Slowing down a 12v motor speed plus running on 24v ?

[wookie]

I'd just run a tap fron the middle of the two batteries then find some way of regulating them.

Dont do this.

It results in the batteries getting out of sync re the state of charge. Then one either gets over or under charged all the time & will fail sooner.

Seconded, I've seen batteries that have had this trick done to them, one gets run down more and then doesn't get a proper charge whilst the other gets over charged and boils itself dry.

It's a surefire way of killing a pair of batteries in no time, even if you recharge each battery separately you'll still have to monitor each battery individually as you discharge them to make sure you neither gets too low.

 

[CompoSimmonite]

Seconded, I've seen batteries that have had this trick done to them, one gets run down more and then doesn't get a proper charge whilst the other gets over charged and boils itself dry.

It's a surefire way of killing a pair of batteries in no time, even if you recharge each battery separately you'll still have to monitor each battery individually as you discharge them to make sure you neither gets too low.

On my commercial made mobility scooter I fitted a 12v alarm by attaching to one of the batteries. That battery died before the other so net result was an, expensive, new matching pair was required. Learnt my lesson and won't do that again

 

[Wendelspanswick]

I'd be interested in how you connect two batteries in Series and in parallel at the same time without creating a dead short???

My pal has a Toyota Landcruiser, it has 2 x 12V batteries used in series for the starter (24V) but reverts back to both batteries in parallel for every thing else, done with a relay when you flick the key.

 

[MattH]

My pal has a Toyota Landcruiser, it has 2 x 12V batteries used in series for the starter (24V) but reverts back to both batteries in parallel for every thing else, done with a relay when you flick the key.

So not connected in series and parallel at the same time then.

 

[Wendelspanswick]

No and I never said that in my original post:

If your using 2 x 12v batteries in series for your 24V why not just run a seperate circuit for this motor using the 2 batteries in parallel?

 

[KemppiFrog]

Presumably the amount of use for raising and lowering would be miniscule compared with the transport mode, so why not a centre tap and a switch that alternates between batteries for the R & L. KISS

 

[CompoSimmonite]

Presumably the amount of use for raising and lowering would be miniscule compared with the transport mode, so why not a centre tap and a switch that alternates between batteries for the R & L. KISS

Idea is to mount winch low down behind seat so it can use an idler wheel high up to raise / lower seat. Then if scooter got stuck the winch cable could be undone from seat and routed either to front or rear for "self recovery" so it could be working for longer periods.

 

[MattH]

I'd be interested in how you connect two batteries in Series and in parallel at the same time without creating a dead short???

My pal has a Toyota Landcruiser, it has 2 x 12V batteries used in series for the starter (24V) but reverts back to both batteries in parallel for every thing else, done with a relay when you flick the key.

So not connected in series and parallel at the same time then.

No and I never said that in my original post:

Wasn't referring to your original post.

 

[Parm]

vehicle heater motor resistors often rely on air flow to keep from melting

Look for an element from an electric fan heater, I found one that had multiple attachment points as it was switched 1kw, 2kw, 3kw

I used mine as a dummy load for testing high power amplifiers up to 500w or more

not sure what dropping the voltage on the motor would do for the torque though

You got any spare amps that work ??)

 

[the snooper]

vehicle heater motor resistors often rely on air flow to keep from melting

Look for an element from an electric fan heater, I found one that had multiple attachment points as it was switched 1kw, 2kw, 3kw

I used mine as a dummy load for testing high power amplifiers up to 500w or more

not sure what dropping the voltage on the motor would do for the torque though

was that accurate though ? the dummy load resistance would need to match the amplifier ie 2, 4, 8 ohms

 

[500e]

Any help it was for Hi-comp BDA motors etc. put 24 volts on starter, you are not going to be winding seat up & down that much are you

 

[Wendelspanswick]

Wasn't referring to your original post.

Sorry, that's the trouble with communicating by word, its hard to judge without hearing the inflections.

 

[MattH]

Sorry, that's the trouble with communicating by word, its hard to judge without hearing the inflections.

No worries.

The problem the OP is facing is keeping it simple. I'd be inclined to make a simple regulator circuit to give 12v that can then run all the 12v ancillaries from the 24v series batts. I know it's a chunk of Amps but a T03 style reg with a couple of resistors on a small heat sink will easily give 20a.

 

[MattH]

TBF these are cheap enough and will give you the 12v for lights, adjustment motor etc. Then use a small PWM controller to add fine control to the motor.

http://pages.ebay.com/link/?nav=item.view&alt=web&id=281740160175&globalID=EBAY-GB

 

[bigegg]

Can you not just fit a small 12v battery?

 

[MoreWellie]

You got any spare amps that work ??)

Sorry, just sold the last high(ish) power amp, a 1400w Yamaha, a few weeks ago

was that accurate though ? the dummy load resistance would need to match the amplifier ie 2, 4, 8 ohms

As the heater element is one long spiral of wire I use croc clips to connect in wherever I want to get the correct impedance to match the amp. I realise it would change as it heated but I never saw it glow so presumed it didn't vary enough to worry about. I did put a fan on it if soak testing though

 

[CompoSimmonite]

Problem solved
£35 bought me a sub year old wheelchair hoist from an ex Mobility car. Twin 12v electric rams - 4500n and 300mm stroke plus another 3300n and 150mm stroke. Attached the hoist to my outdoor bench with G clamp, connected a battery and was like a kid playing with the up/down & in/out functions
Will use one of the rams (not sure yet which / how) for the seat raiser and then adapt the hoist so hand cable winch use so it can be used for loading things into trailer etc.

 

[Robotstar5]

Connect them together in a 2 stage lift so you can look over hedges?

 

[Justme]

Problem solved

Twin 12v electric rams

Dont you still have the 24v-12v problem?

 

[dannyp]

from my ******* around with dc electric motors all they really seem to care about is heat idthink you chould just pwm drive them with 24v, you probaly would want to go much past 25 % on the pulse width tho as i think that would be overdriveing them then