Dynamic Product Search

Smart Energy Management for Marine and Off Grid

No products in the cart.

REC and WS500 User Forum

Please or Register to create posts and topics.

REC Q Series vs. Victron specific BMS

Thank you for the cool BMS design. While looking at the documentation of the Q series, I noticed the Q series has a sink amperage of 200A, while the Victron model shows 100 Amps. I plan to use the BMS in a system like this:

  • Battery bank: 2P8S of 32.V 280 AH cells to form a 24V 560AH battery bank
  • Victron Multiplus 24v/3000VA Inverter Charger
  • Nations 24V 150A alternator with Wakespeed WS500 alternator regulator

I want to be able to fully power the Multiplus which requires about 120 Amps, and power some DC loads simultaneously. So, 200 Amps would work very well. But, 100 Amps would be insufficient.

Does the REC Q BMS allow a 200 Amp draw? Is it the correct model for my application?

Thank you very much for your assistance!


Hey Ed,
The REC uses an external contactor so it all comes down to what contactor you want to use.  We recommend and stock the Tyco EV200 series.  These are an awesome sealed 500 amp contactor, that includes an economiser circuit that, once the contact is pulled in, uses only a very small current to maintain it.
The REC BMS plays very well with both the WS500 and the Victron Cerbo.  For your reference I have pulled together a quick pre-filled shopping of items you may want to include
  • I have only included the PC config software and no wifi module as you can monitor your system all through your Victron Remote Access portal
  • I have included a Tyco 24v relay
  • I also included a PreCharge module which slowly charges the big capacitors on your MultiPlus and reduces arcing and EMI
  • I created your order as a kit to save you 5% on your accessories.  To edit it, jusst click on the little "Edit" link under the BMS description on the cart page
  • you can likely share your existing current shunt so we just included the cable for it.  You can use the smart shunt CANBus info, but we dont recommend it for loop control over a network
  • I included a BMS to Victron CANBus cable.  If you need to add a WS500 to CANBus cable you can add that separately.
  • All items are stock USA and usually shipping in a day.
  • Shipping in USA is Free
If you have any questions feel free to reach out!

Thank you very much Rick!

To be sure I precisely understand you, the battery bank to consumption devices such as inverters, etc. is not limited in amperage by the REC BMS. The limitation is only the fuse and contractor?

You nailed it !  You also need to size your current shunt for the application.  Ideally you want to run in the 1/10 to 2/3 of its capacity range.  This will provide the most accurate readings and help ensure your SOC is accurate.

Many of the BMS's on the market are application specific and contain an internal SS relay that is limited to a smaller current, usually for single cell applications, such as drop-ins, but the REC BMS is designed for both small and larger ESS applications, and can be applied to most any size of battery system, especially when you start networking them together.

Hello Rick - I have a related question. The Multiplus is an inverter/charger so same conductors are used.  To control charge enable and discharge enable, Victron has separate digital inputs (all Victron devices have these inputs), or you can control through CAN.
System configuration diagrams for REC BMS are overly simplistic and show main contactor in +12V lead to Multiplus. They do not show bussing with other charge sources like alternator and solar.
(Don’t have manual in front of me...). Error logic in REC manual describes independent logic for charge enable (MOSFET output) and discharge enable (internal relay) conditions.  This implies that all loads have to be bussed together for load contactor, and all charge sources bussed with second contactor controlled by MOSFET output, is that correct?   This is complicated.
Do you have a REC-Q in a Victron-based system diagram, including Inverter/charger, solar MPPT, and alternator?


We are currently creating several shapes libraries for a free online design tool called  diagrams.net to help with the system design process.  Its not ready for release yet but I quickly put together an example of how my various networks connect on my demo board.  This sketch will evolve over the next few months but hopefully it helps with your project.


Uploaded files:

On the network diagram please note that Terminators are NOT required on the VE.bus network.

Updated sketch attached

Thanks to Ben for catching this one!


Note:  First revision of file was wrong.  Corrected one now


Uploaded files:
  • REC-Victron-WS500_network_dwg.jpg