Snap on Battery charger 6/12/24 V repair

[chrisf1]

I have just bought an old school snap on battery charger and booster for auto stuff the model no is YAH166B, I have actually rung snap on main depot and they politely told me they no longer repair them so much for lifetime warranty I am willing to pay them but a firm NO. I remember these from years ago and were a very powerful machine mine does not appear to be working correctly it does not appear to be giving out sufficient power is there anyone on here or knows of anyone who would repair it and check it out for me, I am located in Kent, many thanks Chris

 

[Red'n'Black]

I found the schematic, looks like a fairly simple design.

I'd have thought between the knowledgeable folks on here we should be able to help you fix it. What test gear are you able to lay your hands on? DMM etc.

Can you posts some pics of the innards?

 

[chrisf1]

A multi meter that I do not really know what I am doing with? I will take some pics of the magic inside tomorrow

 

[Red'n'Black]

Good stuff. Post a pic of the multimeter as well, that will save a lot of crossed wires

 

[Ross365]

It's a monster; the meter is calibrated 0-100amps. As long as the transformer is good, shouldn't be too hard or expensive to fix. I think that the modern technologies being used in lead acid batteries now may be less tolerant of fast charging than the batteries of yesteryear, so may need using with care when fixed? It certainly has the ability to vaporise a multimeter connected incorrectly.

 

[chrisf1]

I remember this would crank a car and start it on a completely dead flat battery when used as a booster

 

[Alan Reynolds]

When you say ‘enough power’ do you mean voltage or current? Looking at the circuit it’ll probably be a switch interchange problem or possibly the output rectifier. It shouldn’t be too difficult to check out with your multimeter with the unit off in the first instance.

 

[chrisf1]

I just hope with your guidance we can solve the problem as I am not the greatest technician in the world and with electrics I am truly in the dark

 

[Barking Mat]

Good stuff. Post a pic of the multimeter as well, that will save a lot of crossed wires

Post a pic of your multimeter, it will really help.

 

[chrisf1]

About to try and post pics not sure exactly what I am doing but will give it a go

 

[chrisf1]

Here is a few more cant believe it worked for me

 

[Ross365]

That is a fantastic piece of kit, but I'm inclined to say that it's also a bit scary because of its shear power. Do you really need such a thing; is it really suitable for routine charging?

I charge batteries quite often; I have two cars but most weeks do relatively little mileage, so I have to use a charger periodically as the modern security systems slowly discharge batteries. I have a homebuilt charger on which I can adjust the voltage / rate of charge, and with modern (maintenance-free) batteries, I generally stay at no more than ~4amps and terminate charging at no more than 14.8V.

I just wonder whether or not that unit is appropriate to your needs? If not, sell it on and buy something more suited?

To start testing it, you really need a load for it, but if you want test it at currents of more than 5amps ( i.e. a headlight bulb) you really need a flat battery, perhaps with a headlamp bulb in series and measure the voltages (your meter does not have a current range) across the battery and across the bulb.

 

[octo0072000]

are those 3 black headed screws screw in fuses have you checked all of those also inside i would redo all the connections clean all the spades etc first

 

[chrisf1]

I am aware of the power and even though I am now retired I still buy and sell a few cars and a tool like this if I can get it working is a Godsend also not a lot of value selling it not working properly I gambled silly money because it is down on power

 

[Ross365]

are those 3 black headed screws screw in fuses have you checked all of those also inside i would redo all the connections clean all the spades etc first

I don't think those are fuses; the schematic doesn't show any fuses but has "circuit breakers" on both primary and secondary sides.

Cleaning all the connections is a lot of work; I'd be inclined to try and narrow the problem down by doing tests.

 

[Ross365]

See marked up pic attached. First test I'd do would be to measure volts across points shown in line 1 and then line 2; these are the transformer outputs. Set your meter on 200ACV; I guess that you should see somewhere around 16-18 (ac) volts on both positions.

 

[chrisf1]

Hi again Ross do I just need mains power on or do I need to finish circuit with a battery ( have only fully charged at the moment)

 

[Ross365]

That test just requires mains on, no battery. It's checking what AC voltage output there is out of the transformer, which if it's there, then goes on to the two rectifiers, meter and circuit breaker. Having a partially discharged battery to hand would be handy for subsequent tests.

Could you take a pic of the operating instructions printed on the top panel?

 

[chrisf1]

I actually have a download of the instruction manual which I will send let me know if you still want a pic of the top lot, in the pic you sent should I be connecting the tester at each end of No 1 and then 2 and thank you very much for this help as I really do not have a clue electrickery frightens me

 

[Ross365]

Yep; the transformer leads that go to the negative power output cable are from the centre tap of the transformer winding and then each end of the winding goes one of the two rectifiers (mounted on the big ali plate). Here's another diagram showing what I meant by line 1 previously, so do that test and then the equivalent for line 2.

Do remember you have mains voltage inside that unit, though these measurements should only see low voltage, but take care!