Problems Mixing SLA's with Silicones in the E-max

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PJD
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Problems Mixing SLA's with Silicones in the E-max

As an E-max owners who was having a couple individual silicone batteries going bad, I was hoping these could be replaced individually with BB EB20-12 SLA's. But I am runnning into problems.

Recall that the e-max uses eight 20 AH batteries - formerly two series strings that I re-arranged into paralel pairs in seriies, with powercheqs installed between the pairs.

Charging the pack with BB EB20-12 batteries replacing two of the parallel pairs of the silicones resulted in the powercheqs working awful hard. So, checking the charging with the powercheq's disconected yielded 16.2 volts for each of the BB's and about 13.9 volts for the silicones during equalization charging, and about 14.4 volts for the BB's and 13.6 for the silicones during float.

16 volts is well into the gassing range - not good for the new batteries at all.

What is happening here, that the total bulk-charging voltage (59.5 to 60 volts) is disproportionately going to the BB batteries? I assume it is higher charging resistance for the BB's. Also when discharging under a small load (headlight on high beam) the BB's voltages sag more than the silicone by .2 or .3 volt (or the powerchqs spend a lot of time lit up). It appears that the silicones aren't just an SLA with a different name, they seem to have some superior characteristics after all.

So for now, the BB SLA's don't seem to be bulk-charging-or maybe even discharging-compatable with the silicones. I think by buddy-pairing the BB with a still-good silicone battery, and using the powercheqs, the condition will be tolerable.

E-max owners who are keeping the stock battery arrangement will either have to find a source for silicone batteries or replace the whole pack with SLA's - the latter being fairly expensive. (probably the former also)

I started this diccussion in "batteries and chargers", but since it is a problem peculiar to the e-max, I thought discussing it here is also appropriate.

Any ideas?


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