quad batteries

M cebee

i'm changing a couiple of quad batteries


they're standard SLA 12V 7AH


i'll prob fit 8.5AH deep discharge SLA's


just wondering if the existing chargers are going to be ok

they're 30watt 15volt 1.5amp

thanks

Bruthal

They will be fine, lead acid batteries are generally charged at an upper rate of 1/10c or for an 8.5AH battery, that would be 0.85 amps.

M cebee

they have the controls on top which are susceptible to damp

on/off switch and charger socket


is there anything i can do with them

Bruthal

Maybe each switch etc could be changed to weatherproof ones if the ones on it are not. And the actual charger input socket there could be moved to a different position. It looks like it would fill with rain water there where it is anyway.

M cebee

where would i get that gear

cpc don't seem to have DC waterproof switches

Bruthal

AC switches will work on dc loads, they just have to be smaller loads.

Is the on off switch just for swithing on and off the charger?

M cebee

it's the switch marked 'key'


i'll be replacing it with a regular switch

it turns on the quad-and i think it's wired back to a circuit board


i figured you could prob de-rate the AC switches

Bruthal

Yea you can measure the current that switch is taking during operation by breaking it through an ameter and running the thing. Not very much probably. Im using a few relays controlled from some PWM circuits im soldering up, they have AC ratings and a lower DC rating which is what im using them for.

M cebee

thanks

M cebee

is there a name for those input sockets

can't seem to find them

Bruthal

DC power sockets should find them in a search. They are all different sizes as well, the centre pin size and the outer diameter. Might be as well getting a matching pair, plug and socket, and just cut the plug off the power supply if it does not fit the new socket. I think the outer diameter commonly used is 5.5, and probably 2.1 inside pin diameter in the socket.


Here is one in maplin as example.

M cebee

hey robbie

i replaced old battery with a 12v 12ah deep-discharge

and i'm using a new 1amp(16aH) charger


seems to be a bit underpowered for some reason assuming it's charging fully

you have to push it to get it moving


i might parallel it with another one of same capacity
-i'd need a bigger charger for that

Bruthal

Yea paralleling it should work. For charging, a bigger one would be recommended alright. It depends on what charge current the single battery is taking from the charger when its discharged. If it was only taking 0.5 amps at most then it would charge both.

But its more likely you will need a charger of double the output, which would charge both batteries in 10 hours roughly.

Did the new batteries have a discharge current rating on them? As in the continous amps output rating.

Bruthal

If you can as well, put your multimeter measuring the voltage at the battery terminals, and see how much the voltage goes down when you try to drive the quad.

Fully charged the battery should be up around 13v too.

M cebee

the quads seem to be badly designed-they've given a load of trouble with parts

the old battery was 7ah if i recall,the manual says the motor is 120watt

i'll try your suggestions anyhow


not sure on the continous amps output rating

Bruthal

With 12 volt systems, bad connections come into it more than at 230 for the same wattage. So volt test under load at the battery terminals, and at the other end of the cable to motor. If the battery itself is dropping voltage a lot under load, then they are probably not able for the continous 10 amps for 120 watts, although you would think 12ah deep discharege batteries would be able for that, once fully charged. What is the actual battery, any links?

M cebee

http://cpc.farnell.com/camden/beg120120/battery-deep-discharge-gel-12v/dp/BT02861

that's the battery anyhow

i put my fluke multimeter on the battery and it was dropping from 13v to 12v


i might try a car battery before i do anything else

Bruthal

If its 12 volts under load at the battery, and its struggling to drive, then there must be another problem, as 12v should drive it perfectly. Test voltage at the motor end as well, as a bad connection might be possible between battery and motor, or whatever switching arrangement engages the motor. Or a problem with motor such as brushes.

When i converted that childs ride on tractor recently to radio control and fitted a joystick on it for a child with special needs, i used the multimeter to measure the current the motor was taking, so i could get switching relays suitable. As the load on that quad your looking at is 120 watts, a 10amp setting on the multimeter should be able to read it. I put it in series with the main battery by opening one of the connections. It might give you a better idea of how its operating.

Its surprising its not driving right just the same. Your car battery idea might be worth a try alright, once its fully charged. Car batteries are not suitable for deep discharging though, so wouldnt be suitable as a permanent fix.