Quote:
Originally Posted by Christ
. . . I wanted the NiMH modules as direct replacement for the SLA that came on the bike hoping for the benefits of reduced weight/size.
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Hopefully the earlier discussion of relative battery chemistries explains why that is improbable.
Quote:
Originally Posted by Christ
. . . Based on our discussions here, I don't think that I'll be able to achieve those goals without added complexity, but provided the circuit is inexpensive and relatively simple for a novice, I'll humor it.
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Let me suggest searching for the parts needed and posting the list. I can give comments about the strengths and weaknesses. More importantly, you will have identified your source and know the price.
Quote:
Originally Posted by Christ
. . . I'm also thinking that since the bike's electrical system is rated at 6VDC, the battery module could remain somewhere well below the 8V threshold that you point to and still be able to perform it's duties acceptably. I'd be guessing here, but I'd think that 6.5VDC is probably the low-end of the safe SOC spectrum. If you've tested this, care to enlighten?
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Tested, theory verified (see
web page,) and the answer is no. Each cell has a nominal voltage of 1.2 VDC and there are six of them giving 7.2 VDC for the module. Once the NiMH cell falls below 1.2 VDC, it is exhausted. One other 'death' is reverse charging a cell and the 1.2 VDC rectifier is insufficient protection. If you ever run the battery down, it is a coin toss whether it will ever come back.
Quote:
Originally Posted by Christ
. . . I know (not know, but have understood from reading) that the NHW20 modules are charged in such a way that they maintain a tight threshold between 50% and 80% SOC, so as not to reduce the life of the pack. Toyota claims that the pack should last the usable life of the vehicle, and I've seen nothing to indicate otherwise using this method.
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They use a dedicated, battery control module who handles everything. I'm proposing something very cheap, less robust but probably usable.
Quote:
Originally Posted by Christ
. . . Is there any way that I can clamp the rectifier's output to under 8V using an inline circuit, or is that what we're working on now?
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That is the circuit I described. The linear regulator is adjusted to limit the maximum voltage to the NiMH battery. That is why it is in parallel but reversed to the protection rectifier:
Bob Wilson