# Battery charger on sub? **URL:** \ **Category:** General Discussion\ **Created:** [October 20, 2018, 7:20am UTC](https://discuss.bluerobotics.com/t/battery-charger-on-sub/3590 "2018-10-20T07:20:40Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![adam](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/adam/32/9438_2.png) [@adam](https://discuss.bluerobotics.com/u/adam)\ **Post date:** [October 24, 2018, 5:26pm UTC](https://discuss.bluerobotics.com/t/battery-charger-on-sub/3590/2 "2018-10-24T17:26:07Z")
Hi @stewart-marine, A hybrid system like this is certainly possible, but there would be a lot of safety concerns so you need to be sure you know what you are doing. A full charger in a 6" enclosure would not be necessary, you could build a smaller system directly into the existing enclosures. In fact, DC power at 48-72 V would be plenty on its own, depending the amount of copper you have in your tether and the charge current you are looking to achieve, and would be much safer. It would be possibly to be constantly topping off the battery without interfering with anything. We are actually working on a hybrid power system like this, there is no estimated date of availability however. Here are few topics that discuss both hybrid and full topside power over tether in more detail: > [@External Power via Tether](https://discuss.bluerobotics.com/t/external-power-via-tether/686/2): > > @jsnyder, I believe that Rusty has mentioned that BR is working on extending the bottom of the battery by supplying supplemental power over the tether. I do not know that any details are available yet so maybe Rusty will chime in here about what he has in mind. Regards, TCIII AVD > [@Interested in some experimental power+data tether?](https://discuss.bluerobotics.com/t/interested-in-some-experimental-power-data-tether/3293/9): > > Hi All I’m glad to see a bunch of other people interested in this idea! Production time will be about 10 days from the time they get paid, shipment by sea to LA will be similar once it’s on board which may take a few extra days. So I would say about a month. As for the other parts needed-- At the surface I’ll be using a benchtop DC power supply I picked up on on eBay. It can do 120vdc up to 4.5 amps. For the vehicle, I got a Vicor step-down DC power converter designed for an input of roug… > [@AC Power over tether](https://discuss.bluerobotics.com/t/ac-power-over-tether/3492/11): > > I should off course emphasized that deviating from the original BR2 set-up is done at own risk, but that goes without saying, really. Running the motors on 24 volt on full gain over time is not good. However, I would argue, that is not how ROV operations are performed either, We normally go in low gain but if current creates a drag than the gain need to go up as well. Running the system on a lower voltage will be better for the thruster, but the current will increase and hence the heat in the… > [@Charge the battery,as you can do with laptop?](https://discuss.bluerobotics.com/t/charge-the-battery-as-you-can-do-with-laptop/1907/14): > > I have now remove the BMS from bluerov2,i have measured again and battery is only charge at 1.8 Amp that is not sow much. Did not find out why battery only charging at 1.8 Amp,should have charging at 6-7Amp sow maybe it’s BMS board. > [@Hybrid power puzzle](https://discuss.bluerobotics.com/t/hybrid-power-puzzle/3138/6): > > Thanks again for the input here. I am indeed planning to put higher voltage down the tether-- 120vdc, to be exact. By the time it gets to the vehicle with the tether I’m thinking of using it should be down to something like 80 volts, depending on the length. The 72-to-15 volt DC Vicor converter can handle a wide input voltage range, something like 100 to 50 volts, so that will work fine. It’s output can be adjusted up to 16.5v, which is why I was thinking I might be able to get a pair of mat… I have also sent you a private message regarding the other concern you had. -Adam --- _[View the full topic](https://discuss.bluerobotics.com/t/battery-charger-on-sub/3590)._