How bad crimping almost burned down our boat.
After two weeks in Sweden, we came back to Polar Seal on Monday to tackle some serious boat preps ahead of our Atlantic crossing this coming December.
One aspect of these preparations was to replace our Sunbeam deck solar panels, that had been performing poorly since we installed them last year. We had been in touch with Sunbeam the whole time (if the panels didn't perform well, their customer service is absolutely impeccable) and they eventually offered to drive all the way from Malaga to Almerimar to have a look at our panels replace them.
Ryan was as diligent as one can be when he built-our solar setup. Our 8 panels were installed in parallel. The panels installed on port and starboard were connected to a different Victron MPPT (control charger) to minimize the effect of shading. Additionally, all the panels were wired with 6mm cable to ensure optimal output.
Eventually, the poor performance of our panels came down to how they were installed on the deck (not optimally) but we will come back to that another time.
Burnt plastic smell.
What is important is that the moment that Ryan opened our battery compartment to show our setup to the Sunbeam guy, he felt a smell of burnt plastic.
Upon further inspection, Ryan realized that all the cables on the negative side of our system had been melting around the crimping area, and we were essentially a week away from burning down out boat.
Our new electric system.
To understand what happened, we need to backtrack to a few months, to the time we completely overhauled our electric system.
Back in March 2019 and our major refit of Polar Seal, Ryan decided to install lithium batteries onboard. Now before we start, Ryan asked me to stress out that our problem did NOT come from the batteries themselves. Our batteries perform well, and we are very happy with them. (did I do a good job at passing on the message? ;))
Lithium batteries enable us to have more power onboard and use more of it at once while charging faster. With our new lithium batteries, we installed a more powerful inverter (3000 Watts) so that we could use our extra power with household appliances such as our induction stove or... my hairdryer.
We also added 600 Watts of solar panels on an arch to our existing 400 Watts, so that we could charge our batteries faster.
We have used our new electric system, lithium batteries and inverter the entire season and absolutely loved it. The autonomy it gave us allowed us to stay off the grid for as long as our provisions would last, and saved us a lot of money in marina fees.
So what happened?
When we installed our new lithium batteries, Ryan wired them with 70mm2 brand new cable that needed to be crimped onto terminal ends, to ensure that the power would safely run through the system.
A big hydraulic crimper isn't a tool that we carry onboard. Those are only useful to crimp bigger size wire, and apart from the remodel of our electric system, we never need to do that.
So we borrowed crimpers from two different persons (mostly because of timing), one from a friend, one from the local electrician.
As it turned out, the hydraulic crimper we borrowed from our friend didn't crimp the wires well enough, resulting in the melting of the cables over time.
We obviously had no idea what constitutes a good crimp and a bad crimp: we thought both hydraulic crimpers would do the same job! Most sailboat owners do their own electrical work onboard, and we wouldn't be surprised if we weren't the only one to be ignorant in that matter.
Here is what the two different crimpers did. First, our friend's crimper flattened the surface of the terminal end on the 70mm2 wire. Fine we thought: it is crimped, right?
The hydraulic crimper that we borrowed from the electrician "punched a hole" in the terminal end and cable, which holds the cable in place really well and guarantees good contact.
And with electric tape around the terminal ends, there was no way we were going to detect the problem with our bad crimps until the tape melted.
The spiral of disaster.
We believe that the problem started small and grew exponentially bigger over time.
We did load those cables quite a bit, With our new ability to put a lot of power through our system thanks to the lithium batteries and the inverter, but never above their capacity.
Our conclusion is that the more we used power greedy appliances such as our induction stove, the more the poorly crimped wires built heat. The heat melted the cable, and the more melting occurred, the more resistance built-in the system. The more resistance was built in the system, the more heat was built each time we used power greedy appliances, etc...
By the time we discovered the problem, we estimate that we were a couple of weeks away from starting a fire.
All in all
We have very good batteries, a good inverter and bought quality components to build our electric system, but a system is only as strong as its weakest link. In our case, the weakest link was our crimps on the negative side.
This episode was scary and it took Ryan a couple of days to get over the enormous sense of guilt he felt over the incident. Had we not realized that we had a problem now, the consequences could have been absolutely disastrous, as Ryan will be away from the boat next week.
We were extremely lucky in the fact that 1. We found out about it before anything bad could happen and 2. more than half of the 70mm2 cables were crimped with the hydraulic crimper we borrowed from the electrician and are fine.
Today, Ryan is re-crimping/rewiring the affected part of our electric system, and we will be monitoring our wires closely in the future. I hope the tale of our incident will help someone along the way!
If you have any comment or suggestion, feel free to leave them in the comment section below :)
