openspaceman

A google shows a thread on reddit for the ap300 battery which suggests the BMS may store a fault code that needs to be cleared after a repair, it maybe that Stihl have done a John Deere on this. If @kram is right and there is no power control from the BMS via a MOSFET or IGBT then the BMS may communicate something to the charger to prevent charging and even after repair the battery may not work until this is reset.

I think the BMS has disconnected the battery, the small voltage you see is an ephemera of the bms connections. If so nothing will happen. If the battery was just flat the sudden rush of current would probably melt the wires you jumped the two batteries with, after all the 40V is 3 times what a car battery will zap if you touch the terminals together and a lithium ion battery has much lower internal resistance. I've had similar on a cheap ( but useful) Ferrex 40V grinder battery. It was one cell out of the 10 that had failed. I made the mistake of not de soldering the BMS to get at it and struggled to pull the bad cell out from the nickel strips it was spot welded to. Knowing what I do now I would take it to our repair cafe with a new cell with solder tags ( about 6 quid) and get one of the electronics experts fit it. If I am right the other 19 cells will be good. I recycle them by taping 4 together, adding a usb charger with type C charge port and protected usb output as little power packs.

I wouldn't advise taking it apart yet, each cell or pair of cells is probably connected to the battery management system and soldered. Can you count the cells? Fully charged they will each be just over 4.1V. The fact that you are measuring 196mV is either the battery is profoundly flat, which is unlikely or that a cell is out of circuit. Is there any way you can access the terminal each end of each cell?

I would file most chains freehand but the 4mm files had to be in a guide to prevent snapping.

Have you negotiated a commission with the old firm?

The whole series is being published now and I will even watch Chris Packam's effort. Only 82 MPs attended which is a shame but entirely expected. There's a syndrome about populations living under threats like volcanoes coping by ignoring the inevitable. We are like that now. The thing is it's now too late to avert these problems and it was because long dead politicians and dictators didn't take precautions, because the poor aspire to have their share of what the rich have had and the rich won't retrench because they are enjoying what they already have and want more. We have pickled the planet in our effluent. We knew we couldn't rely on fossil fuels beyond a few more generations, and then came the problem from the surge in use of the atmosphere to dump the consequential CO2, but resisted change for all my 3/4 of a century.

I have one from my daughter that packed up for just the reason discussed above, I recharged it but it had lost a lot of capacity and is not much use other than the usb port now. I think they all have pouch cells rather than cylindrical ones as these have a higher discharge current but shorter life. The silly thing is I advised her to buy a cheap lead acid one as her's was an EV that kept discharging the 12V battery, so it wouldn't start, it only needed to produce 12V and a small current to close the contactor on the main battery. Eventually sorted with a firmware upgrade, hence it just got left in the glove box for 3 years. Her new EV (MG4) just came to a halt in traffic and put itself into park before disconnecting everything, no warning. Had to be manually released and towed off. Turns out it was a temperature sensor in the heater circuit reading high. I remember the days when you had an oil pressure light, a temperature gauge and a charge warning light on before the car was not driveable.

Good post @kram. It's a bit like smart chargers for a car battery won't work if the battery is profoundly flat so you have to kickstart it with another good battery across the terminals. There is a good reason for this and that is the electrolyte in a lithium cobalt battery is flammable, if there is a fault in the circuit the charging current heats a cell up until it ignites the electrolyte. I recover batteries that have been left too long by opening them up and using a usb charger attaching it with small magnets one cell at a time.

Good chance this overpopulated islnd will not find food to import in the next 50 years

It's normally in the track motor, the feed only goes to half the pistons in high speed, so doubling the rpm and halving the torque. The trouble with increasing the pump capacity is that everything downstream has to be capable of taking the extra flow, pipes, spools and motors, else the oil gets too hot. and of course the motor and spools have to be rated for the increased flow. I had this problem to deal with on a machine my predecessor had had built and he had just added an oil cooler which didn't solve anything really. I found the spool valves for tracking the Forst too coarse and sudden compared with the Jensen and Greenmech tracked machines but we had the first two tr6s I think.

I felt the same when they were the Greenmech dealer for our area and was happy to deal with a dealer in Birmingham instead, neither are Greenmech dealers now.

These engines have pressure lubrication, i.e. with an oil pump, don't they? If so and the small rectangular hole is an oil gallery it would explain why oil was being pumped into the head rather than combustion gas pumped out.

More simple steps please. I've plucked them, skinned them but if this is simpler and quicker I'll have a go. I've a brace hanging, first in over five years. I shall check the meat for steel shot with a pin pointer.

Good shout, I was thinking an oak and the bark looks like ilex, I cannot remember the heart though.

I think I still have my FiL's empty coke can launcher which is probably much the same.

If oil is not frothing out of the crankcase nothing.

Over full with oil? Can you take crankcase breather off the carb and block the hole into the carb?

I haven't got a proper hang of these check valves but the main jet venturi is only under higher pressure than the diaphragm chamber when the throttle is shut and the downstream idle outlet is subject to full manifold depression. I still wonder if blocking this would overcome the problem at the expense of idling?? I still have a strimmer with the problem of air getting into the chamber via a leaky check valve to fix, along with a heap of other engines that need attention. Will probably have to wait till spring.

I had assumed it would be easier to pull the whole shrub then cut and feed a chipper. So cut and chip then go over the ground to pull roots is better?

Why did that remind me of "in a broken dream"

I doubt it and I bet they cost a lot. Stirling engines are typically in hermetically sealed units, like freezer compressors, to prevent leakage of working gas. The only DIY thing I would consider would need petrol, diesel, LPG or mains gas. A small water cooled engine and in my case just running to charge a battery an hour or two a day in winter.

Just for my interest; is there a shear that would grab a bunch of gorse, birch or holly coppice, pull the whole bush and root up, then shear the root off? Say up to 3" diameter and generally shear 5"? What size 360 would it need?

Yes it's amazing how much wood even this little house gets through and no backboiler. I expect I get through 30kg of dry wood on a cold day. I would like a small version of this: First AllGen Biomass Installations in Germany and Sweden - Microgen WWW.MICROGEN-ENGINE.COM to supplement my solar power in the winter.

I've not been offered any for five years and became wary of stewing them in the slow cooker with an acidy marinade because of the lead. Do you get any with steel shot? Worry there would be breaking teeth.

Yes it's surprising what a small drop of water in the carb can do.