What happens if your Motor Runs Hot?

[MaxxPain]

I have a few questions. I’m new to the Blackjack and are running 8000 Maxamp Lipo’s. Boat is all Stock. I set the programmer to

Battery Type: Lipo
Cutoff Voltage: High
Cutoff Type: Slow Down
Brake: Off
Timing: Low
Throttle Curve: Linear

I’ve only ran the boat 5 times so far. But one thing I have noticed is after driving the boat for about 10 to 15min, it’s a bit slower. Not quite as much punch as when I first started. I also tape the lid with the Hatch Tape at all 4 corners to keep the water out. I have also lubed the shaft after the first run. I have noticed on one run quite a bit of water in the hull, I would guess about a cup or so. I was wonder if this was weighing my boat down is the issue. But after emptying it, it didn’t seem to be much faster. It was better, but after reading some posts here. I was wondering if it was the timing I chose. Could the motor be running hot possibly? I never thought to check to see if the motor was hot. I always see water pumping out the side so I knew it was cooling. So I wanted to ask if that sounds like a hot motor or could it be something else.

Thanks Brad

[Ub Hauled]

A couple of things I have to mention here...
running the boat for 10-15 mins is a loooong time. you may be depleting your batteries.
The BJ is 26" long and a cup of water should not make a big difference in the speed.
Now... you NEED to check the motor temps! Not only will a hot motor make the boat slow down but it will destroy the magnets and eventually it will destroy the ESC as well... your settings are good but that is not what will dictate the temps of the motor alone... the strut setting have a big role in it. Make sure that the strut is not too deep in the water.
When you tape the hatch down are you taping the entire seem or just the corners? It should be the whole thing... none of the seem should be exposed.
Lastly, just to be sure, the flex cable is running freely inside the stuffing tube correct?

Hope it helps.

[MaxxPain]

Thanks for the reply, I tape the lid 100%. The strut setting I have not touched. The manual says to adjust it if the conditions are questionable. What are the guidelines for proper adjustment? I usually run in pretty smooth conditions, but I have had a few turnovers so it could have come out of adjustment. Yea the run time I have not be able to fully reach. So I don't know what the 8000 will deliver time wise. But 25 to 30 mins I have done. I will definitely check the motor temp on the next run. The flex cable is running free last I checked. But will recheck.

[Ub Hauled]

The prop shaft should be leveled ( zero degrees) and about 1/8" above the sponsons.
I have never seen anyone run their hulls for that amount of time (30mins), if the motor is NOT running hot (about 130 degrees after your run), then something else is slowing the boat down... the lipo cutoff could be it. One solution would be, don't run as long, over using the batteries will damage them to the point of termination. Once you notice the boat slowing down it's time to bring her in and charge the cells.

[andym]

WOW 30 mins, I am happy with 4min in sport trim and 2 1/2 in race trim. No electric motor likes spinning hard for that long. Even my Dremmel starts to suffer after 5min..................

[azjc]

IMO 15 mins is a long time.... lipos will slow down just before they reach thier LVC and if you are running the stock ESC I dont think it has a LVC ( The stock SV27 doesn"t) if you go below the LVC (usually set no lower than 3 VPC) you could puff and damage the lipo beyond repair

[Ub Hauled]

The BJ ESC has a soft lipo cutoff, that is one of the differences between the BJ and the SV.

[MaxxPain]

Thanks for the input guys, I will be allot gentler with her from now on. I have a temp gun so I will make sure she is running cool from now on.

[ED66677]

get an eagle tree recorder to see how many mA you drain out of the batt during a 5 minute run, you don't want to pull more than 70-80% of their capacity, you might be in a situation where you pull "few" amp so the voltage only drop to the cut-off level when the pack is completely empty!
just an idea!

[MaxxPain]

I called Horizon Tech Support yesterday and asked there 2 cents on why the boat would be running slower after 10 to 15mins of run time. They said the 10 or 15mins of run time was not a real concern unless the motor was indeed hot and to check it. But they were interested in the Lipos. What was there voltage when I noticed a decrease in performance and to check each cells voltage. That maybe the batteries are dropping to the LVC early and that is why I'm driving around for 25mins or so. I did a few things, charged both packs after my 25min run on Monday and both packs charged to only 4300mah. That seems a bit low. I was expecting them to be either dead or pretty close to being dead. I have an Ice Charger. So I did a discharge on them at 10amps and they both discharged to around 7000mah. I also checked each cells voltage fully charged and they were 4.21 to 4.25 volts. The other thing I'm going to do is install my React Radio which has a voltage sensor that I can install were I can see the voltage while I'm driving. So if I see it drop below 12volts then I know the LVC is kicking in. So we will see this weekend.

[ryan_t888]

With 8000mAh packs you should only discharge a maximum of 6500mAh or so. This results in a run time of about 12 minutes @ 35A.

With a run time of 25min and replacing only 4300mAh, this means you are only drawing an average of 10A. In order to maintain an average of 10A, you must rarely get the boat even on plane.

Also, fully charged packs should reach a maximum of 4.220 volts per cell. If you are reaching 4.250 v per cell, this can be dangerous. When I check my packs after a charge they are under 4.200v per cell.

After about four minutes of running my motor, I pull just under 3000mAh out of my 5000mAh pack. I'm averaging 36A according to the data logger.

Ryan

[Ub Hauled]

Maxx,
if you are not balancing your packs you should... it seems that you are charging them and they are uneven, that will result in lower then suitable voltage in one or a few cells. The LVC calculates the average of the whole pack, not each cell...
One other thing and I am not sure about the visual feedback you get from your charger but, on my Hyperion it tells me the amount of mAh that went in (charge) and not the amount of mAh in the pack... be sure of what is shown on your display.
What Ryan is saying is correct, do not discharge more then 75% of you pack... it can start taking a toll on the cells.

[MaxxPain]

Thank you very much for the info. I didn't realize how important the 10ths of a volt are with these batteries. I normally balance the batteries while I charge. I have a Hyperion LBA10 balancer. Part of the problem I see I was doing was not letting the packs balance for long enough. Last night I let the balancer sit on the pack for 3 hours and it finally was perfectly balanced. I have never left it on the pack that long before.

[Ub Hauled]

Remember that the balancing will discharge the batteries. The proper way to do it when the pack is very UNeven is:
fully charge with balancer, let it balance alone and recharge with balance. Once you have your packs properly balanced you can just balance them during the charge.

[azjc]

I balance while I charge ( I use the Hyperion 0610i with builtin balancer) and also the battery quality matters...if you use an enerland based cells the need for balancing goes way down, if you use maxamps packs the balancer will light up like a christmas tree