Off road tyres driving me INSANE

[Burgerman]

>>>New issue, since 6 days ago my charger (Sterilng) isn't marking as complete, just sits on charging light even after 8 hours, chair seems perfectly charged though and the charger isn't hot at all like it is during the first few hours, any ideas??


YES, leave it longer. It takes about 12 hours give or take a few to REALLY fully charge a set of lead batteries. 99 percent done after maybe 5 or 7. That last tiny bit is the difference between a sulphated battery or not. It must get a complete charge at least weekly (sunday morning?) to prevent this. This is why mobility chargers kill batteries. They usually shut off way too soon.

Or get a Hyperion, so you can SEE what is happening on your PC and watch, and control it on your laptop, with Remote desktop, or even your smartphone. Remote Desktop for your android? Email me for the best one!

[Burgerman]

Your casters should track straight and true 99.9 percent of the time or greater. 80 percent is a big problem that will not allow you to enjoy the chair and will eat tyres. They shouldnt shake.

[alexapc]

Casters - damn fork was bent and the bottom bearing was broken, top also has give. We swapped the bearings round for now and straightened the fork, it now runs fine 95% of the time, will replace the lot soon, any idea what the bearing size is?

Charger - left it on for 10-12 hours for 3 nights (even over 12 hours one night) and still wasn't complete!!!!!! However woke up this morning after 10 hours - COMPLETE!! What the hell?????

[Burgerman]

A FULL charge if they were a bit low on that charger (10 amp?) will take that long if they were Gel MK, or high resistance (cheap) AGMs. Many chargers will say done after half that time, but they will not be. The last couple of percent takes forever on these batteries. And it matters if you want the full cycle life.

How are you bending/breaking casters and bearings? Crashes? I take about a year to abuse and bend mine!

[Martin O Refurbisher]

Alexpc,
I assume that the caster problems you are talking about here relate to the damage by the airline that you emailed me about?

Best,

Martin

[Martin O Refurbisher]

Alexpc
Battery charging is still black magic!
If say you get to 90% charged in 8 hours, then 95% in 12 hours, it could take another 8 hours to reach 99%. You do need to read all that BM has written on batteries.
What range are you using daily, and do you recharge at the end of each day?
Best,

Martin

[alexapc]

BM, I don't crash! I just go FULL OUT all the time over crap pavements, hit a very bad pothole the other day? Maybe it was 3 weeks of rattle that bent it??

Martin, I'm not so sure that it was the airline because that caster was never right, but since they managed to screw up the back end maybe it was them too. It won't hurt them to put their hands in their pockets either way!

The base of the forks on my casters are different widths, the bad side being much narrower, will get pics

I have never seen this charger take so long and still be charging, used it for 1.5 years with Odysseys, like I said this morning it was complete for the first time in 10 days so we'll see how it goes now.

[Burgerman]

You cant bend them without either hitting a curb fairly hard or landing heavily from countless wheelies on bad surfaces when they are sideways... Just going flat out and a bIt of shaking wont do that. You would be spat out first before you bend them..

Your batteries are what? Gel batteries I think, or maybe martins cheap AGMs. These charge typically 2 times slower than the Odyssey batteries.
Due to their int resistance and other characteristics. You need to get a set of odyssey batteries, or accept that mobility batteries will be either not completely charged or will take forever. The marine charger is properly charging the batteries. The typical "ready in 5 to 6 hours" mobility charger doesent do a complete charge. They stop too soon so users dont complain.

The difference between charger voltage and battery voltage near the end of charge may be a small part of a volt. Battery resistance directly affects the amount of amps that flow in. Odyssey batteries have about half the resistance of the rest of the market. So charge literally 2x as fast. Or better. They also stay at max charge amps longer too (Much longer at CC before amps drop away)

Put simply an odyssey is like filling a bucket with a hose, compared to a straw...

[Burgerman]

http://www.mkbattery.com/images/VRLA_TechManual.pdf

page 12 says a 70Ah MK will take 13 hours to charge to 90 percent with a 7 amp charger. See chart... That last 10 percent may take another 5!

[alexapc]

I'm with Martin's Haze batteries for now, so far they are going really well and were affordable, hopefully will get a year out of them, getting way more range right now than on my old chair with Odysseys.

This morning after 9 hours it was still charging and after 10 was complete.

See pics for what I mean about the widths on the caster bases.

[Burgerman]

Definetely bent. Have you rammed a curb hard? Are they both like that?

As far as range goes then the chair is less "greedy" than your old one, or your odyssey batteries were less than new. Capacity drops as you use them. Range should be about the same between the AGMs of martin and the Odyssey even though odyssey are smaller/lighter and 68Ah instead of 80Ah. Because of peukert and his law. At high discharge rates capacity is actually the same give or take a bit.

But the odyssey will charge much faster as they are almost twice as good here. Due to having practically half the internal resistance. If you dont want to wait 10 hours, you just need a more powerful charger, or swap them for odyssey.

The difference is that the odyssey will charge at the full charger power for more of the charge, The CC bit, and the last slow part will happen much faster too. At any given state of charge the odyssey will be pulling more amps. Its an Ohms law thing.

[alexapc]

Which one is bent, good caster or bad caster? That is both of them!

Yep I get the battery thing, I'm running well for now so let's see how it goes!

[woodygb]

The two stems certainly look different.....
A mixed pair rather than a matched pair ...different years / models?

bad-good-caster.JPG (22.47 KiB) Viewed 576 times

[Burgerman]

1st one is from very old MK1 model F55. 2nd one is from one that is MK2 / MK3 newer versions.

[woodygb]

It would then follow that there is probably a dimensional/geometry difference between the two years that could/would cause castor flutter?

[woodygb]

Found the answer ....

F55 Frame types - Mk 1
by Martin O Refurbisher on Wed Sep 07, 2011 6:56 am

I omitted to add another variationin the tubular frames - the fork shaft length is longer on the earliest Mk1 models - later ones (Mk 2 & Mk 3) are interchangeable.

Best,

Martin

See the two different types here.

The later design is the one with the thread on the outside.

Best,

Martin

[Burgerman]

There is a very very old 3rd type. Different length. Thats not common and I never saw one yet.

[alexapc]

Straightened the fork, tightened it really hard and the rattle has completely gone, 2 weeks and counting!

Do your Kenda tyres screech like crazy? It was funny at first but now it's annoying and embarrassing

[Burgerman]

They did for the first few weeks but they settle down and stop once worn in. But they wear so slowly that this may take a while. Of course it depends on the chair. Theres a lot of weight over mine. If yours is nose heavy they will break traction much more easily.

[alexapc]

Still haven't managed to find the right new type forks, driving me nuts!

Also all 4 bearings are RED after just 2 months. What proper ones should I get and what size?