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WattCycle 12V 300Ah Mini inside look

Following....
My second mini is on the way. First had the top displaced... I agreed to keep it/repair myself and purchased a second at a discounted price. Now I'm concerned this may be a more serious issue than first thought. Hoping @WillProwse chimes in with his thoughts on if this is a safety concern!
 
UPDATE :

reply from Wattcycle 1/21/2025

I don't understand how any competent engineer could see this and say it is safe.
If one of these lids happens to pops off as you are traveling down the road, one of the main terminals under the lid could contact the BMS and spark an electrical fire.
I had high hopes for these batteries after Will Prowse did the first test on the 12v 100ah trolling battery.
But now I am considering returning these 300ah mini batteries.

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I have my battery strapped down firmly so the top cannot pop up. I am more concerned with the bolt head in your photo that appears to be contacting the top of the cell. What if it rubs thru the cell casing? Do you think that could happen??
 
I have my battery strapped down firmly so the top cannot pop up. I am more concerned with the bolt head in your photo that appears to be contacting the top of the cell. What if it rubs thru the cell casing? Do you think that could happen??


If it rubs through the top of the cell the electrolyte may be loose to leak into the case.... if there is a short/overcharge/overtemp/etc then it could be a vent and explosive.

I just looked at mine - the bolts are contacting the cell tops in the same ways and the BMS is contacting the battery top - I would say these are only useful if you are stationary OR if you pad the lid up from the case with some heavy foam and tape around it... adding around 1/4 inch of height internally to cure the rubbing issues. Might take something more rigid like a quare wooden dowl with foam on both sides so you can strap it down

bad design

And I have ordered a JBD 300amp BMS to replace the wattcycle one - this is post review by Will where it shows they allow around 800amps for extended period of time before they turn off... i.e. no overcurrent protection... no short circuit protection... etc...

At least with the JBD I can tell the cell voltages and other details and set an overcurrent cutoff that is reasonable.
 
Is there any way we can get Will to review this and give us his thoughts????
 
He has already reviewed the Wattcycle 300ah battery --- that is how we know they are really 280ah and can get a $50 refund.

@Will Prowse - When doing the review of the 300ah - did you notice how the top of the case is bulged before cutting it open? And inside the clearance between the battery terminal bolts and the top of the cells is ZERO? And the wires + BMS screws touching the inside of the lid is what is causing the lids to pop open?

Might be worth doing an update on the review
 
He has already reviewed the Wattcycle 300ah battery --- that is how we know they are really 280ah and can get a $50 refund.

@Will Prowse - When doing the review of the 300ah - did you notice how the top of the case is bulged before cutting it open? And inside the clearance between the battery terminal bolts and the top of the cells is ZERO? And the wires + BMS screws touching the inside of the lid is what is causing the lids to pop open?

Might be worth doing an update on the review
Being that he cut the tops off of them it’s probably too late to look at the one he has to see if it had that same issue. I live near him and have one with the top popped part way off he could look at for a follow-up (non destructive lol) review.
 
My top won't stay on even when popped back down it just pops up when I move or otherwise shift the battery --
 
He has already reviewed the Wattcycle 300ah battery --- that is how we know they are really 280ah and can get a $50 refund.

@Will Prowse - When doing the review of the 300ah - did you notice how the top of the case is bulged before cutting it open? And inside the clearance between the battery terminal bolts and the top of the cells is ZERO? And the wires + BMS screws touching the inside of the lid is what is causing the lids to pop open?

Might be worth doing an update on the review
No mine was not bulging. Mine was a recent update without the lid issues
 
Received my two 12V 300ah mini's with similar issues.
One battery had the lid popped off and the other seemed fine at first.
After further inspection during my install I noticed that the top had a large bulge in it. I believe due to the BMS contacting the lid.
This is obviously the reason for the lids piping off in shipping.
And will most likely have the same problem when they are bouncing down the road in my motorhome.
I agreed with customer service to reattach the lid of the first one. but after doing that it is obvious that that battery has the same issue.
Contacted Wattcycle again with pictures of the issue. Hope we can fix this. these are the perfect size and spec's for my application.

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What the heck?! they better refund your money or give you a new one
 
No mine was not bulging. Mine was a recent update without the lid issues

I wonder what they changed - Looking at your video again it seems like the lid is the same ... I am thinking maybe their fix was to just let the glue dry more - and once replaced the wires don't ever lay flat again ... either way I have scuff marks inside my lid and on the top of the cell directly under the terminal screws

They should just send a new battery to anyone that had the lid pop or refund - period - the 100ah battery they sent free would be fine if it was just a loose lid - but not with the other issues.

And everytime I move it, the lid pops back off
 
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I just checked all over my buildings and I can't find the case. I think I threw it out in the trash guy came yesterday. My lid fit perfectly though. Just wanted to see if there were scuff marks under the top
 
Check the cable lengths between the BMS and the cells and the BMS and the terminal please? My cables to the terminal are a touch over 12" long. The ones to the cells are around 8" long. My positive cables cell to terminal are 9" long.

Kinda looks like faint signs of pinching on them. I wonder if they are just to long to fold under properly
 
An extra 18" of cable overall... seems like that might cause the bulge.... doesn't fix the rubbing and zero clearance issues.
 
I wonder what they changed - Looking at your video again it seems like the lid is the same ... I am thinking maybe their fix was to just let the glue dry more - and once replaced the wires don't ever lay flat again ... either way I have scuff marks inside my lid and on the top of the cell directly under the terminal screws

They should just send a new battery to anyone that had the lid pop or refund - period - the 100ah battery they sent free would be fine if it was just a loose lid - but not with the other issues.

And everytime I move it, the lid pops back off
When I received mine I did not notice anything wrong with it and went ahead and installed it in my motorhome. A week later I removed it to install hold down straps and noticed the top wasn’t sitting flat.
I contacted them and they offered me the standard $50 refund and a free100 amp hour battery. Being I did not have any need for a 100ah they offered to credit me $150 towards the purchase of a second 300ah (280) mini (going to parallel with the first one). Right after I ordered it I saw this post.
So now that one is on the way to me- not sure what to do now!
 

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Well, I am going to have to think about things. I ordered a new BMS for mine to fixed the issues that came up in the video. Since then I have asked for a refund. If they want it back I'll order mb31 cells to make a battery. If they let me keep it I'll just replace the BMS.

Might be able to just cut the longer cables off and recrimp the terminal cables so there is room to put the lid back on and let it stay on. Then add padding under the bolt heads... or just a bit on top of the U shipped metal.
 
Update : 1/22/25

New response from Wattcycle below.
I don't believe anyone in customer support relies this is a serious safety issue.
How could a terminal leaving an impression on the top of the cells be a safe distance from the cell ???????

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I am having them issue a return label - or at least that is what I asked for. and I told them to make certain the label has a hazard warning on it identifying it as a LFP battery (damaged) ....

Will see what they say.
 

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