Dual battery monitor or not ?

Submitted: Saturday, Feb 16, 2008 at 18:37
ThreadID: 54633 Views:6086 Replies:6 FollowUps:6
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Hi all,

I have a Piranha dual battery set-up (DBE180S) and was thinking that if they have specials at Wandin 4wd show tomorrow I might buy a DBM Mark4 battery monitor. I have already stuffed one battery some time back as it drained the auxiliary to many times and was thinking that the auto cut-off is the way to go, could i have your thoughts and experiences.
Cheers Walter
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Reply By: Member - Troll 81 (QLD) - Saturday, Feb 16, 2008 at 19:41

Saturday, Feb 16, 2008 at 19:41
I have a monitor and it's nice to know what the battery is doing...beats popping the bonnet and getting the meter onto it
AnswerID: 287817

Reply By: That Troopy Bloke (SA) - Saturday, Feb 16, 2008 at 19:52

Saturday, Feb 16, 2008 at 19:52
I have the same set-up (DBE180S +DBM4). I use the monitor's low voltage cut-out in preference to the one built in to my Waeco.
The cut-out can be over-ridden if needed.
It just works:-)

Cheers
Glenn
AnswerID: 287821

Reply By: Richard W (NSW) - Saturday, Feb 16, 2008 at 20:50

Saturday, Feb 16, 2008 at 20:50
Walter,

I've also got the DBE180S. I use a battery voltage/fridge temp monitor purchased from Jaycar. Doesn't auto cutout though.
AnswerID: 287831

Reply By: Sand Man (SA) - Sunday, Feb 17, 2008 at 15:22

Sunday, Feb 17, 2008 at 15:22
I definitely recommend a battery monitor, low voltage cutout, discharge protector, or whatever other name they go by, which automatically cuts the battery supply if the voltage drops below 11.6 volts.

I am not familiar with the Piranha product, but you can get devices from around $30 for the Projecta discharge protector (ODP500) to $98 for an Engel Battery Monitor.

I notice the Piranha monitor doesn't cut out until the voltage has reached 10.5 volts and this is too low IMO, as 10.5 volts is FLAT.

The Engel has a selectable toggle switch of 10.5 (too low) or 11.5 (better).
The Projecta ODP500 is fixed at 11.6v (30% battery capacity) which is about where the supply should be interrupted before permanent damage may occur.

I think Derek from ABR (Advertiser on this site) also has a unit the same or similar to the Projecta device.


Bill


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AnswerID: 287952

Follow Up By: That Troopy Bloke (SA) - Sunday, Feb 17, 2008 at 19:48

Sunday, Feb 17, 2008 at 19:48
The low voltage cut-out on the DBM4 is selectable....10.5V or 11.5V.

Cheers
Glenn
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Follow Up By: Sand Man (SA) - Sunday, Feb 17, 2008 at 21:21

Sunday, Feb 17, 2008 at 21:21
OK Glenn,

I guess you should know if you have one.

The Piranha Web site states it is preset to 10.5V.

Battery Monitor

Old info obviously.
Bill


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Follow Up By: That Troopy Bloke (SA) - Monday, Feb 18, 2008 at 07:14

Monday, Feb 18, 2008 at 07:14
"The Piranha Web site states it is preset to 10.5V.
Old info obviously."

Or perhaps not....mine is about 3 years old and looks slightly different to the one in your link. Mine has a little push button on the left to switch between the various modes....the one in the link appears to have a small toggle? switch on the right.
Surely they wouldn't release a new model with only a 10.5V cut-out....kind of defeats the purpose of a low voltage cut-out if it doesn't cut out until the battery is flat.
Perhaps what they are trying to say is that it comes preset at 10.5V, but you can change it yourself to suit (kinda like a set of stauns come preset at 18 psi, but you can adjust them to suit your needs).

I'll be down near the local TJM outlet this arvo....might pop in and check it out in the flesh.

Cheers
Glenn
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Follow Up By: Sand Man (SA) - Monday, Feb 18, 2008 at 09:38

Monday, Feb 18, 2008 at 09:38
Glenn,

Yes, it makes you wonder sometimes.
I was having a look at the Engel Voltage Monitor on the weekend and it has a dual selection of 10.5 and 11.5 by means of a toggle switch.
This unit sells for $98 dollars and has a digital meter displaying the current voltage. This is a good feature, but the toggle switch could easily be knocked and 10.5 volts is definitely too low IMO.

I think I will stay with the $30 Projecta unit I have. These have a fixed cutout at 11.6 volts. The only negative with these is the crappy plug and socket they come with, but I have changed over to a Hella plug & in line socket which is the same as the Merit brand.

Bill


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Follow Up By: Member - Mike DID - Monday, Feb 18, 2008 at 11:15

Monday, Feb 18, 2008 at 11:15
Not everyone has heavy-duty wiring to the back of the vehicle or trailer.

If there's a 1.0 volt drop in thin wiring to the fridge, then if the cutout trips at 10.5 volt while the compressor is running, the voltage at the battery is 11.5 volt.
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Reply By: apriti00 - Sunday, Feb 17, 2008 at 17:16

Sunday, Feb 17, 2008 at 17:16
Thank you all for your replies and based on the general consensus a monitor with a low voltage cut-off is the way to go. I still have one query, I understand that too low a cut -off can cause permanent damage to a battery and I am currently running a AGM type deep cycle to run the fridge and some other minor accessories and was under the belief that this type of battery is designed for a deeper discharge. Am I wrong before I do any permanent damage.

Cheers Walter
AnswerID: 287971

Follow Up By: Member - Mike DID - Sunday, Feb 17, 2008 at 19:26

Sunday, Feb 17, 2008 at 19:26
Wetcell Deepcycle batteries are generally recommended to be discharged no more than 50%.

AGM batteries are usually recommended to discharge down to 20% remaining.
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FollowupID: 553281

Reply By: Mainey (wa) - Sunday, Feb 17, 2008 at 21:17

Sunday, Feb 17, 2008 at 21:17
# State of Charge
For longest life, batteries should be maintained above 50% State of Charge
Occasional drops to 30% & 20% are not harmful, but continual discharges to those levels will shorten battery life considerably.


S o C _ Voltage
100% __ 12.7
90% _ _ 12.5
80% _ _ 12.4
70% _ _ 12.3
60% _ _ 12.2
50% _ _ 12.1
40% _ _ 11.9
30% _ _ 11.7
20% _ _ 11.6
10% _ _ 11.3
0% _ _ _ 10.5

Mainey . . .
AnswerID: 288024

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