NiMH Packs in the Revolt

[nickB722]

:help:

Hey Guys,

After years of lurking and planning on buying a "real" boat (I finally got sick of my dad's old MRP cat last weekend after a pathetic test with a brushless system out of my Evader), I finally pulled the trigger and bought an Impulse last Friday and had some fun with her over the weekend. Due to house rules I can't have Lipos, but I've got plenty of NiMH packs around. I ran the boat with 2 7.2 volt packs this weekend, but I purchased a pair of 8.4 volt packs with the boat as well. The information on the ProBoat website seems to contradict itself and the manual as the 60 amp ESC page seems to indicate that 2 7 cell batteries will work, but the boat's manual and page indicate that 2 6 cells is the max voltage the ESC can take. I don't want to chance frying my ESC at this point, does anyone have experience with running the boat on 7 cell NiMH packs or does anyone know if it exceeds what the speed control can handle? I'm running the Deans connectors and stock bullets (for now), but that will likely change in the not too distant future.

Thanks in advance for any help.

Edit: Title Change (I should NOT be posting new threads that late at night after 2 hours of sleep the prior night :olleyes:)

[roadrashracing]

I ran them for ever in my pro boats before switching to lipos, you might need to get the card though because the speed controls might come in lipo mode now.

[nickB722]

I ran them for ever in my pro boats before switching to lipos, you might need to get the card though because the speed controls might come in lipo mode now.

Thanks for the reply! I had mine programmed for NiMH at the hobby shop I purchased it at just to make sure, and so far everything's been good, I just wasn't sure about running the bigger packs with the stock electronics even though it seems intuitive that the NiMH would be easier on the gear than the LiPos.

If anyone else has experience running 8.4s in this (or similar) boats with the 60 amp esc I'd appreciate hearing about it!

[LarrysDrifter]

Call proboat tomorrow and ask them.

[nickB722]

I tried to call them yesterday but was on hold for a while and had a party to get to. I'll give them a call tomorrow morning, figured I may get a quicker reply on here.

[bigcam406]

how did it perform with the nihms? decent speed and runtimes? just wondering.

[roadrashracing]

It will be slower than lipos.

[nickB722]

how did it perform with the nihms? decent speed and runtimes? just wondering.

Honestly I felt like it performed decently all things considered. That said, this is my first true FE boat, but it didn't seem slow compared to a friend's Miss Geico I ran with LiPos a while back. I haven't been able to do any meaningful setup work or get a radar gun/GPS on her. I was running in a busy marina and had to pull over after every few speed runs (to avoid traffic and I was checking temps constantly out of an abundance of caution), but I was getting probably 7-10 minutes out of the batteries (7.2 v 5100 mah Dynamites) with the stock prop (sharpened and balanced, still waiting for a polish job).

Will it beat another Impulse 31 with LiPos? Maybe if the water is rough and the driver of the NiMH boat totally outclasses the LiPo boat, but it was fun, and fast enough to keep me interested. I also run a brushless stadium truck that I've GPS'd at about 34-35 mph on 7.2 volts, and it is a bit slower than that but not by a huge amount.

I'm on the phone with ProBoat checking on the 7 cell usability now, I'll report back when I get an answer.

Mods: Is there a way to change the title of the original thread from Revolt to Impulse?

[nickB722]

Well I just got off the phone with ProBoat and they did not recommend running the 8.4s in the Impulse, a bit sad, but that means I just have to work a bit harder to get that setup just right! Apparently the V2 boats will be compatible with 8.4 volt batteries due to the larger/newer/higher quality speed controls.

[Rumdog]

What do you mean by house rules?

[nickB722]

What do you mean by house rules?

By "house rules" I mean that my stubborn parents refuse to allow Lipos in the house or on the family boats (where I generally run from) due to a story they heard about a friend's lipo catching fire (after being improperly charged, over-discharged and dunked in the lake multiple times) despite the fact that I had planned on using lipo sacks inside ammo cans for storage and charging.

[bigcam406]

thanks for the reply Nick.i was wondering maybe look into the possibility of running a couple LIFE packs..a little less voltage,but safer than lipos,and longer runtimes than NIHMS.ive heard that they are a great alternative.no need to reprogram the boat either,as they dont require LVC.love to see a vid if possible.

[nickB722]

thanks for the reply Nick.i was wondering maybe look into the possibility of running a couple LIFE packs..a little less voltage,but safer than lipos,and longer runtimes than NIHMS.ive heard that they are a great alternative.no need to reprogram the boat either,as they dont require LVC.love to see a vid if possible.

bigcam,

You're in luck on the video but I won't be able to get it until next week. I've got a friend in video production coming in town for the 4th who will be more than happy to shoot some awesome video in exchange for a bit of drivetime. After his stuff I've just gotta get my hand on one of my race team's GoPros to get onboard footage!

As for LiFE, I don't know much about them, all I can say is the voltage will be lower than even NiMH. That said, with longer runtimes and less volatility than LiPos, they'd probably be a viable option for sport running.

[roadrashracing]

just run the 8.4s and have fun.

[nickB722]

Roadrash,

Right now I'm a bit more concerned with getting my setup right and getting the M445 prop fully prepped, once I do that I'll consider running the 8.4s but it's still a chance I'm not sure I'm willing to take. I don't want to fry and ESC and put the boat out of commission as I don't have the money to replace it and I doubt ProBoat/Horizon would replace one that was run on 16.8 volts when the listed limit is 14.8. What boat(s) did you run the 7 cell packs in and with what props? (if you recall, I'm sure it's been a while since you made the switch to LiPos) Did you add the 5.5 bullets or just run with the stock ones?

Thanks

[roadrashracing]

When I ran them, I ran them stock everything, I used traxxas connectors. The batteries did not really like prop changes, make sure you watch the temps, I made the mistake of running the batteries to low damaging them, the only reason my esc blew is because I hooked something up wrong. I did the motor to 4mm connectors. The 45 amp handles up to 21 v.

[nickB722]

In that case it stands to reason that the 60 amp ESC should be able to handle the voltage. I'm not sure though, the 45 amp ESC is rated to 21 volts whereas the 60 is rated to only 14.8. If I convert that into terms of power, the 45 amp is putting out 954 watts at 21 volts, the 60 puts out 888 with 4s of Lipo power, and over 1000 watts with 16.8 volts of NiMH (at least in theory), which is effectively 12% over the rated limit. I'd like to think ProBoat is using a safety factor in excess of .12, but I'm not sure it's a good idea.

I've been keeping the runs short to check temps thusfar and that won't change with any battery I put in. I'm not sure if I'll put the 8.4s in, I really want to, and it is tempting, but also risky. I'd hate to lose the boat for the long vacation the family has planned, all of it in/around water.

[bigcam406]

i wouldnt chance trying the 8.4's either.if Proboat says not to,then dont.use what you have and enjoy yourself.but i'd look into the LIFE batteries,from what ive read and heard,they are a great bang for the buck.you will need a charger that has the LIFE battery option on it for charging though.

[nickB722]

i wouldnt chance trying the 8.4's either.if Proboat says not to,then dont.use what you have and enjoy yourself.but i'd look into the LIFE batteries,from what ive read and heard,they are a great bang for the buck.you will need a charger that has the LIFE battery option on it for charging though.

It's an option I will be looking at for sure, but the lower voltage is certainly a potential turn off even with the longer run times. Might be a good idea with the M445 prop though, as the higher speed the prop gives may be offset by the lower voltage (but longer runtime).