As part of the research I have been doing for a presentation I am giving at=
GMCWS in October on whether or not to upgrade a GMC to Lithium based batte=
ries and if so, how to do it properly, I have been examining alternatives f=
or our stock alternators. Anything larger than a 100ah LiFePO4 house batte=
ry bank could really tax our stock alternators. There are electronic devic=
es that can resolve the issues surrounding the two different voltage regime=
s in which lead/acid and LiFePO4 batteries function, and even a few designe=
d to lighten the load on the sub 100 amp alternators like those in most of =
our coaches. Those generally operate by limiting the alternator duty cycle=
by allowing the alternator to send charge current to the house battery ban=
k for something like 10 to 15 minutes out of every 30 or so minutes the eng=
ine is running. The reasoning is that will allow the alternator to cool d=
own sufficiently to prevent over heating the alternator during the relative=
ly short time it takes to recharge lithium house batteries which accept way=
higher charge current than their lead/acid counterparts - basically everyt=
hing the alternator can put out. These have no effect on recharging of the=
starting battery. They also serve as a battery isolator when the engine i=
s turned off. Given the recent dialog about serial alternator failures=
I am wondering whether these $200 smart duty cycle control isolators might=
not also be a good idea for all our GMCs, even the ones with lead/acid hou=
se battery banks. Yes, it might lengthen the time required to fully rechar=
ge the house batteries if you kept your lead/acid battery bank, but it woul=
dn=E2=80=99t matter if you were charging lithium batteries which charge in =
a fraction of the time it takes lead/acid batteries to recharge anyway. Wo=
uld they cool off the alternators enough to keep even the cheap rebuilt uni=
ts alive a lot longer? One question for the whole group. Have any of =
you found a higher output alternator that will fit the stock mounting suppo=
rts that can be successfully driven off of our stock one or two pulley V be=
lt drive? Or, have you found a way to add a second alternator without too =
much fabrication or having to spin the water pump the wrong direction? =
Within the last couple of years appropriate lithium battery technology h=
as changed a lot with the addition of sophisticated, on-board battery manag=
ement at the cell level and automatic cell balancing that makes these a saf=
e and reliable choice for our application. And, prices have come down to =
the point that it will be hard for many of our GMC owners to resist the man=
y, many benefits of lithium over lead/acid house batteries, but I am still =
concerned about how to solve the issues surrounding keeping our 40 year old=
, sub 100 amp first generation alternators alive. So, I am all ears on you=
r suggestions. PS - I really don=E2=80=99t want to debate lithium vs l=
ead/acid batteries in this thread, so wait until after the presentation to =
do that. I would like to keep this thread focused just on the alternator q=
uestion. Thanks. Jerry Jerry Work The Dovetail Joint Fine furni=
ture designed and hand crafted in the 1907 former Masonic Temple building i=
n historic Kerby, OR glwork http://jerrywork.com =
GMCWS in October on whether or not to upgrade a GMC to Lithium based batte=
ries and if so, how to do it properly, I have been examining alternatives f=
or our stock alternators. Anything larger than a 100ah LiFePO4 house batte=
ry bank could really tax our stock alternators. There are electronic devic=
es that can resolve the issues surrounding the two different voltage regime=
s in which lead/acid and LiFePO4 batteries function, and even a few designe=
d to lighten the load on the sub 100 amp alternators like those in most of =
our coaches. Those generally operate by limiting the alternator duty cycle=
by allowing the alternator to send charge current to the house battery ban=
k for something like 10 to 15 minutes out of every 30 or so minutes the eng=
ine is running. The reasoning is that will allow the alternator to cool d=
own sufficiently to prevent over heating the alternator during the relative=
ly short time it takes to recharge lithium house batteries which accept way=
higher charge current than their lead/acid counterparts - basically everyt=
hing the alternator can put out. These have no effect on recharging of the=
starting battery. They also serve as a battery isolator when the engine i=
s turned off. Given the recent dialog about serial alternator failures=
I am wondering whether these $200 smart duty cycle control isolators might=
not also be a good idea for all our GMCs, even the ones with lead/acid hou=
se battery banks. Yes, it might lengthen the time required to fully rechar=
ge the house batteries if you kept your lead/acid battery bank, but it woul=
dn=E2=80=99t matter if you were charging lithium batteries which charge in =
a fraction of the time it takes lead/acid batteries to recharge anyway. Wo=
uld they cool off the alternators enough to keep even the cheap rebuilt uni=
ts alive a lot longer? One question for the whole group. Have any of =
you found a higher output alternator that will fit the stock mounting suppo=
rts that can be successfully driven off of our stock one or two pulley V be=
lt drive? Or, have you found a way to add a second alternator without too =
much fabrication or having to spin the water pump the wrong direction? =
Within the last couple of years appropriate lithium battery technology h=
as changed a lot with the addition of sophisticated, on-board battery manag=
ement at the cell level and automatic cell balancing that makes these a saf=
e and reliable choice for our application. And, prices have come down to =
the point that it will be hard for many of our GMC owners to resist the man=
y, many benefits of lithium over lead/acid house batteries, but I am still =
concerned about how to solve the issues surrounding keeping our 40 year old=
, sub 100 amp first generation alternators alive. So, I am all ears on you=
r suggestions. PS - I really don=E2=80=99t want to debate lithium vs l=
ead/acid batteries in this thread, so wait until after the presentation to =
do that. I would like to keep this thread focused just on the alternator q=
uestion. Thanks. Jerry Jerry Work The Dovetail Joint Fine furni=
ture designed and hand crafted in the 1907 former Masonic Temple building i=
n historic Kerby, OR glwork http://jerrywork.com =
