PINNED - AGM & GEL battery info lead battery info

[steves1977uk]

Gnomatic, this PSU would solve your issues as it's adjustable... http://www.ebay.com/itm/SKYRC-eFuel-50A ... Sw5IJWc2qB

Steve

[Burgerman]

I doubt he will see that again.

[Gnomatic]

Thanks Steve I'll check that one out. It's a bit pricey compared to what I have but not too bad in the scheme of things.

[Gnomatic]

Here's what the charge volts look like w/ the PL8 look like. Held rock steady @28.22v during CV. I charged at 18A because I have too much stuff plugged into one circuit here at home. While not as long as a mobility charger, it still took some time before CV finished. I believe the current had fallen to .5A roughly by the time it was finished.

[Burgerman]

Thats what a CV stage is supposed to look like.

Wheres the Amp curve?

Heres one from a lithium...

You need to see that it isnt rising. It is obvious that those batteries are not new. Or the CV would have dropped below .5A and ended. As it is they ran the full 8 hour CV time limit.

[Gnomatic]

These batteries are off brand gel, not MK about 6 months old. Heres the amps graph of the charge.

[Burgerman]

Was still dropping. Those are slow to charge. Probably high impedance. Its one of those batteries where the lights dim if you climb a ramp. It cant be charged fast. About 8mohm or more and tons of peukert. It may end charge better at a slower charge rate say 12A.

[Gnomatic]

I'm not mistaken they had an IR rating of like 7 or 8mOhm when I looked them up so yeah definitely not MK. Is that why the 8hr CV stage time limit was hit before the current ever fell below .5A?

[Burgerman]

Yep. And why you can charge odyssey 2.5mOhm batts at 2.45v per cell, at 40A and they drop to 1000thC in about 5 hours. Thats 0.068A

And why they have no max current limit. The low impedance means they dont get warm, and pull more amps for longer in the charge cycle. All gel take forever though. And never drop as low. The danger is that they start to rise again, hence the need for a time limit.

[Gnomatic]

They're good for ~2.5hrs offroad before they quit.

[Burgerman]

They're good for ~2.5hrs offroad before they quit.

How many Ah was returned? Usually about 25 to 30% more than you get out.

[Gnomatic]

They weren't very run down when I began charging but something like ~45Ah was returned.

[Burgerman]

So about 35 used? Are these grp24? If so then you wont get very much more out in 2.5 hours. Peukert and voltage depression...

THIS is the best page I ever saw for explaining the difference between lead and lithium in performance at high loads.

https://www.victronenergy.com/blog/2015 ... on-vs-agm/

[Gnomatic]

yeah group 24 ~75Ah rating

[Burgerman]

USABLE ENERGY LEAD

[Burgerman]

USABLE ENERGY LITHIUM

[Burgerman]

Look at the percentages at the top. The orange is the bit its best not to use.

Remember that at say 7mph, 2 hours is max range, about 14 miles in most chairs. So the 2 hour rate is relevant. Lead is shit!

[Gnomatic]

When new, the range of these batteries was surprisingly good(for lead), *if* used of flat paved surfaces like old rail roads converted to paved bike trails. I could easily get more than 14mi out of them in that scenario.

Anyway, I have no intention of replacing these with lead.

[Burgerman]

They are lead. Did you mean lithium?

You could make an addon pack...

[Gnomatic]

They are lead.

Yes, they are. And I intend on replacing them with Lithium.

[KittyP]

An old thread, but can I revive it by asking what tips folk have on keeping their batteries alive in cold weather? I enjoy a bit of wildlife watching, and as access at nature reserves has now begun to improve even for folk without 'offroad' powerchairs, I've been going out more and more in the last three years. The best birdwatching in the UK coincides with the colder weather, though, which robs battery charge like crazy – I seem to get 30 to 40% less out of mine on a really cold morning. I'm never sure whether it's safe to add a bit of insulation around them (e.g. polystyrene foam), or whether even setting off with a hot water bottle on top would help a bit! Be interested to know what others do...or whether you've found that it's essentially impossible to make much difference.

[Burgerman]

Warm batteries definitely work better. Insulation is hard to do because if theres room for insulation it would be better filled with more battery...

And a hot water bottle underneath may help! But not much. So I think you are basically stuck. Even lithium doesn't like the cold.

[KittyP]

But it wouldn't be dangerous to try and insulate? Sorry, I'm technically clueless, and struggle even to put in a screw these days because so many of my finger joints are permanently fused. Powerchair alterations/finding ways to instal bigger batteries/etc are out of the question for me, but there is potentially space for a bit of insulation...and I can at least still use sticky tape...

[Burgerman]

Its unlikely you can get enough around them on every face to make any difference.

[KittyP]

Fair dos – thanks!

[expresso]

A while back a friend of mine Quickiee2 - had the issue with the battery keep draining fast and no one knew what was happening etc. - i convinced her to switch to my vendor - finally i found out today what the problem was

my tech and his supervisor was in my building for another user and stopped by to say hi - i asked about it - i was told - it was the battery - but it was one of the fuses on the battery which blew - you cant know since the fuses are heatshrinked etc, -

so when they changed batteries before - they just remove the wiring harness with fuses - put new batteries and put back the same blown fuse on one battery each time - since there are two fuses - one for each battery - only one blew -

so the chair was running off one battery at 12V all the time -

i couldnt find the section i started about this a while back so i posted this here - my 646se is set up the same way on the lead - good to know - dosnt matter to me know - i have the 100A breaker on the lithium pack -
my other chair has a breaker also - P222se - which is at 70A - never tripped it in 5 years -

thinking back - this happen when she started to use the 20A charger i gave her - for some reason there was a spark or some EMI - maybe it blew the fuse at that moment - no one would have known -

wonder what the fuse rating was or is on her chair - invacare with the GB motors

Could it have been the charger to blew the fuse when first plugged in and switched on ? the charge has a on and off flip switch - i used to connect it with everything off - chair and charger - then flip the charger on - maybe it didnt like that on her chair - it worked fine for a while before that one instance she got a spark or something when connecting it or when turning it on - not sure when -

what would be the proper way to connect the charger - should you plug the charger in the wall and turn it on first - then connect it to the chair ? i always figured and have done it the opposite way -

this is with lead - dumd charger 20A model - Shauer 24V -

my other Salmex does not have a switch to turn on or off - i used to use a power strip but did it the same way - turn it on last once all connected - never had a issue -

which is the correct way to do it ? i though connecting it when its powered on would be the wrong way -

[steves1977uk]

Strange because a power module shuts down if there's less than 16v, so I can't see how it would run from a single 12v battery

Steve

[Burgerman]

If one fuse is blown, no power at all. So thats bovine excrement!

[expresso]

ok then everyone is just full shit - i dont known - the way the batteries are connected - looks as if thats possible - i though one fuse blows - thats it - dosnt work

but when he said that - i figure ok maybe the battery harness with the fuses are arranged in a way that would allow it work even if one blows - there are two fuses on the harness - one for each battery

hes full of shit also then - the supervisor - i will question that next time if i see him again and this topic comes up - she just got new MK gel today again -

we see if it continues -

she never got this issue before - first time and it happened at the same time we started to use the 20A charger etc - so that first thing she figured was the issue -

after what i was told today - i figure ok - maybe that was it - now who knows - - hey if its the same way - they will get another call in a few days for new batteries

[shirley_hkg]

Bull shit … … all those blown fuse / 12V run .

It's your 20A charger , which never did the charge complete . The current is too big for G24 gel batt .