I’m currently doing research to begin my first eBoard build and I have a couple of questions. So I’m thinking of using two 3S 5200mAh 10C (20C Peak) 11.1V batteries and the r-spec motor from enertion. However I can’t decide if I should put the batteries in series or in parallel. From what I understand, if I put the batteries in series, I would have an output voltage of 22.2V which would be enough to start the motor (14 - 44V Max) but would hinder its performance since the nominal output current for the battery is only 10C ( 10C x 5.2A = 52A and 2400W / 22.2V = 108A so the battery cannot output enough current). On the other hand, if I put them in parallel, I could output enough current ( 10C x 10.4A = 104A) but my output voltage (11.1V) would not be sufficient to start the motor (14 - 44V Max). The obvious solution to this problem would be to get more batteries and have two pairs of two batteries in series then connect them in parallel but that would increase the cost quite a bit so my main question is would it be possible to use this motor with just two batteries that I mentioned or do I HAVE to get more batteries to solve this issue. Thanks in advance.
Running 3s is a little low. I’d recommend getting 3s 20c batteries an putting them in series.
Thanks for the reply, I have thought about that but when I went on hobbyking to look at batteries, I can’t seem to find a 5000mAh 20C battery that has a TX60 connector which I need to use the VESC from enertion. Most of them come with 5.5mm bullet connectors but hobbyking doesn’t sell 5.5mm bullet connector to TX60 adaptors. Is there a way to get around that or will I have to make my own adaptor? Thanks
No problem! Yes, you can just cut the connect off and solder on an XT60. I would not recommend this if you have never soldered before or have a small soldering iron.
Ok great, soldering is not really a problem for me so this solution should work out. I do have another question. What kind of range do you think putting two 5000mAh 20C batteries in series would give me ( I weigh 53 kg)? I want to be able to ride for at least 5km, would this setup be able to achieve this range? Thanks in advance.
I’m running 3x2s 5000mah in series to get 6s which is what you would be looking at minimum. I also run a 245kv single motor with 16-32t gearing which roughly I’m getting 9km out of a charge. This is mainly on flat ground with only a short up hill so depending on the terrain your running on will determine how far you will get.
Ok thanks for the suggestion. Would you say that 3x2s 5000mah is better than 2x3s 5000mah setup?
No wouldn’t make any difference if they are same c rating. Just I run a drop through deck and needed to be as thin as I can. How much would two new 3s cost you as there are pre built options available.
2x3s is better. Your not going to want to charge all of those batteries.
From what I can see 2x3s 5000mah is going to be around 36 GBP and I will also have to buy TX60 connectors to solder them on which costs around 3 GBP. Can you link me to pre built options? Thank you
I charge mine as one 6s so no extra time in that
This is a prebuilt option but also double the mah with 10000mah so lot more but everything is done. Where in U.K. Are you.
I live in London. This looks really impressive but is considerably more expensive than what I had in mind. Thanks for the suggestion anyway. Speaking of which, what kind of charger do you use? I’ve been looking at this one http://www.hobbyking.com/hobbyking/store/_103697__HobbyKing_C3_50W_Charger_Discharger_AC_DC_UK_Plug_UK_Warehouse.html which looks good enough but I’m not sure if it’s the best I can get. Also are BMS necessary? If so will this one which seems to be both an indicator and a manager work ok ( http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=43590 ) ? Thanks in advance and sorry for the long question.
Yea mine cost me like £40 for the 3 and mine are 35c just more work involved in wiring them together. Ok there are some on here that are in London I’m further up north in Cumbria.
Yea I figured putting more work in wiring them up should save me some money. Speaking of which, what kind of charger do you use? I’ve been looking at this one http://www.hobbyking.com/hobbyking/store/_103697__HobbyKing_C3_50W_Charger_Discharger_AC_DC_UK_Plug_UK_Warehouse.html which looks good enough but I’m not sure if it’s the best I can get. Also are BMS necessary? If so will this one ( http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=43590 ) which seems to be both an indicator and a manager work ok? Thanks in advance and sorry for the long question.
That charger seem OK similar to the bmax 6 ac that others use. As for bms it’s not necessary if you are going to use one of these charger you just have to be carful with the voltage and not running them to low so my esc has a cutoff of 3.4v per cell so x6=20.4v and I now run a volt meter on my board. And as long as you balance charge them with that charger the levels should stay good.
Ok I see. Can you link me to the volt metre you’re using? Also, how do you decide on the cutoff voltage? Thanks
Will get a link just on eBay https://www.ebay.co.uk/itm/331724469467
The cutoff is what’s been researched by a lot of people from Rc community, when the voltage drop to low they can get damaged and possibly catch fire which is why you need to take lots of care with lipo when discharging and charging.
I think you have some good suggestions and options already, but wanted to clarify the C rating of the batteries. I wouldn’t go below a 100a ability of the batteries (my minimum) as most are marketing from the company and totally unreliable and likely incorrect. So an example is the 3s 5000mAh 20c (20c * 5Ah = 100a). The better they can provide, or the more in parallel to lessen the load - the less voltage sag - and if you don’t heavily draw (=heat) the batteries they will also last longer.
I also recommend DIY w/ two 3s for 6s. I usually get the thinnest (C dimensions on HK) batteries i can find - and with only 3s you can get some super thin ones around 20-25mm. Nice and stealthy!
Cutoff voltage - i set mine to 3.6v because with a little bit of sag you can pull them lower and i don’t want to damage my cells. Also get a lipo alarm to yell when you hit that voltage - vs just relying on the ESC to let you know, or by feel.
GL!
Thanks for the additional info. I’m guessing to be safe getting two 3s 5000mAh 25C would be best?