Battery options ....

hobie

Currently use a 7.2V Pack 1800mAh Ni-Cad battery for a water based model but find running time a bit short ....

What are my options to get something with more capacity ? .....

Where is the best place to try for it? ..... preferably here in IRL .... I don't really want to spend a fortune .... :rolleyes:

cheers for any info ....

T-Maxx

Really depends on what a "fortune" is...;)

You could get 3000mAh plus NiMH packs from less than €20 all the way up to like €80. But if you want to buy locally, I'd say contact (Yup, you guessed it):

Green Hobby & Model

vectra

3000 Mah for £9.95

3300 Mah for £9.95

3700 Mah for £12.50


Really go for a long runtime with these 4300 Mah packs For £19.50
That should get you going..

g5hn710m4xpdwy

:othanks for the link(s) vectra. I am gonna be ordering 2 3300's soon:D

coolwings

Max Discharge Current : 30 Amps !

vectra

coolwings wrote:

Max Discharge Current : 30 Amps !

??
Isnt that enough ?

g5hn710m4xpdwy

More than enough I was thinking... Thats very high ampage, although I dont know much about these batterys and discharging

coolwings

Power:
At the moment of startup, a bogstandard 540 motor hits 89 amps briefly. Then as the motor begins to rotate, the current falls down from the startup spike, and reduces to the level dictated by the running load of the car/throttle.
Continuous current of a standard "car" motor: About 18-20 amps flat out with no load (freewheeling the motor with nothing connected).

What the continuous current at full throttle (when installed and driving the car) would depend on car weight, if accellerating, and friction in the linkages. Too hard to guess - there is a huge variation between makes. I suppose it is reasonable to assume average 15 amps with surges on accelleration/braking of double that.
That current would give 8 minutes from a 2000 battery. So if you have in the past got 8 mins from 2000s then those estimates would be close to what your were consuming.

A hot motor would double those figures easily.

The battery pack:
The price says it all. You get exactly what you pay for.
eg a 3000 budget pack has half the price, and also half the lifespan, and half the power of a similarly labelled 3000 which has far more efficient chemistry inside.
Those "yellow pack batteries" are fine for beginners, so if that is what you want, cheap and it goes, ... it's not much money, buy two.
The cheap batteries require a slow charge rate, no faster than 40 minutes, and preferably at least an hour or they get really hot.
These will also be very hot after a run , so leave them to cool before putting them on the next charge.

I would rather have one performance pack myself though. The model would go better.

vectra

coolwings wrote:

I would rather have one performance pack myself though. The model would go better.

I would Prefer decent batteries myself. But I only pointed him towards those ones as they seem good value at less than a tenner easch and he stressed that he didnt want to spend a lot. :cool:

coolwings

vectra wrote:

I would Prefer decent batteries myself. But I only pointed him towards those ones as they seem good value at less than a tenner easch and he stressed that he didnt want to spend a lot. :cool:

Quite right.
The car would go faster with a good battery. People have said things like "Twice the speed for twice as long with the better battery" to me in the past. This is an exaggeration, but it is how they see the difference, and is significantly faster for a good time longer.
Note that this might be comparing a 2000 cheapie with a 2000 premium battery. So the battery capacity is the same, but it is far better at passing the power in an out without wastage.

I agree and suggest the way to go with cheapie packs is to buy several of them, charge from the mains in advance, and use them in sequence until they are all empty, then pack up for the day. It suits the person without a fast charger or the power source to feed one when "in the field"..

But I too prefer the performance batteries.

vectra

coolwings wrote:

I too prefer the performance batteries.

Yeah,
That the reason I got some Schumacher IB4200 Worlds cells.. BLOODY AWESOME packs..!!

hobie

Thanks for all the input guys ... really appreciate it ....

I only have the one Boat ..... my existing Ni-Cad 1800 lasts 10 to 15 minutes ..... I only have a mains charger so a second battery seems to be the way to go per coolwings suggestion ..... managed to locate one in my local Maplins at 17.00 yo yo's ......

I'll see how I get on with the two ...... :rolleyes:

couple of questions ..... do I need to charge the batteries within a reasonable time period of intended use (say the night before) or will they hold their full charge for a few days? .....

What's the best way to ensure they are fully discharged before charging ? .... my charger is a simple mains type and doesn't have a discharge option .....

cheers ......

coolwings

hobie wrote:

..... do I need to charge the batteries within a reasonable time period of intended use (say the night before) or will they hold their full charge for a few days? .....

They will "leak a bit" when fully charged, say about 5% over a week, or 10% in a month. Not a problem if you charge today and run tomorrow.

hobie wrote:

..... What's the best way to ensure they are fully discharged before charging ? .... my charger is a simple mains type and doesn't have a discharge option ....

Do you need to discharge? I mean the model will discharge them when you run it.
They can be recharged from empty, or from half full, or from just below full if already charged a few days ago. The charge tops them up back to full.
Just don't put them on a fast charge if nearly full already, unless you have an auto peak detect charger.

vectra

coolwings wrote:

Do you need to discharge? I mean the model will discharge them when you run it.
They can be recharged from empty, or from half full, or from just below full if already charged a few days ago. The charge tops them up back to full.
Just don't put them on a fast charge if nearly full already, unless you have an auto peak detect charger.

Yes, You do need to discharge them if they are Ni-Cads as they develop a Memory effect...Dont they?

It is ok to charge Nimh from any state of charge ( top up ) as they do not suffer from a memory effect.

@ Coolwings... Correct me if I am wrong ( as I know you will do )

T-Maxx

If you frequently only top-up your NiCd's, they will develop a "memory effect" and false peak. On the other hand, if you more often than not run them down in your model, you should be alright.

(BTW, NiMH's also suffer from "memory effect" but to a waaaaay lesser extend.)

coolwings

Memory effect in nimh is so slight, that one power discharge (say in a year) and one or two fast charges (during a year) would totally eradicate it so it was so small as to unable to measure.
This was more significant in nicad batteries as TMaxx said.

hobie

The instuction leaflet mentioned battery should be fully discharged before charging and the charge time to be exactly 5 hours .....

(Batt is 1800MAh and charger is 350 MAh) .........

I can put the charger on a timer and I'll try to ensure I run the battery right down when used on the model .....

Thanks again ....

coolwings

hobie wrote:

The instuction leaflet mentioned battery should be fully discharged before charging and the charge time to be exactly 5 hours .....
(Batt is 1800MAh and charger is 350 MAh) ....

Sounds like that will work.

With my own charger and batteries (Aeronaut Vario & Graupner Ultra Duo Plus chargers, and GP cells) I would be more likely to charge at 5.5 amps and have it done in 25 minutes.
But that would melt the low cost cells .... don't try it, just follow the instructions that came with them.

hobie

Would this be considered an up market battery (versus the yellow packs) ........

(for a Ni-Cd battery)

http://www.camelionbattery.com/showbat1.asp?bat=168

coolwings

All nicads are obsolete. But they can recharged fast, and are cheap.
Nicads will soon be made illegal due to the toxic nickel-cadmium chemicals used inside them.

The newer nimh could possibly suffer under the same eco legislation. But they are a more up to date technology.

hobie

coolwings wrote:

All nicads are obsolete. But they can recharged fast, and are cheap.
Nicads will soon be made illegal due to the toxic nickel-cadmium chemicals used inside them.

The newer nimh could possibly suffer under the same eco legislation. But they are a more up to date technology.

The reason I ask is because I purchased the Maplin battery and used it for the first time yesterday ..... despite being the same rating as the original battery supplied with the boat, it lasts far longer than the original

The original battery is the classic yellow appearance ..... no manufacturer, just the rating .... :rolleyes: