MemberOctober 7, 2016 at 8:09 am
I have a customer with a Bison 80, when I first went to site, the batteries were flat and datum was lost.
â€‹I removed the batteries, charged them, replaced them and reset the datum and the lift worked fine but wouldn’t charge.
With a new power supply fitted it still wouldn’t charge and the power supply voltage was dropping to 15v. It was trying to charge with some very random 100ma or so spikes.
I assumed a fault on the charging circuit on the board so took the board to a repairer who couldn’t find anything wrong – not that he could fix at least.
With a new board being very expensive, can I replace the power supply with a proper 24v NiCad charger and connect directly to the battery terminals inside the stairlift- via the charge points.
I am worried that the stairlift uses the 33v power supply to reset datum and that the stairlift might get lost all the time. Also I am not sure if the charger might feed back into the board and cause a problem.
Any advice would be appreciated.
MemberOctober 7, 2016 at 5:22 pm
Cant see that working as the batteries will always be too low to power the lift. If the bats drop below a certain voltage the lift wont start and display b. Circuit board charging takes the bats well in excess of 24v and if you fit a standard charger there will be no switching. Don’t think the datum would be an issue though as this is set up in programming.
MemberOctober 7, 2016 at 9:19 pm
The charger will connect and charge when the stairlift is not in use so the voltage should not drop any more than with the standard set up.
I know the datum is set up in the program but it might re-set itself every time it sees one of the charge points – to prevent drift I guess. Other equipment I have worked on (not stairlifts) do this.
Appreciate your comments Ian
MemberOctober 8, 2016 at 3:57 am
Still don’t think the datum will be an issue as the lift will run without the charger on (battery charge condition permitting) I’m pretty sure it doesn’t reset itself . Once set its set so to speak.
Not like the thyssen flow’s that do reset on charge point (bottom one) Although it doesn’t need voltage present just a resistance.
MemberOctober 8, 2016 at 2:09 pm
Thanks Ian. I am pretty sure you are correct.
â€‹I have ordered a charger and will give it a go.
MemberOctober 8, 2016 at 2:28 pm
I have a work mate who is ex bison. I will run this problem etc by him for his opinion and report back Mike.
MemberOctober 10, 2016 at 11:47 am
The datum should only reset when in program mode, so shouldn’t be an issue. You will have the constant bleeping though if you bypass the board
MemberOctober 10, 2016 at 5:32 pm
Spoke to a bison engineer today and he raised a concern that you could cook the batteries as it wont drop to a trickle charge when the batteries reach charge capacity, And the other potential problem is if the batteries are not sufficiently charged by your set up the lift may refuse to start giving you a “b” battery error. He did say the datum should not be an issue.
MemberOctober 11, 2016 at 7:53 am
I believe he was suggesting replacing it with a charger and not a power supply so would drop to trickle, therefore should always be sufficiently charged
Will be really interesting to see the outcome of this, in theory should work fine
MemberOctober 13, 2016 at 6:07 pm
I worked on this stairlift today and fitted a proper 20 cell 3 stage NiCad charger. ( cooking the batteries will not happen.)
The beeper wouldnt shut up of course but was easy to remove.
Setting the datum is the biggest problem as I had to temporarily refit a 33v power supply to the charge point, remove the wires to the battery and reconnect the charge pick up plug on the board. Not ideal!
I imagine the stairlift will still give the b battery error code as it must be a function of battery voltage and independent from the charge circuit.
So it works but I wouldn’t recommend it unless you have no other option.
All advice appreciated – I will let you know how it pans out long term.
MemberOctober 14, 2016 at 8:24 am
That’s interesting, thanks for the update
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