lithium iron phosphate trolling motor batteries ?

[CP]

Are they worth the money?  Prices keep coming down and the weight reduction is pretty compelling.  Any downsides beside cost?

[Hilltop123]

 Along for the ride.........

[scotsman]

You’ll need a different charger. Lithium batteries can be quickly ruined by using a charger designed for lead acid Types.

[CP]

According to Battleborn, a standard charger set to the AGM setting is “great”.

https://battlebornbatteries.com/charging-battleborn-lifepo4-batteries/

They recommend a bulk and absorption voltage of 14.4 V. Float is not necessary but as long as the float is less than 13.6 V it “is fine”

I would expect the battery’s BMS to cut off charging when the battery is fully charged, so I don’t see why float would be an issue.

But my old “dumb” chargers don’t go over 13.3VDC so they aren’t going to cut it.

I have a wall mounted Charles that charges at 14.2 and floats at 13.4 when on AGM setting.  Should work fine as long as I bring the battery to the charger.

[Stein]

I would be pretty careful with any lithium battery.  Battle Born doesn't make the batteries they sell, so I would look other places for confirmation on safe charging. In the article linked, they mention "A float is unnecessary, since li-ion batteries do not leak charge" which is incorrect as they have self discharge just like any battery and the fact they used a term like "leak charge" leads me to believe they aren't overly educated on the topic.

Lithium batteries have a very nasty tendency toward thermal runaway.  The lithium iron phosphate batteries are supposed to be safer as they are more stable, but they are still pretty new and I haven't seen a bunch of data on them yet.

No way I would leave any lithium battery larger than a laptop charging unattended, much less on an AGM charger.  It might end up being OK, but I would wait for the AGM chargers to be certified to charge them before I got too excited about using one.  Just because they may have solved one problem doesn't mean they didn't create another one (or even not solve the first one).

Even with lithium iron phosphate, a bunch are likely coming out of China and they can vary in quality dramatically.  I would only trust known manufacturers that either produce their own cells or are pretty transparent about where they get them.  I wouldn't be surprised if you saw mislabeled cells on the market just like anything else coming from China.

[CP]

Well, that’s a buzz kill.  I was under the impression LiFePO4 is safer than Li-ion or lead acid.  They don’t even require venting.  I’ll do some more research.

[Stein]

They probably are, at least in the aspect of thermal runaway.  I don't know that has been fully tested yet and even if it was, would be based on a certain charger or charge profile.  I'm not saying they aren't the greatest thing since sliced bread, I'm just saying I'm not leaving them plugged in in my garage or next to my house until we know more.

The guys like the one you linked "assemble" the batteries which means they buy them from someone, package them in a nice looking container and sell them under their brand.  The are likely not intimately familiar with the chemistry or manufacturing process of the battery or the chargers they sell - not a dig as nobody in their place does.  Same with Cabelas, they slap their label on a reel and have no idea how it was designed or built.  Nearly every battery manufacturer will tell you how safe their batteries are and how awesome and unique their manufacturing process is, kind of like every industry.

There are big challenges with lithium ion batteries in manufacturing, a tiny issue at the factory leads to big problems in the field.  At one factory, they had a tiny problem with one of their suppliers and it ended up in fires in the field.  One of the challenges with new technology in batteries is we only know what went wrong with the last ones, i.e., we don't know what we don't know.  It might be an overly cautious perspective, but I'm pretty close to some of the issues in the past and am likely over sensitive.

[CP]

Gotta love YouTube.  This guy tears apart $1000 batteries to see how they are constructed.  Most seem to be junk, but some are very well made.

I’m leaning toward the SOK.  Looks well-made and thoughtfully engineered.  I like the idea of serviceable battery, not so sure of the steel case though. 

[CP]

I ordered a SOK 100ah.  $570, free shipping, no tax when ordered directly.  Compare that to $993.40 for a Battle Born.

https://www.sokbattery.com/100ah-12v-lifepo4-deep-cycle-battery.html

Great customer service; they answered my questions almost instantly.  Charging isn’t a problem, any charger that provides about 14.6V will work.  The BMS protects for over & under voltage, high & low temperature and over current.

Shipping is slow but I don’t need it right away.  Not really fishing weather out there.

If it works out, I’ll buy some more for my off-grid cabin.

[bassquatch]

I have been running my Ionics since July-ish and will never go back! 

[CP]

I have been running my Ionics since July-ish and will never go back! 

Nice.  That's a lot of battery.

[Stein]

It's tempting, I could pull 80 pounds out of the back of my boat but it would cost at least $1100 to do it.

[Stein]

I ordered a SOK 100ah.  $570, free shipping, no tax when ordered directly.  Compare that to $993.40 for a Battle Born.

https://www.sokbattery.com/100ah-12v-lifepo4-deep-cycle-battery.html

Great customer service; they answered my questions almost instantly.  Charging isn’t a problem, any charger that provides about 14.6V will work.  The BMS protects for over & under voltage, high & low temperature and over current.

Shipping is slow but I don’t need it right away.  Not really fishing weather out there.

If it works out, I’ll buy some more for my off-grid cabin.

Did you happen to ask them about the discharge current?  It lists 100A but I haven't been able to find any data on whether you can run that continuous or only for 3 seconds?

There are good uses for these, but they don't seem to be great starter batteries unless you go pretty big.  I'm thinking I only need maybe 50-60 Ahr but the discharge current may not support my monster pot puller.

[CP]

I ordered a SOK 100ah.  $570, free shipping, no tax when ordered directly.  Compare that to $993.40 for a Battle Born.

https://www.sokbattery.com/100ah-12v-lifepo4-deep-cycle-battery.html

Great customer service; they answered my questions almost instantly.  Charging isn’t a problem, any charger that provides about 14.6V will work.  The BMS protects for over & under voltage, high & low temperature and over current.

Shipping is slow but I don’t need it right away.  Not really fishing weather out there.

If it works out, I’ll buy some more for my off-grid cabin.

Did you happen to ask them about the discharge current?  It lists 100A but I haven't been able to find any data on whether you can run that continuous or only for 3 seconds?

There are good uses for these, but they don't seem to be great starter batteries unless you go pretty big.  I'm thinking I only need maybe 50-60 Ahr but the discharge current may not support my monster pot puller.

I didn't ask about max discharge.  But it does list 100Amps on the battery box. 

Shoot them an email, they are very helpful:

https://www.sokbattery.com/contact

[CP]

Found it:

100A continuous, it's in the spec sheet:

https://www.sokbattery.com/pub/media/sparsh/product_attachment/SK12V100-0915.pdf

 

[Stein]

Cool, thanks.  I'm also thinking about going from a two battery bank to a single and then just have a small jump starter pack, so I need to figure out which way I want to go.

I do like the versions that have bluetooth so you know exactly where they are at, I haven't done enough research to see if they have any alarm features which would give some security.

I talked to a few people who know more than I (chemistry PhD) and their advice was to not leave them on the charger (floating).  It's probably OK, but the battery BMS is likely not expecting or designed for that, so better to pull it off when charged.

I noticed a bunch of existing chargers have slapped Lithium into their title or description, same charger as 10 years ago, but marketing heard they could use it.  There are a few dedicated chargers, but not many.

[CP]

I'm no expert but it would appear that too low a float voltage would drain the battery down to the float level.  I don't think that will harm the battery but it would limit its performance.

A simple DC power supply of steady 14.4 - 14.6VDC is probably the best method of charging these.

[Stein]

Yeah, that's one issue, most chargers are designed to charge, not discharge.  I don't think any of them are tested for reverse current except maybe a few niche cases.

There is also a slight mismatch in cell voltages between the technologies that leads to the slight difference in full charge voltages and most chargers are designed for lead batteries which are slightly lower.  I know my existing charger is pretty smart, the voltage varies over the charge cycle and in addition to the charge cycle it automatically has float and some type of periodic regeneration or maintenance cycle.  Definitely not a good choice for lithium iron phosphate that wants a steady voltage just high enough for 100% charge.

Ironically, with a BMS the charger should be more simple, just apply a set voltage until the BMS shuts it off and then go away.  That's what happens in a simplified discussion of electric vehicle chargers, they produce power until the car (BMS) stops taking it.  This is different than older technology where the charger protects the battery and decides when it has had enough.  Using an old charger on a battery with a BMS means two systems will simultaneously try to control the charging and that's the unknown.  Probably ok if not ideal (potential lower full charger value) and in my personal opinion more likely to harm the charger than battery.

This all assumes the BMS is reliable and when fails, fails safely. 

I would imagine new chargers will come out soon, they should be pretty easy and inexpensive to build.

[CP]

Found an excellent writeup on these batteries, answered a lot of my questions:


https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/

[CP]

To follow-up on this thread, I put together a small LiFePO4 battery box with a couple cheap batteries off Amazon.  This was originally to power a kayak fish finder, but it turned out to be way overkill for that.  In fact, this little battery box almost matches the performance of a group 31, 100ah AGM battery and it’s both cheaper and lighter than the AGM.

About 14lbs and $170 vs 69lbs and about $280 for the AGM.

I’m sure that the build quality of these batteries (Miady) can’t match the Battle Born or Ionic but they are about 1/3 of the cost per watthour.

[HUNTINCOUPLE]

Found an excellent writeup on these batteries, answered a lot of my questions:


https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/

Thanks for that link! Good stuff!

[GWP]

I am coming up on either building a custom battery pack or buying a number of smaller production batteries and linking them in parallel. Prices are coming down enough I may go the ‘link’ method if they have a BMS as I could just bank all of them on a charger at one time. It would almost be worth sending one to ‘The Guy’ and having him tear it down for inspection. Watch his channel often.
Keep us posted on how those hold up!

[CP]

The little battery pack pulled me all over the lake this morning.  Worked great.  The fishing wasn't exactly great though.

 

[Stein]

That's pretty impressive for that size of battery.

[CP]

Yeah it's impressive but I don't recommend doing this.  That motor is capable of drawing 55amps.  Those batteries are only rated for 40 so I've fused them accordingly.  Too aggressive on the throttle and I'll be changing fuses.     

[GWP]

Now you made me curious! I have a few different clamp on style amp meters (Fluke) and may take one with me on the next outing to see how much my 80lb 24v Terrova pulls. It is pretty oversized for my 16ft boat, so I am curious what it will draw wide open. I have hit the 'rabbit' button a few times on the water and it does around 6mph on a GPS.

[Dhoey07]

Yeah it's impressive but I don't recommend doing this.  That motor is capable of drawing 55amps.  Those batteries are only rated for 40 so I've fused them accordingly.  Too aggressive on the throttle and I'll be changing fuses.   

Which batteries from amazon did you go with?  I have a little minnekota that only has a 30 amp max draw. 

[CP]

Yeah it's impressive but I don't recommend doing this.  That motor is capable of drawing 55amps.  Those batteries are only rated for 40 so I've fused them accordingly.  Too aggressive on the throttle and I'll be changing fuses.   

Which batteries from amazon did you go with?  I have a little minnekota that only has a 30 amp max draw.

I used two of the 20Ah but they appear to be sold out of those.  They do have 36ah - one of those might suit your needs.

https://www.amazon.com/gp/product/B089VXSBC6/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

[CP]

I finally got the SOK 100ah battery and tested it and, yeah, lead acid deep cycle batteries are obsolete.  50 to 60ah of LiFePO4 will easily replace and outperform any 100ah lead-acid battery.

[Stein]

Wow, that's impressive.  I'm seriously considering going to a single battery in my boat.  I think that plus a small jump starter battery pack as a backup would do the trick and save a bunch of weight and space.  Hopefully they are back in stock soon.

[GWP]

Keep in mind the charging is different for Lithiums, and hard sudden draw (starting) can damage them for the long term from what I have read? Others on here may know more.

[Stein]

Most of the batteries have ratings for maximum continuous draw as well as peak or surge loads, often 3-30 seconds.  The 100 AH batteries usually can support 100 A continuous and surge about double that which should cover many starting applications.