Mountfield s46 hp li 80V

[openspaceman]

Long time since I have been here with a problem; I have had a 80V cordless Mountfield mower brought to me which will not go. The dealer that supplied it has said it is not repairable. The 80V battery shows three green lights and measures 80V across the terminals.

I know it is basically a Stiga system  but just wonder if there are any swift checks or common faults people are aware of I can look at first?

[Mick]

Welcome back.  I'm not going to be much help on this one because I've not had any dealings with the Mountfield / Stiga cordless stuff at all. 

I'm assuming the machine has basically the same components as in a switch / Motor/ and motor controller.  The EGO machines also have safety switches on the extendable and folding handles, but I've no idea if the machine you have is similar in that respect. 

Does the MF / Stiga machine have a hidden fuse somewhere like some of the others (EGO) do?

[openspaceman]

Thanks Mick

As far as I can see there is commonality between Mountfield, Stiga and Greenworks mowers.

The motor is brushless (Sanyo?) and the main parts are the motor, a controller PCB and the 80V battery.

This one has a safety button that is pressed first and then the motor control trigger is pulled.

In this case when the trigger is pulled there is a faint click from the PCB relay I think. Subsequent release and depression of the safety button emits a double beep from the PCB sounder. There is no motor movement but it rotates with the cogging one would expect from a brushless motor.

A search reveals the PCB  is available in America where it was also used in a snow blower.

The PCB serial number 362011505D 12/1/15 on mine differs only on the Letter D after the number from the Greenworks stuff mentioned on a search with the "2 beeps of death". The PCB is embedded in plastic but you can see the shapes of ICs and IGBTs plus capacitors, sounder and solenoid on the board. The parts see to be rated at less than 80V!

So I guess it is the PCB but cannot find one in UK and worry that if it is the motor I will have wasted the cost of the PCB.

I wonder what other cordless machines take the 80V battery as I hanker after a long reach hedgecutter, having broken the gearbox on my Stihl HL75

[Mick]

The downside of cordless machines as it stands, is the parts to fix them cost an arm and a leg atm.  The cost of any of the four main components (including battery) will probably render most of them scrap. 

They are great to own while in warranty, but after that it could get expensive.

[openspaceman]

So it seems Mick, which is why I shall try and find a use for the battery, even if I have to break thee cells out and rebuild a pack for my drill or angle grinder.

I would expect there to be a generic motor controller, if it comes to it I'll have a look at the motor and see if it will run, else it will make a little alternator.

[Mick]

I would expect there to be a generic motor controller,

I've actually been searching for a low cost controller for my old 21"EGO mower.  There's loads of them about on Wish or ebay etc, but not sure what wattage etc I would need if I'm honest. I will investigate more  

[openspaceman]

I have just had a quote for the PCB of £314 and no stock, this writes the mower off as Mick says.

[openspaceman]

Worse still my local stiga dealer says the 80V battery has been phased out, only a short 2ft hedge cutter was available with it apart from the mowers. So it will be a struggle even to make use of the bits, I have yet to get to the motor.

Where's Barrie the stiga dealer when I need him?

[Mick]

Where's Barrie the stiga dealer when I need him?

Good question, lets tag him and see if he responds @GardenKit

[GardenKit]

Hello Guys!
Sorry, I have not looked in for months so only just seen this as a post appeared on my fb page somehow and reminded me!
Hope you are both keeping well.
Regards the 46hp li, maybe its sorted by now, or scrapped, or just sitting there awaiting inspiration!

I do have a trouble shooting manual for this that I can email you if you let me have your email, but TBH you are probably on a loser anyway.
Check all connections first, it may be that simple but I guess you have done that.
If you find you need a motor they are available at £210, but the PCB is not orderable and has no official part number according to the Siga dealer site.

The 80v system was technology that Stiga bought in from Greenworks and fitted to their own mowers. It was short lived whilst they developed their own unique 300,500,700 and 900 series kit all using the same 48volt batteries of their own design and manufacture which have proved to be very good. Unfortunateley the 80V stuff and many dedicated spares are now on very low stock or obsolete.
email me if you want the manual. barrie@gardenkit.co.uk

[openspaceman]

Hi Barrie

Thanks for the reply, better late than never eh?

Thanks for the history and confirming it's probably not worth going further with.

Not being able to re use the battery disappoints me most. I shall probably strip it and see if the cells are common to any of my power tools.

The motor interests me in that it will make a small alternator and I'm tempted to stick a honda motor on the deck as its own has rusted away. Something to play with before spring.

[GardenKit]

Good plan to put the Honda motor on, but you will need a blade boss too and the handlebars are different. You will need the OPC bar and cable.

If the battery is good you could probably get a few quid on ebay, although technically you cannot send them by carrier as they are a restricted item. They are over £400 new!

Same applies for the charge which is £120 new.

[openspaceman]

I'll try and use the blade and honda motor as a push along.

I'll move the wheel drive mechanism to my other honda that has a broken one.

When I picked up the cordless to see if I could repair it the owners kept the charger which was new. I offered the battery back to them but they weren't bothered so breaking it down to cells seems the only option.

I did go to a Stiga dealer to see if I could buy a hedgecutter or other tool that used the 80V battery but nothing presented itself.

[openspaceman]

Good plan to put the Honda motor on, but you will need a blade boss too and the handlebars are different. You will need the OPC bar and cable.

It takes me a long time to get anything done nowadays but the bank holiday weekend gave me the chance to have a bash at this. The Honda motor from an eco HRG46c, which I had been given with an extremely corroded deck, bolted straight onto the pristine Mountfield S46 deck using 3 bolts. The blade cutting edge is 1/8" higher than the deck bottom so should work fine. The top half of the Honda handle fitted directly onto the bottom of the mountfield s46 handle.

The engine is a pig to start, doesn't smoke and sounds fine but the speed control doesn't see to have any effect on the governed speed, it sits at 2400rpm. Fuel cap missing too but else looks good.

What is the normal top governed speed of these engines?

I was also given a Halfords jump starter pack complete with inverter and compressor with a duff 17Ah gel cell battery. The battery pack from the S46 fits exactly in the space the gel cell vacated once the 80V bms and power management circuit boards are removed. It should be an easy job to  reconfigure the 32 Lithium ion cells to a 4S configuration (4 strings in series of 8cells in parallel) and I have a new 16V 40A  BMS for the purpose. I hope I can find someone with a spot welder to make up the connections with nickel strips.

The transmission from the honda mower looks good and should be a direct fit into the Honda powered champion mower I first came to this forum to ask about. So with a bit of luck I shall have a walk behind rather than push along mower, lithium ion 16V power pack and a push along mower to give away from all the freebie bits I have collected in the last year or so.