# Can I use two 2s lipo batteries to power my FPV DJI goggles?

The FPV DJI goggles can take 7.4-17.6 Voltage. I am using a 2S 3000mAh LiPo battery. My plan is to buy another of the same liPo battery and attach it with a female to 2 male TX60 connector, making it a 4s lipo battery of 3000mAh(14.8 - 16.8V) .

Do I need to consider anything else?

Connecting the batteries in series or parallel brings two new issues with it that you need to consider before you start using them and they are both related to batteries that are not on the same charge level.

• If you put two batteries of a different charge in parallel, the battery with the highest charge will charge the other one and very high currents can flow which can damage your batteries.
• If you put two batteries of a different charge in series they will both discharge at the same rate during use and the battery with the lowest charge will discharge a lot deeper potentially causing a lot of damage.

So if you want to do this always take this into consideration:

Parallel connection: Make sure the batteries are at the same charge level.

Series connection: Make sure the batteries are at the same charge level AND of the same capacity.

So if you want the higher capacity and don't necessary need the higher voltage (in this case you don't): parallel connection is better and safer than in series.

Using two 2s batteries should work just fine. Just make sure that the connecter you buy is a series connecter in order to get the 4s voltage. (series = added voltage, parallel = added capacity). And this isn't a big deal, but buying a 4s battery to use might be easier than attaching two 2s batteries in series every time you want to use your goggles.

• Thank you for the series and parallel explanation. That's something I didn't know Commented Jun 18, 2020 at 20:57

Yes.

When we talk about a multi-cell battery like a 4s battery, what we're actually talking about is a collection of cells are connected in series. If you were to disassemble a 4s battery and the proposed dual 2s battery, the result would be very similar; 4 3000mah 1s LiPo cells, all wired together in series. The only real difference is that between cells 2 and 3 are a pair of xt60 connectors instead of being soldered to each other. Electrically speaking, the result is identical, except the 2s batteries in serial will have a higher internal resistance and be more difficult to charge.

• Also: I assume the reason you're looking at doing this is because the high capacity 2s batteries marketed for goggles are quite cheap (<$20), and the high capacity 4s batteries are pretty expensive (>$50). That's because they're low C rating. I'd shop around a bit, a bit of poking turned up some low C rating 4s batteries (~$30) that were about the same price as a 2s+serial connector ($7). IMO, the price difference is worth it being easier to charge/handle a single battery. Commented Jun 18, 2020 at 21:30
• I really appreciate the advice! I'll definitely look into that. Commented Jun 18, 2020 at 21:42