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Old 09-25-2011, 09:36 AM   #21
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RE: Starting battery - need your input

Quote:
FF wrote:
"and no more forgetting to select the house only at anchor after selecting 'All' for charging while on the engine(s). "

This seamless operation can be has with an $18.00 RV solenoid,
Can RV solenoids handle the current required to start an engine, or is it just for charging?* The BlueSea ACRs are rated at 120A or 500A.* I have the 500A version ($150), which should be enough to handle both the starting current, and the current into the starting battery if I'm using the house batteries to deal with a dead (or cold) starting battery.
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Old 09-26-2011, 01:00 PM   #22
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RE: Starting battery - need your input

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bobc wrote:* The BlueSea ACRs are rated at 120A or 500A.* I have the 500A version ($150), which should be enough to handle both the starting current, and the current into the starting battery if I'm using the house batteries to deal with a dead (or cold) starting battery.
*The 120A is continoius use rating. Its higher for temp use such as cranking or pulling up a hook.

we have the 120A version and its worked fine, however i would really have liked it much better had it had the manual override option, local and remotely.
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Old 09-27-2011, 04:20 AM   #23
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RE: Starting battery - need your input

"Can RV solenoids handle the current required to start an engine, or is it just for charging?"

No merge unit , except high quality rotaries can handle START currents. at times 2000Amps

The Engine system is seperate from the house system .

ONLY when the engine is operating is the merge solenoid closed to allow the engine system to charge the house side.

IF an emergency start is required from dead engine batts , either the std rotary switch in parallel (with key lock to keep guests from "helping") or a set of jumper cables connect the house to the engine , and will handle 700+ amps of a diesel start - if its warm.

Many more amps required for cold weather cranking.
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Old 09-27-2011, 11:43 AM   #24
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RE: Starting battery - need your input

comment to FF:

thats the (almost) entire point of using and ACR or solenoid, exactly that to ONLY combine the two batts DURING charging and possible some light house loads.
never was intention of blue sea to merge/combine for cranking.
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Old 09-28-2011, 04:06 AM   #25
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RE: Starting battery - need your input

thats the (almost) entire point of using and ACR or solenoid

My point on the RV unit is you get the same result for $18. bucks ( per 75A) with a really robust method,,

instead of big bucks and transistor brain that can not be repaired.
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Old 09-28-2011, 08:22 AM   #26
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RE: Starting battery - need your input

The recommended start battery size for my JD 4045TFM engine is 640CCA. My guess is that actual starting currents are far less than that. Surge currents may be higher.

Here are the BlueSea ratings. I think I'm safe trying to start the engine through the ACR.

Cranking Rating: 10 sec. 2,500 Amps*
Cranking Rating: 1 min. 1,100 Amps*
Intermittent Rating: 5 min. 700 Amps*
Continuous Rating 500 Amps*
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Old 09-28-2011, 11:29 AM   #27
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RE: Starting battery - need your input

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ONLY when the engine is operating is the merge solenoid closed to allow the engine system to charge the house side.


*if you use the startkey to energize the solenoid then in fact the current is going thru the solenoid when cranking, but if you use something like an oilpressure switch then obviously the engine is running already.

how is yours wired?
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Old 09-28-2011, 03:10 PM   #28
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RE: Starting battery - need your input

Quote:
bobc wrote:FF wrote:
"and no more forgetting to select the house only at anchor after selecting 'All' for charging while on the engine(s). "

*I have set mine up with 3 on off switches. One always on for house bank. One always on for start battery. One always off for combining the two.**A combiner charges both.

So I don't have to switch anything.**If the start ever runs low I can manually combine the two banks.

SD
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Old 09-28-2011, 04:00 PM   #29
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RE: Starting battery - need your input

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skipperdude wrote:bobc wrote:FF wrote:
"and no more forgetting to select the house only at anchor after selecting 'All' for charging while on the engine(s). "

*I have set mine up with 3 on off switches. One always on for house bank. One always on for start battery. One always off for combining the two.**A combiner charges both.

So I don't have to switch anything.**If the start ever runs low I can manually combine the two banks.

SD

*i think that was discussed also, however its an awful lot of heavy cabeling.
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Old 09-29-2011, 05:11 AM   #30
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RE: Starting battery - need your input

" if you use the startkey to energize the solenoid then in fact the current is going thru the solenoid when cranking,"

No the acc terminal is NOT powered as the fear of a stuck starter being spun by the engine (hundreds off volts) is too great.
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Old 09-29-2011, 02:00 PM   #31
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RE: Starting battery - need your input

so which mechanism switch the solenoid to merge?
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Old 09-30-2011, 03:57 AM   #32
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RE: Starting battery - need your input

"so which mechanism switch the solenoid to merge?"


The ACC terminal , off when key is off , and off during start sequence , but ON during run.

It is also on in ACC position, so dockside once every few weeks simply leaving the key in Acc will allow the start batts to see the battery charger.

KISS
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