd need diode protection for the battery to keep it from being charged uncontrollably through its discharge leads by the vehicle's bus.
 
Chalo said:
I thought you were talking about using a DC-DC converter as an intermediary between a vehicular alternator + voltage regulator and a lithium iron phosphate battery used in place of a lead acid battery. In that case, you'd need diode protection for the battery to keep it from being charged uncontrollably through its discharge leads by the vehicle's bus.
Going to need a heck of a diode to pass 500 amps cranking current
 
Chalo said:
john61ct said:
Chalo said:
john61ct said:
That's what DCDC chargers are for.

Sterling is my choice

So, DC-DC converter to charge, and diode protection on the discharge side?

Sorry what is the diode preventing?

And a charger is different from a converter.

I thought you were talking about using a DC-DC converter as an intermediary between a vehicular alternator + voltage regulator and a lithium iron phosphate battery used in place of a lead acid battery.
The Starter batt, which usually remains lead, is hardwired on the engine/alt circuit, which is the input side of the DC charger.

On its output is the House bank, say 1200Ah of LFP. This bank has no direct connection to the engine's circuits, if that is what you mean by

> the vehicle's bus

And in fact the House circuits may be 24V while the Starter side is 12V. Besides converting/ regulating output voltages, ideally CC/CV/Float each user custom adjustable, the DCDC charger's other job is is limiting the House bank's current draw from the alt/VR, IOW

> to keep it from being charged uncontrollably

That House bank may have a single set of power leads used for charge and discharge, or if it has a BMS, charge and discharge may be controlled separately and connect to separate busses.

When the alt is not outputting, there is no current flow in either direction, DCDC charger acts as combiner / isolator, ACR/VSR, no additional diode required.

There could also be a "rough" solar output wired to the Starter side (or wind, shore charger, hydro, fuel cell whatever) in which case the DCDC charger would automatically condition that flow.

Some DCDC chargers include solar controller circuitry, but I personally have not yet seen one I would use, and would put the SC output directly to House, letting Starter get charged by the alt alone.


 
I received the cells. Seven had a manufacturing date of summer 2017. One was summer 2019. I decided to first charge each cell and reviewed the datasheet: 3.65 volts = OK, holly shinola! standard charge rate is 3C ... that is 3 x 8 = 24 Amps per cell. For 2P that would be 48 Amps. Now I am looking at my poor, little, wimpy (costly) 6 Amp 60 volt variable power supply :?: :?: :?: :?:
 
Any LFP cells are fine with 3C, just won't get longest cycle lifespan.

If you want longevity stick to 0.4C
 
john61ct said:
Any LFP cells are fine with 3C, just won't get longest cycle lifespan.

If you want longevity stick to 0.4C

For A123? That would be missing the point.
 
Chalo said:
john61ct said:
Any LFP cells are fine with 3C, just won't get longest cycle lifespan.

If you want longevity stick to 0.4C

For A123? That would be missing the point.
Actually "longevity" is the point.
Mute point as 6 Amps is as much as I can pump out anyway :|
 
OK .. I will end this thread with two pictures because you are not likely to find this information elsewhere (I looked). The overall length of the cell differs from Headway's specification. These are the actual measured dimensions. Also note that the holder is an injected molded part and as such the 'precision' of the measurements may be somewhat open to debate. Consider these files to be Public Domain.
LFP-38120HP-Side-View-Dim-Small.png
LFP-38120HP-Holder(2D)small.jpg
 
Chalo said:
john61ct said:
Any LFP cells are fine with 3C, just won't get longest cycle lifespan.

If you want longevity stick to 0.4C

For A123? That would be missing the point.
Sadly your response is to a fella with more Google experience than actual build experience. Long on comments short on hands on.
 
I like the Headway 38120HP 8 Ah cell but volumetric density of 188 Wh/L is only 36% of a Sansung 25R which has 527 Wh/L.

Weight density of 84 Wh/kg gives it 42% the density of a Samsung 25R which is 200 Wh/kg.

So while it's max continuous discharge rate is 15C a person will only be able to pack in about 1/3 the watt-hours of the 8C maximum continuous discharge Samsung 25R in the same battery space. That means your max continuous amps from that same battery space will be about 67% of what the same volume of 25R would give you.

P.S. The Battery Hookup House brand 32650 6 Ah cells https://batteryhookup.com/products/100-brand-new-lifep04-32650-3-2v-6000mah-cells (an energy dense LFE design at 136 Wh/kg) does better compared to the Samsung 35E ( an energy dense Lion design at 260 Wh/kg). Volumetric density of Battery Hookup house brand 32650 6 Ah is 342 Wh/L compared to 715 Wh/L for Samsung 35E. So in this comparison LFE had 48% the volumetric density and 52% the gravimetric density of Samsung Lion. This is much better than the 36% volumetric and 42% gravimetric of the previous comparison using the power dense cells. In all fairness though, the difference in max continuous discharge was greater in the previous comparison (15C for Headway vs. 8C for 25R compared to 3C for Battery Hookup 6Ah 32650 vs. 2.29C for Samsung 35E).

Note: When I did volume calculations for the Battery Hookup House brand 32650 6 Ah LFE cells I used the true length of 70mm. I did not use 65mm.
 
ebike4healthandfitness said:
I like the Headway 38120HP 8 Ah cell but volumetric density of 188 Wh/L is only 36% of a Sansung 25R which has 527 Wh/L.
...
I do not plan on using 38120HP cells on an Ebike. I bought eight in order to build a 12 Volt battery for other purposes. One of which is getting to know the Daly Smart BMS.

I do plan on using Headway cells on my next EBike but those will be 40152S which have a better power density though they do not compare to Sansung 25R. I will pay the weight penalty for for better longevity, cycle life, reliability, serviceability and safety. Even if the additional weigh were 10 pounds it is relative small relative the to the weight of the bike, rider and cargo.
 
LewTwo said:
Ultimately I am interested in a LiFePO4 battery for my next E-Bike project. My past experience is that a new LiFePO4 battery can last over 6 years. At this point I plan on using new Headway 40152S (16 Ah) cells for that project. This will give me a bit of experience working with headway cells ... all-be-it a different size/model.

Lithium Ion can last a lot of cycles if you don't charge to 4.2v, but instead use 4.1v (doubles cycles at the cost of only getting 85% to 90% the capacity of 4.2v) or 4.0v (quadruples cycle life at the cost of only getting 70% to 75% the capacity of 4.2v). This in a package that would also be lighter and more compact than the equivalent capacity of LFE.

Yeah, so I'm not sure LFE is worth buying for cycle life. Though I have seen some information that you can get up to 15,000 cycles if you limit depth of discharge to 10% (i.e. using only 10% of the capacity of the LFE cell before recharging again):

https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries

The main advantage I see with Headway LFE is fast charging that is also safe. The Headway 38120 max charges at 10C. That is impressive! And still impressive when we factor in the reduced volumetric (and gravimetric) density of Headway 38120 compared to Lion.
 
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