Charger/discharge new batteries stopped working

Hi, I have a dual battery set up, but after three minutes, the Rudder swung in one direction and would not change. I also have an ESS sound system that I installed. I have a Y Cable set up to except two batteries in parallel. Then I have a split off cable for the ESS system which goes to a single ESC. The batteries are three months old and are charged every time I use the boat which is twice a month. When I checked the batteries they were at 3.1 V each. What could possibly be the problem and I also charge the transmitter with a new battery. I’m starting to think that maybe the low-voltage made the servo swing but then I had enough power to intermittently use the throttle to get it back to shore, as it made it circles . The ESS is a dual plus system. Shouldn’t the two batteries in parallel and split off at the single cable or the bottom of the Y remain at the same higher voltage and not 3.1 V. I’m thinking maybe because I do not have a charger/dish charger  and never had discharge these batteries. I don’t know very much about the electronics necessary for a charger but I was looking to try and find one that is pretty much automatic and will charge and discharge that I can use. Could that possibly be the problem? I separately charge each battery  and then checked to see and they were at approximately 9 V each. Why did they discharge so quickly for batteries that are only three months old however, without the ESS it ran fine. Please help this newbie idiot. First do I need to charge/discharge the batteries to get them up to par as possible problem? Let’s start there. Thank you very much.

OK - lets start with the basics. What type of batteries? NiMh. NiCd, Lead acid or Lithium. 

Barrie

Sounds like you run all the boat electrics of the same batteries. I have for more years than I care to count, have for safety sake used separate batteries for the radio receiver/servers. Thus I have avoided your problem. In order to test your batteries there are a number of Charger/discharger testers. Again used one for years as I do use a lot of rechargeable batteries of various sizes, and have found that many advertised capacities are a piece of fiction, hence every rechargeable battery I  buy is tested to see if the publish amp/hrs is correct. What size/type of batteries are you using

One last question "why do you you have the batteries in parallel"

OK, I am using an IMH 8.4 V 3300MAH. I put two batteries in parallel for more runtime. The more I thought about it the more I decided to experiment so when I came home from lunch I took one battery for the 550 brush motor And the other hooked to the ESS sound simulator and it worked. How long it will work I don’t know. I guess I will find out. But I do need to know the best charger/discharger so that I can keep the batteries in tiptop shape , but now I’m only using one battery for the motor and do not have any idea how long it will run for. I figured about five minutes, but I don’t know being lazy. I need to get something as automatic as I possibly can so that I can discharge and recharge at least 2 to 3 times to bring the batteries back up I guess. It is never been done. What do you think?

I use a G T Power c60 mini 10a 100w which covers most kinds of batteries you can get, but you may need to get connectors that fit. It was around £35 However I have had this for some years and there most likely now better ones on the market-try talking to a model shop, they usually are happy to give advice. Of course this may depend on the country you are in, I am in the UK

As to your run time, stick it in the bath and run it with as much power as you can and time it. The battery you are using (if the 3300mAh is true) should give you a safe run time of around 15-20 mins depending on the load you put on it.

Thank you for your reply I have two 3300 MAH batteries NIMH.. I was looking at the tenor geez TB6B charger. Is that good for what I want and also do you think it would be wise to just run one battery for the main drive and buy a spare if I want to run more time or keep the two batteries in parallel for run time and buy a separate battery of whatever size which I don’t know independent for the ESS

As I have said my advice would always use a separate battery for the receiver. No idea about the charger, as I said talk to your model shop. If in UK try Cornwall model boats, always had good advice, get number from the web site

Thanks, brother, that’s exactly what I’m gonna do. I just have to figure out what type of battery pack to put in because as you know weight matters and that sound simulator for the motor will be on continuously as long as I use the boat so do you have any preference? AAA, AA, or C batteries and what MAH do you recommend? By the way, thank you for your advice. It’s well appreciated.

Thanks, brother, that’s exactly what I’m gonna do. I just have to figure out what type of battery pack to put in because as you know weight matters and that sound simulator for the motor will be on continuously as long as I use the boat so do you have any preference? AAA, AA, or C batteries and what MAH do you recommend? By the way, thank you for your advice. It’s well appreciated.
Nimh

I use a NiMH small battery pack for the receiver/servos, Overlander 4.8v rated 2300mAh which plugs into the battery socket on the receiver, the size is 56mm x 50mm x 15mm