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70 Posts
Discussion Starter #1
My GEL TECH 8G24 by E P M Products had a post melt so I went to American Ba=
ttery =

and bought a replacement. It wasn't the same post style but it was the s=
ame =

case and Jim assured me it was made by the same company(MK maybe)as the =
sticker =

is put on by a reseller. My cables fit. I'm getting about a third of =
a volt =

difference every time I discharge the pack. I am trying long steady char=
ging =

but after a few weeks and maybe 20 charge cycles it's still acting like a =

stinker. I got the pack for free but I feel like I'm abusing the new bat=
tery. =

The new battery comes up to voltage at high rate charging but at low rate i=
t =

takes much longer. I got the pack for free so I'm not too concerned but =
I would =

like the new battery to start acting like the old ones. I thought it wou=
ld be =

the other way around. Lawrence Rhodes..

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Discussion Starter #2
What did Jim say?
GEL batteries are a little different than most lead-acids
especially in that you can't charge them as high and
definitely be *very* careful if you want to balance them,
they can only take a very low "overcharge" current or you
will blow the gel away from the plate when bubbles form =

and the capacity will be permanently reduced.
They are a step up in level of finicky from AGMs.
(floodeds will take severe abuse,
AGMs can be abused as long as you don't make them lose water or reverse a =
cell
but GELs cannot really be abused and both charge and
discharge currents are generally lower than AGMs, but
the cycle life is typically much longer....) =


BTW, new batteries behave different than old batteries,
so do not be worried about differences between your
new/old batteries, but only if the new battery does
not behave as you would expect according to its spec
(for example, much lower capacity).
Then it is time to check warranty...

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behal=
f Of Lawrence Rhodes
Sent: Friday, January 14, 2011 9:22 AM
To: [email protected]
Subject: [EVDL] New gel battery breakin. Still low.

My GEL TECH 8G24 by E P M Products had a post melt so I went to American Ba=
ttery and bought a replacement. It wasn't the same post style but it was=
the same case and Jim assured me it was made by the same company(MK maybe)=
as the sticker is put on by a reseller. My cables fit. I'm getting=
about a third of a volt difference every time I discharge the pack. I a=
m trying long steady charging but after a few weeks and maybe 20 charge cyc=
les it's still acting like a stinker. I got the pack for free but I feel=
like I'm abusing the new battery. The new battery comes up to voltage at h=
igh rate charging but at low rate it takes much longer. I got the pack f=
or free so I'm not too concerned but I would like the new battery to start =
acting like the old ones. I thought it would be the other way around.=
Lawrence Rhodes..

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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Discussion Starter #3
> I'm getting about a third of a volt difference every time I discharge
> the pack. I am trying long steady charging but after a few weeks and
> maybe 20 charge cycles it's still acting like a stinker. =


What do you mean by "a third of a volt difference"? Is the new one low or =

high? Is that voltage under load or resting? What does it do on charge? =

Have you tested actual AH capacity for this and the other batteries?

If I'm not mistaken, all the Geltech and MK gel batteries are made by East =

Penn. They're very high quality batteries but not well suited for low =

voltage EVs because of high internal resistance. You shouldn't ask for mor=
e =

than about 250-300 amps from these batteries, depending on size.

On charge final voltage for these batteries should never exceed 14.3 volts =

(East Penn recommends 14.1 to 14.2, but I've used 14.3 successfully for man=
y =

years). This voltage should be temperature compensated.

David Roden - Akron, Ohio, USA
EVDL Administrator

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70 Posts
Discussion Starter #4
The voltage of the new battery is low. I have tried a little boost charg=
e using =

a 12v battery charger in addition to bulk charging. It does attain a ful=
l =

charge but lags behind the rest of the pack. I just did it again and wil=
l check =

the resting voltages today. Lawrence Rhodes.....

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