question

pommesfrites avatar image
pommesfrites asked

Lynx BMS Overheating while charging

Lynx Smart BMS is overheating with 12V 300A charge from alternators for 30 minutes.

I'm getting a BMS internal temperature too high alarm via bluetooth in Victron App. I have 2x 250A alternators regulated to a max of 150A each. Clamp amp meter confirms 300 Amps headed to a 600ah battery setup. In theory, I should be able to get pretty close to charging 50% of capacity in 1 hour. In reality, the BMS is overheating in about 25 minutes.

1) Has anyone upgraded heat dissipation? I'm thinking of adding a heat sink, or possibly using a PC computer's liquid cool system to transfer heat away from bms installation.

2) Does anyone know the temperature at which the BMS internal heat alarm signals? I will test with laser thermometer next time, but would love to know the spec, which isn't in the published manuals.

lynx bmsTemperature Alarm
11 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ commented ·

Are there consumers that discharge the battery at the same time (adds to the total current that flows through the contactor)?

Have you checked if the internal fan is running?

0 Likes 0 ·
Show more comments
oldchubbyknuckle avatar image oldchubbyknuckle commented ·

Any update on this? Was it poor connections on the bus bar or lugs?

0 Likes 0 ·
1 Answer
pommesfrites avatar image
pommesfrites answered ·

I tested this this thoroughly, and become convinced it was not fasteners or cable crimps. I used a laser thermometer and carefully checked the temps on either side of each connection, looking for a delta. I could find none.


In the end, I decided that it must have been some unknown combination of the ambient temperature, a loose connection, or undersized alternator cabling. I rewired the alternators with 000 cables, and moved the batteries and bms to another location. I created all the new cable lugs and precisely torqued the fasteners.


Some combination of those solutions solved the problem. The bms doesn’t heat up past 40c, even when charging at 300 amps for an hour.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Related Resources

Additional resources still need to be added for this topic

LED indications, warnings, alarm and error codes

Lynx Smart BMS product page

Lynx Smart BMS online manual

Additional resources still need to be added for this topic