A call from a "friend" looking to rope me into replacing the batteries
in his powerchair (again -- No Good Deed Goes Unpunished). I begged
off as my schedule is overly full for the next few months (fourth
quarter is usually spent upgrading and replacing kit).

This proving to be a good choice as he's making noises about
switching to LiFePO4 batteries instead of the SLAs he's always
used (the SLAs being cheaper but have relatively short lifespans...
a few years). That looks like it will quickly become a timesink.

But, it got me thinking about whether I should make that change
for *my* chairs.

The SLAs are typically 12V @ 75AHr -- about 50 pounds each. Comparable (physical) *size* lithiums are about double that capacity and don't
"degrade while parked" (if you kill the parasitic loads as I do, given
that my chairs are seldom used).

I see two major problems:
- the charger will have to be replaced (and consideration for anything
that might be impacted along the wiring harness with such a change
as you can't easily access the batteries)
- the "fuel gauge" will be useless (as it relies on the discharge
characteristics of the SLA pack)
This last being the most serious as you can't easily recover from a
battery that's "suddenly" gone flat (like driving in a car with a
broken fuel gauge)

I can address both of these issues -- but, it rises to the level of a
real "project"; not some quick fix.

Anything else that could complicate such a decision? (I haven't researched travel or shipping issues which could be complicated, given the association
of "lithium" with "spectacular fires")

[Replacing the chair is not practical as it's not something that I "need"
or for which I could justify the outrageous cost...]

[[I know a guy who has done this but he REALLY made a project out of it... replacing all of the drive electronics, motors, brakes, etc.]]


--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 9/1/26 11:21 PM, Don Y wrote:

A call from a "friend" looking to rope me into replacing the batteries
in his powerchair (again -- No Good Deed Goes Unpunished).ÿ I begged
off as my schedule is overly full for the next few months (fourth
quarter is usually spent upgrading and replacing kit).

This proving to be a good choice as he's making noises about
switching to LiFePO4 batteries instead of the SLAs he's always
used (the SLAs being cheaper but have relatively short lifespans...
a few years).ÿ That looks like it will quickly become a timesink.

But, it got me thinking about whether I should make that change
for *my* chairs.

The SLAs are typically 12V @ 75AHr -- about 50 pounds each.ÿ Comparable (physical) *size* lithiums are about double that capacity and don't
"degrade while parked" (if you kill the parasitic loads as I do, given
that my chairs are seldom used).

I see two major problems:
- the charger will have to be replaced (and consideration for anything
ÿ that might be impacted along the wiring harness with such a change
ÿ as you can't easily access the batteries)
- the "fuel gauge" will be useless (as it relies on the discharge
ÿ characteristics of the SLA pack)
This last being the most serious as you can't easily recover from a
battery that's "suddenly" gone flat (like driving in a car with a
broken fuel gauge)

I can address both of these issues -- but, it rises to the level of a
real "project"; not some quick fix.

Anything else that could complicate such a decision?ÿ (I haven't researched travel or shipping issues which could be complicated, given the association of "lithium" with "spectacular fires")

[Replacing the chair is not practical as it's not something that I "need"
or for which I could justify the outrageous cost...]

[[I know a guy who has done this but he REALLY made a project out of it... replacing all of the drive electronics, motors, brakes, etc.]]

There are many LIFPO 12V batteries with built-in charge displays from 4
or 5 bars to LCD screens, and many also have Bluetooth or wi-fi and apps
to see anything you want about the internal state. I'd start by
browsing on Amazon, then go to YouTube and search for "Will Prowse",
pick a video at random and click more to see all of the description and
click the link to his website to see what brands he does and does not recommend.

--
Regards,
Carl

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 02/09/2026 04:21, Don Y wrote:

A call from a "friend" looking to rope me into replacing the batteries
in his powerchair (again -- No Good Deed Goes Unpunished).ÿ I begged
off as my schedule is overly full for the next few months (fourth
quarter is usually spent upgrading and replacing kit).

This proving to be a good choice as he's making noises about
switching to LiFePO4 batteries instead of the SLAs he's always
used (the SLAs being cheaper but have relatively short lifespans...
a few years).ÿ That looks like it will quickly become a timesink.

But, it got me thinking about whether I should make that change
for *my* chairs.

The SLAs are typically 12V @ 75AHr -- about 50 pounds each.ÿ Comparable (physical) *size* lithiums are about double that capacity and don't
"degrade while parked" (if you kill the parasitic loads as I do, given
that my chairs are seldom used).

That could be an advantage in your usage. Would you use same physical
size of lithium or something intermediate to get a lighter machine?

I see two major problems:
- the charger will have to be replaced (and consideration for anything
ÿ that might be impacted along the wiring harness with such a change
ÿ as you can't easily access the batteries)
- the "fuel gauge" will be useless (as it relies on the discharge
ÿ characteristics of the SLA pack)
This last being the most serious as you can't easily recover from a
battery that's "suddenly" gone flat (like driving in a car with a
broken fuel gauge)

I can address both of these issues -- but, it rises to the level of a
real "project"; not some quick fix.

Anything else that could complicate such a decision?ÿ (I haven't researched travel or shipping issues which could be complicated, given the association of "lithium" with "spectacular fires")

The latest LiFePO4 are a lot less volatile than the earlier generation
LiNiCo (etc) but I'm not sure I would want to sit on one if I was not
able to run away from it PDQ. You have about 15s from the first signs of
the magic smoke coming out to it venting to get away from it. Sparks and flames are more or less guaranteed with the old chemistry but the newer
iron ones just get hot and emit copious white flammable solvent fog.

Not nice in an enclosed space and potentially problematic if there are
any ignition sources nearby. Flashover fuel air explosion from the
battery solvent mist is a real risk to firefighters in a confined space.

Main risks are over charging, over discharge(wrecks them) and physical
damage. SLA by comparison are practically benign if rather heavy.

Provided you charge (and discharge) them properly they should be fine
but there have been a lot of modded e-bikes going up in flames
spectacularly after unwise (illegal) go faster modifications.

[Replacing the chair is not practical as it's not something that I "need"
or for which I could justify the outrageous cost...]

So long as you look after the battery it should be fine.

--
Martin Brown


--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 9/2/2026 8:22 AM, Carl wrote:

On 9/1/26 11:21 PM, Don Y wrote:

A call from a "friend" looking to rope me into replacing the batteries
in his powerchair (again -- No Good Deed Goes Unpunished).ÿ I begged
off as my schedule is overly full for the next few months (fourth
quarter is usually spent upgrading and replacing kit).

This proving to be a good choice as he's making noises about
switching to LiFePO4 batteries instead of the SLAs he's always
used (the SLAs being cheaper but have relatively short lifespans...
a few years).ÿ That looks like it will quickly become a timesink.

But, it got me thinking about whether I should make that change
for *my* chairs.

The SLAs are typically 12V @ 75AHr -- about 50 pounds each.ÿ Comparable
(physical) *size* lithiums are about double that capacity and don't
"degrade while parked" (if you kill the parasitic loads as I do, given
that my chairs are seldom used).

I see two major problems:
- the charger will have to be replaced (and consideration for anything
ÿÿ that might be impacted along the wiring harness with such a change
ÿÿ as you can't easily access the batteries)
- the "fuel gauge" will be useless (as it relies on the discharge
ÿÿ characteristics of the SLA pack)
This last being the most serious as you can't easily recover from a
battery that's "suddenly" gone flat (like driving in a car with a
broken fuel gauge)

I can address both of these issues -- but, it rises to the level of a
real "project"; not some quick fix.

Anything else that could complicate such a decision?ÿ (I haven't researched >> travel or shipping issues which could be complicated, given the association >> of "lithium" with "spectacular fires")

[Replacing the chair is not practical as it's not something that I "need"
or for which I could justify the outrageous cost...]

[[I know a guy who has done this but he REALLY made a project out of it... >> replacing all of the drive electronics, motors, brakes, etc.]]

There are many LIFPO 12V batteries with built-in charge displays from 4 or 5 bars to LCD screens, and many also have Bluetooth or wi-fi and apps to see anything you want about the internal state.

Batteries are almost universally inaccessible in use. They are usually hidden under the seat -- which may be designed to support a person weighing hundreds of pounds (up to 450!) *plus* the weight of the seat itself. My chairs each (originally) weighed about 300 pounds.

This is a video of the battery removal process for a similar chair:
<https://www.youtube.com/watch?v=N1uFxG2hsS4>

Other "scooters" often have smaller battery packs -- some that even have handles to enable you to remove them easily from the scooter for charging
or swap-out (keep a fully charged spare to replace a depleted one).

An "app" would likely not tell you much about the sort of usage you can get from the chair as it wouldn't know the rate at which you are likely to
consume power (climbing hills, operating the various actuators on the chair, headlights, etc.).

But, could represent a "hook" to enable a BETTER app to be created to
track this information despite the erroneous indications presented on
the gas gauge.

I'd start by browsing on Amazon,
then go to YouTube and search for "Will Prowse", pick a video at random and click more to see all of the description and click the link to his website to
see what brands he does and does not recommend.

He seems more focused on solar power applications? There, you don't
have the same sort of constraints as in a wheelchair (size, shape,
connections, etc.)

There are many sites that tout "lithium upgrades" for wheelchair battery
packs. But, often are incomplete -- trying to sell the idea or a specific battery pack. They gloss over these issues (e.g., what charger will I
be using? Will the wire that carries the charge current from the charger connection *to* the battery be sufficient to handle that current -- as it
and the connectors along the way -- was likely sized for the charger sold
with the SLA battery pack.

My lawyer points out that such a modification likely raises safety and liability issues (but, that's what lawyers are paid to think about!).
OTOH, I'm not planning on SELLING such modifications but, rather, exploiting ONE modification to simplify *my* usage. (to reduce the maintenance
issues that I face due to my LACK of use)

OToOH, if it proves to be that this modification enhances my application,
then it leaves me in the position of having to figure out how to make it available while limiting my legal exposure.


--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Anything else that could complicate such a decision?ÿ (I haven't researched >> travel or shipping issues which could be complicated, given the association >> of "lithium" with "spectacular fires")

The latest LiFePO4 are a lot less volatile than the earlier generation LiNiCo
(etc) but I'm not sure I would want to sit on one if I was not able to run away
from it PDQ.

When I was doing the certification to operate a fork lift, I asked
the instructor how to handle an engine fire (you are seated ON an internal combustion engine with the fuel tank immediately behind your backrest).

"Get off the lift (keep in mind, the number one rule is that you
have SECURED yourself to the vehicle lest you accidentally become
separated from it!) and TRY to turn off the gas valve. Call the
fire department and be sure to tell them you have a PROPANE FORK
LIFT fire. They will arrive and PARK A BLOCK AWAY..."

I.e., YOU should put a similar distance between yourself and the
fire and not just sit around watching it as a propane explosion
will likely take out a whole block! Just how fast can you run?
And, how disciplined are you NOT to watch a fire???

You have about 15s from the first signs of the magic smoke coming
out to it venting to get away from it. Sparks and flames are more or less guaranteed with the old chemistry but the newer iron ones just get hot and emit
copious white flammable solvent fog.

Hmmmm.... I had thought the whole point of the new one was safety.
But, I guess that's a relative term...

Not nice in an enclosed space and potentially problematic if there are any ignition sources nearby. Flashover fuel air explosion from the battery solvent
mist is a real risk to firefighters in a confined space.

The SLAs always are at risk of outgassing. Rarely a risk of spilled electrolyte -- though chairs can and do tip (usually because of carelessness
on the driver's part -- trying to tackle too steep of a grade or failing to take approach it "head on").

[Our street curbs are sloped instead of "abrupt". E.g., a car can ride up
on the curb without realizing it as it is not an abrupt "step". But, they
are steep enough that approaching them head-on is unsettling when in a chair; you feel like you are falling backwards and instinctively lead HARD forward
to move the chair's center of mass. *So*, you want to take them at an
angle -- which just makes you feel like you are tipping SIDEWAYS (there aren't many things that can be done to prevent this sort of fall!)]

The batteries are typically in a steel framework under the chair (see video linked elsewhere this thread). Ideally, sized to exactly fit that enclosure so there is no room for them to slide, tip over, etc. Of course, if the ENCLOSURE is tipped over, all bets are off; there is an assumption that the weight of the batteries holds them in place -- with the expectation that gravity operates on them in a specific orientation!

Main risks are over charging, over discharge(wrecks them) and physical damage.
SLA by comparison are practically benign if rather heavy.

I thought the BMS handled all of those cases.

Provided you charge (and discharge) them properly they should be fine but there
have been a lot of modded e-bikes going up in flames spectacularly after unwise
(illegal) go faster modifications.

[Replacing the chair is not practical as it's not something that I "need"
or for which I could justify the outrageous cost...]

So long as you look after the battery it should be fine.

That has been the problem with the SLAs. As I don't "need" a chair, I keep mine stored in the garage. I periodically take it out for a drive around the neighborhood (~2 miles) to "exercise" the battery before reconnecting to the charger.

If I give a demo and need it to be fully charged, then I can reconnect it
the night before and "top off" the battery. (Demos tend not to use much
stored energy so even a partially discharged battery is often adequate)

But, in summer, it's just too damn hot to be driving around any time other
than just before sunrise (while the chair has driving/backup/signal lights
that make it reasonably safe to operate in the dark, doing so in the
evening means contending with ~100F temperatures almost until midnight).

Add to that, the inhospitable environment in the garage and I usually end up having to address a battery issue. (I can often rescue a set of replacements that haven't sulfated -- but, that's still a chore to do the replacement)

[My second chair has been modified for yardwork and, as such, is happily powered with an oversized power supply rescued from a server (70A @ 24VDC)
as the presence of a "trailing power cord" isn't an issue in that application.]

From discussions, today, the concensus is:
- maintain the existing battery (regardless of the inconvenience)
OR
- replace it each summer (though with a smaller pack that has just enough
capacity for your "demo" needs)

I think I will opt for the second option -- using a smaller group size
and "fleshing it out" to fill the same volume as the intended battery.
This will save a few bucks *and* make it considerably easier to replace
the batteries.

[Of course, if I happen to be disciplined enough to maintain them
properly, then that replacement can be avoided! (crawling around on
the floor is tedious)]

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 9/2/26 04:21, Don Y wrote:

A call from a "friend" looking to rope me into replacing the batteries
in his powerchair (again -- No Good Deed Goes Unpunished).ÿ I begged
off as my schedule is overly full for the next few months (fourth
quarter is usually spent upgrading and replacing kit).

This proving to be a good choice as he's making noises about
switching to LiFePO4 batteries instead of the SLAs he's always
used (the SLAs being cheaper but have relatively short lifespans...
a few years).ÿ That looks like it will quickly become a timesink.

But, it got me thinking about whether I should make that change
for *my* chairs.

The SLAs are typically 12V @ 75AHr -- about 50 pounds each.ÿ Comparable (physical) *size* lithiums are about double that capacity and don't
"degrade while parked" (if you kill the parasitic loads as I do, given
that my chairs are seldom used).

I see two major problems:
- the charger will have to be replaced (and consideration for anything
ÿ that might be impacted along the wiring harness with such a change
ÿ as you can't easily access the batteries)
- the "fuel gauge" will be useless (as it relies on the discharge
ÿ characteristics of the SLA pack)
This last being the most serious as you can't easily recover from a
battery that's "suddenly" gone flat (like driving in a car with a
broken fuel gauge)

I can address both of these issues -- but, it rises to the level of a
real "project"; not some quick fix.

Anything else that could complicate such a decision?ÿ (I haven't researched travel or shipping issues which could be complicated, given the association of "lithium" with "spectacular fires")

[Replacing the chair is not practical as it's not something that I "need"
or for which I could justify the outrageous cost...]

[[I know a guy who has done this but he REALLY made a project out of it... replacing all of the drive electronics, motors, brakes, etc.]]

The main problem that would need more research, is that Lithium
need a completely different regime in therms of charging,
and also limiting discharge to level that does not destroy
the battery. I would not consider it safe to just swap one for
the other. Fire hazard, explosions, and threat to the safety
of life. Not helpful if immobile in a wheelchair.

Stick to lead acid, but perhaps replace with deep discharge
types.

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On Fri, 4 Sep 2026 21:11:37 +0100, chrisq wrote:

On 9/2/26 04:21, Don Y wrote:

A call from a "friend" looking to rope me into replacing the batteries
in his powerchair (again -- No Good Deed Goes Unpunished).ÿ I begged
off as my schedule is overly full for the next few months (fourth
quarter is usually spent upgrading and replacing kit).

This proving to be a good choice as he's making noises about switching
to LiFePO4 batteries instead of the SLAs he's always used (the SLAs
being cheaper but have relatively short lifespans...
a few years).ÿ That looks like it will quickly become a timesink.

But, it got me thinking about whether I should make that change for
*my* chairs.

The SLAs are typically 12V @ 75AHr -- about 50 pounds each.ÿ Comparable
(physical) *size* lithiums are about double that capacity and don't
"degrade while parked" (if you kill the parasitic loads as I do, given
that my chairs are seldom used).

I see two major problems:
- the charger will have to be replaced (and consideration for anything
ÿ that might be impacted along the wiring harness with such a change
ÿ as you can't easily access the batteries)
- the "fuel gauge" will be useless (as it relies on the discharge
ÿ characteristics of the SLA pack)
This last being the most serious as you can't easily recover from a
battery that's "suddenly" gone flat (like driving in a car with a
broken fuel gauge)

I can address both of these issues -- but, it rises to the level of a
real "project"; not some quick fix.

Anything else that could complicate such a decision?ÿ (I haven't
researched travel or shipping issues which could be complicated, given
the association of "lithium" with "spectacular fires")

[Replacing the chair is not practical as it's not something that I
"need" or for which I could justify the outrageous cost...]

[[I know a guy who has done this but he REALLY made a project out of
it... replacing all of the drive electronics, motors, brakes, etc.]]

The main problem that would need more research, is that Lithium need a completely different regime in therms of charging,
and also limiting discharge to level that does not destroy the battery.
I would not consider it safe to just swap one for the other. Fire
hazard, explosions, and threat to the safety of life. Not helpful if
immobile in a wheelchair.

Stick to lead acid, but perhaps replace with deep discharge types.

This covers the conversion requirements: https://coresparkbattery.com/how-to-replace-lead-acid-with-lifepo4-safely/




--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Glen Walpert <nospam@null.void> wrote:

On Fri, 4 Sep 2026 21:11:37 +0100, chrisq wrote:

The main problem that would need more research, is that Lithium need a

completely different regime in therms of charging,
and also limiting discharge to level that does not destroy the battery.
I would not consider it safe to just swap one for the other. Fire
hazard, explosions, and threat to the safety of life. Not helpful if immobile in a wheelchair.

Stick to lead acid, but perhaps replace with deep discharge types.

This covers the conversion requirements: https://coresparkbattery.com/how-to-replace-lead-acid-with-lifepo4-safely/

That smells a lot like AI slop (including AI generated images). Not saying it's wrong, but I would not trust a company who markets their products as superior based on AI output. As AI does, it takes a lot of words to make
its point.

When you're buying an LFP pack, it comes with a BMS which is intended to protect the battery from over voltage, over discharge, over temperature - it isolates the battery if it detects any of those. The quality of BMSes... varies. As does the physical construction of the pack - eg fusing, cell pressure and mechanical protection.

But the main issue is you need to replace the charger, and if it's in a
system that expects lead acid charging behaviour (eg cars with alternators) then that's a problem.

Also things that rely on the internal resistance of lead acid may not be
happy with a different chemistry. And cold temperatures are a problem too (unless you go sodium ion, which has different challenges).

OTOH if the system is uncomplicated - (replaceable) external charger charges battery to full offline; vehicle discharges to empty; repeat - then there's more chance of success.

Another option is to get some prismatic LFP cells from CATL or EVE (via intermediaries - they don't sell direct) and do your own mounting and add a commercial BMS. By DIYing you can aim for quality. Although testing is
then your problem (and you do need to avoid shady sellers giving you
relabelled reject cells).

Theo

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 9/4/2026 2:32 PM, Glen Walpert wrote:

This covers the conversion requirements: https://coresparkbattery.com/how-to-replace-lead-acid-with-lifepo4-safely/

I think *most* could be easily addressed. My concerns would be
charging -- because the "charging port" on most chairs is located
at the tip of an armrest, as part of the "joystick controller"
assembly. A single conductor that brings B+ to the controller
acts to deliver charge current to the battery.

This conductor passes through several connectors that have
been sized for the charging current delivered by the "best"
SLA charger. Sizing a charger for a lithium pack typically
delivers considerably higher charge currents which likely
aren't expected in the original design. So, I'd have to
deliberately downsize the charger (which means any attempt to
exploit the additional capability of the lithium would be
met with INCREASED charge times beyond the typical "overnight")

*I* can ignore the "gas gauge" issue as I'm not putting
significant demands on the battery that would even approach
*partial* discharge. With the SLAs, I was routinely taking
the chair out for a joyride for the express purpose of burning
off some charge to make sense of recharging -- assuming the
SLAs drop 10-15% in the time between joyrides, plus another
10% for the joyride itself (a charge may be good for 15-20
miles of travel)

I'd have to reprogram some of the operating parameters of the
motor controller but that's relatively easy (if you have the
correct tools and understand what all of the parameters mean
and their effect on the chair's use).

I still think the most effective (for MY use case) approach is
to install smaller (much easier to man-handle than 50-pounders!)
SLAs and fabricate an "outer shell" to ensure they religiously
comply with the size and shape of the original battery group
as the "packaging" relies on a tight fit to keep things in
place.

Newer chairs designed to exploit the battery chemistry are
designed with that in mind, not as an afterthought. The folks
I know who have done such conversions have taken that more
"wholistic" approach to the problem. But, their motivations
are far more practical than mine; I just need the chair to
be "available" for my short little dog-and-ponies without
having to panic because the existing batteries have gone flat
forcing me to get them replaced on short notice.

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 9/4/2026 4:01 PM, Theo wrote:

But the main issue is you need to replace the charger, and if it's in a system that expects lead acid charging behaviour (eg cars with alternators) then that's a problem.

The charger is the main *electrical* issue. But, it's not a simplistic "charger->two wires->battery" model (as it MAY be in some applications).

We looked at the wiring diagram and schematic for the electronics in
*my* chair to see what sorts of issues might arise in use.

E.g., the size of the conductor from the charging port to the physical
battery, the number (and type) of connectors it passes through, the
effect on the "system" if the battery is disconnected (e.g., main circuit breaker opened), the attachment to the battery, the effect of charge cycles
on the battery in a tight, unventilated space, etc.

The other (perhaps MORE) important issues are physical; e.g., the battery
is inaccessible during use and charging, the battery is not physically
secured in place (relying on size and mass to keep it where intended),
the locations of the "binding posts" for the batteries, their weight
(a battery with insufficient mass is going to be tossed around in
normal use -- a wheelchair ride is NOT "smooth")

Also things that rely on the internal resistance of lead acid may not be happy with a different chemistry. And cold temperatures are a problem too (unless you go sodium ion, which has different challenges).

Cold, here, is a non issue. I don't think we saw a single "below freezing"
day in the past two years (and that assumes storing the chair outdoors).

Heat, OTOH, is a pisser and eats SLAs in short order (one replaces the
starting battery for their vehicle religiously at 36 month intervals
to avoid being "disappointed" by it!)

OTOH if the system is uncomplicated - (replaceable) external charger charges battery to full offline; vehicle discharges to empty; repeat - then there's more chance of success.

You can't discharge to a point below which the controller locks out
action (based on *its* notion of state of charge). This leaves the
"driver" stranded (an electric wheelchair without power is like
pushing a wagon without wheels -- the weight of the chair plus occupant
is 500-600 pounds and the drive is far from frictionless, even when disengaged).

Another option is to get some prismatic LFP cells from CATL or EVE (via intermediaries - they don't sell direct) and do your own mounting and add a commercial BMS. By DIYing you can aim for quality. Although testing is
then your problem (and you do need to avoid shady sellers giving you relabelled reject cells).

That requires a lot of work and assumption of liability. When you
don't have control over -- or detailed knowledge of -- your load,
thats a crap-shoot.

I.e., I would never consent to doing such a modification for someone,
even if all of the "tough thinking" had been sorted out. Now, YOU are
stuck as the support system for that "product".

By contrast, "buy THESE batteries, call me when they are on hand and
I'll come over to replace the old ones" is a low risk, easy to gauge
task, thankless as it may be.

For most users who NEED a chair, I think insurance/gummit covers
routine replacement (~5 yrs) so there is less concern *if* you can
eke that amount of service life out of your existing kit. But, this
requires attention to maintenance, etc. (clearly not something that
*I* have been concerned with -- batteries are relatively cheap
compared to the time involved in servicing/maintaining them)

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 9/4/2026 4:25 PM, Don Y wrote:

On 9/4/2026 2:32 PM, Glen Walpert wrote:

This covers the conversion requirements:
https://coresparkbattery.com/how-to-replace-lead-acid-with-lifepo4-safely/

I think *most* could be easily addressed.ÿ My concerns would be
charging -- because the "charging port" on most chairs is located
at the tip of an armrest, as part of the "joystick controller"
assembly.ÿ A single conductor that brings B+ to the controller
acts to deliver charge current to the battery.

For example, when the batteries *die* in the chair, you have to
elevate the seating assembly to gain access to the battery compartment
(even removing the cosmetic cover is difficult without this step).

The "approved" method of doing this is to remove the seat cushions
and thread a long (12"?) tool through the (metal) seat bottom to
engage a screw drive that allows you to manually "drive" the
elevator mechanism.

Of course, there is some serious gear reduction involved to lessen the
load on the elevator motor (you don't need fast response from the elevator
as its range of motion is O(8 inches).

But, you can isolate the "dead" battery pack by opening the main
circuit breaker.

And, back feed "battery voltage" to the charging port (often an XLR
connector in the joystick controller) to make SOME power available
to the elevator motor. AFTER taking care to disable the "inhibit"
function that prevents any motion while the "charger" is connected.

<https://static-data2.manualslib.com/product-images/254/25323/2532253/raw.jpg> <https://www.sovereignmedsupply.com/cdn/shop/files/IMG_7602_grande.webp?v=1715109336>

[The charge port is visible as the round yellow connector in the
second image]


BUT, all of the power to the chair mechanisms is now being fed through
the circuit path that was originally intended to carry ONLY charger
current. So, don't accidentally engage the drive motors, etc. even
if your back fed power might be capable of operating the chair
IF CONNECTED *AS* THE BATTERY.

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

"While it is often marketed as a physical "drop-in" replacement, swapping chemistries transforms the electrical system from a passive chemical device into an active electronic component. This invalidates existing device safety certifications and triggers distinct logistics and environmental liabilities.

If the device or appliance was previously certified by an agency like Underwriters Laboratories (UL), swapping the battery chemistry voids the original equipment certification."

That's all you need to know. It means don't do it.

--
For full context, visit https://www.electrondepot.com/electrodesign/lifepo4-replacement-for-large-sla-4409825-.htm


--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 9/9/2026 10:45 AM, someone wrote:

"While it is often marketed as a physical "drop-in" replacement, swapping chemistries transforms the electrical system from a passive chemical device into an active electronic component. This invalidates existing device safety certifications and triggers distinct logistics and environmental liabilities.

If the device or appliance was previously certified by an agency like Underwriters Laboratories (UL), swapping the battery chemistry voids the original equipment certification."

That's all you need to know. It means don't do it.

No, that means "don't do it for someone else or commercially".

People routinely modify their chairs, altering safety-related
issues /for themselves/. These can be retuning the controls
to be more responsive -- despite the driver's ability to CONTROL
the chair with those modifications. Or, oversized tires to better
navigate outdoor terrain (yet complicate operation in an existing
structure). Or, boosting the top speed (most chairs run at ~6MPH
but I have seen chairs that can do 15MPH. Controlling such a
chair on "typical driving surfaces" is almost impossible -- even
with a joystick (with a mouthstick or any other physical shortcoming,
next to impossible. Or, disabling the inhibit on operation while
charging. Or, with seat elevated. Or...

And, you know SOMEONE likely made those modifications (for a price!)
for those drivers!



--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)