Hi Dennis,
It's a 50V system, charger, controller, motor so wiring the 32ea 3.3V Thundersky 100ah LiFePO4 batteris in series for 100V would pop things or running a controller continuously at 50% duty cycle is inefficient.
Anyway I remember Lee saying something about buddy pairing lithium's that there's a chance that if one cell shorts (without buddy pair fuses) a fire can happen (not good in a wooden boat). But have there been *any* recorded incidences of lithium batteries internally shorting? I can find lithium fires due to overcharging/discharging but don't see any shorted cells on the great god Google (unless I'm missing something). So unless there's a valid reason to keep all those 32 pesky buddy pair 60A fuses, I'll remove them (and put in a central 200A pack fuse). I also thought of installing #12 fusible link wire for the #8 buddy pair wire (two #8's in parallel for 100A). I need to bump up the current rating for a larger Etek-RT 48-72V I'm putting on.
Wikipedia says that fusible link wire is 4 sizes smaller than the wire it protects (but don't see any actual current rating "amps" specs on fusible link wire just this rule of thumb). Is there anyone that's buddy pairing T-Sky etc lithiums using a fuse per battery, does it make sense to do so?
Have a LiFePO4 day,
mark
www.reevadiy.org
>
> ------------------------------
>
> Message: 29
> Date: Wed, 29 Sep 2010 12:32:32 -0400
> From: Dennis Miles <[email protected]>
> Subject: Re: [EVDL] Parallel Fuses or just wire together? LiFePO4
> Buddy balancing
> To: Electric Vehicle Discussion List <[email protected]>
> Message-ID:
> <[email protected]>
> Content-Type: text/plain; charset="iso-8859-1"
>
> There are many solutions, some seem more reliable than others especially in
> a marine environment, any fuse holder with a slight amount of corrosion may
> blow the paralleled fuse followed immediately by itself. Batteries behave
> much better in series, so why not put all in a single series string,
> (Systems generally are better with more voltage and somewhat less current
> and besides) the controller translates the power efficiently into pulses and
> the motor inductance and the Diodes in the controller give a higher current
> in the motor than the batteries need to supply, and you would only need one
> fuse, The batteries are much more reliable in one series string, the only
> drawback is needing a higher voltage charger,or charge half the pack at a
> time but be careful to maintain balance.
> Regards,
> *Dennis Lee Miles* (Director) *E.V.T.I. inc*.
> *www.E-V-T-I-Inc.COM <http://www.e-v-t-i-inc.com/> *(Adviser)*
> EVTI-EVAEducation Chapter
> *
> Phone (863) 944 - 9913
> Initial demand (computed by extrapolating the reservations for GM Volt and
> Nissan Leaf,) shall exceed 200,000 vehicles in 2010 and 2011. However only
> 50,000 vehicles will be marketed, so a LARGE demand for Nice Newer
> Conversions is predicted!
> ==================================================================
>
>
It's a 50V system, charger, controller, motor so wiring the 32ea 3.3V Thundersky 100ah LiFePO4 batteris in series for 100V would pop things or running a controller continuously at 50% duty cycle is inefficient.
Anyway I remember Lee saying something about buddy pairing lithium's that there's a chance that if one cell shorts (without buddy pair fuses) a fire can happen (not good in a wooden boat). But have there been *any* recorded incidences of lithium batteries internally shorting? I can find lithium fires due to overcharging/discharging but don't see any shorted cells on the great god Google (unless I'm missing something). So unless there's a valid reason to keep all those 32 pesky buddy pair 60A fuses, I'll remove them (and put in a central 200A pack fuse). I also thought of installing #12 fusible link wire for the #8 buddy pair wire (two #8's in parallel for 100A). I need to bump up the current rating for a larger Etek-RT 48-72V I'm putting on.
Wikipedia says that fusible link wire is 4 sizes smaller than the wire it protects (but don't see any actual current rating "amps" specs on fusible link wire just this rule of thumb). Is there anyone that's buddy pairing T-Sky etc lithiums using a fuse per battery, does it make sense to do so?
Have a LiFePO4 day,
mark
www.reevadiy.org
>
> ------------------------------
>
> Message: 29
> Date: Wed, 29 Sep 2010 12:32:32 -0400
> From: Dennis Miles <[email protected]>
> Subject: Re: [EVDL] Parallel Fuses or just wire together? LiFePO4
> Buddy balancing
> To: Electric Vehicle Discussion List <[email protected]>
> Message-ID:
> <[email protected]>
> Content-Type: text/plain; charset="iso-8859-1"
>
> There are many solutions, some seem more reliable than others especially in
> a marine environment, any fuse holder with a slight amount of corrosion may
> blow the paralleled fuse followed immediately by itself. Batteries behave
> much better in series, so why not put all in a single series string,
> (Systems generally are better with more voltage and somewhat less current
> and besides) the controller translates the power efficiently into pulses and
> the motor inductance and the Diodes in the controller give a higher current
> in the motor than the batteries need to supply, and you would only need one
> fuse, The batteries are much more reliable in one series string, the only
> drawback is needing a higher voltage charger,or charge half the pack at a
> time but be careful to maintain balance.
> Regards,
> *Dennis Lee Miles* (Director) *E.V.T.I. inc*.
> *www.E-V-T-I-Inc.COM <http://www.e-v-t-i-inc.com/> *(Adviser)*
> EVTI-EVAEducation Chapter
> *
> Phone (863) 944 - 9913
> Initial demand (computed by extrapolating the reservations for GM Volt and
> Nissan Leaf,) shall exceed 200,000 vehicles in 2010 and 2011. However only
> 50,000 vehicles will be marketed, so a LARGE demand for Nice Newer
> Conversions is predicted!
> ==================================================================
>
>
