Battery question, NiCD to Lipo

[LostFedExMan]

Hi everybody, so I just bought an RC boat (ABC Hobbies Super Hawaii 46) off craigslist. The previous owner jerry rigged up 2, NiCD batteries (6 cell I think, 3500MAH) as you can see in the picture here.



I dunno if these are the stock batteries but I'm assuming they are.

Now I want to get rid of these NiCD batteries and swap them out for a single lipo. So my question is, can I just get a 4S 20C lipo, solder on deans connectors to the battery and boat and call it good?

Thanks for any help

EDIT: The batteries have no specs on them anywhere, so I don't know for sure what they are.

Double EDIT: This is the battery I'm thinking of getting
http://hobbyking.com/hobbyking/store...Lipo_Pack.html

[Greatscott]

My guess is that you will give that boat a Viking funeral if you wire up 4S 20C lipos to that thing. I don't think that MSC will handle the throughput of lipo amperage and will fry it, and likely the rest of the boat.

Recommend getting a water cooled ESC with lipo cutoff, then install the lipos.

I had a Traxxas XL10 I bought new about 10 years ago. It was the ESC I pull off the shelf I bought rollers, to decide if they were worth dropping money into. If I decided I liked the truck I would get an ESC specifically for that rig, but I normally ran NiMH power through it. Recently I bought a B4 to see how well I like racing, and I installed my trusty XL10, but I also fed it 2S 40C lipos as well. It tried it's damnest, but that 10 y/o ESC just could not handle the continuous amperage of the Lipos. Luckily when it went nuclear it spared the lipo and the truck itself.

That aside, the boat looks like a great find and will be a lot of fun!

[AutoCrawler]

How many cells each are the original batteries? NiCd cells are around 1.2v. Lipo cells are around 3.7v. So you can replace 6 NiMH cells (7.2v) with 2 Lipo cells (7.4v).

You need to check of the existing batteries are wired in parallel or in series. If in parallel then you have a 7.2v system and you should only uses 2S Lipo . If in series then you have a 14.4v system and you can use a 4S lipo.

Since LiPos weigh much less then NIMH you can get higher rated mAH battery for the same weight for longer run times.

If you convert to LiPos you will need to add a battery voltage cutoff or alarm to protect your battery as LiPos do not like to be fully discharged. Since this is a boat you probably want an alarm in any case to tell you to bring the boat in before the battery dies.

[pritch]

No way would I be running lipos on an old MSC as Greatscott has already said. Anything less than full throttle will put a great strain on the resistor.

First upgrade would be a good watercooled 4S ESC like those found in the Miss Geico.

[AutoCrawler]

Originally Posted by pritch

No way would I be running lipos on an old MSC as Greatscott has already said. Anything less than full throttle will put a great strain on the resistor.

First upgrade would be a good watercooled 4S ESC like those found in the Miss Geico.

Why? Apart from this thing being old tech and obviously a modern ESC is better, a lipo is just a battery (safety concerns aside). If the resistor is in good condition and the contacts are not worn out and the motors are in good shape I don't' see what the problems using a lipo could cause vs using any other type of battery so long as you use the correct voltage.

The motors will only pull the current they need so if you change out the motors from original then yes they might draw more current than the resistor is designed for but if they are the original system and it worked fine on the NiCd batteries it will work fine on the same voltage Lipos.

Lipos don't magically push current just because they are lipos. They do have the capacity to deliver more current so if you get a short or a motor stall the battery won't limit the current for you. A simple in line fuse will fix that if it's a concern.

[AutoCrawler]

Looks like the batteries are wired in parallel so 2S max only is my guess but you should count the cells and check They look quite small so could be only 4 cell which is 5v. which would make using a lipo of any kind more difficult. 1S is likely too low and and 2S is too high. To be safe you would have to use a Voltage Controller (like a BEC) of some sort to bring the 2S voltage down a bit. At that point probably you either find 5v/6v NiCd/NiMh packs or or do the full upgrade.

Not saying you shouldn't just upgrade the electronics, the boat will work much better, but sometimes there is joy in making old tech work.

[AxialJeepster]

TRY ITTTTTT ...

kidding.. but really, those old MSC's are sometimes very burley and can handle alot more than you think. I bet you can run a good 25c 3s lipo and be good2go.. you need to regulate what goes into your RX tho. BEC.

BUT, I would recomend you going to Hobbyking.com and looking around, they have nice units that are 50 to 100amp 3-4s capable watercooled or not, for 25 bucks on up. CHEAP..!!

if you want to keep the same motors, try getting an old e-maxx esc 14.4, get a BEC for your rx/servos, run 4s and an alarm along with a fan for the esc.

few options.

my MSC in my 18v drill does great on 6s lipo LOL

[LostFedExMan]

Sweet thanks for the replies guys. I guess what I really need to find out is weather they are wired in series or parallel. Does anybody know how I would find this out?

The way the PO had it is 2 NiCD batteries plugged into a 'Y' adapter then the single plug from the other side of the 'Y' adapter powering the boat. Since it's 2 batteries going into 1 connection I assumed the batteries were used in series, still not for sure tho, anybody know?

I believe the original batteries are 6 cell, but I'm not positive. I've never had NiCD batteries before. They are the same size as the old NiMh I use to use, and those were 6 cell. Are NiCD and NiMh cells the same size? Would a 6 cell NiCD and a 6 cell NiMh be virtually the same size?

If the batteries are wired in series, which means the boat would be running on 14.4v, why would it make any difference where the 14.4 volts are coming from? Weather it be a NiCD, a NiHm or a LiPo. 14.4 volts is 14.4 volts isn't it? The motors are going to draw the same amount of power regardless of what type of battery is powering the boat, as long as it's 14.4v that is powering the boat correct? (Assuming the batteries are wired in series)

Thanks again for the help guys, I already run LiPo in my crawler, so I have a couple low voltage alarms already. Just need to find out what voltage this boat is running off of so I can buy a couple more batteries.

Appreciate the hlep

Edit: I just remembered the comment about adding a fuse, there is currently a 25 amp fuse on the power wires for the boat.

[heartless]

a little video explaining the differences between series & parallel...

RC Day: Lipo Batteries - Parallel vs Series adapter - How to make your own adapter soldering - YouTube


From your picture, I would say that the current setup is definitely parallel - longer run time, but same voltage as a single battery...

so, you need to determine voltage of those batteries - either a digital readout battery charger, or a multimeter, reading a fully charged battery would give you that info - and proceed from there.

[LostFedExMan]

Heartless thank you so much! That video helped a LOT! Alright, so I'm pretty convinced the batteries are being run in parallel. Which means if they're 6 cell NiCD's I can run a 2S Lipo because both are 7.2 v

So what I'm going to do when I get home is take the ugly tape off the jerry rigged 'Y' connector and find out for sure if the batteries are in series or parallel. Then I'll know weather to order 2S or 4S Lipo's. I'm pretty stoked to get this thing on the water.

This is the battery I am considering now, probably going to buy 2 Turnigy 5000mAh 2S 20C Lipo Pack

[Trubble]

Originally Posted by LostFedExMan

Sweet thanks for the replies guys. I guess what I really need to find out is weather they are wired in series or parallel. Does anybody know how I would find this out?

Yes, you need to peel off that green tape and see what's underneath it. For the life of me, I don't know how people can make the call that it's parallel. Must have x-ray vision or something.

Once you peel off the tape you're going to find one of two things. Either there'll be two 'scotch-locs' or butt connectors, with all the reds connected to reds, and all the blacks connected to blacks. This would be parallel and you'd need to order up a 2 cell LiPo (or 3S if you're feeling lucky )
Or you'll find the black going to one Tamiya connector, the red going to the other Tamiya connector, and a loop (could be any color) going from Tamiya connector to Tamiya connector. This would be series and you can get your 4S LiPo.
Judging from the size of the ball of tape, I would lean towards the second of the two possibilities above, but until you unwrap it, can't know for sure.

Originally Posted by LostFedExMan

The way the PO had it is 2 NiCD batteries plugged into a 'Y' adapter then the single plug from the other side of the 'Y' adapter powering the boat. Since it's 2 batteries going into 1 connection I assumed the batteries were used in series, still not for sure tho, anybody know?

Potentially dangerous assumption. Post up a pic with the tape off, and we'll see if we can't get ya straightened out.

Originally Posted by LostFedExMan

I believe the original batteries are 6 cell, but I'm not positive. I've never had NiCD batteries before. They are the same size as the old NiMh I use to use, and those were 6 cell. Are NiCD and NiMh cells the same size? Would a 6 cell NiCD and a 6 cell NiMh be virtually the same size?

Those are not 4 cell packs. Period. Those aren't even 2/3A packs. There's a receiver and some Tamiya connectors right there to get a sense of scale from, plus those packs go nearly clean across the boat! Now my Great Planes Stinger (boat) was much wider, but I still remember how of it looked when I had it.
And NiCad packs seem to stop at around 1800 mAh, so if those are 3800's as you said in your first post, those likely are NiMhs. And NiMh cells are very similar in size to NiCads, maybe some difference in diameter, but not much. If they were unwrapped and placed on a table, I firmly believe a vast majority of the people here couldn't tell the difference. I've been rebuilding NiMh/NiCad packs for 25+ years, and I doubt even I could tell. So a NiCad pack would be the same size as a comparable NiMh pack.

Originally Posted by LostFedExMan

If the batteries are wired in series, which means the boat would be running on 14.4v, why would it make any difference where the 14.4 volts are coming from? Weather it be a NiCD, a NiHm or a LiPo. 14.4 volts is 14.4 volts isn't it? The motors are going to draw the same amount of power regardless of what type of battery is powering the boat, as long as it's 14.4v that is powering the boat correct? (Assuming the batteries are wired in series)

Now you're thinkin' witcher dipstick!
You almost HAVE to go LiPo, really. I mean, your average NiMh/NiCad cell when fully charged is usually 1.45-1.5 volts. Your average LiPo cell is 4.2 volts fully charged. Thus the six cell packs you have are 8.7-9.0 volts when fully charged, a 2S LiPo would be 8.4 volts fully charged. Thus, doesn't it make sense that you'd actually be giving old electronics something of a break by running just a wee bit less voltage? You'd be doing it a favor, you almost HAVE to go LiPo. And if those packs are in series, your looking at 17.4-18.0 volts when fully charged. A fully charged 4S would only be at 16.8 tops. Again, you'd be doing your old boat a favor.

Originally Posted by LostFedExMan

I already run LiPo in my crawler, so I have a couple low voltage alarms already.

LVA=Excellent idea.

I also like the fact that you're running a 4 cell AA holder for your radio and servos, just never been a fan of BECs in boats or airplanes.
My Aero-Zeta didn't even have a BEC circuit in it. Handled 12 (or occasionally 14) cells, fed two motors and lived in the radio box with the rest of the electronics. Surprised that thing never melted down.

Anyways, post up a pic of that adapter unwrapped, I'd like to see what's in there.

[pritch]

Originally Posted by AutoCrawler

Why? Apart from this thing being old tech and obviously a modern ESC is better, a lipo is just a battery (safety concerns aside). If the resistor is in good condition and the contacts are not worn out and the motors are in good shape I don't' see what the problems using a lipo could cause vs using any other type of battery so long as you use the correct voltage.

The motors will only pull the current they need so if you change out the motors from original then yes they might draw more current than the resistor is designed for but if they are the original system and it worked fine on the NiCd batteries it will work fine on the same voltage Lipos.

Lipos don't magically push current just because they are lipos. They do have the capacity to deliver more current so if you get a short or a motor stall the battery won't limit the current for you. A simple in line fuse will fix that if it's a concern.

Yeah fair points, but I still would not feel comfortable running around with powerful lipo batteries hooked up to an old MSC, in the context of a r/c boat. An MSC resistor experiences heat build-up at partial throttle and NOT running at full throttle with an MSC and lipos nearby is just asking for problems IMO. It might be fine, but it might not, and as it's a boat if it's the latter your goose may be cooked. Why risk it?

I agree it's cool to make old tech work and I never throw away anything related to the hobby away, but I couldn't do this in either of my two boats, especially when modern ESCs are so much better and more efficient.

[LostFedExMan]

Originally Posted by Trubble

Yes, you need to peel off that green tape and see what's underneath it. For the life of me, I don't know how people can make the call that it's parallel. Must have x-ray vision or something.

Once you peel off the tape you're going to find one of two things. Either there'll be two 'scotch-locs' or butt connectors, with all the reds connected to reds, and all the blacks connected to blacks. This would be parallel and you'd need to order up a 2 cell LiPo (or 3S if you're feeling lucky )
Or you'll find the black going to one Tamiya connector, the red going to the other Tamiya connector, and a loop (could be any color) going from Tamiya connector to Tamiya connector. This would be series and you can get your 4S LiPo.
Judging from the size of the ball of tape, I would lean towards the second of the two possibilities above, but until you unwrap it, can't know for sure.




Potentially dangerous assumption. Post up a pic with the tape off, and we'll see if we can't get ya straightened out.



Those are not 4 cell packs. Period. Those aren't even 2/3A packs. There's a receiver and some Tamiya connectors right there to get a sense of scale from, plus those packs go nearly clean across the boat! Now my Great Planes Stinger (boat) was much wider, but I still remember how of it looked when I had it.
And NiCad packs seem to stop at around 1800 mAh, so if those are 3800's as you said in your first post, those likely are NiMhs. And NiMh cells are very similar in size to NiCads, maybe some difference in diameter, but not much. If they were unwrapped and placed on a table, I firmly believe a vast majority of the people here couldn't tell the difference. I've been rebuilding NiMh/NiCad packs for 25+ years, and I doubt even I could tell. So a NiCad pack would be the same size as a comparable NiMh pack.



Now you're thinkin' witcher dipstick!
You almost HAVE to go LiPo, really. I mean, your average NiMh/NiCad cell when fully charged is usually 1.45-1.5 volts. Your average LiPo cell is 4.2 volts fully charged. Thus the six cell packs you have are 8.7-9.0 volts when fully charged, a 2S LiPo would be 8.4 volts fully charged. Thus, doesn't it make sense that you'd actually be giving old electronics something of a break by running just a wee bit less voltage? You'd be doing it a favor, you almost HAVE to go LiPo. And if those packs are in series, your looking at 17.4-18.0 volts when fully charged. A fully charged 4S would only be at 16.8 tops. Again, you'd be doing your old boat a favor.



LVA=Excellent idea.

I also like the fact that you're running a 4 cell AA holder for your radio and servos, just never been a fan of BECs in boats or airplanes.
My Aero-Zeta didn't even have a BEC circuit in it. Handled 12 (or occasionally 14) cells, fed two motors and lived in the radio box with the rest of the electronics. Surprised that thing never melted down.

Anyways, post up a pic of that adapter unwrapped, I'd like to see what's in there.

Thank you sir for the wealth of information! I really do appreciate it! I will unwrap the tape and take a pic and post it when I get off work today. The real reason for me buying this boat is to take it fishing. Already got one of my ice fishing poles rigged to it, now I just need to get the batteries (ordered 2 of these Turnigy 5000mAh 2S 20C Lipo Pack figured if it's 2s then I'll have 2 batteries, if it's 4s then I'll just wire them up in series) and get out on the water! WooHoo!!!!



Thank you everybody for ALL of the help! I love this friggen site! I will keep you all updated on what ends up happening.

Thanks again

[millfire517]

Make sure you get some video of that things first run on lipos, lol

[LostFedExMan]

Alright so I got that mess of tape off and took some pictures, I'm going to have to go back and watch that video again because I can't determine weather the batteries are wired in series or parallel. Let me know your thoughts.





I really wish I could just find the stock specs somewhere online, but I feel like I've searched everywhere with no luck.

So any input would be great, thanks guys.

[LostFedExMan]

After watching the video it looks to me like the batteries are setup to run in parallel, still not sure on that though. Thoughts?

[RiceBurner]

Yep parallel, 7.2 and a long run time.

[LostFedExMan]

Awesome thank you my friend

[AutoCrawler]

agreed - batteries are Red to Red to the Red power wire and Black to Black to the Black power wire so definitely parallel. Just imagine the tamiya connectors in the picture are the batteries and it makes sense.

Note; If it was series then the black of the first battery would would go to the black power wire, the red of the second battery would go to the red power wire and the red from the first battery would go the black of the second.

Other things we could check before you wire it up.
How many cells in the old batteries?
Does the resistive motor controller have a brand or model number? If so we can do a google search for any specs on it which may be interesting.

[LostFedExMan]

Thanks Auto, the batteries are 6 cell, I haven't even thought about closely inspecting the resistive motor controller for a brand name or model number. I will try to do that and see if I find anything tonight after I get off work, then I will report back.

Thanks again everyone