12v 90ah trolling batterybox

[DeAverage]

Hi all,

Seeing as how I got the inspiration to make my own lithium based battery from the video`s by Will Prowse and the posts on this forum, I thought it only fair to post the build here.

I`ve been lugging heavy lead acid batteries around for a while when fishing, so I decided to look into Lithium, mainly 18650 cells. But quickly realised that they weren't particularly well suited for their intend use (too high a voltage or too low). And quite a hassle to assemble, not to mention the possibility to have them go up in rather spectacular flames. Then I stumbled into Will`s video`s on Lifepo4 cells. This chemistry/format seemed to solve all those issues so I figured it was finally time to have a go at it. Many weeks later I managed to get all the parts and tools and this is the result.

The list of parts:
- 90ah EVE cells *
- 60a Daly BMS **
- waterproof voltage indicator (touch activated)
- waterproof 12v car plug
- 50a anderson connector (3d printed flush mount & waterproofed the cables with grommets)
- 60a automatic fuse
- junction block for the negative end (3d printed)
- a pelican style box 35x29.5x15cm (tight fit, the cells don't seem to move)
- 18a 14.6v wall-charger for lifepo4 from aliexpress (Waouks) ***

* I used 90ah EVE cells, which were sourced from Xuba on alibaba. Which was a hassle-free experience, shipped straight to my house with all taxes paid. Extremely well packaged too btw. They're the exact same size as the 105ah`s, but the pricing was a lot better. I tested the cells and the capacity checks out, so thumbs up!
** The BMS is probably undersized. During a testrun the BMS overheated at anything above 30a (after 1hr or so). Granted, I had it encased in foam...now its glued to strips of aluminium and the foam has been removed. Will test this soon if this fixes the issue, might have to go with 80-100a BMS though.
*** Didn't see many recommendations for chargers so I just picked one that seemed to fit the bill and doesn't break the bank. These seem be sold locally as well, but rebranded and priced much much higher. So far its been performing nicely.

Hopefully this will help someone that's in the same boat as I was. And feel free to point out possible issues or improvements, since its my first build I'm sure i've overlooked many a thing.

 

[Supervstech]

Looks nice! I like the waterproofing you did with the andersons... care to link the files for those with 3D printer access?

if you regularly draw down the cells, and fast charge them, kapton tape likely won’t hold the cells together. You might want to get some steel strapping around them.

 

[DeAverage]

Sure, I posted it on Thingiverse just now: Anderson flush mount

Didnt know that was a problem, they expand a bit I guess when charging? I'll see if i can find some steel straps.

 

[Aggie_Aloha]

I ran across the YouTube Channel and this forum specifically to make a lithium trolling battery. Bought the similar batteries (hasn't shipped yet) and BMS (just got my tracking information). I also went with an undersized 60A BMS thinking it would save me from having to put in a circuit breaker for my 30A max Minn Kota C2 motor (maybe my logic is wrong). I would be curious to see how your mod develops, as well as which charger you got (I actually came on this forum looking for LiFePO4 charger recommendations. I'm assuming you got the case from HF - which size ended up fitting the battery? Thanks in advance.

 

[DeAverage]

I actually made 2 packs, tried the other with the heatsink on. But no luck, this other pack cuts out even faster. The BMS stays cool...so I doubt that its overheating. Even tried 2 in parallel, no change. The voltage gets cut off completely, then once the load is disconnected the voltage comes back up, one or a few cells at a time. So it looks like the BMS intervenes for some reason. Now to figure out the cause...

Either the BMS`s are wonky or (some of) the cells are dropping below 2.5v when under a load of 30a+.The cells are rated for 2-3c, the max my motor will pull is ~50a, which is only a fraction of that.

So, I just ordered a cell-monitor (isdt battgo bg-8s) to see if the cells are causing the issue.

The case I got from amazon.de, it`s sold by quite few stores, under different names and prices. Conrad also sells it for instance.
This is the charger I got, I personally stuck with 0.2C.

 

[Aggie_Aloha]

@DeAverage - Thanks for the reply. Sorry to hear about the issues. 90Ah is more than enough for a trolling motor. I'm new at this myself, but I hope one of the more senior members on here can chime in and help trouble shoot this. I'd love to hear the solution or any tips you may have based on your experience. AliExpress says my battery won't arrive until November 20th . I'm hoping that is a conservative estimate. I'll have to make due with my SLA until then - fall fishing is coming up and I'd love to spend more time on the water catching fish than paddling after my sla battery dies. Thanks for the link. I'll order the charger, since all of the US retailers seem to have a fraction of that amperage at twice the cost.

 

[JoeHam]

Nicely done!

I hope that is a Bussman breaker and not the T Tocas crap one.

 

[Aggie_Aloha]

Nicely done!

I hope that is a Bussman breaker and not the T Tocas crap one.

Joe - do you know of a Bussmann 12V 50A breaker? I couldn't find one. The only one that comes up is either a short stop, an inline fuse, or a variation of T Tocas.

 

[JoeHam]

You will be well served to use a 48v breaker, don't get hung up on the 12v nominal.

Remember that the purpose of your breaker is to protect the wire.

The reason I bring that up is that the only Bussman's I can find right now are 35 and 80 amps. With properly sized wire either one may work for you.

See here:

Amazon.com

I believe Blue Seas is a rebranded Bussman. Amazon currently has those in 50 amps but for some reason the price is almost double.

The T Tocas crap has had reports of catastrophic failure, including melting in the closed position which lets all the smoke out of your system.

 

[DeAverage]

Interesting, I got a cheap generic one from aliexpress. Same as this one.
One of the bad reviews describes my problem. Havent checked this before, since it doesnt trip....i`ll test it this weekend.

Absolute garbage! Worked less than 2 hours before it started loosing continuity. Was using on a small trolling motor and kept loosing power, after using a multimeter to track down the lost voltage finally found it was the breaker, NOT TRIPPED just loosing connection. Spend a little extra and get a Bussman or Velvac. Switching to a Velvac solved my problem completely. These look cool but reliability is questionable at best!

 

[BiduleOhm]

Joe - do you know of a Bussmann 12V 50A breaker? I couldn't find one. The only one that comes up is either a short stop, an inline fuse, or a variation of T Tocas.

Panel mount:

187-Series Circuit Breaker - Panel Mount 50A - Blue Sea Systems

Thermal circuit breakers provide heavy duty circuit protection for 25 to 200 Amp loads when switching and circuit protection are both required.

www.bluesea.com

285-Series Circuit Breaker - Panel Mount 50A - Blue Sea Systems

Thermal circuit breakers provides medium duty circuit protection for 25 to 150 Amp loads when switching and circuit protection are both required.

www.bluesea.com

Surface mount:

187-Series Circuit Breaker - Surface Mount 50A - Blue Sea Systems

Thermal circuit breakers provide heavy duty circuit protection for 25 to 200 Amp loads when switching and circuit protection are both required.

www.bluesea.com

285-Series Circuit Breaker - Surface Mount 50A - Blue Sea Systems

Thermal circuit breakers provides medium duty circuit protection for 25 to 150 Amp loads when switching and circuit protection are both required.

www.bluesea.com

 

[Luthj]

Breakers are rated for maximum nominal voltage. Using them with a lower voltage is typically acceptable. Note that DC and AC ratings are not interchangeable, so read the spec for DC ratings, as they are almost always lower.

 

[Aggie_Aloha]

Thank you both

 

[DeAverage]

Problem solved! Turns out it was the breaker, replaced it with a 60a mini anl fuse. Ran the motor at 100% for an extended period, no issues. BMS stays cool, wires got like lukewarm.

Also added some hose clamps. Can't really torque them down tight though so theres still some play, especially on the wider side of the cells. Gonna add some doublesided tape between them. Ordered some studs and flanged nuts with serrations as well to replace the bolts on the bussbars.

 

[HRTKD]

I've been using the 150 amp version of this breaker for the past three years. It's located between my 1000 watt inverter and the battery bank. It was located outside my trailer, on the underside, where it was exposed to the elements. It's seen snow, mud and rain.

I'm pointing this one out because A) it never failed and B) there is a different version available now. The old version has a stud to connect a ring terminal to. When I converted my system to LiFePO4 I carefully examined the mounting method of the breaker. While I didn't apply power to it to test this theory, or check continuity, it looks like the power goes through the stud. There is a washer-like surface on the face of the breaker that the stud comes up through. I don't think current goes through the washer. If you don't get a good connection to the stud, you could have issues.

The new design, as seen on the 150 amp version in the link provided, does not use a stud. Instead, it uses a screw down terminal block. I think this method is a lot less likely to have connectivity issues. The Blue Sea (Bussman) breakers that I use within the circuit between the solar panels and the bus bar look similar to the above picture.